[cparser] / parser.c

/*
 * This file is part of cparser.
 * Copyright (C) 2007-2009 Matthias Braun <matze@braunis.de>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 */
#include <config.h>

#include <assert.h>
#include <stdarg.h>
#include <stdbool.h>

#include "parser.h"
#include "diagnostic.h"
#include "format_check.h"
#include "lexer.h"
#include "symbol_t.h"
#include "token_t.h"
#include "types.h"
#include "type_t.h"
#include "type_hash.h"
#include "ast_t.h"
#include "entity_t.h"
#include "attribute_t.h"
#include "lang_features.h"
#include "walk_statements.h"
#include "warning.h"
#include "printer.h"
#include "adt/bitfiddle.h"
#include "adt/error.h"
#include "adt/array.h"

//#define PRINT_TOKENS
#define MAX_LOOKAHEAD 1

typedef struct {
        entity_t           *old_entity;
        symbol_t           *symbol;
        entity_namespace_t  namespc;
} stack_entry_t;

typedef struct declaration_specifiers_t  declaration_specifiers_t;
struct declaration_specifiers_t {
        source_position_t  source_position;
        storage_class_t    storage_class;
        unsigned char      alignment;         /**< Alignment, 0 if not set. */
        bool               is_inline    : 1;
        bool               thread_local : 1;  /**< GCC __thread */
        attribute_t       *attributes;        /**< list of attributes */
        type_t            *type;
};

/**
 * An environment for parsing initializers (and compound literals).
 */
typedef struct parse_initializer_env_t {
        type_t     *type;   /**< the type of the initializer. In case of an
                                 array type with unspecified size this gets
                                 adjusted to the actual size. */
        entity_t   *entity; /**< the variable that is initialized if any */
        bool        must_be_constant;
} parse_initializer_env_t;

typedef entity_t* (*parsed_declaration_func) (entity_t *declaration, bool is_definition);

/** The current token. */
static token_t              token;
/** The lookahead ring-buffer. */
static token_t              lookahead_buffer[MAX_LOOKAHEAD];
/** Position of the next token in the lookahead buffer. */
static size_t               lookahead_bufpos;
static stack_entry_t       *environment_stack = NULL;
static stack_entry_t       *label_stack       = NULL;
static scope_t             *file_scope        = NULL;
static scope_t             *current_scope     = NULL;
/** Point to the current function declaration if inside a function. */
static function_t          *current_function  = NULL;
static entity_t            *current_entity    = NULL;
static entity_t            *current_init_decl = NULL;
static switch_statement_t  *current_switch    = NULL;
static statement_t         *current_loop      = NULL;
static statement_t         *current_parent    = NULL;
static ms_try_statement_t  *current_try       = NULL;
static linkage_kind_t       current_linkage   = LINKAGE_INVALID;
static goto_statement_t    *goto_first        = NULL;
static goto_statement_t   **goto_anchor       = NULL;
static label_statement_t   *label_first       = NULL;
static label_statement_t  **label_anchor      = NULL;
/** current translation unit. */
static translation_unit_t  *unit              = NULL;
/** true if we are in a type property context (evaluation only for type) */
static bool                 in_type_prop      = false;
/** true if we are in an __extension__ context. */
static bool                 in_gcc_extension  = false;
static struct obstack       temp_obst;
static entity_t            *anonymous_entity;
static declaration_t      **incomplete_arrays;


#define PUSH_PARENT(stmt)                          \
        statement_t *const prev_parent = current_parent; \
        ((void)(current_parent = (stmt)))
#define POP_PARENT ((void)(current_parent = prev_parent))

/** special symbol used for anonymous entities. */
static symbol_t *sym_anonymous = NULL;

/** The token anchor set */
static unsigned char token_anchor_set[T_LAST_TOKEN];

/** The current source position. */
#define HERE (&token.source_position)

/** true if we are in GCC mode. */
#define GNU_MODE ((c_mode & _GNUC) || in_gcc_extension)

static statement_t *parse_compound_statement(bool inside_expression_statement);
static statement_t *parse_statement(void);

static expression_t *parse_subexpression(precedence_t);
static expression_t *parse_expression(void);
static type_t       *parse_typename(void);
static void          parse_externals(void);
static void          parse_external(void);

static void parse_compound_type_entries(compound_t *compound_declaration);

static void check_call_argument(type_t          *expected_type,
                                                                call_argument_t *argument, unsigned pos);

typedef enum declarator_flags_t {
        DECL_FLAGS_NONE             = 0,
        DECL_MAY_BE_ABSTRACT        = 1U << 0,
        DECL_CREATE_COMPOUND_MEMBER = 1U << 1,
        DECL_IS_PARAMETER           = 1U << 2
} declarator_flags_t;

static entity_t *parse_declarator(const declaration_specifiers_t *specifiers,
                                  declarator_flags_t flags);

static void semantic_comparison(binary_expression_t *expression);

#define STORAGE_CLASSES       \
        STORAGE_CLASSES_NO_EXTERN \
        case T_extern:

#define STORAGE_CLASSES_NO_EXTERN \
        case T_typedef:         \
        case T_static:          \
        case T_auto:            \
        case T_register:        \
        case T___thread:

#define TYPE_QUALIFIERS     \
        case T_const:           \
        case T_restrict:        \
        case T_volatile:        \
        case T_inline:          \
        case T__forceinline:    \
        case T___attribute__:

#define COMPLEX_SPECIFIERS  \
        case T__Complex:
#define IMAGINARY_SPECIFIERS \
        case T__Imaginary:

#define TYPE_SPECIFIERS       \
        case T__Bool:             \
        case T___builtin_va_list: \
        case T___typeof__:        \
        case T__declspec:         \
        case T_bool:              \
        case T_char:              \
        case T_double:            \
        case T_enum:              \
        case T_float:             \
        case T_int:               \
        case T_long:              \
        case T_short:             \
        case T_signed:            \
        case T_struct:            \
        case T_union:             \
        case T_unsigned:          \
        case T_void:              \
        case T_wchar_t:           \
        case T__int8:             \
        case T__int16:            \
        case T__int32:            \
        case T__int64:            \
        case T__int128:           \
        COMPLEX_SPECIFIERS        \
        IMAGINARY_SPECIFIERS

#define DECLARATION_START   \
        STORAGE_CLASSES         \
        TYPE_QUALIFIERS         \
        TYPE_SPECIFIERS

#define DECLARATION_START_NO_EXTERN \
        STORAGE_CLASSES_NO_EXTERN       \
        TYPE_QUALIFIERS                 \
        TYPE_SPECIFIERS

#define TYPENAME_START      \
        TYPE_QUALIFIERS         \
        TYPE_SPECIFIERS

#define EXPRESSION_START              \
        case '!':                         \
        case '&':                         \
        case '(':                         \
        case '*':                         \
        case '+':                         \
        case '-':                         \
        case '~':                         \
        case T_ANDAND:                    \
        case T_CHARACTER_CONSTANT:        \
        case T_FLOATINGPOINT:             \
        case T_FLOATINGPOINT_HEXADECIMAL: \
        case T_INTEGER:                   \
        case T_INTEGER_HEXADECIMAL:       \
        case T_INTEGER_OCTAL:             \
        case T_MINUSMINUS:                \
        case T_PLUSPLUS:                  \
        case T_STRING_LITERAL:            \
        case T_WIDE_CHARACTER_CONSTANT:   \
        case T_WIDE_STRING_LITERAL:       \
        case T___FUNCDNAME__:             \
        case T___FUNCSIG__:               \
        case T___FUNCTION__:              \
        case T___PRETTY_FUNCTION__:       \
        case T___alignof__:               \
        case T___builtin_classify_type:   \
        case T___builtin_constant_p:      \
        case T___builtin_isgreater:       \
        case T___builtin_isgreaterequal:  \
        case T___builtin_isless:          \
        case T___builtin_islessequal:     \
        case T___builtin_islessgreater:   \
        case T___builtin_isunordered:     \
        case T___builtin_offsetof:        \
        case T___builtin_va_arg:          \
        case T___builtin_va_copy:         \
        case T___builtin_va_start:        \
        case T___func__:                  \
        case T___noop:                    \
        case T__assume:                   \
        case T_delete:                    \
        case T_false:                     \
        case T_sizeof:                    \
        case T_throw:                     \
        case T_true:

/**
 * Returns the size of a statement node.
 *
 * @param kind  the statement kind
 */
static size_t get_statement_struct_size(statement_kind_t kind)
{
        static const size_t sizes[] = {
                [STATEMENT_INVALID]     = sizeof(invalid_statement_t),
                [STATEMENT_EMPTY]       = sizeof(empty_statement_t),
                [STATEMENT_COMPOUND]    = sizeof(compound_statement_t),
                [STATEMENT_RETURN]      = sizeof(return_statement_t),
                [STATEMENT_DECLARATION] = sizeof(declaration_statement_t),
                [STATEMENT_IF]          = sizeof(if_statement_t),
                [STATEMENT_SWITCH]      = sizeof(switch_statement_t),
                [STATEMENT_EXPRESSION]  = sizeof(expression_statement_t),
                [STATEMENT_CONTINUE]    = sizeof(statement_base_t),
                [STATEMENT_BREAK]       = sizeof(statement_base_t),
                [STATEMENT_GOTO]        = sizeof(goto_statement_t),
                [STATEMENT_LABEL]       = sizeof(label_statement_t),
                [STATEMENT_CASE_LABEL]  = sizeof(case_label_statement_t),
                [STATEMENT_WHILE]       = sizeof(while_statement_t),
                [STATEMENT_DO_WHILE]    = sizeof(do_while_statement_t),
                [STATEMENT_FOR]         = sizeof(for_statement_t),
                [STATEMENT_ASM]         = sizeof(asm_statement_t),
                [STATEMENT_MS_TRY]      = sizeof(ms_try_statement_t),
                [STATEMENT_LEAVE]       = sizeof(leave_statement_t)
        };
        assert(kind < lengthof(sizes));
        assert(sizes[kind] != 0);
        return sizes[kind];
}

/**
 * Returns the size of an expression node.
 *
 * @param kind  the expression kind
 */
static size_t get_expression_struct_size(expression_kind_t kind)
{
        static const size_t sizes[] = {
                [EXPR_INVALID]                    = sizeof(expression_base_t),
                [EXPR_REFERENCE]                  = sizeof(reference_expression_t),
                [EXPR_REFERENCE_ENUM_VALUE]       = sizeof(reference_expression_t),
                [EXPR_LITERAL_INTEGER]            = sizeof(literal_expression_t),
                [EXPR_LITERAL_INTEGER_OCTAL]      = sizeof(literal_expression_t),
                [EXPR_LITERAL_INTEGER_HEXADECIMAL]= sizeof(literal_expression_t),
                [EXPR_LITERAL_FLOATINGPOINT]      = sizeof(literal_expression_t),
                [EXPR_LITERAL_FLOATINGPOINT_HEXADECIMAL] = sizeof(literal_expression_t),
                [EXPR_LITERAL_CHARACTER]          = sizeof(literal_expression_t),
                [EXPR_LITERAL_WIDE_CHARACTER]     = sizeof(literal_expression_t),
                [EXPR_STRING_LITERAL]             = sizeof(string_literal_expression_t),
                [EXPR_WIDE_STRING_LITERAL]        = sizeof(string_literal_expression_t),
                [EXPR_COMPOUND_LITERAL]           = sizeof(compound_literal_expression_t),
                [EXPR_CALL]                       = sizeof(call_expression_t),
                [EXPR_UNARY_FIRST]                = sizeof(unary_expression_t),
                [EXPR_BINARY_FIRST]               = sizeof(binary_expression_t),
                [EXPR_CONDITIONAL]                = sizeof(conditional_expression_t),
                [EXPR_SELECT]                     = sizeof(select_expression_t),
                [EXPR_ARRAY_ACCESS]               = sizeof(array_access_expression_t),
                [EXPR_SIZEOF]                     = sizeof(typeprop_expression_t),
                [EXPR_ALIGNOF]                    = sizeof(typeprop_expression_t),
                [EXPR_CLASSIFY_TYPE]              = sizeof(classify_type_expression_t),
                [EXPR_FUNCNAME]                   = sizeof(funcname_expression_t),
                [EXPR_BUILTIN_CONSTANT_P]         = sizeof(builtin_constant_expression_t),
                [EXPR_BUILTIN_TYPES_COMPATIBLE_P] = sizeof(builtin_types_compatible_expression_t),
                [EXPR_OFFSETOF]                   = sizeof(offsetof_expression_t),
                [EXPR_VA_START]                   = sizeof(va_start_expression_t),
                [EXPR_VA_ARG]                     = sizeof(va_arg_expression_t),
                [EXPR_VA_COPY]                    = sizeof(va_copy_expression_t),
                [EXPR_STATEMENT]                  = sizeof(statement_expression_t),
                [EXPR_LABEL_ADDRESS]              = sizeof(label_address_expression_t),
        };
        if (kind >= EXPR_UNARY_FIRST && kind <= EXPR_UNARY_LAST) {
                return sizes[EXPR_UNARY_FIRST];
        }
        if (kind >= EXPR_BINARY_FIRST && kind <= EXPR_BINARY_LAST) {
                return sizes[EXPR_BINARY_FIRST];
        }
        assert(kind < lengthof(sizes));
        assert(sizes[kind] != 0);
        return sizes[kind];
}

/**
 * Allocate a statement node of given kind and initialize all
 * fields with zero. Sets its source position to the position
 * of the current token.
 */
static statement_t *allocate_statement_zero(statement_kind_t kind)
{
        size_t       size = get_statement_struct_size(kind);
        statement_t *res  = allocate_ast_zero(size);

        res->base.kind            = kind;
        res->base.parent          = current_parent;
        res->base.source_position = token.source_position;
        return res;
}

/**
 * Allocate an expression node of given kind and initialize all
 * fields with zero.
 *
 * @param kind  the kind of the expression to allocate
 */
static expression_t *allocate_expression_zero(expression_kind_t kind)
{
        size_t        size = get_expression_struct_size(kind);
        expression_t *res  = allocate_ast_zero(size);

        res->base.kind            = kind;
        res->base.type            = type_error_type;
        res->base.source_position = token.source_position;
        return res;
}

/**
 * Creates a new invalid expression at the source position
 * of the current token.
 */
static expression_t *create_invalid_expression(void)
{
        return allocate_expression_zero(EXPR_INVALID);
}

/**
 * Creates a new invalid statement.
 */
static statement_t *create_invalid_statement(void)
{
        return allocate_statement_zero(STATEMENT_INVALID);
}

/**
 * Allocate a new empty statement.
 */
static statement_t *create_empty_statement(void)
{
        return allocate_statement_zero(STATEMENT_EMPTY);
}

static function_parameter_t *allocate_parameter(type_t *const type)
{
        function_parameter_t *const param
                = obstack_alloc(type_obst, sizeof(*param));
        memset(param, 0, sizeof(*param));
        param->type = type;
        return param;
}

/**
 * Returns the size of an initializer node.
 *
 * @param kind  the initializer kind
 */
static size_t get_initializer_size(initializer_kind_t kind)
{
        static const size_t sizes[] = {
                [INITIALIZER_VALUE]       = sizeof(initializer_value_t),
                [INITIALIZER_STRING]      = sizeof(initializer_string_t),
                [INITIALIZER_WIDE_STRING] = sizeof(initializer_wide_string_t),
                [INITIALIZER_LIST]        = sizeof(initializer_list_t),
                [INITIALIZER_DESIGNATOR]  = sizeof(initializer_designator_t)
        };
        assert(kind < lengthof(sizes));
        assert(sizes[kind] != 0);
        return sizes[kind];
}

/**
 * Allocate an initializer node of given kind and initialize all
 * fields with zero.
 */
static initializer_t *allocate_initializer_zero(initializer_kind_t kind)
{
        initializer_t *result = allocate_ast_zero(get_initializer_size(kind));
        result->kind          = kind;

        return result;
}

/**
 * Returns the index of the top element of the environment stack.
 */
static size_t environment_top(void)
{
        return ARR_LEN(environment_stack);
}

/**
 * Returns the index of the top element of the global label stack.
 */
static size_t label_top(void)
{
        return ARR_LEN(label_stack);
}

/**
 * Return the next token.
 */
static inline void next_token(void)
{
        token                              = lookahead_buffer[lookahead_bufpos];
        lookahead_buffer[lookahead_bufpos] = lexer_token;
        lexer_next_token();

        lookahead_bufpos = (lookahead_bufpos + 1) % MAX_LOOKAHEAD;

#ifdef PRINT_TOKENS
        print_token(stderr, &token);
        fprintf(stderr, "\n");
#endif
}

static inline bool next_if(int const type)
{
        if (token.type == type) {
                next_token();
                return true;
        } else {
                return false;
        }
}

/**
 * Return the next token with a given lookahead.
 */
static inline const token_t *look_ahead(size_t num)
{
        assert(0 < num && num <= MAX_LOOKAHEAD);
        size_t pos = (lookahead_bufpos + num - 1) % MAX_LOOKAHEAD;
        return &lookahead_buffer[pos];
}

/**
 * Adds a token type to the token type anchor set (a multi-set).
 */
static void add_anchor_token(int token_type)
{
        assert(0 <= token_type && token_type < T_LAST_TOKEN);
        ++token_anchor_set[token_type];
}

/**
 * Set the number of tokens types of the given type
 * to zero and return the old count.
 */
static int save_and_reset_anchor_state(int token_type)
{
        assert(0 <= token_type && token_type < T_LAST_TOKEN);
        int count = token_anchor_set[token_type];
        token_anchor_set[token_type] = 0;
        return count;
}

/**
 * Restore the number of token types to the given count.
 */
static void restore_anchor_state(int token_type, int count)
{
        assert(0 <= token_type && token_type < T_LAST_TOKEN);
        token_anchor_set[token_type] = count;
}

/**
 * Remove a token type from the token type anchor set (a multi-set).
 */
static void rem_anchor_token(int token_type)
{
        assert(0 <= token_type && token_type < T_LAST_TOKEN);
        assert(token_anchor_set[token_type] != 0);
        --token_anchor_set[token_type];
}

/**
 * Return true if the token type of the current token is
 * in the anchor set.
 */
static bool at_anchor(void)
{
        if (token.type < 0)
                return false;
        return token_anchor_set[token.type];
}

/**
 * Eat tokens until a matching token type is found.
 */
static void eat_until_matching_token(int type)
{
        int end_token;
        switch (type) {
                case '(': end_token = ')';  break;
                case '{': end_token = '}';  break;
                case '[': end_token = ']';  break;
                default:  end_token = type; break;
        }

        unsigned parenthesis_count = 0;
        unsigned brace_count       = 0;
        unsigned bracket_count     = 0;
        while (token.type        != end_token ||
               parenthesis_count != 0         ||
               brace_count       != 0         ||
               bracket_count     != 0) {
                switch (token.type) {
                case T_EOF: return;
                case '(': ++parenthesis_count; break;
                case '{': ++brace_count;       break;
                case '[': ++bracket_count;     break;

                case ')':
                        if (parenthesis_count > 0)
                                --parenthesis_count;
                        goto check_stop;

                case '}':
                        if (brace_count > 0)
                                --brace_count;
                        goto check_stop;

                case ']':
                        if (bracket_count > 0)
                                --bracket_count;
check_stop:
                        if (token.type        == end_token &&
                            parenthesis_count == 0         &&
                            brace_count       == 0         &&
                            bracket_count     == 0)
                                return;
                        break;

                default:
                        break;
                }
                next_token();
        }
}

/**
 * Eat input tokens until an anchor is found.
 */
static void eat_until_anchor(void)
{
        while (token_anchor_set[token.type] == 0) {
                if (token.type == '(' || token.type == '{' || token.type == '[')
                        eat_until_matching_token(token.type);
                next_token();
        }
}

/**
 * Eat a whole block from input tokens.
 */
static void eat_block(void)
{
        eat_until_matching_token('{');
        next_if('}');
}

#define eat(token_type) (assert(token.type == (token_type)), next_token())

/**
 * Report a parse error because an expected token was not found.
 */
static
#if defined __GNUC__ && __GNUC__ >= 4
__attribute__((sentinel))
#endif
void parse_error_expected(const char *message, ...)
{
        if (message != NULL) {
                errorf(HERE, "%s", message);
        }
        va_list ap;
        va_start(ap, message);
        errorf(HERE, "got %K, expected %#k", &token, &ap, ", ");
        va_end(ap);
}

/**
 * Report an incompatible type.
 */
static void type_error_incompatible(const char *msg,
                const source_position_t *source_position, type_t *type1, type_t *type2)
{
        errorf(source_position, "%s, incompatible types: '%T' - '%T'",
               msg, type1, type2);
}

/**
 * Expect the current token is the expected token.
 * If not, generate an error, eat the current statement,
 * and goto the error_label label.
 */
#define expect(expected, error_label)                     \
        do {                                                  \
                if (UNLIKELY(token.type != (expected))) {         \
                        parse_error_expected(NULL, (expected), NULL); \
                        add_anchor_token(expected);                   \
                        eat_until_anchor();                           \
                        next_if((expected));                          \
                        rem_anchor_token(expected);                   \
                        goto error_label;                             \
                }                                                 \
                next_token();                                     \
        } while (0)

/**
 * Push a given scope on the scope stack and make it the
 * current scope
 */
static scope_t *scope_push(scope_t *new_scope)
{
        if (current_scope != NULL) {
                new_scope->depth = current_scope->depth + 1;
        }

        scope_t *old_scope = current_scope;
        current_scope      = new_scope;
        return old_scope;
}

/**
 * Pop the current scope from the scope stack.
 */
static void scope_pop(scope_t *old_scope)
{
        current_scope = old_scope;
}

/**
 * Search an entity by its symbol in a given namespace.
 */
static entity_t *get_entity(const symbol_t *const symbol,
                            namespace_tag_t namespc)
{
        entity_t *entity = symbol->entity;
        for (; entity != NULL; entity = entity->base.symbol_next) {
                if (entity->base.namespc == namespc)
                        return entity;
        }

        return NULL;
}

/* §6.2.3:1 24)  There is only one name space for tags even though three are
 * possible. */
static entity_t *get_tag(symbol_t const *const symbol,
                         entity_kind_tag_t const kind)
{
        entity_t *entity = get_entity(symbol, NAMESPACE_TAG);
        if (entity != NULL && entity->kind != kind) {
                errorf(HERE,
                                "'%Y' defined as wrong kind of tag (previous definition %P)",
                                symbol, &entity->base.source_position);
                entity = NULL;
        }
        return entity;
}

/**
 * pushs an entity on the environment stack and links the corresponding symbol
 * it.
 */
static void stack_push(stack_entry_t **stack_ptr, entity_t *entity)
{
        symbol_t           *symbol  = entity->base.symbol;
        entity_namespace_t  namespc = entity->base.namespc;
        assert(namespc != NAMESPACE_INVALID);

        /* replace/add entity into entity list of the symbol */
        entity_t **anchor;
        entity_t  *iter;
        for (anchor = &symbol->entity; ; anchor = &iter->base.symbol_next) {
                iter = *anchor;
                if (iter == NULL)
                        break;

                /* replace an entry? */
                if (iter->base.namespc == namespc) {
                        entity->base.symbol_next = iter->base.symbol_next;
                        break;
                }
        }
        *anchor = entity;

        /* remember old declaration */
        stack_entry_t entry;
        entry.symbol     = symbol;
        entry.old_entity = iter;
        entry.namespc    = namespc;
        ARR_APP1(stack_entry_t, *stack_ptr, entry);
}

/**
 * Push an entity on the environment stack.
 */
static void environment_push(entity_t *entity)
{
        assert(entity->base.source_position.input_name != NULL);
        assert(entity->base.parent_scope != NULL);
        stack_push(&environment_stack, entity);
}

/**
 * Push a declaration on the global label stack.
 *
 * @param declaration  the declaration
 */
static void label_push(entity_t *label)
{
        /* we abuse the parameters scope as parent for the labels */
        label->base.parent_scope = &current_function->parameters;
        stack_push(&label_stack, label);
}

/**
 * pops symbols from the environment stack until @p new_top is the top element
 */
static void stack_pop_to(stack_entry_t **stack_ptr, size_t new_top)
{
        stack_entry_t *stack = *stack_ptr;
        size_t         top   = ARR_LEN(stack);
        size_t         i;

        assert(new_top <= top);
        if (new_top == top)
                return;

        for (i = top; i > new_top; --i) {
                stack_entry_t *entry = &stack[i - 1];

                entity_t           *old_entity = entry->old_entity;
                symbol_t           *symbol     = entry->symbol;
                entity_namespace_t  namespc    = entry->namespc;

                /* replace with old_entity/remove */
                entity_t **anchor;
                entity_t  *iter;
                for (anchor = &symbol->entity; ; anchor = &iter->base.symbol_next) {
                        iter = *anchor;
                        assert(iter != NULL);
                        /* replace an entry? */
                        if (iter->base.namespc == namespc)
                                break;
                }

                /* restore definition from outer scopes (if there was one) */
                if (old_entity != NULL) {
                        old_entity->base.symbol_next = iter->base.symbol_next;
                        *anchor                      = old_entity;
                } else {
                        /* remove entry from list */
                        *anchor = iter->base.symbol_next;
                }
        }

        ARR_SHRINKLEN(*stack_ptr, new_top);
}

/**
 * Pop all entries from the environment stack until the new_top
 * is reached.
 *
 * @param new_top  the new stack top
 */
static void environment_pop_to(size_t new_top)
{
        stack_pop_to(&environment_stack, new_top);
}

/**
 * Pop all entries from the global label stack until the new_top
 * is reached.
 *
 * @param new_top  the new stack top
 */
static void label_pop_to(size_t new_top)
{
        stack_pop_to(&label_stack, new_top);
}

static int get_akind_rank(atomic_type_kind_t akind)
{
        return (int) akind;
}

/**
 * Return the type rank for an atomic type.
 */
static int get_rank(const type_t *type)
{
        assert(!is_typeref(type));
        if (type->kind == TYPE_ENUM)
                return get_akind_rank(type->enumt.akind);

        assert(type->kind == TYPE_ATOMIC);
        return get_akind_rank(type->atomic.akind);
}

/**
 * §6.3.1.1:2  Do integer promotion for a given type.
 *
 * @param type  the type to promote
 * @return the promoted type
 */
static type_t *promote_integer(type_t *type)
{
        if (type->kind == TYPE_BITFIELD)
                type = type->bitfield.base_type;

        if (get_rank(type) < get_akind_rank(ATOMIC_TYPE_INT))
                type = type_int;

        return type;
}

/**
 * Create a cast expression.
 *
 * @param expression  the expression to cast
 * @param dest_type   the destination type
 */
static expression_t *create_cast_expression(expression_t *expression,
                                            type_t *dest_type)
{
        expression_t *cast = allocate_expression_zero(EXPR_UNARY_CAST_IMPLICIT);

        cast->unary.value = expression;
        cast->base.type   = dest_type;

        return cast;
}

/**
 * Check if a given expression represents a null pointer constant.
 *
 * @param expression  the expression to check
 */
static bool is_null_pointer_constant(const expression_t *expression)
{
        /* skip void* cast */
        if (expression->kind == EXPR_UNARY_CAST ||
                        expression->kind == EXPR_UNARY_CAST_IMPLICIT) {
                type_t *const type = skip_typeref(expression->base.type);
                if (types_compatible(type, type_void_ptr))
                        expression = expression->unary.value;
        }

        type_t *const type = skip_typeref(expression->base.type);
        return
                is_type_integer(type)              &&
                is_constant_expression(expression) &&
                !fold_constant_to_bool(expression);
}

/**
 * Create an implicit cast expression.
 *
 * @param expression  the expression to cast
 * @param dest_type   the destination type
 */
static expression_t *create_implicit_cast(expression_t *expression,
                                          type_t *dest_type)
{
        type_t *const source_type = expression->base.type;

        if (source_type == dest_type)
                return expression;

        return create_cast_expression(expression, dest_type);
}

typedef enum assign_error_t {
        ASSIGN_SUCCESS,
        ASSIGN_ERROR_INCOMPATIBLE,
        ASSIGN_ERROR_POINTER_QUALIFIER_MISSING,
        ASSIGN_WARNING_POINTER_INCOMPATIBLE,
        ASSIGN_WARNING_POINTER_FROM_INT,
        ASSIGN_WARNING_INT_FROM_POINTER
} assign_error_t;

static void report_assign_error(assign_error_t error, type_t *orig_type_left,
                                const expression_t *const right,
                                const char *context,
                                const source_position_t *source_position)
{
        type_t *const orig_type_right = right->base.type;
        type_t *const type_left       = skip_typeref(orig_type_left);
        type_t *const type_right      = skip_typeref(orig_type_right);

        switch (error) {
        case ASSIGN_SUCCESS:
                return;
        case ASSIGN_ERROR_INCOMPATIBLE:
                errorf(source_position,
                       "destination type '%T' in %s is incompatible with type '%T'",
                       orig_type_left, context, orig_type_right);
                return;

        case ASSIGN_ERROR_POINTER_QUALIFIER_MISSING: {
                if (warning.other) {
                        type_t *points_to_left  = skip_typeref(type_left->pointer.points_to);
                        type_t *points_to_right = skip_typeref(type_right->pointer.points_to);

                        /* the left type has all qualifiers from the right type */
                        unsigned missing_qualifiers
                                = points_to_right->base.qualifiers & ~points_to_left->base.qualifiers;
                        warningf(source_position,
                                        "destination type '%T' in %s from type '%T' lacks qualifiers '%Q' in pointer target type",
                                        orig_type_left, context, orig_type_right, missing_qualifiers);
                }
                return;
        }

        case ASSIGN_WARNING_POINTER_INCOMPATIBLE:
                if (warning.other) {
                        warningf(source_position,
                                        "destination type '%T' in %s is incompatible with '%E' of type '%T'",
                                        orig_type_left, context, right, orig_type_right);
                }
                return;

        case ASSIGN_WARNING_POINTER_FROM_INT:
                if (warning.other) {
                        warningf(source_position,
                                        "%s makes pointer '%T' from integer '%T' without a cast",
                                        context, orig_type_left, orig_type_right);
                }
                return;

        case ASSIGN_WARNING_INT_FROM_POINTER:
                if (warning.other) {
                        warningf(source_position,
                                        "%s makes integer '%T' from pointer '%T' without a cast",
                                        context, orig_type_left, orig_type_right);
                }
                return;

        default:
                panic("invalid error value");
        }
}

/** Implements the rules from §6.5.16.1 */
static assign_error_t semantic_assign(type_t *orig_type_left,
                                      const expression_t *const right)
{
        type_t *const orig_type_right = right->base.type;
        type_t *const type_left       = skip_typeref(orig_type_left);
        type_t *const type_right      = skip_typeref(orig_type_right);

        if (is_type_pointer(type_left)) {
                if (is_null_pointer_constant(right)) {
                        return ASSIGN_SUCCESS;
                } else if (is_type_pointer(type_right)) {
                        type_t *points_to_left
                                = skip_typeref(type_left->pointer.points_to);
                        type_t *points_to_right
                                = skip_typeref(type_right->pointer.points_to);
                        assign_error_t res = ASSIGN_SUCCESS;

                        /* the left type has all qualifiers from the right type */
                        unsigned missing_qualifiers
                                = points_to_right->base.qualifiers & ~points_to_left->base.qualifiers;
                        if (missing_qualifiers != 0) {
                                res = ASSIGN_ERROR_POINTER_QUALIFIER_MISSING;
                        }

                        points_to_left  = get_unqualified_type(points_to_left);
                        points_to_right = get_unqualified_type(points_to_right);

                        if (is_type_atomic(points_to_left, ATOMIC_TYPE_VOID))
                                return res;

                        if (is_type_atomic(points_to_right, ATOMIC_TYPE_VOID)) {
                                /* ISO/IEC 14882:1998(E) §C.1.2:6 */
                                return c_mode & _CXX ? ASSIGN_ERROR_INCOMPATIBLE : res;
                        }

                        if (!types_compatible(points_to_left, points_to_right)) {
                                return ASSIGN_WARNING_POINTER_INCOMPATIBLE;
                        }

                        return res;
                } else if (is_type_integer(type_right)) {
                        return ASSIGN_WARNING_POINTER_FROM_INT;
                }
        } else if ((is_type_arithmetic(type_left) && is_type_arithmetic(type_right)) ||
                        (is_type_atomic(type_left, ATOMIC_TYPE_BOOL)
                                && is_type_pointer(type_right))) {
                return ASSIGN_SUCCESS;
        } else if ((is_type_compound(type_left)  && is_type_compound(type_right))
                        || (is_type_builtin(type_left) && is_type_builtin(type_right))) {
                type_t *const unqual_type_left  = get_unqualified_type(type_left);
                type_t *const unqual_type_right = get_unqualified_type(type_right);
                if (types_compatible(unqual_type_left, unqual_type_right)) {
                        return ASSIGN_SUCCESS;
                }
        } else if (is_type_integer(type_left) && is_type_pointer(type_right)) {
                return ASSIGN_WARNING_INT_FROM_POINTER;
        }

        if (!is_type_valid(type_left) || !is_type_valid(type_right))
                return ASSIGN_SUCCESS;

        return ASSIGN_ERROR_INCOMPATIBLE;
}

static expression_t *parse_constant_expression(void)
{
        expression_t *result = parse_subexpression(PREC_CONDITIONAL);

        if (!is_constant_expression(result)) {
                errorf(&result->base.source_position,
                       "expression '%E' is not constant", result);
        }

        return result;
}

static expression_t *parse_assignment_expression(void)
{
        return parse_subexpression(PREC_ASSIGNMENT);
}

static void warn_string_concat(const source_position_t *pos)
{
        if (warning.traditional) {
                warningf(pos, "traditional C rejects string constant concatenation");
        }
}

static string_t parse_string_literals(void)
{
        assert(token.type == T_STRING_LITERAL);
        string_t result = token.literal;

        next_token();

        while (token.type == T_STRING_LITERAL) {
                warn_string_concat(&token.source_position);
                result = concat_strings(&result, &token.literal);
                next_token();
        }

        return result;
}

/**
 * compare two string, ignoring double underscores on the second.
 */
static int strcmp_underscore(const char *s1, const char *s2)
{
        if (s2[0] == '_' && s2[1] == '_') {
                size_t len2 = strlen(s2);
                size_t len1 = strlen(s1);
                if (len1 == len2-4 && s2[len2-2] == '_' && s2[len2-1] == '_') {
                        return strncmp(s1, s2+2, len2-4);
                }
        }

        return strcmp(s1, s2);
}

static attribute_t *allocate_attribute_zero(attribute_kind_t kind)
{
        attribute_t *attribute = allocate_ast_zero(sizeof(*attribute));
        attribute->kind        = kind;
        return attribute;
}

/**
 * Parse (gcc) attribute argument. From gcc comments in gcc source:
 *
 *  attribute:
 *    __attribute__ ( ( attribute-list ) )
 *
 *  attribute-list:
 *    attrib
 *    attribute_list , attrib
 *
 *  attrib:
 *    empty
 *    any-word
 *    any-word ( identifier )
 *    any-word ( identifier , nonempty-expr-list )
 *    any-word ( expr-list )
 *
 *  where the "identifier" must not be declared as a type, and
 *  "any-word" may be any identifier (including one declared as a
 *  type), a reserved word storage class specifier, type specifier or
 *  type qualifier.  ??? This still leaves out most reserved keywords
 *  (following the old parser), shouldn't we include them, and why not
 *  allow identifiers declared as types to start the arguments?
 *
 *  Matze: this all looks confusing and little systematic, so we're even less
 *  strict and parse any list of things which are identifiers or
 *  (assignment-)expressions.
 */
static attribute_argument_t *parse_attribute_arguments(void)
{
        attribute_argument_t  *first  = NULL;
        attribute_argument_t **anchor = &first;
        if (token.type != ')') do {
                attribute_argument_t *argument = allocate_ast_zero(sizeof(*argument));

                /* is it an identifier */
                if (token.type == T_IDENTIFIER
                                && (look_ahead(1)->type == ',' || look_ahead(1)->type == ')')) {
                        symbol_t *symbol   = token.symbol;
                        argument->kind     = ATTRIBUTE_ARGUMENT_SYMBOL;
                        argument->v.symbol = symbol;
                        next_token();
                } else {
                        /* must be an expression */
                        expression_t *expression = parse_assignment_expression();

                        argument->kind         = ATTRIBUTE_ARGUMENT_EXPRESSION;
                        argument->v.expression = expression;
                }

                /* append argument */
                *anchor = argument;
                anchor  = &argument->next;
        } while (next_if(','));
        expect(')', end_error);

        return first;

end_error:
        /* TODO... */
        return first;
}

static attribute_t *parse_attribute_asm(void)
{
        eat(T_asm);

        attribute_t *attribute = allocate_attribute_zero(ATTRIBUTE_GNU_ASM);

        expect('(', end_error);
        attribute->a.arguments = parse_attribute_arguments();
        return attribute;

end_error:
        return NULL;
}

static symbol_t *get_symbol_from_token(void)
{
        switch(token.type) {
        case T_IDENTIFIER:
                return token.symbol;
        case T_auto:
        case T_char:
        case T_double:
        case T_enum:
        case T_extern:
        case T_float:
        case T_int:
        case T_long:
        case T_register:
        case T_short:
        case T_static:
        case T_struct:
        case T_union:
        case T_unsigned:
        case T_void:
        case T_bool:
        case T__Bool:
        case T_class:
        case T_explicit:
        case T_export:
        case T_wchar_t:
        case T_const:
        case T_signed:
        case T___real__:
        case T___imag__:
        case T_restrict:
        case T_volatile:
        case T_inline:
                /* maybe we need more tokens ... add them on demand */
                return get_token_symbol(&token);
        default:
                return NULL;
        }
}

static attribute_t *parse_attribute_gnu_single(void)
{
        /* parse "any-word" */
        symbol_t *symbol = get_symbol_from_token();
        if (symbol == NULL) {
                parse_error_expected("while parsing attribute((", T_IDENTIFIER, NULL);
                return NULL;
        }

        const char *name = symbol->string;
        next_token();

        attribute_kind_t kind;
        for (kind = ATTRIBUTE_GNU_FIRST; kind <= ATTRIBUTE_GNU_LAST; ++kind) {
                const char *attribute_name = get_attribute_name(kind);
                if (attribute_name != NULL
                                && strcmp_underscore(attribute_name, name) == 0)
                        break;
        }

        if (kind >= ATTRIBUTE_GNU_LAST) {
                if (warning.attribute) {
                        warningf(HERE, "unknown attribute '%s' ignored", name);
                }
                /* TODO: we should still save the attribute in the list... */
                kind = ATTRIBUTE_UNKNOWN;
        }

        attribute_t *attribute = allocate_attribute_zero(kind);

        /* parse arguments */
        if (next_if('('))
                attribute->a.arguments = parse_attribute_arguments();

        return attribute;
}

static attribute_t *parse_attribute_gnu(void)
{
        attribute_t  *first  = NULL;
        attribute_t **anchor = &first;

        eat(T___attribute__);
        expect('(', end_error);
        expect('(', end_error);

        if (token.type != ')') do {
                attribute_t *attribute = parse_attribute_gnu_single();
                if (attribute == NULL)
                        goto end_error;

                *anchor = attribute;
                anchor  = &attribute->next;
        } while (next_if(','));
        expect(')', end_error);
        expect(')', end_error);

end_error:
        return first;
}

/** Parse attributes. */
static attribute_t *parse_attributes(attribute_t *first)
{
        attribute_t **anchor = &first;
        for (;;) {
                while (*anchor != NULL)
                        anchor = &(*anchor)->next;

                attribute_t *attribute;
                switch (token.type) {
                case T___attribute__:
                        attribute = parse_attribute_gnu();
                        break;

                case T_asm:
                        attribute = parse_attribute_asm();
                        break;

                case T_cdecl:
                        next_token();
                        attribute = allocate_attribute_zero(ATTRIBUTE_MS_CDECL);
                        break;

                case T__fastcall:
                        next_token();
                        attribute = allocate_attribute_zero(ATTRIBUTE_MS_FASTCALL);
                        break;

                case T__forceinline:
                        next_token();
                        attribute = allocate_attribute_zero(ATTRIBUTE_MS_FORCEINLINE);
                        break;

                case T__stdcall:
                        next_token();
                        attribute = allocate_attribute_zero(ATTRIBUTE_MS_STDCALL);
                        break;

                case T___thiscall:
                        next_token();
                        /* TODO record modifier */
                        if (warning.other)
                                warningf(HERE, "Ignoring declaration modifier %K", &token);
                        attribute = allocate_attribute_zero(ATTRIBUTE_MS_THISCALL);
                        break;

                default:
                        return first;
                }

                *anchor = attribute;
                anchor  = &attribute->next;
        }
}

static void mark_vars_read(expression_t *expr, entity_t *lhs_ent);

static entity_t *determine_lhs_ent(expression_t *const expr,
                                   entity_t *lhs_ent)
{
        switch (expr->kind) {
                case EXPR_REFERENCE: {
                        entity_t *const entity = expr->reference.entity;
                        /* we should only find variables as lvalues... */
                        if (entity->base.kind != ENTITY_VARIABLE
                                        && entity->base.kind != ENTITY_PARAMETER)
                                return NULL;

                        return entity;
                }

                case EXPR_ARRAY_ACCESS: {
                        expression_t *const ref = expr->array_access.array_ref;
                        entity_t     *      ent = NULL;
                        if (is_type_array(skip_typeref(revert_automatic_type_conversion(ref)))) {
                                ent     = determine_lhs_ent(ref, lhs_ent);
                                lhs_ent = ent;
                        } else {
                                mark_vars_read(expr->select.compound, lhs_ent);
                        }
                        mark_vars_read(expr->array_access.index, lhs_ent);
                        return ent;
                }

                case EXPR_SELECT: {
                        if (is_type_compound(skip_typeref(expr->base.type))) {
                                return determine_lhs_ent(expr->select.compound, lhs_ent);
                        } else {
                                mark_vars_read(expr->select.compound, lhs_ent);
                                return NULL;
                        }
                }

                case EXPR_UNARY_DEREFERENCE: {
                        expression_t *const val = expr->unary.value;
                        if (val->kind == EXPR_UNARY_TAKE_ADDRESS) {
                                /* *&x is a NOP */
                                return determine_lhs_ent(val->unary.value, lhs_ent);
                        } else {
                                mark_vars_read(val, NULL);
                                return NULL;
                        }
                }

                default:
                        mark_vars_read(expr, NULL);
                        return NULL;
        }
}

#define ENT_ANY ((entity_t*)-1)

/**
 * Mark declarations, which are read.  This is used to detect variables, which
 * are never read.
 * Example:
 * x = x + 1;
 *   x is not marked as "read", because it is only read to calculate its own new
 *   value.
 *
 * x += y; y += x;
 *   x and y are not detected as "not read", because multiple variables are
 *   involved.
 */
static void mark_vars_read(expression_t *const expr, entity_t *lhs_ent)
{
        switch (expr->kind) {
                case EXPR_REFERENCE: {
                        entity_t *const entity = expr->reference.entity;
                        if (entity->kind != ENTITY_VARIABLE
                                        && entity->kind != ENTITY_PARAMETER)
                                return;

                        if (lhs_ent != entity && lhs_ent != ENT_ANY) {
                                if (entity->kind == ENTITY_VARIABLE) {
                                        entity->variable.read = true;
                                } else {
                                        entity->parameter.read = true;
                                }
                        }
                        return;
                }

                case EXPR_CALL:
                        // TODO respect pure/const
                        mark_vars_read(expr->call.function, NULL);
                        for (call_argument_t *arg = expr->call.arguments; arg != NULL; arg = arg->next) {
                                mark_vars_read(arg->expression, NULL);
                        }
                        return;

                case EXPR_CONDITIONAL:
                        // TODO lhs_decl should depend on whether true/false have an effect
                        mark_vars_read(expr->conditional.condition, NULL);
                        if (expr->conditional.true_expression != NULL)
                                mark_vars_read(expr->conditional.true_expression, lhs_ent);
                        mark_vars_read(expr->conditional.false_expression, lhs_ent);
                        return;

                case EXPR_SELECT:
                        if (lhs_ent == ENT_ANY
                                        && !is_type_compound(skip_typeref(expr->base.type)))
                                lhs_ent = NULL;
                        mark_vars_read(expr->select.compound, lhs_ent);
                        return;

                case EXPR_ARRAY_ACCESS: {
                        expression_t *const ref = expr->array_access.array_ref;
                        mark_vars_read(ref, lhs_ent);
                        lhs_ent = determine_lhs_ent(ref, lhs_ent);
                        mark_vars_read(expr->array_access.index, lhs_ent);
                        return;
                }

                case EXPR_VA_ARG:
                        mark_vars_read(expr->va_arge.ap, lhs_ent);
                        return;

                case EXPR_VA_COPY:
                        mark_vars_read(expr->va_copye.src, lhs_ent);
                        return;

                case EXPR_UNARY_CAST:
                        /* Special case: Use void cast to mark a variable as "read" */
                        if (is_type_atomic(skip_typeref(expr->base.type), ATOMIC_TYPE_VOID))
                                lhs_ent = NULL;
                        goto unary;


                case EXPR_UNARY_THROW:
                        if (expr->unary.value == NULL)
                                return;
                        /* FALLTHROUGH */
                case EXPR_UNARY_DEREFERENCE:
                case EXPR_UNARY_DELETE:
                case EXPR_UNARY_DELETE_ARRAY:
                        if (lhs_ent == ENT_ANY)
                                lhs_ent = NULL;
                        goto unary;

                case EXPR_UNARY_NEGATE:
                case EXPR_UNARY_PLUS:
                case EXPR_UNARY_BITWISE_NEGATE:
                case EXPR_UNARY_NOT:
                case EXPR_UNARY_TAKE_ADDRESS:
                case EXPR_UNARY_POSTFIX_INCREMENT:
                case EXPR_UNARY_POSTFIX_DECREMENT:
                case EXPR_UNARY_PREFIX_INCREMENT:
                case EXPR_UNARY_PREFIX_DECREMENT:
                case EXPR_UNARY_CAST_IMPLICIT:
                case EXPR_UNARY_ASSUME:
unary:
                        mark_vars_read(expr->unary.value, lhs_ent);
                        return;

                case EXPR_BINARY_ADD:
                case EXPR_BINARY_SUB:
                case EXPR_BINARY_MUL:
                case EXPR_BINARY_DIV:
                case EXPR_BINARY_MOD:
                case EXPR_BINARY_EQUAL:
                case EXPR_BINARY_NOTEQUAL:
                case EXPR_BINARY_LESS:
                case EXPR_BINARY_LESSEQUAL:
                case EXPR_BINARY_GREATER:
                case EXPR_BINARY_GREATEREQUAL:
                case EXPR_BINARY_BITWISE_AND:
                case EXPR_BINARY_BITWISE_OR:
                case EXPR_BINARY_BITWISE_XOR:
                case EXPR_BINARY_LOGICAL_AND:
                case EXPR_BINARY_LOGICAL_OR:
                case EXPR_BINARY_SHIFTLEFT:
                case EXPR_BINARY_SHIFTRIGHT:
                case EXPR_BINARY_COMMA:
                case EXPR_BINARY_ISGREATER:
                case EXPR_BINARY_ISGREATEREQUAL:
                case EXPR_BINARY_ISLESS:
                case EXPR_BINARY_ISLESSEQUAL:
                case EXPR_BINARY_ISLESSGREATER:
                case EXPR_BINARY_ISUNORDERED:
                        mark_vars_read(expr->binary.left,  lhs_ent);
                        mark_vars_read(expr->binary.right, lhs_ent);
                        return;

                case EXPR_BINARY_ASSIGN:
                case EXPR_BINARY_MUL_ASSIGN:
                case EXPR_BINARY_DIV_ASSIGN:
                case EXPR_BINARY_MOD_ASSIGN:
                case EXPR_BINARY_ADD_ASSIGN:
                case EXPR_BINARY_SUB_ASSIGN:
                case EXPR_BINARY_SHIFTLEFT_ASSIGN:
                case EXPR_BINARY_SHIFTRIGHT_ASSIGN:
                case EXPR_BINARY_BITWISE_AND_ASSIGN:
                case EXPR_BINARY_BITWISE_XOR_ASSIGN:
                case EXPR_BINARY_BITWISE_OR_ASSIGN: {
                        if (lhs_ent == ENT_ANY)
                                lhs_ent = NULL;
                        lhs_ent = determine_lhs_ent(expr->binary.left, lhs_ent);
                        mark_vars_read(expr->binary.right, lhs_ent);
                        return;
                }

                case EXPR_VA_START:
                        determine_lhs_ent(expr->va_starte.ap, lhs_ent);
                        return;

                EXPR_LITERAL_CASES
                case EXPR_UNKNOWN:
                case EXPR_INVALID:
                case EXPR_STRING_LITERAL:
                case EXPR_WIDE_STRING_LITERAL:
                case EXPR_COMPOUND_LITERAL: // TODO init?
                case EXPR_SIZEOF:
                case EXPR_CLASSIFY_TYPE:
                case EXPR_ALIGNOF:
                case EXPR_FUNCNAME:
                case EXPR_BUILTIN_CONSTANT_P:
                case EXPR_BUILTIN_TYPES_COMPATIBLE_P:
                case EXPR_OFFSETOF:
                case EXPR_STATEMENT: // TODO
                case EXPR_LABEL_ADDRESS:
                case EXPR_REFERENCE_ENUM_VALUE:
                        return;
        }

        panic("unhandled expression");
}

static designator_t *parse_designation(void)
{
        designator_t  *result = NULL;
        designator_t **anchor = &result;

        for (;;) {
                designator_t *designator;
                switch (token.type) {
                case '[':
                        designator = allocate_ast_zero(sizeof(designator[0]));
                        designator->source_position = token.source_position;
                        next_token();
                        add_anchor_token(']');
                        designator->array_index = parse_constant_expression();
                        rem_anchor_token(']');
                        expect(']', end_error);
                        break;
                case '.':
                        designator = allocate_ast_zero(sizeof(designator[0]));
                        designator->source_position = token.source_position;
                        next_token();
                        if (token.type != T_IDENTIFIER) {
                                parse_error_expected("while parsing designator",
                                                     T_IDENTIFIER, NULL);
                                return NULL;
                        }
                        designator->symbol = token.symbol;
                        next_token();
                        break;
                default:
                        expect('=', end_error);
                        return result;
                }

                assert(designator != NULL);
                *anchor = designator;
                anchor  = &designator->next;
        }
end_error:
        return NULL;
}

static initializer_t *initializer_from_string(array_type_t *const type,
                                              const string_t *const string)
{
        /* TODO: check len vs. size of array type */
        (void) type;

        initializer_t *initializer = allocate_initializer_zero(INITIALIZER_STRING);
        initializer->string.string = *string;

        return initializer;
}

static initializer_t *initializer_from_wide_string(array_type_t *const type,
                                                   const string_t *const string)
{
        /* TODO: check len vs. size of array type */
        (void) type;

        initializer_t *const initializer =
                allocate_initializer_zero(INITIALIZER_WIDE_STRING);
        initializer->wide_string.string = *string;

        return initializer;
}

/**
 * Build an initializer from a given expression.
 */
static initializer_t *initializer_from_expression(type_t *orig_type,
                                                  expression_t *expression)
{
        /* TODO check that expression is a constant expression */

        /* §6.7.8.14/15 char array may be initialized by string literals */
        type_t *type           = skip_typeref(orig_type);
        type_t *expr_type_orig = expression->base.type;
        type_t *expr_type      = skip_typeref(expr_type_orig);

        if (is_type_array(type) && expr_type->kind == TYPE_POINTER) {
                array_type_t *const array_type   = &type->array;
                type_t       *const element_type = skip_typeref(array_type->element_type);

                if (element_type->kind == TYPE_ATOMIC) {
                        atomic_type_kind_t akind = element_type->atomic.akind;
                        switch (expression->kind) {
                        case EXPR_STRING_LITERAL:
                                if (akind == ATOMIC_TYPE_CHAR
                                                || akind == ATOMIC_TYPE_SCHAR
                                                || akind == ATOMIC_TYPE_UCHAR) {
                                        return initializer_from_string(array_type,
                                                        &expression->string_literal.value);
                                }
                                break;

                        case EXPR_WIDE_STRING_LITERAL: {
                                type_t *bare_wchar_type = skip_typeref(type_wchar_t);
                                if (get_unqualified_type(element_type) == bare_wchar_type) {
                                        return initializer_from_wide_string(array_type,
                                                        &expression->string_literal.value);
                                }
                                break;
                        }

                        default:
                                break;
                        }
                }
        }

        assign_error_t error = semantic_assign(type, expression);
        if (error == ASSIGN_ERROR_INCOMPATIBLE)
                return NULL;
        report_assign_error(error, type, expression, "initializer",
                            &expression->base.source_position);

        initializer_t *const result = allocate_initializer_zero(INITIALIZER_VALUE);
        result->value.value = create_implicit_cast(expression, type);

        return result;
}

/**
 * Checks if a given expression can be used as an constant initializer.
 */
static bool is_initializer_constant(const expression_t *expression)
{
        return is_constant_expression(expression)
                || is_address_constant(expression);
}

/**
 * Parses an scalar initializer.
 *
 * §6.7.8.11; eat {} without warning
 */
static initializer_t *parse_scalar_initializer(type_t *type,
                                               bool must_be_constant)
{
        /* there might be extra {} hierarchies */
        int braces = 0;
        if (next_if('{')) {
                if (warning.other)
                        warningf(HERE, "extra curly braces around scalar initializer");
                do {
                        ++braces;
                } while (next_if('{'));
        }

        expression_t *expression = parse_assignment_expression();
        mark_vars_read(expression, NULL);
        if (must_be_constant && !is_initializer_constant(expression)) {
                errorf(&expression->base.source_position,
                       "initialisation expression '%E' is not constant",
                       expression);
        }

        initializer_t *initializer = initializer_from_expression(type, expression);

        if (initializer == NULL) {
                errorf(&expression->base.source_position,
                       "expression '%E' (type '%T') doesn't match expected type '%T'",
                       expression, expression->base.type, type);
                /* TODO */
                return NULL;
        }

        bool additional_warning_displayed = false;
        while (braces > 0) {
                next_if(',');
                if (token.type != '}') {
                        if (!additional_warning_displayed && warning.other) {
                                warningf(HERE, "additional elements in scalar initializer");
                                additional_warning_displayed = true;
                        }
                }
                eat_block();
                braces--;
        }

        return initializer;
}

/**
 * An entry in the type path.
 */
typedef struct type_path_entry_t type_path_entry_t;
struct type_path_entry_t {
        type_t *type;       /**< the upper top type. restored to path->top_tye if this entry is popped. */
        union {
                size_t         index;          /**< For array types: the current index. */
                declaration_t *compound_entry; /**< For compound types: the current declaration. */
        } v;
};

/**
 * A type path expression a position inside compound or array types.
 */
typedef struct type_path_t type_path_t;
struct type_path_t {
        type_path_entry_t *path;         /**< An flexible array containing the current path. */
        type_t            *top_type;     /**< type of the element the path points */
        size_t             max_index;    /**< largest index in outermost array */
};

/**
 * Prints a type path for debugging.
 */
static __attribute__((unused)) void debug_print_type_path(
                const type_path_t *path)
{
        size_t len = ARR_LEN(path->path);

        for (size_t i = 0; i < len; ++i) {
                const type_path_entry_t *entry = & path->path[i];

                type_t *type = skip_typeref(entry->type);
                if (is_type_compound(type)) {
                        /* in gcc mode structs can have no members */
                        if (entry->v.compound_entry == NULL) {
                                assert(i == len-1);
                                continue;
                        }
                        fprintf(stderr, ".%s",
                                entry->v.compound_entry->base.symbol->string);
                } else if (is_type_array(type)) {
                        fprintf(stderr, "[%u]", (unsigned) entry->v.index);
                } else {
                        fprintf(stderr, "-INVALID-");
                }
        }
        if (path->top_type != NULL) {
                fprintf(stderr, "  (");
                print_type(path->top_type);
                fprintf(stderr, ")");
        }
}

/**
 * Return the top type path entry, ie. in a path
 * (type).a.b returns the b.
 */
static type_path_entry_t *get_type_path_top(const type_path_t *path)
{
        size_t len = ARR_LEN(path->path);
        assert(len > 0);
        return &path->path[len-1];
}

/**
 * Enlarge the type path by an (empty) element.
 */
static type_path_entry_t *append_to_type_path(type_path_t *path)
{
        size_t len = ARR_LEN(path->path);
        ARR_RESIZE(type_path_entry_t, path->path, len+1);

        type_path_entry_t *result = & path->path[len];
        memset(result, 0, sizeof(result[0]));
        return result;
}

/**
 * Descending into a sub-type. Enter the scope of the current top_type.
 */
static void descend_into_subtype(type_path_t *path)
{
        type_t *orig_top_type = path->top_type;
        type_t *top_type      = skip_typeref(orig_top_type);

        type_path_entry_t *top = append_to_type_path(path);
        top->type              = top_type;

        if (is_type_compound(top_type)) {
                compound_t *compound  = top_type->compound.compound;
                entity_t   *entry     = compound->members.entities;

                if (entry != NULL) {
                        assert(entry->kind == ENTITY_COMPOUND_MEMBER);
                        top->v.compound_entry = &entry->declaration;
                        path->top_type = entry->declaration.type;
                } else {
                        path->top_type = NULL;
                }
        } else if (is_type_array(top_type)) {
                top->v.index   = 0;
                path->top_type = top_type->array.element_type;
        } else {
                assert(!is_type_valid(top_type));
        }
}

/**
 * Pop an entry from the given type path, ie. returning from
 * (type).a.b to (type).a
 */
static void ascend_from_subtype(type_path_t *path)
{
        type_path_entry_t *top = get_type_path_top(path);

        path->top_type = top->type;

        size_t len = ARR_LEN(path->path);
        ARR_RESIZE(type_path_entry_t, path->path, len-1);
}

/**
 * Pop entries from the given type path until the given
 * path level is reached.
 */
static void ascend_to(type_path_t *path, size_t top_path_level)
{
        size_t len = ARR_LEN(path->path);

        while (len > top_path_level) {
                ascend_from_subtype(path);
                len = ARR_LEN(path->path);
        }
}

static bool walk_designator(type_path_t *path, const designator_t *designator,
                            bool used_in_offsetof)
{
        for (; designator != NULL; designator = designator->next) {
                type_path_entry_t *top       = get_type_path_top(path);
                type_t            *orig_type = top->type;

                type_t *type = skip_typeref(orig_type);

                if (designator->symbol != NULL) {
                        symbol_t *symbol = designator->symbol;
                        if (!is_type_compound(type)) {
                                if (is_type_valid(type)) {
                                        errorf(&designator->source_position,
                                               "'.%Y' designator used for non-compound type '%T'",
                                               symbol, orig_type);
                                }

                                top->type             = type_error_type;
                                top->v.compound_entry = NULL;
                                orig_type             = type_error_type;
                        } else {
                                compound_t *compound = type->compound.compound;
                                entity_t   *iter     = compound->members.entities;
                                for (; iter != NULL; iter = iter->base.next) {
                                        if (iter->base.symbol == symbol) {
                                                break;
                                        }
                                }
                                if (iter == NULL) {
                                        errorf(&designator->source_position,
                                               "'%T' has no member named '%Y'", orig_type, symbol);
                                        goto failed;
                                }
                                assert(iter->kind == ENTITY_COMPOUND_MEMBER);
                                if (used_in_offsetof) {
                                        type_t *real_type = skip_typeref(iter->declaration.type);
                                        if (real_type->kind == TYPE_BITFIELD) {
                                                errorf(&designator->source_position,
                                                       "offsetof designator '%Y' must not specify bitfield",
                                                       symbol);
                                                goto failed;
                                        }
                                }

                                top->type             = orig_type;
                                top->v.compound_entry = &iter->declaration;
                                orig_type             = iter->declaration.type;
                        }
                } else {
                        expression_t *array_index = designator->array_index;
                        assert(designator->array_index != NULL);

                        if (!is_type_array(type)) {
                                if (is_type_valid(type)) {
                                        errorf(&designator->source_position,
                                               "[%E] designator used for non-array type '%T'",
                                               array_index, orig_type);
                                }
                                goto failed;
                        }

                        long index = fold_constant_to_int(array_index);
                        if (!used_in_offsetof) {
                                if (index < 0) {
                                        errorf(&designator->source_position,
                                               "array index [%E] must be positive", array_index);
                                } else if (type->array.size_constant) {
                                        long array_size = type->array.size;
                                        if (index >= array_size) {
                                                errorf(&designator->source_position,
                                                       "designator [%E] (%d) exceeds array size %d",
                                                       array_index, index, array_size);
                                        }
                                }
                        }

                        top->type    = orig_type;
                        top->v.index = (size_t) index;
                        orig_type    = type->array.element_type;
                }
                path->top_type = orig_type;

                if (designator->next != NULL) {
                        descend_into_subtype(path);
                }
        }
        return true;

failed:
        return false;
}

static void advance_current_object(type_path_t *path, size_t top_path_level)
{
        type_path_entry_t *top = get_type_path_top(path);

        type_t *type = skip_typeref(top->type);
        if (is_type_union(type)) {
                /* in unions only the first element is initialized */
                top->v.compound_entry = NULL;
        } else if (is_type_struct(type)) {
                declaration_t *entry = top->v.compound_entry;

                entity_t *next_entity = entry->base.next;
                if (next_entity != NULL) {
                        assert(is_declaration(next_entity));
                        entry = &next_entity->declaration;
                } else {
                        entry = NULL;
                }

                top->v.compound_entry = entry;
                if (entry != NULL) {
                        path->top_type = entry->type;
                        return;
                }
        } else if (is_type_array(type)) {
                assert(is_type_array(type));

                top->v.index++;

                if (!type->array.size_constant || top->v.index < type->array.size) {
                        return;
                }
        } else {
                assert(!is_type_valid(type));
                return;
        }

        /* we're past the last member of the current sub-aggregate, try if we
         * can ascend in the type hierarchy and continue with another subobject */
        size_t len = ARR_LEN(path->path);

        if (len > top_path_level) {
                ascend_from_subtype(path);
                advance_current_object(path, top_path_level);
        } else {
                path->top_type = NULL;
        }
}

/**
 * skip any {...} blocks until a closing bracket is reached.
 */
static void skip_initializers(void)
{
        next_if('{');

        while (token.type != '}') {
                if (token.type == T_EOF)
                        return;
                if (token.type == '{') {
                        eat_block();
                        continue;
                }
                next_token();
        }
}

static initializer_t *create_empty_initializer(void)
{
        static initializer_t empty_initializer
                = { .list = { { INITIALIZER_LIST }, 0 } };
        return &empty_initializer;
}

/**
 * Parse a part of an initialiser for a struct or union,
 */
static initializer_t *parse_sub_initializer(type_path_t *path,
                type_t *outer_type, size_t top_path_level,
                parse_initializer_env_t *env)
{
        if (token.type == '}') {
                /* empty initializer */
                return create_empty_initializer();
        }

        type_t *orig_type = path->top_type;
        type_t *type      = NULL;

        if (orig_type == NULL) {
                /* We are initializing an empty compound. */
        } else {
                type = skip_typeref(orig_type);
        }

        initializer_t **initializers = NEW_ARR_F(initializer_t*, 0);

        while (true) {
                designator_t *designator = NULL;
                if (token.type == '.' || token.type == '[') {
                        designator = parse_designation();
                        goto finish_designator;
                } else if (token.type == T_IDENTIFIER && look_ahead(1)->type == ':') {
                        /* GNU-style designator ("identifier: value") */
                        designator = allocate_ast_zero(sizeof(designator[0]));
                        designator->source_position = token.source_position;
                        designator->symbol          = token.symbol;
                        eat(T_IDENTIFIER);
                        eat(':');

finish_designator:
                        /* reset path to toplevel, evaluate designator from there */
                        ascend_to(path, top_path_level);
                        if (!walk_designator(path, designator, false)) {
                                /* can't continue after designation error */
                                goto end_error;
                        }

                        initializer_t *designator_initializer
                                = allocate_initializer_zero(INITIALIZER_DESIGNATOR);
                        designator_initializer->designator.designator = designator;
                        ARR_APP1(initializer_t*, initializers, designator_initializer);

                        orig_type = path->top_type;
                        type      = orig_type != NULL ? skip_typeref(orig_type) : NULL;
                }

                initializer_t *sub;

                if (token.type == '{') {
                        if (type != NULL && is_type_scalar(type)) {
                                sub = parse_scalar_initializer(type, env->must_be_constant);
                        } else {
                                eat('{');
                                if (type == NULL) {
                                        if (env->entity != NULL) {
                                                errorf(HERE,
                                                     "extra brace group at end of initializer for '%Y'",
                                                     env->entity->base.symbol);
                                        } else {
                                                errorf(HERE, "extra brace group at end of initializer");
                                        }
                                } else
                                        descend_into_subtype(path);

                                add_anchor_token('}');
                                sub = parse_sub_initializer(path, orig_type, top_path_level+1,
                                                            env);
                                rem_anchor_token('}');

                                if (type != NULL) {
                                        ascend_from_subtype(path);
                                        expect('}', end_error);
                                } else {
                                        expect('}', end_error);
                                        goto error_parse_next;
                                }
                        }
                } else {
                        /* must be an expression */
                        expression_t *expression = parse_assignment_expression();
                        mark_vars_read(expression, NULL);

                        if (env->must_be_constant && !is_initializer_constant(expression)) {
                                errorf(&expression->base.source_position,
                                       "Initialisation expression '%E' is not constant",
                                       expression);
                        }

                        if (type == NULL) {
                                /* we are already outside, ... */
                                if (outer_type == NULL)
                                        goto error_parse_next;
                                type_t *const outer_type_skip = skip_typeref(outer_type);
                                if (is_type_compound(outer_type_skip) &&
                                    !outer_type_skip->compound.compound->complete) {
                                        goto error_parse_next;
                                }
                                goto error_excess;
                        }

                        /* handle { "string" } special case */
                        if ((expression->kind == EXPR_STRING_LITERAL
                                        || expression->kind == EXPR_WIDE_STRING_LITERAL)
                                        && outer_type != NULL) {
                                sub = initializer_from_expression(outer_type, expression);
                                if (sub != NULL) {
                                        next_if(',');
                                        if (token.type != '}' && warning.other) {
                                                warningf(HERE, "excessive elements in initializer for type '%T'",
                                                                 orig_type);
                                        }
                                        /* TODO: eat , ... */
                                        return sub;
                                }
                        }

                        /* descend into subtypes until expression matches type */
                        while (true) {
                                orig_type = path->top_type;
                                type      = skip_typeref(orig_type);

                                sub = initializer_from_expression(orig_type, expression);
                                if (sub != NULL) {
                                        break;
                                }
                                if (!is_type_valid(type)) {
                                        goto end_error;
                                }
                                if (is_type_scalar(type)) {
                                        errorf(&expression->base.source_position,
                                                        "expression '%E' doesn't match expected type '%T'",
                                                        expression, orig_type);
                                        goto end_error;
                                }

                                descend_into_subtype(path);
                        }
                }

                /* update largest index of top array */
                const type_path_entry_t *first      = &path->path[0];
                type_t                  *first_type = first->type;
                first_type                          = skip_typeref(first_type);
                if (is_type_array(first_type)) {
                        size_t index = first->v.index;
                        if (index > path->max_index)
                                path->max_index = index;
                }

                if (type != NULL) {
                        /* append to initializers list */
                        ARR_APP1(initializer_t*, initializers, sub);
                } else {
error_excess:
                        if (warning.other) {
                                if (env->entity != NULL) {
                                        warningf(HERE, "excess elements in initializer for '%Y'",
                                                 env->entity->base.symbol);
                                } else {
                                        warningf(HERE, "excess elements in initializer");
                                }
                        }
                }

error_parse_next:
                if (token.type == '}') {
                        break;
                }
                expect(',', end_error);
                if (token.type == '}') {
                        break;
                }

                if (type != NULL) {
                        /* advance to the next declaration if we are not at the end */
                        advance_current_object(path, top_path_level);
                        orig_type = path->top_type;
                        if (orig_type != NULL)
                                type = skip_typeref(orig_type);
                        else
                                type = NULL;
                }
        }

        size_t len  = ARR_LEN(initializers);
        size_t size = sizeof(initializer_list_t) + len * sizeof(initializers[0]);
        initializer_t *result = allocate_ast_zero(size);
        result->kind          = INITIALIZER_LIST;
        result->list.len      = len;
        memcpy(&result->list.initializers, initializers,
               len * sizeof(initializers[0]));

        DEL_ARR_F(initializers);
        ascend_to(path, top_path_level+1);

        return result;

end_error:
        skip_initializers();
        DEL_ARR_F(initializers);
        ascend_to(path, top_path_level+1);
        return NULL;
}

static expression_t *make_size_literal(size_t value)
{
        expression_t *literal = allocate_expression_zero(EXPR_LITERAL_INTEGER);
        literal->base.type    = type_size_t;

        char buf[128];
        snprintf(buf, sizeof(buf), "%u", (unsigned) value);
        literal->literal.value = make_string(buf);

        return literal;
}

/**
 * Parses an initializer. Parsers either a compound literal
 * (env->declaration == NULL) or an initializer of a declaration.
 */
static initializer_t *parse_initializer(parse_initializer_env_t *env)
{
        type_t        *type      = skip_typeref(env->type);
        size_t         max_index = 0;
        initializer_t *result;

        if (is_type_scalar(type)) {
                result = parse_scalar_initializer(type, env->must_be_constant);
        } else if (token.type == '{') {
                eat('{');

                type_path_t path;
                memset(&path, 0, sizeof(path));
                path.top_type = env->type;
                path.path     = NEW_ARR_F(type_path_entry_t, 0);

                descend_into_subtype(&path);

                add_anchor_token('}');
                result = parse_sub_initializer(&path, env->type, 1, env);
                rem_anchor_token('}');

                max_index = path.max_index;
                DEL_ARR_F(path.path);

                expect('}', end_error);
        } else {
                /* parse_scalar_initializer() also works in this case: we simply
                 * have an expression without {} around it */
                result = parse_scalar_initializer(type, env->must_be_constant);
        }

        /* §6.7.8:22 array initializers for arrays with unknown size determine
         * the array type size */
        if (is_type_array(type) && type->array.size_expression == NULL
                        && result != NULL) {
                size_t size;
                switch (result->kind) {
                case INITIALIZER_LIST:
                        assert(max_index != 0xdeadbeaf);
                        size = max_index + 1;
                        break;

                case INITIALIZER_STRING:
                        size = result->string.string.size;
                        break;

                case INITIALIZER_WIDE_STRING:
                        size = result->wide_string.string.size;
                        break;

                case INITIALIZER_DESIGNATOR:
                case INITIALIZER_VALUE:
                        /* can happen for parse errors */
                        size = 0;
                        break;

                default:
                        internal_errorf(HERE, "invalid initializer type");
                }

                type_t *new_type = duplicate_type(type);

                new_type->array.size_expression   = make_size_literal(size);
                new_type->array.size_constant     = true;
                new_type->array.has_implicit_size = true;
                new_type->array.size              = size;
                env->type = new_type;
        }

        return result;
end_error:
        return NULL;
}

static void append_entity(scope_t *scope, entity_t *entity)
{
        if (scope->last_entity != NULL) {
                scope->last_entity->base.next = entity;
        } else {
                scope->entities = entity;
        }
        entity->base.parent_entity = current_entity;
        scope->last_entity         = entity;
}


static compound_t *parse_compound_type_specifier(bool is_struct)
{
        eat(is_struct ? T_struct : T_union);

        symbol_t    *symbol   = NULL;
        compound_t  *compound = NULL;
        attribute_t *attributes = NULL;

        if (token.type == T___attribute__) {
                attributes = parse_attributes(NULL);
        }

        entity_kind_tag_t const kind = is_struct ? ENTITY_STRUCT : ENTITY_UNION;
        if (token.type == T_IDENTIFIER) {
                /* the compound has a name, check if we have seen it already */
                symbol = token.symbol;
                next_token();

                entity_t *entity = get_tag(symbol, kind);
                if (entity != NULL) {
                        compound = &entity->compound;
                        if (compound->base.parent_scope != current_scope &&
                            (token.type == '{' || token.type == ';')) {
                                /* we're in an inner scope and have a definition. Shadow
                                 * existing definition in outer scope */
                                compound = NULL;
                        } else if (compound->complete && token.type == '{') {
                                assert(symbol != NULL);
                                errorf(HERE, "multiple definitions of '%s %Y' (previous definition %P)",
                                       is_struct ? "struct" : "union", symbol,
                                       &compound->base.source_position);
                                /* clear members in the hope to avoid further errors */
                                compound->members.entities = NULL;
                        }
                }
        } else if (token.type != '{') {
                if (is_struct) {
                        parse_error_expected("while parsing struct type specifier",
                                             T_IDENTIFIER, '{', NULL);
                } else {
                        parse_error_expected("while parsing union type specifier",
                                             T_IDENTIFIER, '{', NULL);
                }

                return NULL;
        }

        if (compound == NULL) {
                entity_t *entity = allocate_entity_zero(kind);
                compound         = &entity->compound;

                compound->alignment            = 1;
                compound->base.namespc         = NAMESPACE_TAG;
                compound->base.source_position = token.source_position;
                compound->base.symbol          = symbol;
                compound->base.parent_scope    = current_scope;
                if (symbol != NULL) {
                        environment_push(entity);
                }
                append_entity(current_scope, entity);
        }

        if (token.type == '{') {
                parse_compound_type_entries(compound);

                /* ISO/IEC 14882:1998(E) §7.1.3:5 */
                if (symbol == NULL) {
                        assert(anonymous_entity == NULL);
                        anonymous_entity = (entity_t*)compound;
                }
        }

        if (attributes != NULL) {
                handle_entity_attributes(attributes, (entity_t*) compound);
        }

        return compound;
}

static void parse_enum_entries(type_t *const enum_type)
{
        eat('{');

        if (token.type == '}') {
                errorf(HERE, "empty enum not allowed");
                next_token();
                return;
        }

        add_anchor_token('}');
        do {
                if (token.type != T_IDENTIFIER) {
                        parse_error_expected("while parsing enum entry", T_IDENTIFIER, NULL);
                        eat_block();
                        rem_anchor_token('}');
                        return;
                }

                entity_t *entity             = allocate_entity_zero(ENTITY_ENUM_VALUE);
                entity->enum_value.enum_type = enum_type;
                entity->base.symbol          = token.symbol;
                entity->base.source_position = token.source_position;
                next_token();

                if (next_if('=')) {
                        expression_t *value = parse_constant_expression();

                        value = create_implicit_cast(value, enum_type);
                        entity->enum_value.value = value;

                        /* TODO semantic */
                }

                record_entity(entity, false);
        } while (next_if(',') && token.type != '}');
        rem_anchor_token('}');

        expect('}', end_error);

end_error:
        ;
}

static type_t *parse_enum_specifier(void)
{
        entity_t *entity;
        symbol_t *symbol;

        eat(T_enum);
        switch (token.type) {
                case T_IDENTIFIER:
                        symbol = token.symbol;
                        next_token();

                        entity = get_tag(symbol, ENTITY_ENUM);
                        if (entity != NULL) {
                                if (entity->base.parent_scope != current_scope &&
                                                (token.type == '{' || token.type == ';')) {
                                        /* we're in an inner scope and have a definition. Shadow
                                         * existing definition in outer scope */
                                        entity = NULL;
                                } else if (entity->enume.complete && token.type == '{') {
                                        errorf(HERE, "multiple definitions of 'enum %Y' (previous definition %P)",
                                                        symbol, &entity->base.source_position);
                                }
                        }
                        break;

                case '{':
                        entity = NULL;
                        symbol = NULL;
                        break;

                default:
                        parse_error_expected("while parsing enum type specifier",
                                        T_IDENTIFIER, '{', NULL);
                        return NULL;
        }

        if (entity == NULL) {
                entity                       = allocate_entity_zero(ENTITY_ENUM);
                entity->base.namespc         = NAMESPACE_TAG;
                entity->base.source_position = token.source_position;
                entity->base.symbol          = symbol;
                entity->base.parent_scope    = current_scope;
        }

        type_t *const type = allocate_type_zero(TYPE_ENUM);
        type->enumt.enume  = &entity->enume;
        type->enumt.akind  = ATOMIC_TYPE_INT;

        if (token.type == '{') {
                if (symbol != NULL) {
                        environment_push(entity);
                }
                append_entity(current_scope, entity);
                entity->enume.complete = true;

                parse_enum_entries(type);
                parse_attributes(NULL);

                /* ISO/IEC 14882:1998(E) §7.1.3:5 */
                if (symbol == NULL) {
                        assert(anonymous_entity == NULL);
                        anonymous_entity = entity;
                }
        } else if (!entity->enume.complete && !(c_mode & _GNUC)) {
                errorf(HERE, "'enum %Y' used before definition (incomplete enums are a GNU extension)",
                       symbol);
        }

        return type;
}

/**
 * if a symbol is a typedef to another type, return true
 */
static bool is_typedef_symbol(symbol_t *symbol)
{
        const entity_t *const entity = get_entity(symbol, NAMESPACE_NORMAL);
        return entity != NULL && entity->kind == ENTITY_TYPEDEF;
}

static type_t *parse_typeof(void)
{
        eat(T___typeof__);

        type_t *type;

        expect('(', end_error);
        add_anchor_token(')');

        expression_t *expression  = NULL;

        bool old_type_prop     = in_type_prop;
        bool old_gcc_extension = in_gcc_extension;
        in_type_prop           = true;

        while (next_if(T___extension__)) {
                /* This can be a prefix to a typename or an expression. */
                in_gcc_extension = true;
        }
        switch (token.type) {
        case T_IDENTIFIER:
                if (is_typedef_symbol(token.symbol)) {
        TYPENAME_START
                        type = parse_typename();
                } else {
        default:
                        expression = parse_expression();
                        type       = revert_automatic_type_conversion(expression);
                }
                break;
        }
        in_type_prop     = old_type_prop;
        in_gcc_extension = old_gcc_extension;

        rem_anchor_token(')');
        expect(')', end_error);

        type_t *typeof_type              = allocate_type_zero(TYPE_TYPEOF);
        typeof_type->typeoft.expression  = expression;
        typeof_type->typeoft.typeof_type = type;

        return typeof_type;
end_error:
        return NULL;
}

typedef enum specifiers_t {
        SPECIFIER_SIGNED    = 1 << 0,
        SPECIFIER_UNSIGNED  = 1 << 1,
        SPECIFIER_LONG      = 1 << 2,
        SPECIFIER_INT       = 1 << 3,
        SPECIFIER_DOUBLE    = 1 << 4,
        SPECIFIER_CHAR      = 1 << 5,
        SPECIFIER_WCHAR_T   = 1 << 6,
        SPECIFIER_SHORT     = 1 << 7,
        SPECIFIER_LONG_LONG = 1 << 8,
        SPECIFIER_FLOAT     = 1 << 9,
        SPECIFIER_BOOL      = 1 << 10,
        SPECIFIER_VOID      = 1 << 11,
        SPECIFIER_INT8      = 1 << 12,
        SPECIFIER_INT16     = 1 << 13,
        SPECIFIER_INT32     = 1 << 14,
        SPECIFIER_INT64     = 1 << 15,
        SPECIFIER_INT128    = 1 << 16,
        SPECIFIER_COMPLEX   = 1 << 17,
        SPECIFIER_IMAGINARY = 1 << 18,
} specifiers_t;

static type_t *create_builtin_type(symbol_t *const symbol,
                                   type_t *const real_type)
{
        type_t *type            = allocate_type_zero(TYPE_BUILTIN);
        type->builtin.symbol    = symbol;
        type->builtin.real_type = real_type;
        return identify_new_type(type);
}

static type_t *get_typedef_type(symbol_t *symbol)
{
        entity_t *entity = get_entity(symbol, NAMESPACE_NORMAL);
        if (entity == NULL || entity->kind != ENTITY_TYPEDEF)
                return NULL;

        type_t *type            = allocate_type_zero(TYPE_TYPEDEF);
        type->typedeft.typedefe = &entity->typedefe;

        return type;
}

static attribute_t *parse_attribute_ms_property(attribute_t *attribute)
{
        expect('(', end_error);

        attribute_property_argument_t *property
                = allocate_ast_zero(sizeof(*property));

        do {
                if (token.type != T_IDENTIFIER) {
                        parse_error_expected("while parsing property declspec",
                                             T_IDENTIFIER, NULL);
                        goto end_error;
                }

                bool is_put;
                symbol_t *symbol = token.symbol;
                next_token();
                if (strcmp(symbol->string, "put") == 0) {
                        is_put = true;
                } else if (strcmp(symbol->string, "get") == 0) {
                        is_put = false;
                } else {
                        errorf(HERE, "expected put or get in property declspec");
                        goto end_error;
                }
                expect('=', end_error);
                if (token.type != T_IDENTIFIER) {
                        parse_error_expected("while parsing property declspec",
                                             T_IDENTIFIER, NULL);
                        goto end_error;
                }
                if (is_put) {
                        property->put_symbol = token.symbol;
                } else {
                        property->get_symbol = token.symbol;
                }
                next_token();
        } while (next_if(','));

        attribute->a.property = property;

        expect(')', end_error);

end_error:
        return attribute;
}

static attribute_t *parse_microsoft_extended_decl_modifier_single(void)
{
        attribute_kind_t kind = ATTRIBUTE_UNKNOWN;
        if (next_if(T_restrict)) {
                kind = ATTRIBUTE_MS_RESTRICT;
        } else if (token.type == T_IDENTIFIER) {
                const char *name = token.symbol->string;
                next_token();
                for (attribute_kind_t k = ATTRIBUTE_MS_FIRST; k <= ATTRIBUTE_MS_LAST;
                     ++k) {
                        const char *attribute_name = get_attribute_name(k);
                        if (attribute_name != NULL && strcmp(attribute_name, name) == 0) {
                                kind = k;
                                break;
                        }
                }

                if (kind == ATTRIBUTE_UNKNOWN && warning.attribute) {
                        warningf(HERE, "unknown __declspec '%s' ignored", name);
                }
        } else {
                parse_error_expected("while parsing __declspec", T_IDENTIFIER, NULL);
                return NULL;
        }

        attribute_t *attribute = allocate_attribute_zero(kind);

        if (kind == ATTRIBUTE_MS_PROPERTY) {
                return parse_attribute_ms_property(attribute);
        }

        /* parse arguments */
        if (next_if('('))
                attribute->a.arguments = parse_attribute_arguments();

        return attribute;
}

static attribute_t *parse_microsoft_extended_decl_modifier(attribute_t *first)
{
        eat(T__declspec);

        expect('(', end_error);

        if (next_if(')'))
                return NULL;

        add_anchor_token(')');

        attribute_t **anchor = &first;
        do {
                while (*anchor != NULL)
                        anchor = &(*anchor)->next;

                attribute_t *attribute
                        = parse_microsoft_extended_decl_modifier_single();
                if (attribute == NULL)
                        goto end_error;

                *anchor = attribute;
                anchor  = &attribute->next;
        } while (next_if(','));

        rem_anchor_token(')');
        expect(')', end_error);
        return first;

end_error:
        rem_anchor_token(')');
        return first;
}

static entity_t *create_error_entity(symbol_t *symbol, entity_kind_tag_t kind)
{
        entity_t *entity             = allocate_entity_zero(kind);
        entity->base.source_position = *HERE;
        entity->base.symbol          = symbol;
        if (is_declaration(entity)) {
                entity->declaration.type     = type_error_type;
                entity->declaration.implicit = true;
        } else if (kind == ENTITY_TYPEDEF) {
                entity->typedefe.type    = type_error_type;
                entity->typedefe.builtin = true;
        }
        if (kind != ENTITY_COMPOUND_MEMBER)
                record_entity(entity, false);
        return entity;
}

static void parse_declaration_specifiers(declaration_specifiers_t *specifiers)
{
        type_t            *type              = NULL;
        type_qualifiers_t  qualifiers        = TYPE_QUALIFIER_NONE;
        unsigned           type_specifiers   = 0;
        bool               newtype           = false;
        bool               saw_error         = false;
        bool               old_gcc_extension = in_gcc_extension;

        specifiers->source_position = token.source_position;

        while (true) {
                specifiers->attributes = parse_attributes(specifiers->attributes);

                switch (token.type) {
                /* storage class */
#define MATCH_STORAGE_CLASS(token, class)                                  \
                case token:                                                        \
                        if (specifiers->storage_class != STORAGE_CLASS_NONE) {         \
                                errorf(HERE, "multiple storage classes in declaration specifiers"); \
                        }                                                              \
                        specifiers->storage_class = class;                             \
                        if (specifiers->thread_local)                                  \
                                goto check_thread_storage_class;                           \
                        next_token();                                                  \
                        break;

                MATCH_STORAGE_CLASS(T_typedef,  STORAGE_CLASS_TYPEDEF)
                MATCH_STORAGE_CLASS(T_extern,   STORAGE_CLASS_EXTERN)
                MATCH_STORAGE_CLASS(T_static,   STORAGE_CLASS_STATIC)
                MATCH_STORAGE_CLASS(T_auto,     STORAGE_CLASS_AUTO)
                MATCH_STORAGE_CLASS(T_register, STORAGE_CLASS_REGISTER)

                case T__declspec:
                        specifiers->attributes
                                = parse_microsoft_extended_decl_modifier(specifiers->attributes);
                        break;

                case T___thread:
                        if (specifiers->thread_local) {
                                errorf(HERE, "duplicate '__thread'");
                        } else {
                                specifiers->thread_local = true;
check_thread_storage_class:
                                switch (specifiers->storage_class) {
                                        case STORAGE_CLASS_EXTERN:
                                        case STORAGE_CLASS_NONE:
                                        case STORAGE_CLASS_STATIC:
                                                break;

                                                char const* wrong;
                                        case STORAGE_CLASS_AUTO:     wrong = "auto";     goto wrong_thread_storage_class;
                                        case STORAGE_CLASS_REGISTER: wrong = "register"; goto wrong_thread_storage_class;
                                        case STORAGE_CLASS_TYPEDEF:  wrong = "typedef";  goto wrong_thread_storage_class;
wrong_thread_storage_class:
                                                errorf(HERE, "'__thread' used with '%s'", wrong);
                                                break;
                                }
                        }
                        next_token();
                        break;

                /* type qualifiers */
#define MATCH_TYPE_QUALIFIER(token, qualifier)                          \
                case token:                                                     \
                        qualifiers |= qualifier;                                    \
                        next_token();                                               \
                        break

                MATCH_TYPE_QUALIFIER(T_const,    TYPE_QUALIFIER_CONST);
                MATCH_TYPE_QUALIFIER(T_restrict, TYPE_QUALIFIER_RESTRICT);
                MATCH_TYPE_QUALIFIER(T_volatile, TYPE_QUALIFIER_VOLATILE);
                MATCH_TYPE_QUALIFIER(T__w64,     TYPE_QUALIFIER_W64);
                MATCH_TYPE_QUALIFIER(T___ptr32,  TYPE_QUALIFIER_PTR32);
                MATCH_TYPE_QUALIFIER(T___ptr64,  TYPE_QUALIFIER_PTR64);
                MATCH_TYPE_QUALIFIER(T___uptr,   TYPE_QUALIFIER_UPTR);
                MATCH_TYPE_QUALIFIER(T___sptr,   TYPE_QUALIFIER_SPTR);

                case T___extension__:
                        next_token();
                        in_gcc_extension = true;
                        break;

                /* type specifiers */
#define MATCH_SPECIFIER(token, specifier, name)                         \
                case token:                                                     \
                        if (type_specifiers & specifier) {                           \
                                errorf(HERE, "multiple " name " type specifiers given"); \
                        } else {                                                    \
                                type_specifiers |= specifier;                           \
                        }                                                           \
                        next_token();                                               \
                        break

                MATCH_SPECIFIER(T__Bool,      SPECIFIER_BOOL,      "_Bool");
                MATCH_SPECIFIER(T__Complex,   SPECIFIER_COMPLEX,   "_Complex");
                MATCH_SPECIFIER(T__Imaginary, SPECIFIER_IMAGINARY, "_Imaginary");
                MATCH_SPECIFIER(T__int128,    SPECIFIER_INT128,    "_int128");
                MATCH_SPECIFIER(T__int16,     SPECIFIER_INT16,     "_int16");
                MATCH_SPECIFIER(T__int32,     SPECIFIER_INT32,     "_int32");
                MATCH_SPECIFIER(T__int64,     SPECIFIER_INT64,     "_int64");
                MATCH_SPECIFIER(T__int8,      SPECIFIER_INT8,      "_int8");
                MATCH_SPECIFIER(T_bool,       SPECIFIER_BOOL,      "bool");
                MATCH_SPECIFIER(T_char,       SPECIFIER_CHAR,      "char");
                MATCH_SPECIFIER(T_double,     SPECIFIER_DOUBLE,    "double");
                MATCH_SPECIFIER(T_float,      SPECIFIER_FLOAT,     "float");
                MATCH_SPECIFIER(T_int,        SPECIFIER_INT,       "int");
                MATCH_SPECIFIER(T_short,      SPECIFIER_SHORT,     "short");
                MATCH_SPECIFIER(T_signed,     SPECIFIER_SIGNED,    "signed");
                MATCH_SPECIFIER(T_unsigned,   SPECIFIER_UNSIGNED,  "unsigned");
                MATCH_SPECIFIER(T_void,       SPECIFIER_VOID,      "void");
                MATCH_SPECIFIER(T_wchar_t,    SPECIFIER_WCHAR_T,   "wchar_t");

                case T_inline:
                        next_token();
                        specifiers->is_inline = true;
                        break;

#if 0
                case T__forceinline:
                        next_token();
                        specifiers->modifiers |= DM_FORCEINLINE;
                        break;
#endif

                case T_long:
                        if (type_specifiers & SPECIFIER_LONG_LONG) {
                                errorf(HERE, "multiple type specifiers given");
                        } else if (type_specifiers & SPECIFIER_LONG) {
                                type_specifiers |= SPECIFIER_LONG_LONG;
                        } else {
                                type_specifiers |= SPECIFIER_LONG;
                        }
                        next_token();
                        break;

#define CHECK_DOUBLE_TYPE()        \
                        if ( type != NULL)     \
                                errorf(HERE, "multiple data types in declaration specifiers");

                case T_struct:
                        CHECK_DOUBLE_TYPE();
                        type = allocate_type_zero(TYPE_COMPOUND_STRUCT);

                        type->compound.compound = parse_compound_type_specifier(true);
                        break;
                case T_union:
                        CHECK_DOUBLE_TYPE();
                        type = allocate_type_zero(TYPE_COMPOUND_UNION);
                        type->compound.compound = parse_compound_type_specifier(false);
                        break;
                case T_enum:
                        CHECK_DOUBLE_TYPE();
                        type = parse_enum_specifier();
                        break;
                case T___typeof__:
                        CHECK_DOUBLE_TYPE();
                        type = parse_typeof();
                        break;
                case T___builtin_va_list:
                        CHECK_DOUBLE_TYPE();
                        type = duplicate_type(type_valist);
                        next_token();
                        break;

                case T_IDENTIFIER: {
                        /* only parse identifier if we haven't found a type yet */
                        if (type != NULL || type_specifiers != 0) {
                                /* Be somewhat resilient to typos like 'unsigned lng* f()' in a
                                 * declaration, so it doesn't generate errors about expecting '(' or
                                 * '{' later on. */
                                switch (look_ahead(1)->type) {
                                        STORAGE_CLASSES
                                        TYPE_SPECIFIERS
                                        case T_const:
                                        case T_restrict:
                                        case T_volatile:
                                        case T_inline:
                                        case T__forceinline: /* ^ DECLARATION_START except for __attribute__ */
                                        case T_IDENTIFIER:
                                        case '&':
                                        case '*':
                                                errorf(HERE, "discarding stray %K in declaration specifier", &token);
                                                next_token();
                                                continue;

                                        default:
                                                goto finish_specifiers;
                                }
                        }

                        type_t *const typedef_type = get_typedef_type(token.symbol);
                        if (typedef_type == NULL) {
                                /* Be somewhat resilient to typos like 'vodi f()' at the beginning of a
                                 * declaration, so it doesn't generate 'implicit int' followed by more
                                 * errors later on. */
                                token_type_t const la1_type = (token_type_t)look_ahead(1)->type;
                                switch (la1_type) {
                                        DECLARATION_START
                                        case T_IDENTIFIER:
                                        case '&':
                                        case '*': {
                                                errorf(HERE, "%K does not name a type", &token);

                                                entity_t *entity =
                                                        create_error_entity(token.symbol, ENTITY_TYPEDEF);

                                                type = allocate_type_zero(TYPE_TYPEDEF);
                                                type->typedeft.typedefe = &entity->typedefe;

                                                next_token();
                                                saw_error = true;
                                                if (la1_type == '&' || la1_type == '*')
                                                        goto finish_specifiers;
                                                continue;
                                        }

                                        default:
                                                goto finish_specifiers;
                                }
                        }

                        next_token();
                        type = typedef_type;
                        break;
                }

                /* function specifier */
                default:
                        goto finish_specifiers;
                }
        }

finish_specifiers:
        specifiers->attributes = parse_attributes(specifiers->attributes);

        in_gcc_extension = old_gcc_extension;

        if (type == NULL || (saw_error && type_specifiers != 0)) {
                atomic_type_kind_t atomic_type;

                /* match valid basic types */
                switch (type_specifiers) {
                case SPECIFIER_VOID:
                        atomic_type = ATOMIC_TYPE_VOID;
                        break;
                case SPECIFIER_WCHAR_T:
                        atomic_type = ATOMIC_TYPE_WCHAR_T;
                        break;
                case SPECIFIER_CHAR:
                        atomic_type = ATOMIC_TYPE_CHAR;
                        break;
                case SPECIFIER_SIGNED | SPECIFIER_CHAR:
                        atomic_type = ATOMIC_TYPE_SCHAR;
                        break;
                case SPECIFIER_UNSIGNED | SPECIFIER_CHAR:
                        atomic_type = ATOMIC_TYPE_UCHAR;
                        break;
                case SPECIFIER_SHORT:
                case SPECIFIER_SIGNED | SPECIFIER_SHORT:
                case SPECIFIER_SHORT | SPECIFIER_INT:
                case SPECIFIER_SIGNED | SPECIFIER_SHORT | SPECIFIER_INT:
                        atomic_type = ATOMIC_TYPE_SHORT;
                        break;
                case SPECIFIER_UNSIGNED | SPECIFIER_SHORT:
                case SPECIFIER_UNSIGNED | SPECIFIER_SHORT | SPECIFIER_INT:
                        atomic_type = ATOMIC_TYPE_USHORT;
                        break;
                case SPECIFIER_INT:
                case SPECIFIER_SIGNED:
                case SPECIFIER_SIGNED | SPECIFIER_INT:
                        atomic_type = ATOMIC_TYPE_INT;
                        break;
                case SPECIFIER_UNSIGNED:
                case SPECIFIER_UNSIGNED | SPECIFIER_INT:
                        atomic_type = ATOMIC_TYPE_UINT;
                        break;
                case SPECIFIER_LONG:
                case SPECIFIER_SIGNED | SPECIFIER_LONG:
                case SPECIFIER_LONG | SPECIFIER_INT:
                case SPECIFIER_SIGNED | SPECIFIER_LONG | SPECIFIER_INT:
                        atomic_type = ATOMIC_TYPE_LONG;
                        break;
                case SPECIFIER_UNSIGNED | SPECIFIER_LONG:
                case SPECIFIER_UNSIGNED | SPECIFIER_LONG | SPECIFIER_INT:
                        atomic_type = ATOMIC_TYPE_ULONG;
                        break;

                case SPECIFIER_LONG | SPECIFIER_LONG_LONG:
                case SPECIFIER_SIGNED | SPECIFIER_LONG | SPECIFIER_LONG_LONG:
                case SPECIFIER_LONG | SPECIFIER_LONG_LONG | SPECIFIER_INT:
                case SPECIFIER_SIGNED | SPECIFIER_LONG | SPECIFIER_LONG_LONG
                        | SPECIFIER_INT:
                        atomic_type = ATOMIC_TYPE_LONGLONG;
                        goto warn_about_long_long;

                case SPECIFIER_UNSIGNED | SPECIFIER_LONG | SPECIFIER_LONG_LONG:
                case SPECIFIER_UNSIGNED | SPECIFIER_LONG | SPECIFIER_LONG_LONG
                        | SPECIFIER_INT:
                        atomic_type = ATOMIC_TYPE_ULONGLONG;
warn_about_long_long:
                        if (warning.long_long) {
                                warningf(&specifiers->source_position,
                                         "ISO C90 does not support 'long long'");
                        }
                        break;

                case SPECIFIER_UNSIGNED | SPECIFIER_INT8:
                        atomic_type = unsigned_int8_type_kind;
                        break;

                case SPECIFIER_UNSIGNED | SPECIFIER_INT16:
                        atomic_type = unsigned_int16_type_kind;
                        break;

                case SPECIFIER_UNSIGNED | SPECIFIER_INT32:
                        atomic_type = unsigned_int32_type_kind;
                        break;

                case SPECIFIER_UNSIGNED | SPECIFIER_INT64:
                        atomic_type = unsigned_int64_type_kind;
                        break;

                case SPECIFIER_UNSIGNED | SPECIFIER_INT128:
                        atomic_type = unsigned_int128_type_kind;
                        break;

                case SPECIFIER_INT8:
                case SPECIFIER_SIGNED | SPECIFIER_INT8:
                        atomic_type = int8_type_kind;
                        break;

                case SPECIFIER_INT16:
                case SPECIFIER_SIGNED | SPECIFIER_INT16:
                        atomic_type = int16_type_kind;
                        break;

                case SPECIFIER_INT32:
                case SPECIFIER_SIGNED | SPECIFIER_INT32:
                        atomic_type = int32_type_kind;
                        break;

                case SPECIFIER_INT64:
                case SPECIFIER_SIGNED | SPECIFIER_INT64:
                        atomic_type = int64_type_kind;
                        break;

                case SPECIFIER_INT128:
                case SPECIFIER_SIGNED | SPECIFIER_INT128:
                        atomic_type = int128_type_kind;
                        break;

                case SPECIFIER_FLOAT:
                        atomic_type = ATOMIC_TYPE_FLOAT;
                        break;
                case SPECIFIER_DOUBLE:
                        atomic_type = ATOMIC_TYPE_DOUBLE;
                        break;
                case SPECIFIER_LONG | SPECIFIER_DOUBLE:
                        atomic_type = ATOMIC_TYPE_LONG_DOUBLE;
                        break;
                case SPECIFIER_BOOL:
                        atomic_type = ATOMIC_TYPE_BOOL;
                        break;
                case SPECIFIER_FLOAT | SPECIFIER_COMPLEX:
                case SPECIFIER_FLOAT | SPECIFIER_IMAGINARY:
                        atomic_type = ATOMIC_TYPE_FLOAT;
                        break;
                case SPECIFIER_DOUBLE | SPECIFIER_COMPLEX:
                case SPECIFIER_DOUBLE | SPECIFIER_IMAGINARY:
                        atomic_type = ATOMIC_TYPE_DOUBLE;
                        break;
                case SPECIFIER_LONG | SPECIFIER_DOUBLE | SPECIFIER_COMPLEX:
                case SPECIFIER_LONG | SPECIFIER_DOUBLE | SPECIFIER_IMAGINARY:
                        atomic_type = ATOMIC_TYPE_LONG_DOUBLE;
                        break;
                default:
                        /* invalid specifier combination, give an error message */
                        if (type_specifiers == 0) {
                                if (saw_error)
                                        goto end_error;

                                /* ISO/IEC 14882:1998(E) §C.1.5:4 */
                                if (!(c_mode & _CXX) && !strict_mode) {
                                        if (warning.implicit_int) {
                                                warningf(HERE, "no type specifiers in declaration, using 'int'");
                                        }
                                        atomic_type = ATOMIC_TYPE_INT;
                                        break;
                                } else {
                                        errorf(HERE, "no type specifiers given in declaration");
                                }
                        } else if ((type_specifiers & SPECIFIER_SIGNED) &&
                                  (type_specifiers & SPECIFIER_UNSIGNED)) {
                                errorf(HERE, "signed and unsigned specifiers given");
                        } else if (type_specifiers & (SPECIFIER_SIGNED | SPECIFIER_UNSIGNED)) {
                                errorf(HERE, "only integer types can be signed or unsigned");
                        } else {
                                errorf(HERE, "multiple datatypes in declaration");
                        }
                        goto end_error;
                }

                if (type_specifiers & SPECIFIER_COMPLEX) {
                        type                = allocate_type_zero(TYPE_COMPLEX);
                        type->complex.akind = atomic_type;
                } else if (type_specifiers & SPECIFIER_IMAGINARY) {
                        type                  = allocate_type_zero(TYPE_IMAGINARY);
                        type->imaginary.akind = atomic_type;
                } else {
                        type                 = allocate_type_zero(TYPE_ATOMIC);
                        type->atomic.akind   = atomic_type;
                }
                newtype = true;
        } else if (type_specifiers != 0) {
                errorf(HERE, "multiple datatypes in declaration");
        }

        /* FIXME: check type qualifiers here */
        type->base.qualifiers = qualifiers;

        if (newtype) {
                type = identify_new_type(type);
        } else {
                type = typehash_insert(type);
        }

        if (specifiers->attributes != NULL)
                type = handle_type_attributes(specifiers->attributes, type);
        specifiers->type = type;
        return;

end_error:
        specifiers->type = type_error_type;
}

static type_qualifiers_t parse_type_qualifiers(void)
{
        type_qualifiers_t qualifiers = TYPE_QUALIFIER_NONE;

        while (true) {
                switch (token.type) {
                /* type qualifiers */
                MATCH_TYPE_QUALIFIER(T_const,    TYPE_QUALIFIER_CONST);
                MATCH_TYPE_QUALIFIER(T_restrict, TYPE_QUALIFIER_RESTRICT);
                MATCH_TYPE_QUALIFIER(T_volatile, TYPE_QUALIFIER_VOLATILE);
                /* microsoft extended type modifiers */
                MATCH_TYPE_QUALIFIER(T__w64,     TYPE_QUALIFIER_W64);
                MATCH_TYPE_QUALIFIER(T___ptr32,  TYPE_QUALIFIER_PTR32);
                MATCH_TYPE_QUALIFIER(T___ptr64,  TYPE_QUALIFIER_PTR64);
                MATCH_TYPE_QUALIFIER(T___uptr,   TYPE_QUALIFIER_UPTR);
                MATCH_TYPE_QUALIFIER(T___sptr,   TYPE_QUALIFIER_SPTR);

                default:
                        return qualifiers;
                }
        }
}

/**
 * Parses an K&R identifier list
 */
static void parse_identifier_list(scope_t *scope)
{
        do {
                entity_t *entity = allocate_entity_zero(ENTITY_PARAMETER);
                entity->base.source_position = token.source_position;
                entity->base.namespc         = NAMESPACE_NORMAL;
                entity->base.symbol          = token.symbol;
                /* a K&R parameter has no type, yet */
                next_token();

                if (scope != NULL)
                        append_entity(scope, entity);
        } while (next_if(',') && token.type == T_IDENTIFIER);
}

static entity_t *parse_parameter(void)
{
        declaration_specifiers_t specifiers;
        memset(&specifiers, 0, sizeof(specifiers));

        parse_declaration_specifiers(&specifiers);

        entity_t *entity = parse_declarator(&specifiers,
                        DECL_MAY_BE_ABSTRACT | DECL_IS_PARAMETER);
        anonymous_entity = NULL;
        return entity;
}

static void semantic_parameter_incomplete(const entity_t *entity)
{
        assert(entity->kind == ENTITY_PARAMETER);

        /* §6.7.5.3:4  After adjustment, the parameters in a parameter type
         *             list in a function declarator that is part of a
         *             definition of that function shall not have
         *             incomplete type. */
        type_t *type = skip_typeref(entity->declaration.type);
        if (is_type_incomplete(type)) {
                errorf(&entity->base.source_position,
                                "parameter '%#T' has incomplete type",
                                entity->declaration.type, entity->base.symbol);
        }
}

static bool has_parameters(void)
{
        /* func(void) is not a parameter */
        if (token.type == T_IDENTIFIER) {
                entity_t const *const entity = get_entity(token.symbol, NAMESPACE_NORMAL);
                if (entity == NULL)
                        return true;
                if (entity->kind != ENTITY_TYPEDEF)
                        return true;
                if (skip_typeref(entity->typedefe.type) != type_void)
                        return true;
        } else if (token.type != T_void) {
                return true;
        }
        if (look_ahead(1)->type != ')')
                return true;
        next_token();
        return false;
}

/**
 * Parses function type parameters (and optionally creates variable_t entities
 * for them in a scope)
 */
static void parse_parameters(function_type_t *type, scope_t *scope)
{
        eat('(');
        add_anchor_token(')');
        int saved_comma_state = save_and_reset_anchor_state(',');

        if (token.type == T_IDENTIFIER &&
            !is_typedef_symbol(token.symbol)) {
                token_type_t la1_type = (token_type_t)look_ahead(1)->type;
                if (la1_type == ',' || la1_type == ')') {
                        type->kr_style_parameters = true;
                        parse_identifier_list(scope);
                        goto parameters_finished;
                }
        }

        if (token.type == ')') {
                /* ISO/IEC 14882:1998(E) §C.1.6:1 */
                if (!(c_mode & _CXX))
                        type->unspecified_parameters = true;
                goto parameters_finished;
        }

        if (has_parameters()) {
                function_parameter_t **anchor = &type->parameters;
                do {
                        switch (token.type) {
                        case T_DOTDOTDOT:
                                next_token();
                                type->variadic = true;
                                goto parameters_finished;

                        case T_IDENTIFIER:
                        case T___extension__:
                        DECLARATION_START
                        {
                                entity_t *entity = parse_parameter();
                                if (entity->kind == ENTITY_TYPEDEF) {
                                        errorf(&entity->base.source_position,
                                                        "typedef not allowed as function parameter");
                                        break;
                                }
                                assert(is_declaration(entity));

                                semantic_parameter_incomplete(entity);

                                function_parameter_t *const parameter =
                                        allocate_parameter(entity->declaration.type);

                                if (scope != NULL) {
                                        append_entity(scope, entity);
                                }

                                *anchor = parameter;
                                anchor  = &parameter->next;
                                break;
                        }

                        default:
                                goto parameters_finished;
                        }
                } while (next_if(','));
        }


parameters_finished:
        rem_anchor_token(')');
        expect(')', end_error);

end_error:
        restore_anchor_state(',', saved_comma_state);
}

typedef enum construct_type_kind_t {
        CONSTRUCT_INVALID,
        CONSTRUCT_POINTER,
        CONSTRUCT_REFERENCE,
        CONSTRUCT_FUNCTION,
        CONSTRUCT_ARRAY
} construct_type_kind_t;

typedef union construct_type_t construct_type_t;

typedef struct construct_type_base_t {
        construct_type_kind_t  kind;
        construct_type_t      *next;
} construct_type_base_t;

typedef struct parsed_pointer_t {
        construct_type_base_t  base;
        type_qualifiers_t      type_qualifiers;
        variable_t            *base_variable;  /**< MS __based extension. */
} parsed_pointer_t;

typedef struct parsed_reference_t {
        construct_type_base_t base;
} parsed_reference_t;

typedef struct construct_function_type_t {
        construct_type_base_t  base;
        type_t                *function_type;
} construct_function_type_t;

typedef struct parsed_array_t {
        construct_type_base_t  base;
        type_qualifiers_t      type_qualifiers;
        bool                   is_static;
        bool                   is_variable;
        expression_t          *size;
} parsed_array_t;

union construct_type_t {
        construct_type_kind_t     kind;
        construct_type_base_t     base;
        parsed_pointer_t          pointer;
        parsed_reference_t        reference;
        construct_function_type_t function;
        parsed_array_t            array;
};

static construct_type_t *allocate_declarator_zero(construct_type_kind_t const kind, size_t const size)
{
        construct_type_t *const cons = obstack_alloc(&temp_obst, size);
        memset(cons, 0, size);
        cons->kind = kind;
        return cons;
}

/* §6.7.5.1 */
static construct_type_t *parse_pointer_declarator(void)
{
        eat('*');

        construct_type_t *const cons = allocate_declarator_zero(CONSTRUCT_POINTER, sizeof(parsed_pointer_t));
        cons->pointer.type_qualifiers = parse_type_qualifiers();
        //cons->pointer.base_variable   = base_variable;

        return cons;
}

/* ISO/IEC 14882:1998(E) §8.3.2 */
static construct_type_t *parse_reference_declarator(void)
{
        eat('&');

        if (!(c_mode & _CXX))
                errorf(HERE, "references are only available for C++");

        construct_type_t *const cons = allocate_declarator_zero(CONSTRUCT_REFERENCE, sizeof(parsed_reference_t));

        return cons;
}

/* §6.7.5.2 */
static construct_type_t *parse_array_declarator(void)
{
        eat('[');
        add_anchor_token(']');

        construct_type_t *const cons  = allocate_declarator_zero(CONSTRUCT_ARRAY, sizeof(parsed_array_t));
        parsed_array_t   *const array = &cons->array;

        bool is_static = next_if(T_static);

        type_qualifiers_t type_qualifiers = parse_type_qualifiers();

        if (!is_static)
                is_static = next_if(T_static);

        array->type_qualifiers = type_qualifiers;
        array->is_static       = is_static;

        expression_t *size = NULL;
        if (token.type == '*' && look_ahead(1)->type == ']') {
                array->is_variable = true;
                next_token();
        } else if (token.type != ']') {
                size = parse_assignment_expression();

                /* §6.7.5.2:1  Array size must have integer type */
                type_t *const orig_type = size->base.type;
                type_t *const type      = skip_typeref(orig_type);
                if (!is_type_integer(type) && is_type_valid(type)) {
                        errorf(&size->base.source_position,
                               "array size '%E' must have integer type but has type '%T'",
                               size, orig_type);
                }

                array->size = size;
                mark_vars_read(size, NULL);
        }

        if (is_static && size == NULL)
                errorf(HERE, "static array parameters require a size");

        rem_anchor_token(']');
        expect(']', end_error);

end_error:
        return cons;
}

/* §6.7.5.3 */
static construct_type_t *parse_function_declarator(scope_t *scope)
{
        type_t          *type  = allocate_type_zero(TYPE_FUNCTION);
        function_type_t *ftype = &type->function;

        ftype->linkage            = current_linkage;
        ftype->calling_convention = CC_DEFAULT;

        parse_parameters(ftype, scope);

        construct_type_t *const cons = allocate_declarator_zero(CONSTRUCT_FUNCTION, sizeof(construct_function_type_t));
        cons->function.function_type = type;

        return cons;
}

typedef struct parse_declarator_env_t {
        bool               may_be_abstract : 1;
        bool               must_be_abstract : 1;
        decl_modifiers_t   modifiers;
        symbol_t          *symbol;
        source_position_t  source_position;
        scope_t            parameters;
        attribute_t       *attributes;
} parse_declarator_env_t;

/* §6.7.5 */
static construct_type_t *parse_inner_declarator(parse_declarator_env_t *env)
{
        /* construct a single linked list of construct_type_t's which describe
         * how to construct the final declarator type */
        construct_type_t  *first      = NULL;
        construct_type_t **anchor     = &first;

        env->attributes = parse_attributes(env->attributes);

        for (;;) {
                construct_type_t *type;
                //variable_t       *based = NULL; /* MS __based extension */
                switch (token.type) {
                        case '&':
                                type = parse_reference_declarator();
                                break;

                        case T__based: {
                                panic("based not supported anymore");
                                /* FALLTHROUGH */
                        }

                        case '*':
                                type = parse_pointer_declarator();
                                break;

                        default:
                                goto ptr_operator_end;
                }

                *anchor = type;
                anchor  = &type->base.next;

                /* TODO: find out if this is correct */
                env->attributes = parse_attributes(env->attributes);
        }

ptr_operator_end: ;
        construct_type_t *inner_types = NULL;

        switch (token.type) {
        case T_IDENTIFIER:
                if (env->must_be_abstract) {
                        errorf(HERE, "no identifier expected in typename");
                } else {
                        env->symbol          = token.symbol;
                        env->source_position = token.source_position;
                }
                next_token();
                break;
        case '(':
                /* §6.7.6:2 footnote 126:  Empty parentheses in a type name are
                 * interpreted as ``function with no parameter specification'', rather
                 * than redundant parentheses around the omitted identifier. */
                if (look_ahead(1)->type != ')') {
                        next_token();
                        add_anchor_token(')');
                        inner_types = parse_inner_declarator(env);
                        if (inner_types != NULL) {
                                /* All later declarators only modify the return type */
                                env->must_be_abstract = true;
                        }
                        rem_anchor_token(')');
                        expect(')', end_error);
                } else if (!env->may_be_abstract) {
                        errorf(HERE, "declarator must have a name");
                        goto error_out;
                }
                break;
        default:
                if (env->may_be_abstract)
                        break;
                parse_error_expected("while parsing declarator", T_IDENTIFIER, '(', NULL);
error_out:
                eat_until_anchor();
                return NULL;
        }

        construct_type_t **const p = anchor;

        for (;;) {
                construct_type_t *type;
                switch (token.type) {
                case '(': {
                        scope_t *scope = NULL;
                        if (!env->must_be_abstract) {
                                scope = &env->parameters;
                        }

                        type = parse_function_declarator(scope);
                        break;
                }
                case '[':
                        type = parse_array_declarator();
                        break;
                default:
                        goto declarator_finished;
                }

                /* insert in the middle of the list (at p) */
                type->base.next = *p;
                *p              = type;
                if (anchor == p)
                        anchor = &type->base.next;
        }

declarator_finished:
        /* append inner_types at the end of the list, we don't to set anchor anymore
         * as it's not needed anymore */
        *anchor = inner_types;

        return first;
end_error:
        return NULL;
}

static type_t *construct_declarator_type(construct_type_t *construct_list,
                                         type_t *type)
{
        construct_type_t *iter = construct_list;
        for (; iter != NULL; iter = iter->base.next) {
                switch (iter->kind) {
                case CONSTRUCT_INVALID:
                        break;
                case CONSTRUCT_FUNCTION: {
                        construct_function_type_t *function      = &iter->function;
                        type_t                    *function_type = function->function_type;

                        function_type->function.return_type = type;

                        type_t *skipped_return_type = skip_typeref(type);
                        /* §6.7.5.3:1 */
                        if (is_type_function(skipped_return_type)) {
                                errorf(HERE, "function returning function is not allowed");
                        } else if (is_type_array(skipped_return_type)) {
                                errorf(HERE, "function returning array is not allowed");
                        } else {
                                if (skipped_return_type->base.qualifiers != 0 && warning.other) {
                                        warningf(HERE,
                                                "type qualifiers in return type of function type are meaningless");
                                }
                        }

                        /* The function type was constructed earlier.  Freeing it here will
                         * destroy other types. */
                        type = typehash_insert(function_type);
                        continue;
                }

                case CONSTRUCT_POINTER: {
                        if (is_type_reference(skip_typeref(type)))
                                errorf(HERE, "cannot declare a pointer to reference");

                        parsed_pointer_t *pointer = &iter->pointer;
                        type = make_based_pointer_type(type, pointer->type_qualifiers, pointer->base_variable);
                        continue;
                }

                case CONSTRUCT_REFERENCE:
                        if (is_type_reference(skip_typeref(type)))
                                errorf(HERE, "cannot declare a reference to reference");

                        type = make_reference_type(type);
                        continue;

                case CONSTRUCT_ARRAY: {
                        if (is_type_reference(skip_typeref(type)))
                                errorf(HERE, "cannot declare an array of references");

                        parsed_array_t *array      = &iter->array;
                        type_t         *array_type = allocate_type_zero(TYPE_ARRAY);

                        expression_t *size_expression = array->size;
                        if (size_expression != NULL) {
                                size_expression
                                        = create_implicit_cast(size_expression, type_size_t);
                        }

                        array_type->base.qualifiers       = array->type_qualifiers;
                        array_type->array.element_type    = type;
                        array_type->array.is_static       = array->is_static;
                        array_type->array.is_variable     = array->is_variable;
                        array_type->array.size_expression = size_expression;

                        if (size_expression != NULL) {
                                if (is_constant_expression(size_expression)) {
                                        long const size
                                                = fold_constant_to_int(size_expression);
                                        array_type->array.size          = size;
                                        array_type->array.size_constant = true;
                                        /* §6.7.5.2:1  If the expression is a constant expression, it shall
                                         * have a value greater than zero. */
                                        if (size <= 0) {
                                                if (size < 0 || !GNU_MODE) {
                                                        errorf(&size_expression->base.source_position,
                                                                        "size of array must be greater than zero");
                                                } else if (warning.other) {
                                                        warningf(&size_expression->base.source_position,
                                                                        "zero length arrays are a GCC extension");
                                                }
                                        }
                                } else {
                                        array_type->array.is_vla = true;
                                }
                        }

                        type_t *skipped_type = skip_typeref(type);
                        /* §6.7.5.2:1 */
                        if (is_type_incomplete(skipped_type)) {
                                errorf(HERE, "array of incomplete type '%T' is not allowed", type);
                        } else if (is_type_function(skipped_type)) {
                                errorf(HERE, "array of functions is not allowed");
                        }
                        type = identify_new_type(array_type);
                        continue;
                }
                }
                internal_errorf(HERE, "invalid type construction found");
        }

        return type;
}

static type_t *automatic_type_conversion(type_t *orig_type);

static type_t *semantic_parameter(const source_position_t *pos,
                                  type_t *type,
                                  const declaration_specifiers_t *specifiers,
                                  symbol_t *symbol)
{
        /* §6.7.5.3:7  A declaration of a parameter as ``array of type''
         *             shall be adjusted to ``qualified pointer to type'',
         *             [...]
         * §6.7.5.3:8  A declaration of a parameter as ``function returning
         *             type'' shall be adjusted to ``pointer to function
         *             returning type'', as in 6.3.2.1. */
        type = automatic_type_conversion(type);

        if (specifiers->is_inline && is_type_valid(type)) {
                errorf(pos, "parameter '%#T' declared 'inline'", type, symbol);
        }

        /* §6.9.1:6  The declarations in the declaration list shall contain
         *           no storage-class specifier other than register and no
         *           initializations. */
        if (specifiers->thread_local || (
                        specifiers->storage_class != STORAGE_CLASS_NONE   &&
                        specifiers->storage_class != STORAGE_CLASS_REGISTER)
           ) {
                errorf(pos, "invalid storage class for parameter '%#T'", type, symbol);
        }

        /* delay test for incomplete type, because we might have (void)
         * which is legal but incomplete... */

        return type;
}

static entity_t *parse_declarator(const declaration_specifiers_t *specifiers,
                                  declarator_flags_t flags)
{
        parse_declarator_env_t env;
        memset(&env, 0, sizeof(env));
        env.may_be_abstract = (flags & DECL_MAY_BE_ABSTRACT) != 0;

        construct_type_t *construct_type = parse_inner_declarator(&env);
        type_t           *orig_type      =
                construct_declarator_type(construct_type, specifiers->type);
        type_t           *type           = skip_typeref(orig_type);

        if (construct_type != NULL) {
                obstack_free(&temp_obst, construct_type);
        }

        attribute_t *attributes = parse_attributes(env.attributes);
        /* append (shared) specifier attribute behind attributes of this
         * declarator */
        attribute_t **anchor = &attributes;
        while (*anchor != NULL)
                anchor = &(*anchor)->next;
        *anchor = specifiers->attributes;

        entity_t *entity;
        if (specifiers->storage_class == STORAGE_CLASS_TYPEDEF) {
                entity                       = allocate_entity_zero(ENTITY_TYPEDEF);
                entity->base.symbol          = env.symbol;
                entity->base.source_position = env.source_position;
                entity->typedefe.type        = orig_type;

                if (anonymous_entity != NULL) {
                        if (is_type_compound(type)) {
                                assert(anonymous_entity->compound.alias == NULL);
                                assert(anonymous_entity->kind == ENTITY_STRUCT ||
                                       anonymous_entity->kind == ENTITY_UNION);
                                anonymous_entity->compound.alias = entity;
                                anonymous_entity = NULL;
                        } else if (is_type_enum(type)) {
                                assert(anonymous_entity->enume.alias == NULL);
                                assert(anonymous_entity->kind == ENTITY_ENUM);
                                anonymous_entity->enume.alias = entity;
                                anonymous_entity = NULL;
                        }
                }
        } else {
                /* create a declaration type entity */
                if (flags & DECL_CREATE_COMPOUND_MEMBER) {
                        entity = allocate_entity_zero(ENTITY_COMPOUND_MEMBER);

                        if (env.symbol != NULL) {
                                if (specifiers->is_inline && is_type_valid(type)) {
                                        errorf(&env.source_position,
                                                        "compound member '%Y' declared 'inline'", env.symbol);
                                }

                                if (specifiers->thread_local ||
                                                specifiers->storage_class != STORAGE_CLASS_NONE) {
                                        errorf(&env.source_position,
                                                        "compound member '%Y' must have no storage class",
                                                        env.symbol);
                                }
                        }
                } else if (flags & DECL_IS_PARAMETER) {
                        orig_type = semantic_parameter(&env.source_position, orig_type,
                                                       specifiers, env.symbol);

                        entity = allocate_entity_zero(ENTITY_PARAMETER);
                } else if (is_type_function(type)) {
                        entity = allocate_entity_zero(ENTITY_FUNCTION);

                        entity->function.is_inline  = specifiers->is_inline;
                        entity->function.parameters = env.parameters;

                        if (env.symbol != NULL) {
                                /* this needs fixes for C++ */
                                bool in_function_scope = current_function != NULL;

                                if (specifiers->thread_local || (
                                                        specifiers->storage_class != STORAGE_CLASS_EXTERN &&
                                                        specifiers->storage_class != STORAGE_CLASS_NONE   &&
                                                        (in_function_scope || specifiers->storage_class != STORAGE_CLASS_STATIC)
                                                )) {
                                        errorf(&env.source_position,
                                                        "invalid storage class for function '%Y'", env.symbol);
                                }
                        }
                } else {
                        entity = allocate_entity_zero(ENTITY_VARIABLE);

                        entity->variable.thread_local = specifiers->thread_local;

                        if (env.symbol != NULL) {
                                if (specifiers->is_inline && is_type_valid(type)) {
                                        errorf(&env.source_position,
                                                        "variable '%Y' declared 'inline'", env.symbol);
                                }

                                bool invalid_storage_class = false;
                                if (current_scope == file_scope) {
                                        if (specifiers->storage_class != STORAGE_CLASS_EXTERN &&
                                                        specifiers->storage_class != STORAGE_CLASS_NONE   &&
                                                        specifiers->storage_class != STORAGE_CLASS_STATIC) {
                                                invalid_storage_class = true;
                                        }
                                } else {
                                        if (specifiers->thread_local &&
                                                        specifiers->storage_class == STORAGE_CLASS_NONE) {
                                                invalid_storage_class = true;
                                        }
                                }
                                if (invalid_storage_class) {
                                        errorf(&env.source_position,
                                                        "invalid storage class for variable '%Y'", env.symbol);
                                }
                        }
                }

                if (env.symbol != NULL) {
                        entity->base.symbol          = env.symbol;
                        entity->base.source_position = env.source_position;
                } else {
                        entity->base.source_position = specifiers->source_position;
                }
                entity->base.namespc           = NAMESPACE_NORMAL;
                entity->declaration.type       = orig_type;
                entity->declaration.alignment  = get_type_alignment(orig_type);
                entity->declaration.modifiers  = env.modifiers;
                entity->declaration.attributes = attributes;

                storage_class_t storage_class = specifiers->storage_class;
                entity->declaration.declared_storage_class = storage_class;

                if (storage_class == STORAGE_CLASS_NONE && current_function != NULL)
                        storage_class = STORAGE_CLASS_AUTO;
                entity->declaration.storage_class = storage_class;
        }

        if (attributes != NULL) {
                handle_entity_attributes(attributes, entity);
        }

        return entity;
}

static type_t *parse_abstract_declarator(type_t *base_type)
{
        parse_declarator_env_t env;
        memset(&env, 0, sizeof(env));
        env.may_be_abstract = true;
        env.must_be_abstract = true;

        construct_type_t *construct_type = parse_inner_declarator(&env);

        type_t *result = construct_declarator_type(construct_type, base_type);
        if (construct_type != NULL) {
                obstack_free(&temp_obst, construct_type);
        }
        result = handle_type_attributes(env.attributes, result);

        return result;
}

/**
 * Check if the declaration of main is suspicious.  main should be a
 * function with external linkage, returning int, taking either zero
 * arguments, two, or three arguments of appropriate types, ie.
 *
 * int main([ int argc, char **argv [, char **env ] ]).
 *
 * @param decl    the declaration to check
 * @param type    the function type of the declaration
 */
static void check_main(const entity_t *entity)
{
        const source_position_t *pos = &entity->base.source_position;
        if (entity->kind != ENTITY_FUNCTION) {
                warningf(pos, "'main' is not a function");
                return;
        }

        if (entity->declaration.storage_class == STORAGE_CLASS_STATIC) {
                warningf(pos, "'main' is normally a non-static function");
        }

        type_t *type = skip_typeref(entity->declaration.type);
        assert(is_type_function(type));

        function_type_t *func_type = &type->function;
        if (!types_compatible(skip_typeref(func_type->return_type), type_int)) {
                warningf(pos, "return type of 'main' should be 'int', but is '%T'",
                         func_type->return_type);
        }
        const function_parameter_t *parm = func_type->parameters;
        if (parm != NULL) {
                type_t *const first_type = parm->type;
                if (!types_compatible(skip_typeref(first_type), type_int)) {
                        warningf(pos,
                                 "first argument of 'main' should be 'int', but is '%T'",
                                 first_type);
                }
                parm = parm->next;
                if (parm != NULL) {
                        type_t *const second_type = parm->type;
                        if (!types_compatible(skip_typeref(second_type), type_char_ptr_ptr)) {
                                warningf(pos, "second argument of 'main' should be 'char**', but is '%T'", second_type);
                        }
                        parm = parm->next;
                        if (parm != NULL) {
                                type_t *const third_type = parm->type;
                                if (!types_compatible(skip_typeref(third_type), type_char_ptr_ptr)) {
                                        warningf(pos, "third argument of 'main' should be 'char**', but is '%T'", third_type);
                                }
                                parm = parm->next;
                                if (parm != NULL)
                                        goto warn_arg_count;
                        }
                } else {
warn_arg_count:
                        warningf(pos, "'main' takes only zero, two or three arguments");
                }
        }
}

/**
 * Check if a symbol is the equal to "main".
 */
static bool is_sym_main(const symbol_t *const sym)
{
        return strcmp(sym->string, "main") == 0;
}

static void error_redefined_as_different_kind(const source_position_t *pos,
                const entity_t *old, entity_kind_t new_kind)
{
        errorf(pos, "redeclaration of %s '%Y' as %s (declared %P)",
               get_entity_kind_name(old->kind), old->base.symbol,
               get_entity_kind_name(new_kind), &old->base.source_position);
}

static bool is_error_entity(entity_t *const ent)
{
        if (is_declaration(ent)) {
                return is_type_valid(skip_typeref(ent->declaration.type));
        } else if (ent->kind == ENTITY_TYPEDEF) {
                return is_type_valid(skip_typeref(ent->typedefe.type));
        }
        return false;
}

static bool contains_attribute(const attribute_t *list, const attribute_t *attr)
{
        for (const attribute_t *tattr = list; tattr != NULL; tattr = tattr->next) {
                if (attributes_equal(tattr, attr))
                        return true;
        }
        return false;
}

/**
 * test wether new_list contains any attributes not included in old_list
 */
static bool has_new_attributes(const attribute_t *old_list,
                               const attribute_t *new_list)
{
        for (const attribute_t *attr = new_list; attr != NULL; attr = attr->next) {
                if (!contains_attribute(old_list, attr))
                        return true;
        }
        return false;
}

/**
 * Merge in attributes from an attribute list (probably from a previous
 * declaration with the same name). Warning: destroys the old structure
 * of the attribute list - don't reuse attributes after this call.
 */
static void merge_in_attributes(declaration_t *decl, attribute_t *attributes)
{
        attribute_t *next;
        for (attribute_t *attr = attributes; attr != NULL; attr = next) {
                next = attr->next;
                if (contains_attribute(decl->attributes, attr))
                        continue;

                /* move attribute to new declarations attributes list */
                attr->next       = decl->attributes;
                decl->attributes = attr;
        }
}

/**
 * record entities for the NAMESPACE_NORMAL, and produce error messages/warnings
 * for various problems that occur for multiple definitions
 */
entity_t *record_entity(entity_t *entity, const bool is_definition)
{
        const symbol_t *const    symbol  = entity->base.symbol;
        const namespace_tag_t    namespc = (namespace_tag_t)entity->base.namespc;
        const source_position_t *pos     = &entity->base.source_position;

        /* can happen in error cases */
        if (symbol == NULL)
                return entity;

        entity_t *const previous_entity = get_entity(symbol, namespc);
        /* pushing the same entity twice will break the stack structure */
        assert(previous_entity != entity);

        if (entity->kind == ENTITY_FUNCTION) {
                type_t *const orig_type = entity->declaration.type;
                type_t *const type      = skip_typeref(orig_type);

                assert(is_type_function(type));
                if (type->function.unspecified_parameters &&
                                warning.strict_prototypes &&
                                previous_entity == NULL) {
                        warningf(pos, "function declaration '%#T' is not a prototype",
                                         orig_type, symbol);
                }

                if (warning.main && current_scope == file_scope
                                && is_sym_main(symbol)) {
                        check_main(entity);
                }
        }

        if (is_declaration(entity) &&
                        warning.nested_externs &&
                        entity->declaration.storage_class == STORAGE_CLASS_EXTERN &&
                        current_scope != file_scope) {
                warningf(pos, "nested extern declaration of '%#T'",
                         entity->declaration.type, symbol);
        }

        if (previous_entity != NULL) {
                if (previous_entity->base.parent_scope == &current_function->parameters &&
                                previous_entity->base.parent_scope->depth + 1 == current_scope->depth) {
                        assert(previous_entity->kind == ENTITY_PARAMETER);
                        errorf(pos,
                                        "declaration '%#T' redeclares the parameter '%#T' (declared %P)",
                                        entity->declaration.type, symbol,
                                        previous_entity->declaration.type, symbol,
                                        &previous_entity->base.source_position);
                        goto finish;
                }

                if (previous_entity->base.parent_scope == current_scope) {
                        if (previous_entity->kind != entity->kind) {
                                if (!is_error_entity(previous_entity) && !is_error_entity(entity)) {
                                        error_redefined_as_different_kind(pos, previous_entity,
                                                        entity->kind);
                                }
                                goto finish;
                        }
                        if (previous_entity->kind == ENTITY_ENUM_VALUE) {
                                errorf(pos, "redeclaration of enum entry '%Y' (declared %P)",
                                                symbol, &previous_entity->base.source_position);
                                goto finish;
                        }
                        if (previous_entity->kind == ENTITY_TYPEDEF) {
                                /* TODO: C++ allows this for exactly the same type */
                                errorf(pos, "redefinition of typedef '%Y' (declared %P)",
                                                symbol, &previous_entity->base.source_position);
                                goto finish;
                        }

                        /* at this point we should have only VARIABLES or FUNCTIONS */
                        assert(is_declaration(previous_entity) && is_declaration(entity));

                        declaration_t *const prev_decl = &previous_entity->declaration;
                        declaration_t *const decl      = &entity->declaration;

                        /* can happen for K&R style declarations */
                        if (prev_decl->type       == NULL             &&
                                        previous_entity->kind == ENTITY_PARAMETER &&
                                        entity->kind          == ENTITY_PARAMETER) {
                                prev_decl->type                   = decl->type;
                                prev_decl->storage_class          = decl->storage_class;
                                prev_decl->declared_storage_class = decl->declared_storage_class;
                                prev_decl->modifiers              = decl->modifiers;
                                return previous_entity;
                        }

                        type_t *const orig_type = decl->type;
                        assert(orig_type != NULL);
                        type_t *const type      = skip_typeref(orig_type);
                        type_t *const prev_type = skip_typeref(prev_decl->type);

                        if (!types_compatible(type, prev_type)) {
                                errorf(pos,
                                                "declaration '%#T' is incompatible with '%#T' (declared %P)",
                                                orig_type, symbol, prev_decl->type, symbol,
                                                &previous_entity->base.source_position);
                        } else {
                                unsigned old_storage_class = prev_decl->storage_class;

                                if (warning.redundant_decls               &&
                                                is_definition                     &&
                                                !prev_decl->used                  &&
                                                !(prev_decl->modifiers & DM_USED) &&
                                                prev_decl->storage_class == STORAGE_CLASS_STATIC) {
                                        warningf(&previous_entity->base.source_position,
                                                        "unnecessary static forward declaration for '%#T'",
                                                        prev_decl->type, symbol);
                                }

                                storage_class_t new_storage_class = decl->storage_class;

                                /* pretend no storage class means extern for function
                                 * declarations (except if the previous declaration is neither
                                 * none nor extern) */
                                if (entity->kind == ENTITY_FUNCTION) {
                                        /* the previous declaration could have unspecified parameters or
                                         * be a typedef, so use the new type */
                                        if (prev_type->function.unspecified_parameters || is_definition)
                                                prev_decl->type = type;

                                        switch (old_storage_class) {
                                                case STORAGE_CLASS_NONE:
                                                        old_storage_class = STORAGE_CLASS_EXTERN;
                                                        /* FALLTHROUGH */

                                                case STORAGE_CLASS_EXTERN:
                                                        if (is_definition) {
                                                                if (warning.missing_prototypes &&
                                                                                prev_type->function.unspecified_parameters &&
                                                                                !is_sym_main(symbol)) {
                                                                        warningf(pos, "no previous prototype for '%#T'",
                                                                                        orig_type, symbol);
                                                                }
                                                        } else if (new_storage_class == STORAGE_CLASS_NONE) {
                                                                new_storage_class = STORAGE_CLASS_EXTERN;
                                                        }
                                                        break;

                                                default:
                                                        break;
                                        }
                                } else if (is_type_incomplete(prev_type)) {
                                        prev_decl->type = type;
                                }

                                if (old_storage_class == STORAGE_CLASS_EXTERN &&
                                                new_storage_class == STORAGE_CLASS_EXTERN) {

warn_redundant_declaration: ;
                                        bool has_new_attrs
                                                = has_new_attributes(prev_decl->attributes,
                                                                     decl->attributes);
                                        if (has_new_attrs) {
                                                merge_in_attributes(decl, prev_decl->attributes);
                                        } else if (!is_definition        &&
                                                        warning.redundant_decls  &&
                                                        is_type_valid(prev_type) &&
                                                        strcmp(previous_entity->base.source_position.input_name,
                                                                "<builtin>") != 0) {
                                                warningf(pos,
                                                         "redundant declaration for '%Y' (declared %P)",
                                                         symbol, &previous_entity->base.source_position);
                                        }
                                } else if (current_function == NULL) {
                                        if (old_storage_class != STORAGE_CLASS_STATIC &&
                                                        new_storage_class == STORAGE_CLASS_STATIC) {
                                                errorf(pos,
                                                       "static declaration of '%Y' follows non-static declaration (declared %P)",
                                                       symbol, &previous_entity->base.source_position);
                                        } else if (old_storage_class == STORAGE_CLASS_EXTERN) {
                                                prev_decl->storage_class          = STORAGE_CLASS_NONE;
                                                prev_decl->declared_storage_class = STORAGE_CLASS_NONE;
                                        } else {
                                                /* ISO/IEC 14882:1998(E) §C.1.2:1 */
                                                if (c_mode & _CXX)
                                                        goto error_redeclaration;
                                                goto warn_redundant_declaration;
                                        }
                                } else if (is_type_valid(prev_type)) {
                                        if (old_storage_class == new_storage_class) {
error_redeclaration:
                                                errorf(pos, "redeclaration of '%Y' (declared %P)",
                                                                symbol, &previous_entity->base.source_position);
                                        } else {
                                                errorf(pos,
                                                                "redeclaration of '%Y' with different linkage (declared %P)",
                                                                symbol, &previous_entity->base.source_position);
                                        }
                                }
                        }

                        prev_decl->modifiers |= decl->modifiers;
                        if (entity->kind == ENTITY_FUNCTION) {
                                previous_entity->function.is_inline |= entity->function.is_inline;
                        }
                        return previous_entity;
                }

                if (warning.shadow) {
                        warningf(pos, "%s '%Y' shadows %s (declared %P)",
                                        get_entity_kind_name(entity->kind), symbol,
                                        get_entity_kind_name(previous_entity->kind),
                                        &previous_entity->base.source_position);
                }
        }

        if (entity->kind == ENTITY_FUNCTION) {
                if (is_definition &&
                                entity->declaration.storage_class != STORAGE_CLASS_STATIC) {
                        if (warning.missing_prototypes && !is_sym_main(symbol)) {
                                warningf(pos, "no previous prototype for '%#T'",
                                         entity->declaration.type, symbol);
                        } else if (warning.missing_declarations && !is_sym_main(symbol)) {
                                warningf(pos, "no previous declaration for '%#T'",
                                         entity->declaration.type, symbol);
                        }
                }
        } else if (warning.missing_declarations &&
                        entity->kind == ENTITY_VARIABLE &&
                        current_scope == file_scope) {
                declaration_t *declaration = &entity->declaration;
                if (declaration->storage_class == STORAGE_CLASS_NONE) {
                        warningf(pos, "no previous declaration for '%#T'",
                                 declaration->type, symbol);
                }
        }

finish:
        assert(entity->base.parent_scope == NULL);
        assert(current_scope != NULL);

        entity->base.parent_scope = current_scope;
        entity->base.namespc      = NAMESPACE_NORMAL;
        environment_push(entity);
        append_entity(current_scope, entity);

        return entity;
}

static void parser_error_multiple_definition(entity_t *entity,
                const source_position_t *source_position)
{
        errorf(source_position, "multiple definition of '%Y' (declared %P)",
               entity->base.symbol, &entity->base.source_position);
}

static bool is_declaration_specifier(const token_t *token,
                                     bool only_specifiers_qualifiers)
{
        switch (token->type) {
                TYPE_SPECIFIERS
                TYPE_QUALIFIERS
                        return true;
                case T_IDENTIFIER:
                        return is_typedef_symbol(token->symbol);

                case T___extension__:
                STORAGE_CLASSES
                        return !only_specifiers_qualifiers;

                default:
                        return false;
        }
}

static void parse_init_declarator_rest(entity_t *entity)
{
        assert(is_declaration(entity));
        declaration_t *const declaration = &entity->declaration;

        eat('=');

        type_t *orig_type = declaration->type;
        type_t *type      = skip_typeref(orig_type);

        if (entity->kind == ENTITY_VARIABLE
                        && entity->variable.initializer != NULL) {
                parser_error_multiple_definition(entity, HERE);
        }

        bool must_be_constant = false;
        if (declaration->storage_class == STORAGE_CLASS_STATIC ||
            entity->base.parent_scope  == file_scope) {
                must_be_constant = true;
        }

        if (is_type_function(type)) {
                errorf(&entity->base.source_position,
                       "function '%#T' is initialized like a variable",
                       orig_type, entity->base.symbol);
                orig_type = type_error_type;
        }

        parse_initializer_env_t env;
        env.type             = orig_type;
        env.must_be_constant = must_be_constant;
        env.entity           = entity;
        current_init_decl    = entity;

        initializer_t *initializer = parse_initializer(&env);
        current_init_decl = NULL;

        if (entity->kind == ENTITY_VARIABLE) {
                /* §6.7.5:22  array initializers for arrays with unknown size
                 * determine the array type size */
                declaration->type            = env.type;
                entity->variable.initializer = initializer;
        }
}

/* parse rest of a declaration without any declarator */
static void parse_anonymous_declaration_rest(
                const declaration_specifiers_t *specifiers)
{
        eat(';');
        anonymous_entity = NULL;

        if (warning.other) {
                if (specifiers->storage_class != STORAGE_CLASS_NONE ||
                                specifiers->thread_local) {
                        warningf(&specifiers->source_position,
                                 "useless storage class in empty declaration");
                }

                type_t *type = specifiers->type;
                switch (type->kind) {
                        case TYPE_COMPOUND_STRUCT:
                        case TYPE_COMPOUND_UNION: {
                                if (type->compound.compound->base.symbol == NULL) {
                                        warningf(&specifiers->source_position,
                                                 "unnamed struct/union that defines no instances");
                                }
                                break;
                        }

                        case TYPE_ENUM:
                                break;

                        default:
                                warningf(&specifiers->source_position, "empty declaration");
                                break;
                }
        }
}

static void check_variable_type_complete(entity_t *ent)
{
        if (ent->kind != ENTITY_VARIABLE)
                return;

        /* §6.7:7  If an identifier for an object is declared with no linkage, the
         *         type for the object shall be complete [...] */
        declaration_t *decl = &ent->declaration;
        if (decl->storage_class == STORAGE_CLASS_EXTERN ||
                        decl->storage_class == STORAGE_CLASS_STATIC)
                return;

        type_t *const orig_type = decl->type;
        type_t *const type      = skip_typeref(orig_type);
        if (!is_type_incomplete(type))
                return;

        /* §6.9.2:2 and §6.9.2:5: At the end of the translation incomplete arrays
         * are given length one. */
        if (is_type_array(type) && ent->base.parent_scope == file_scope) {
                ARR_APP1(declaration_t*, incomplete_arrays, decl);
                return;
        }

        errorf(&ent->base.source_position, "variable '%#T' has incomplete type",
                        orig_type, ent->base.symbol);
}


static void parse_declaration_rest(entity_t *ndeclaration,
                const declaration_specifiers_t *specifiers,
                parsed_declaration_func         finished_declaration,
                declarator_flags_t              flags)
{
        add_anchor_token(';');
        add_anchor_token(',');
        while (true) {
                entity_t *entity = finished_declaration(ndeclaration, token.type == '=');

                if (token.type == '=') {
                        parse_init_declarator_rest(entity);
                } else if (entity->kind == ENTITY_VARIABLE) {
                        /* ISO/IEC 14882:1998(E) §8.5.3:3  The initializer can be omitted
                         * [...] where the extern specifier is explicitly used. */
                        declaration_t *decl = &entity->declaration;
                        if (decl->storage_class != STORAGE_CLASS_EXTERN) {
                                type_t *type = decl->type;
                                if (is_type_reference(skip_typeref(type))) {
                                        errorf(&entity->base.source_position,
                                                        "reference '%#T' must be initialized",
                                                        type, entity->base.symbol);
                                }
                        }
                }

                check_variable_type_complete(entity);

                if (!next_if(','))
                        break;

                add_anchor_token('=');
                ndeclaration = parse_declarator(specifiers, flags);
                rem_anchor_token('=');
        }
        expect(';', end_error);

end_error:
        anonymous_entity = NULL;
        rem_anchor_token(';');
        rem_anchor_token(',');
}

static entity_t *finished_kr_declaration(entity_t *entity, bool is_definition)
{
        symbol_t *symbol = entity->base.symbol;
        if (symbol == NULL) {
                errorf(HERE, "anonymous declaration not valid as function parameter");
                return entity;
        }

        assert(entity->base.namespc == NAMESPACE_NORMAL);
        entity_t *previous_entity = get_entity(symbol, NAMESPACE_NORMAL);
        if (previous_entity == NULL
                        || previous_entity->base.parent_scope != current_scope) {
                errorf(HERE, "expected declaration of a function parameter, found '%Y'",
                       symbol);
                return entity;
        }

        if (is_definition) {
                errorf(HERE, "parameter '%Y' is initialised", entity->base.symbol);
        }

        return record_entity(entity, false);
}

static void parse_declaration(parsed_declaration_func finished_declaration,
                              declarator_flags_t      flags)
{
        declaration_specifiers_t specifiers;
        memset(&specifiers, 0, sizeof(specifiers));

        add_anchor_token(';');
        parse_declaration_specifiers(&specifiers);
        rem_anchor_token(';');

        if (token.type == ';') {
                parse_anonymous_declaration_rest(&specifiers);
        } else {
                entity_t *entity = parse_declarator(&specifiers, flags);
                parse_declaration_rest(entity, &specifiers, finished_declaration, flags);
        }
}

/* §6.5.2.2:6 */
static type_t *get_default_promoted_type(type_t *orig_type)
{
        type_t *result = orig_type;

        type_t *type = skip_typeref(orig_type);
        if (is_type_integer(type)) {
                result = promote_integer(type);
        } else if (is_type_atomic(type, ATOMIC_TYPE_FLOAT)) {
                result = type_double;
        }

        return result;
}

static void parse_kr_declaration_list(entity_t *entity)
{
        if (entity->kind != ENTITY_FUNCTION)
                return;

        type_t *type = skip_typeref(entity->declaration.type);
        assert(is_type_function(type));
        if (!type->function.kr_style_parameters)
                return;

        add_anchor_token('{');

        /* push function parameters */
        size_t const  top       = environment_top();
        scope_t      *old_scope = scope_push(&entity->function.parameters);

        entity_t *parameter = entity->function.parameters.entities;
        for ( ; parameter != NULL; parameter = parameter->base.next) {
                assert(parameter->base.parent_scope == NULL);
                parameter->base.parent_scope = current_scope;
                environment_push(parameter);
        }

        /* parse declaration list */
        for (;;) {
                switch (token.type) {
                        DECLARATION_START
                        case T___extension__:
                        /* This covers symbols, which are no type, too, and results in
                         * better error messages.  The typical cases are misspelled type
                         * names and missing includes. */
                        case T_IDENTIFIER:
                                parse_declaration(finished_kr_declaration, DECL_IS_PARAMETER);
                                break;
                        default:
                                goto decl_list_end;
                }
        }
decl_list_end:

        /* pop function parameters */
        assert(current_scope == &entity->function.parameters);
        scope_pop(old_scope);
        environment_pop_to(top);

        /* update function type */
        type_t *new_type = duplicate_type(type);

        function_parameter_t  *parameters = NULL;
        function_parameter_t **anchor     = &parameters;

        /* did we have an earlier prototype? */
        entity_t *proto_type = get_entity(entity->base.symbol, NAMESPACE_NORMAL);
        if (proto_type != NULL && proto_type->kind != ENTITY_FUNCTION)
                proto_type = NULL;

        function_parameter_t *proto_parameter = NULL;
        if (proto_type != NULL) {
                type_t *proto_type_type = proto_type->declaration.type;
                proto_parameter         = proto_type_type->function.parameters;
                /* If a K&R function definition has a variadic prototype earlier, then
                 * make the function definition variadic, too. This should conform to
                 * §6.7.5.3:15 and §6.9.1:8. */
                new_type->function.variadic = proto_type_type->function.variadic;
        } else {
                /* §6.9.1.7: A K&R style parameter list does NOT act as a function
                 * prototype */
                new_type->function.unspecified_parameters = true;
        }

        bool need_incompatible_warning = false;
        parameter = entity->function.parameters.entities;
        for (; parameter != NULL; parameter = parameter->base.next,
                        proto_parameter =
                                proto_parameter == NULL ? NULL : proto_parameter->next) {
                if (parameter->kind != ENTITY_PARAMETER)
                        continue;

                type_t *parameter_type = parameter->declaration.type;
                if (parameter_type == NULL) {
                        if (strict_mode) {
                                errorf(HERE, "no type specified for function parameter '%Y'",
                                       parameter->base.symbol);
                                parameter_type = type_error_type;
                        } else {
                                if (warning.implicit_int) {
                                        warningf(HERE, "no type specified for function parameter '%Y', using 'int'",
                                                 parameter->base.symbol);
                                }
                                parameter_type = type_int;
                        }
                        parameter->declaration.type = parameter_type;
                }

                semantic_parameter_incomplete(parameter);

                /* we need the default promoted types for the function type */
                type_t *not_promoted = parameter_type;
                parameter_type       = get_default_promoted_type(parameter_type);

                /* gcc special: if the type of the prototype matches the unpromoted
                 * type don't promote */
                if (!strict_mode && proto_parameter != NULL) {
                        type_t *proto_p_type = skip_typeref(proto_parameter->type);
                        type_t *promo_skip   = skip_typeref(parameter_type);
                        type_t *param_skip   = skip_typeref(not_promoted);
                        if (!types_compatible(proto_p_type, promo_skip)
                                && types_compatible(proto_p_type, param_skip)) {
                                /* don't promote */
                                need_incompatible_warning = true;
                                parameter_type = not_promoted;
                        }
                }
                function_parameter_t *const parameter
                        = allocate_parameter(parameter_type);

                *anchor = parameter;
                anchor  = &parameter->next;
        }

        new_type->function.parameters = parameters;
        new_type = identify_new_type(new_type);

        if (warning.other && need_incompatible_warning) {
                type_t *proto_type_type = proto_type->declaration.type;
                warningf(HERE,
                         "declaration '%#T' is incompatible with '%#T' (declared %P)",
                         proto_type_type, proto_type->base.symbol,
                         new_type, entity->base.symbol,
                         &proto_type->base.source_position);
        }

        entity->declaration.type = new_type;

        rem_anchor_token('{');
}

static bool first_err = true;

/**
 * When called with first_err set, prints the name of the current function,
 * else does noting.
 */
static void print_in_function(void)
{
        if (first_err) {
                first_err = false;
                diagnosticf("%s: In function '%Y':\n",
                            current_function->base.base.source_position.input_name,
                            current_function->base.base.symbol);
        }
}

/**
 * Check if all labels are defined in the current function.
 * Check if all labels are used in the current function.
 */
static void check_labels(void)
{
        for (const goto_statement_t *goto_statement = goto_first;
            goto_statement != NULL;
            goto_statement = goto_statement->next) {
                /* skip computed gotos */
                if (goto_statement->expression != NULL)
                        continue;

                label_t *label = goto_statement->label;

                label->used = true;
                if (label->base.source_position.input_name == NULL) {
                        print_in_function();
                        errorf(&goto_statement->base.source_position,
                               "label '%Y' used but not defined", label->base.symbol);
                 }
        }

        if (warning.unused_label) {
                for (const label_statement_t *label_statement = label_first;
                         label_statement != NULL;
                         label_statement = label_statement->next) {
                        label_t *label = label_statement->label;

                        if (! label->used) {
                                print_in_function();
                                warningf(&label_statement->base.source_position,
                                         "label '%Y' defined but not used", label->base.symbol);
                        }
                }
        }
}

static void warn_unused_entity(entity_t *entity, entity_t *last)
{
        entity_t const *const end = last != NULL ? last->base.next : NULL;
        for (; entity != end; entity = entity->base.next) {
                if (!is_declaration(entity))
                        continue;

                declaration_t *declaration = &entity->declaration;
                if (declaration->implicit)
                        continue;

                if (!declaration->used) {
                        print_in_function();
                        const char *what = get_entity_kind_name(entity->kind);
                        warningf(&entity->base.source_position, "%s '%Y' is unused",
                                 what, entity->base.symbol);
                } else if (entity->kind == ENTITY_VARIABLE && !entity->variable.read) {
                        print_in_function();
                        const char *what = get_entity_kind_name(entity->kind);
                        warningf(&entity->base.source_position, "%s '%Y' is never read",
                                 what, entity->base.symbol);
                }
        }
}

static void check_unused_variables(statement_t *const stmt, void *const env)
{
        (void)env;

        switch (stmt->kind) {
                case STATEMENT_DECLARATION: {
                        declaration_statement_t const *const decls = &stmt->declaration;
                        warn_unused_entity(decls->declarations_begin,
                                           decls->declarations_end);
                        return;
                }

                case STATEMENT_FOR:
                        warn_unused_entity(stmt->fors.scope.entities, NULL);
                        return;

                default:
                        return;
        }
}

/**
 * Check declarations of current_function for unused entities.
 */
static void check_declarations(void)
{
        if (warning.unused_parameter) {
                const scope_t *scope = &current_function->parameters;

                /* do not issue unused warnings for main */
                if (!is_sym_main(current_function->base.base.symbol)) {
                        warn_unused_entity(scope->entities, NULL);
                }
        }
        if (warning.unused_variable) {
                walk_statements(current_function->statement, check_unused_variables,
                                NULL);
        }
}

static int determine_truth(expression_t const* const cond)
{
        return
                !is_constant_expression(cond) ? 0 :
                fold_constant_to_bool(cond)   ? 1 :
                -1;
}

static void check_reachable(statement_t *);
static bool reaches_end;

static bool expression_returns(expression_t const *const expr)
{
        switch (expr->kind) {
                case EXPR_CALL: {
                        expression_t const *const func = expr->call.function;
                        if (func->kind == EXPR_REFERENCE) {
                                entity_t *entity = func->reference.entity;
                                if (entity->kind == ENTITY_FUNCTION
                                                && entity->declaration.modifiers & DM_NORETURN)
                                        return false;
                        }

                        if (!expression_returns(func))
                                return false;

                        for (call_argument_t const* arg = expr->call.arguments; arg != NULL; arg = arg->next) {
                                if (!expression_returns(arg->expression))
                                        return false;
                        }

                        return true;
                }

                case EXPR_REFERENCE:
                case EXPR_REFERENCE_ENUM_VALUE:
                EXPR_LITERAL_CASES
                case EXPR_STRING_LITERAL:
                case EXPR_WIDE_STRING_LITERAL:
                case EXPR_COMPOUND_LITERAL: // TODO descend into initialisers
                case EXPR_LABEL_ADDRESS:
                case EXPR_CLASSIFY_TYPE:
                case EXPR_SIZEOF: // TODO handle obscure VLA case
                case EXPR_ALIGNOF:
                case EXPR_FUNCNAME:
                case EXPR_BUILTIN_CONSTANT_P:
                case EXPR_BUILTIN_TYPES_COMPATIBLE_P:
                case EXPR_OFFSETOF:
                case EXPR_INVALID:
                        return true;

                case EXPR_STATEMENT: {
                        bool old_reaches_end = reaches_end;
                        reaches_end = false;
                        check_reachable(expr->statement.statement);
                        bool returns = reaches_end;
                        reaches_end = old_reaches_end;
                        return returns;
                }

                case EXPR_CONDITIONAL:
                        // TODO handle constant expression

                        if (!expression_returns(expr->conditional.condition))
                                return false;

                        if (expr->conditional.true_expression != NULL
                                        && expression_returns(expr->conditional.true_expression))
                                return true;

                        return expression_returns(expr->conditional.false_expression);

                case EXPR_SELECT:
                        return expression_returns(expr->select.compound);

                case EXPR_ARRAY_ACCESS:
                        return
                                expression_returns(expr->array_access.array_ref) &&
                                expression_returns(expr->array_access.index);

                case EXPR_VA_START:
                        return expression_returns(expr->va_starte.ap);

                case EXPR_VA_ARG:
                        return expression_returns(expr->va_arge.ap);

                case EXPR_VA_COPY:
                        return expression_returns(expr->va_copye.src);

                EXPR_UNARY_CASES_MANDATORY
                        return expression_returns(expr->unary.value);

                case EXPR_UNARY_THROW:
                        return false;

                EXPR_BINARY_CASES
                        // TODO handle constant lhs of && and ||
                        return
                                expression_returns(expr->binary.left) &&
                                expression_returns(expr->binary.right);

                case EXPR_UNKNOWN:
                        break;
        }

        panic("unhandled expression");
}

static bool initializer_returns(initializer_t const *const init)
{
        switch (init->kind) {
                case INITIALIZER_VALUE:
                        return expression_returns(init->value.value);

                case INITIALIZER_LIST: {
                        initializer_t * const*       i       = init->list.initializers;
                        initializer_t * const* const end     = i + init->list.len;
                        bool                         returns = true;
                        for (; i != end; ++i) {
                                if (!initializer_returns(*i))
                                        returns = false;
                        }
                        return returns;
                }

                case INITIALIZER_STRING:
                case INITIALIZER_WIDE_STRING:
                case INITIALIZER_DESIGNATOR: // designators have no payload
                        return true;
        }
        panic("unhandled initializer");
}

static bool noreturn_candidate;

static void check_reachable(statement_t *const stmt)
{
        if (stmt->base.reachable)
                return;
        if (stmt->kind != STATEMENT_DO_WHILE)
                stmt->base.reachable = true;

        statement_t *last = stmt;
        statement_t *next;
        switch (stmt->kind) {
                case STATEMENT_INVALID:
                case STATEMENT_EMPTY:
                case STATEMENT_ASM:
                        next = stmt->base.next;
                        break;

                case STATEMENT_DECLARATION: {
                        declaration_statement_t const *const decl = &stmt->declaration;
                        entity_t                const *      ent  = decl->declarations_begin;
                        entity_t                const *const last = decl->declarations_end;
                        if (ent != NULL) {
                                for (;; ent = ent->base.next) {
                                        if (ent->kind                 == ENTITY_VARIABLE &&
                                                        ent->variable.initializer != NULL            &&
                                                        !initializer_returns(ent->variable.initializer)) {
                                                return;
                                        }
                                        if (ent == last)
                                                break;
                                }
                        }
                        next = stmt->base.next;
                        break;
                }

                case STATEMENT_COMPOUND:
                        next = stmt->compound.statements;
                        if (next == NULL)
                                next = stmt->base.next;
                        break;

                case STATEMENT_RETURN: {
                        expression_t const *const val = stmt->returns.value;
                        if (val == NULL || expression_returns(val))
                                noreturn_candidate = false;
                        return;
                }

                case STATEMENT_IF: {
                        if_statement_t const *const ifs  = &stmt->ifs;
                        expression_t   const *const cond = ifs->condition;

                        if (!expression_returns(cond))
                                return;

                        int const val = determine_truth(cond);

                        if (val >= 0)
                                check_reachable(ifs->true_statement);

                        if (val > 0)
                                return;

                        if (ifs->false_statement != NULL) {
                                check_reachable(ifs->false_statement);
                                return;
                        }

                        next = stmt->base.next;
                        break;
                }

                case STATEMENT_SWITCH: {
                        switch_statement_t const *const switchs = &stmt->switchs;
                        expression_t       const *const expr    = switchs->expression;

                        if (!expression_returns(expr))
                                return;

                        if (is_constant_expression(expr)) {
                                long                    const val      = fold_constant_to_int(expr);
                                case_label_statement_t *      defaults = NULL;
                                for (case_label_statement_t *i = switchs->first_case; i != NULL; i = i->next) {
                                        if (i->expression == NULL) {
                                                defaults = i;
                                                continue;
                                        }

                                        if (i->first_case <= val && val <= i->last_case) {
                                                check_reachable((statement_t*)i);
                                                return;
                                        }
                                }

                                if (defaults != NULL) {
                                        check_reachable((statement_t*)defaults);
                                        return;
                                }
                        } else {
                                bool has_default = false;
                                for (case_label_statement_t *i = switchs->first_case; i != NULL; i = i->next) {
                                        if (i->expression == NULL)
                                                has_default = true;

                                        check_reachable((statement_t*)i);
                                }

                                if (has_default)
                                        return;
                        }

                        next = stmt->base.next;
                        break;
                }

                case STATEMENT_EXPRESSION: {
                        /* Check for noreturn function call */
                        expression_t const *const expr = stmt->expression.expression;
                        if (!expression_returns(expr))
                                return;

                        next = stmt->base.next;
                        break;
                }

                case STATEMENT_CONTINUE:
                        for (statement_t *parent = stmt;;) {
                                parent = parent->base.parent;
                                if (parent == NULL) /* continue not within loop */
                                        return;

                                next = parent;
                                switch (parent->kind) {
                                        case STATEMENT_WHILE:    goto continue_while;
                                        case STATEMENT_DO_WHILE: goto continue_do_while;
                                        case STATEMENT_FOR:      goto continue_for;

                                        default: break;
                                }
                        }

                case STATEMENT_BREAK:
                        for (statement_t *parent = stmt;;) {
                                parent = parent->base.parent;
                                if (parent == NULL) /* break not within loop/switch */
                                        return;

                                switch (parent->kind) {
                                        case STATEMENT_SWITCH:
                                        case STATEMENT_WHILE:
                                        case STATEMENT_DO_WHILE:
                                        case STATEMENT_FOR:
                                                last = parent;
                                                next = parent->base.next;
                                                goto found_break_parent;

                                        default: break;
                                }
                        }
found_break_parent:
                        break;

                case STATEMENT_GOTO:
                        if (stmt->gotos.expression) {
                                if (!expression_returns(stmt->gotos.expression))
                                        return;

                                statement_t *parent = stmt->base.parent;
                                if (parent == NULL) /* top level goto */
                                        return;
                                next = parent;
                        } else {
                                next = stmt->gotos.label->statement;
                                if (next == NULL) /* missing label */
                                        return;
                        }
                        break;

                case STATEMENT_LABEL:
                        next = stmt->label.statement;
                        break;

                case STATEMENT_CASE_LABEL:
                        next = stmt->case_label.statement;
                        break;

                case STATEMENT_WHILE: {
                        while_statement_t const *const whiles = &stmt->whiles;
                        expression_t      const *const cond   = whiles->condition;

                        if (!expression_returns(cond))
                                return;

                        int const val = determine_truth(cond);

                        if (val >= 0)
                                check_reachable(whiles->body);

                        if (val > 0)
                                return;

                        next = stmt->base.next;
                        break;
                }

                case STATEMENT_DO_WHILE:
                        next = stmt->do_while.body;
                        break;

                case STATEMENT_FOR: {
                        for_statement_t *const fors = &stmt->fors;

                        if (fors->condition_reachable)
                                return;
                        fors->condition_reachable = true;

                        expression_t const *const cond = fors->condition;

                        int val;
                        if (cond == NULL) {
                                val = 1;
                        } else if (expression_returns(cond)) {
                                val = determine_truth(cond);
                        } else {
                                return;
                        }

                        if (val >= 0)
                                check_reachable(fors->body);

                        if (val > 0)
                                return;

                        next = stmt->base.next;
                        break;
                }

                case STATEMENT_MS_TRY: {
                        ms_try_statement_t const *const ms_try = &stmt->ms_try;
                        check_reachable(ms_try->try_statement);
                        next = ms_try->final_statement;
                        break;
                }

                case STATEMENT_LEAVE: {
                        statement_t *parent = stmt;
                        for (;;) {
                                parent = parent->base.parent;
                                if (parent == NULL) /* __leave not within __try */
                                        return;

                                if (parent->kind == STATEMENT_MS_TRY) {
                                        last = parent;
                                        next = parent->ms_try.final_statement;
                                        break;
                                }
                        }
                        break;
                }

                default:
                        panic("invalid statement kind");
        }

        while (next == NULL) {
                next = last->base.parent;
                if (next == NULL) {
                        noreturn_candidate = false;

                        type_t *const type = skip_typeref(current_function->base.type);
                        assert(is_type_function(type));
                        type_t *const ret  = skip_typeref(type->function.return_type);
                        if (warning.return_type                    &&
                            !is_type_atomic(ret, ATOMIC_TYPE_VOID) &&
                            is_type_valid(ret)                     &&
                            !is_sym_main(current_function->base.base.symbol)) {
                                warningf(&stmt->base.source_position,
                                         "control reaches end of non-void function");
                        }
                        return;
                }

                switch (next->kind) {
                        case STATEMENT_INVALID:
                        case STATEMENT_EMPTY:
                        case STATEMENT_DECLARATION:
                        case STATEMENT_EXPRESSION:
                        case STATEMENT_ASM:
                        case STATEMENT_RETURN:
                        case STATEMENT_CONTINUE:
                        case STATEMENT_BREAK:
                        case STATEMENT_GOTO:
                        case STATEMENT_LEAVE:
                                panic("invalid control flow in function");

                        case STATEMENT_COMPOUND:
                                if (next->compound.stmt_expr) {
                                        reaches_end = true;
                                        return;
                                }
                                /* FALLTHROUGH */
                        case STATEMENT_IF:
                        case STATEMENT_SWITCH:
                        case STATEMENT_LABEL:
                        case STATEMENT_CASE_LABEL:
                                last = next;
                                next = next->base.next;
                                break;

                        case STATEMENT_WHILE: {
continue_while:
                                if (next->base.reachable)
                                        return;
                                next->base.reachable = true;

                                while_statement_t const *const whiles = &next->whiles;
                                expression_t      const *const cond   = whiles->condition;

                                if (!expression_returns(cond))
                                        return;

                                int const val = determine_truth(cond);

                                if (val >= 0)
                                        check_reachable(whiles->body);

                                if (val > 0)
                                        return;

                                last = next;
                                next = next->base.next;
                                break;
                        }

                        case STATEMENT_DO_WHILE: {
continue_do_while:
                                if (next->base.reachable)
                                        return;
                                next->base.reachable = true;

                                do_while_statement_t const *const dw   = &next->do_while;
                                expression_t         const *const cond = dw->condition;

                                if (!expression_returns(cond))
                                        return;

                                int const val = determine_truth(cond);

                                if (val >= 0)
                                        check_reachable(dw->body);

                                if (val > 0)
                                        return;

                                last = next;
                                next = next->base.next;
                                break;
                        }

                        case STATEMENT_FOR: {
continue_for:;
                                for_statement_t *const fors = &next->fors;

                                fors->step_reachable = true;

                                if (fors->condition_reachable)
                                        return;
                                fors->condition_reachable = true;

                                expression_t const *const cond = fors->condition;

                                int val;
                                if (cond == NULL) {
                                        val = 1;
                                } else if (expression_returns(cond)) {
                                        val = determine_truth(cond);
                                } else {
                                        return;
                                }

                                if (val >= 0)
                                        check_reachable(fors->body);

                                if (val > 0)
                                        return;

                                last = next;
                                next = next->base.next;
                                break;
                        }

                        case STATEMENT_MS_TRY:
                                last = next;
                                next = next->ms_try.final_statement;
                                break;
                }
        }

        check_reachable(next);
}

static void check_unreachable(statement_t* const stmt, void *const env)
{
        (void)env;

        switch (stmt->kind) {
                case STATEMENT_DO_WHILE:
                        if (!stmt->base.reachable) {
                                expression_t const *const cond = stmt->do_while.condition;
                                if (determine_truth(cond) >= 0) {
                                        warningf(&cond->base.source_position,
                                                 "condition of do-while-loop is unreachable");
                                }
                        }
                        return;

                case STATEMENT_FOR: {
                        for_statement_t const* const fors = &stmt->fors;

                        // if init and step are unreachable, cond is unreachable, too
                        if (!stmt->base.reachable && !fors->step_reachable) {
                                warningf(&stmt->base.source_position, "statement is unreachable");
                        } else {
                                if (!stmt->base.reachable && fors->initialisation != NULL) {
                                        warningf(&fors->initialisation->base.source_position,
                                                 "initialisation of for-statement is unreachable");
                                }

                                if (!fors->condition_reachable && fors->condition != NULL) {
                                        warningf(&fors->condition->base.source_position,
                                                 "condition of for-statement is unreachable");
                                }

                                if (!fors->step_reachable && fors->step != NULL) {
                                        warningf(&fors->step->base.source_position,
                                                 "step of for-statement is unreachable");
                                }
                        }
                        return;
                }

                case STATEMENT_COMPOUND:
                        if (stmt->compound.statements != NULL)
                                return;
                        goto warn_unreachable;

                case STATEMENT_DECLARATION: {
                        /* Only warn if there is at least one declarator with an initializer.
                         * This typically occurs in switch statements. */
                        declaration_statement_t const *const decl = &stmt->declaration;
                        entity_t                const *      ent  = decl->declarations_begin;
                        entity_t                const *const last = decl->declarations_end;
                        if (ent != NULL) {
                                for (;; ent = ent->base.next) {
                                        if (ent->kind                 == ENTITY_VARIABLE &&
                                                        ent->variable.initializer != NULL) {
                                                goto warn_unreachable;
                                        }
                                        if (ent == last)
                                                return;
                                }
                        }
                }

                default:
warn_unreachable:
                        if (!stmt->base.reachable)
                                warningf(&stmt->base.source_position, "statement is unreachable");
                        return;
        }
}

static void parse_external_declaration(void)
{
        /* function-definitions and declarations both start with declaration
         * specifiers */
        declaration_specifiers_t specifiers;
        memset(&specifiers, 0, sizeof(specifiers));

        add_anchor_token(';');
        parse_declaration_specifiers(&specifiers);
        rem_anchor_token(';');

        /* must be a declaration */
        if (token.type == ';') {
                parse_anonymous_declaration_rest(&specifiers);
                return;
        }

        add_anchor_token(',');
        add_anchor_token('=');
        add_anchor_token(';');
        add_anchor_token('{');

        /* declarator is common to both function-definitions and declarations */
        entity_t *ndeclaration = parse_declarator(&specifiers, DECL_FLAGS_NONE);

        rem_anchor_token('{');
        rem_anchor_token(';');
        rem_anchor_token('=');
        rem_anchor_token(',');

        /* must be a declaration */
        switch (token.type) {
                case ',':
                case ';':
                case '=':
                        parse_declaration_rest(ndeclaration, &specifiers, record_entity,
                                        DECL_FLAGS_NONE);
                        return;
        }

        /* must be a function definition */
        parse_kr_declaration_list(ndeclaration);

        if (token.type != '{') {
                parse_error_expected("while parsing function definition", '{', NULL);
                eat_until_matching_token(';');
                return;
        }

        assert(is_declaration(ndeclaration));
        type_t *const orig_type = ndeclaration->declaration.type;
        type_t *      type      = skip_typeref(orig_type);

        if (!is_type_function(type)) {
                if (is_type_valid(type)) {
                        errorf(HERE, "declarator '%#T' has a body but is not a function type",
                               type, ndeclaration->base.symbol);
                }
                eat_block();
                return;
        } else if (is_typeref(orig_type)) {
                /* §6.9.1:2 */
                errorf(&ndeclaration->base.source_position,
                                "type of function definition '%#T' is a typedef",
                                orig_type, ndeclaration->base.symbol);
        }

        if (warning.aggregate_return &&
            is_type_compound(skip_typeref(type->function.return_type))) {
                warningf(HERE, "function '%Y' returns an aggregate",
                         ndeclaration->base.symbol);
        }
        if (warning.traditional && !type->function.unspecified_parameters) {
                warningf(HERE, "traditional C rejects ISO C style function definition of function '%Y'",
                        ndeclaration->base.symbol);
        }
        if (warning.old_style_definition && type->function.unspecified_parameters) {
                warningf(HERE, "old-style function definition '%Y'",
                        ndeclaration->base.symbol);
        }

        /* §6.7.5.3:14 a function definition with () means no
         * parameters (and not unspecified parameters) */
        if (type->function.unspecified_parameters &&
                        type->function.parameters == NULL) {
                type_t *copy                          = duplicate_type(type);
                copy->function.unspecified_parameters = false;
                type                                  = identify_new_type(copy);

                ndeclaration->declaration.type = type;
        }

        entity_t *const entity = record_entity(ndeclaration, true);
        assert(entity->kind == ENTITY_FUNCTION);
        assert(ndeclaration->kind == ENTITY_FUNCTION);

        function_t *function = &entity->function;
        if (ndeclaration != entity) {
                function->parameters = ndeclaration->function.parameters;
        }
        assert(is_declaration(entity));
        type = skip_typeref(entity->declaration.type);

        /* push function parameters and switch scope */
        size_t const  top       = environment_top();
        scope_t      *old_scope = scope_push(&function->parameters);

        entity_t *parameter = function->parameters.entities;
        for (; parameter != NULL; parameter = parameter->base.next) {
                if (parameter->base.parent_scope == &ndeclaration->function.parameters) {
                        parameter->base.parent_scope = current_scope;
                }
                assert(parameter->base.parent_scope == NULL
                                || parameter->base.parent_scope == current_scope);
                parameter->base.parent_scope = current_scope;
                if (parameter->base.symbol == NULL) {
                        errorf(&parameter->base.source_position, "parameter name omitted");
                        continue;
                }
                environment_push(parameter);
        }

        if (function->statement != NULL) {
                parser_error_multiple_definition(entity, HERE);
                eat_block();
        } else {
                /* parse function body */
                int         label_stack_top      = label_top();
                function_t *old_current_function = current_function;
                entity_t   *old_current_entity   = current_entity;
                current_function                 = function;
                current_entity                   = (entity_t*) function;
                current_parent                   = NULL;

                goto_first   = NULL;
                goto_anchor  = &goto_first;
                label_first  = NULL;
                label_anchor = &label_first;

                statement_t *const body = parse_compound_statement(false);
                function->statement = body;
                first_err = true;
                check_labels();
                check_declarations();
                if (warning.return_type      ||
                    warning.unreachable_code ||
                    (warning.missing_noreturn
                     && !(function->base.modifiers & DM_NORETURN))) {
                        noreturn_candidate = true;
                        check_reachable(body);
                        if (warning.unreachable_code)
                                walk_statements(body, check_unreachable, NULL);
                        if (warning.missing_noreturn &&
                            noreturn_candidate       &&
                            !(function->base.modifiers & DM_NORETURN)) {
                                warningf(&body->base.source_position,
                                         "function '%#T' is candidate for attribute 'noreturn'",
                                         type, entity->base.symbol);
                        }
                }

                assert(current_parent   == NULL);
                assert(current_function == function);
                assert(current_entity   == (entity_t*) function);
                current_entity   = old_current_entity;
                current_function = old_current_function;
                label_pop_to(label_stack_top);
        }

        assert(current_scope == &function->parameters);
        scope_pop(old_scope);
        environment_pop_to(top);
}

static type_t *make_bitfield_type(type_t *base_type, expression_t *size,
                                  source_position_t *source_position,
                                  const symbol_t *symbol)
{
        type_t *type = allocate_type_zero(TYPE_BITFIELD);

        type->bitfield.base_type       = base_type;
        type->bitfield.size_expression = size;

        il_size_t bit_size;
        type_t *skipped_type = skip_typeref(base_type);
        if (!is_type_integer(skipped_type)) {
                errorf(HERE, "bitfield base type '%T' is not an integer type",
                       base_type);
                bit_size = 0;
        } else {
                bit_size = get_type_size(base_type) * 8;
        }

        if (is_constant_expression(size)) {
                long v = fold_constant_to_int(size);
                const symbol_t *user_symbol = symbol == NULL ? sym_anonymous : symbol;

                if (v < 0) {
                        errorf(source_position, "negative width in bit-field '%Y'",
                               user_symbol);
                } else if (v == 0 && symbol != NULL) {
                        errorf(source_position, "zero width for bit-field '%Y'",
                               user_symbol);
                } else if (bit_size > 0 && (il_size_t)v > bit_size) {
                        errorf(source_position, "width of '%Y' exceeds its type",
                               user_symbol);
                } else {
                        type->bitfield.bit_size = v;
                }
        }

        return type;
}

static entity_t *find_compound_entry(compound_t *compound, symbol_t *symbol)
{
        entity_t *iter = compound->members.entities;
        for (; iter != NULL; iter = iter->base.next) {
                if (iter->kind != ENTITY_COMPOUND_MEMBER)
                        continue;

                if (iter->base.symbol == symbol) {
                        return iter;
                } else if (iter->base.symbol == NULL) {
                        /* search in anonymous structs and unions */
                        type_t *type = skip_typeref(iter->declaration.type);
                        if (is_type_compound(type)) {
                                if (find_compound_entry(type->compound.compound, symbol)
                                                != NULL)
                                        return iter;
                        }
                        continue;
                }
        }

        return NULL;
}

static void check_deprecated(const source_position_t *source_position,
                             const entity_t *entity)
{
        if (!warning.deprecated_declarations)
                return;
        if (!is_declaration(entity))
                return;
        if ((entity->declaration.modifiers & DM_DEPRECATED) == 0)
                return;

        char const *const prefix = get_entity_kind_name(entity->kind);
        const char *deprecated_string
                        = get_deprecated_string(entity->declaration.attributes);
        if (deprecated_string != NULL) {
                warningf(source_position, "%s '%Y' is deprecated (declared %P): \"%s\"",
                                 prefix, entity->base.symbol, &entity->base.source_position,
                                 deprecated_string);
        } else {
                warningf(source_position, "%s '%Y' is deprecated (declared %P)", prefix,
                                 entity->base.symbol, &entity->base.source_position);
        }
}


static expression_t *create_select(const source_position_t *pos,
                                   expression_t *addr,
                                   type_qualifiers_t qualifiers,
                                                                   entity_t *entry)
{
        assert(entry->kind == ENTITY_COMPOUND_MEMBER);

        check_deprecated(pos, entry);

        expression_t *select          = allocate_expression_zero(EXPR_SELECT);
        select->select.compound       = addr;
        select->select.compound_entry = entry;

        type_t *entry_type = entry->declaration.type;
        type_t *res_type   = get_qualified_type(entry_type, qualifiers);

        /* we always do the auto-type conversions; the & and sizeof parser contains
         * code to revert this! */
        select->base.type = automatic_type_conversion(res_type);
        if (res_type->kind == TYPE_BITFIELD) {
                select->base.type = res_type->bitfield.base_type;
        }

        return select;
}

/**
 * Find entry with symbol in compound. Search anonymous structs and unions and
 * creates implicit select expressions for them.
 * Returns the adress for the innermost compound.
 */
static expression_t *find_create_select(const source_position_t *pos,
                                        expression_t *addr,
                                        type_qualifiers_t qualifiers,
                                        compound_t *compound, symbol_t *symbol)
{
        entity_t *iter = compound->members.entities;
        for (; iter != NULL; iter = iter->base.next) {
                if (iter->kind != ENTITY_COMPOUND_MEMBER)
                        continue;

                symbol_t *iter_symbol = iter->base.symbol;
                if (iter_symbol == NULL) {
                        type_t *type = iter->declaration.type;
                        if (type->kind != TYPE_COMPOUND_STRUCT
                                        && type->kind != TYPE_COMPOUND_UNION)
                                continue;

                        compound_t *sub_compound = type->compound.compound;

                        if (find_compound_entry(sub_compound, symbol) == NULL)
                                continue;

                        expression_t *sub_addr = create_select(pos, addr, qualifiers, iter);
                        sub_addr->base.source_position = *pos;
                        sub_addr->select.implicit      = true;
                        return find_create_select(pos, sub_addr, qualifiers, sub_compound,
                                                  symbol);
                }

                if (iter_symbol == symbol) {
                        return create_select(pos, addr, qualifiers, iter);
                }
        }

        return NULL;
}

static void parse_compound_declarators(compound_t *compound,
                const declaration_specifiers_t *specifiers)
{
        do {
                entity_t *entity;

                if (token.type == ':') {
                        source_position_t source_position = *HERE;
                        next_token();

                        type_t *base_type = specifiers->type;
                        expression_t *size = parse_constant_expression();

                        type_t *type = make_bitfield_type(base_type, size,
                                        &source_position, NULL);

                        attribute_t  *attributes = parse_attributes(NULL);
                        attribute_t **anchor     = &attributes;
                        while (*anchor != NULL)
                                anchor = &(*anchor)->next;
                        *anchor = specifiers->attributes;

                        entity = allocate_entity_zero(ENTITY_COMPOUND_MEMBER);
                        entity->base.namespc                       = NAMESPACE_NORMAL;
                        entity->base.source_position               = source_position;
                        entity->declaration.declared_storage_class = STORAGE_CLASS_NONE;
                        entity->declaration.storage_class          = STORAGE_CLASS_NONE;
                        entity->declaration.type                   = type;
                        entity->declaration.attributes             = attributes;

                        if (attributes != NULL) {
                                handle_entity_attributes(attributes, entity);
                        }
                        append_entity(&compound->members, entity);
                } else {
                        entity = parse_declarator(specifiers,
                                        DECL_MAY_BE_ABSTRACT | DECL_CREATE_COMPOUND_MEMBER);
                        if (entity->kind == ENTITY_TYPEDEF) {
                                errorf(&entity->base.source_position,
                                                "typedef not allowed as compound member");
                        } else {
                                assert(entity->kind == ENTITY_COMPOUND_MEMBER);

                                /* make sure we don't define a symbol multiple times */
                                symbol_t *symbol = entity->base.symbol;
                                if (symbol != NULL) {
                                        entity_t *prev = find_compound_entry(compound, symbol);
                                        if (prev != NULL) {
                                                errorf(&entity->base.source_position,
                                                                "multiple declarations of symbol '%Y' (declared %P)",
                                                                symbol, &prev->base.source_position);
                                        }
                                }

                                if (token.type == ':') {
                                        source_position_t source_position = *HERE;
                                        next_token();
                                        expression_t *size = parse_constant_expression();

                                        type_t *type          = entity->declaration.type;
                                        type_t *bitfield_type = make_bitfield_type(type, size,
                                                        &source_position, entity->base.symbol);

                                        attribute_t *attributes = parse_attributes(NULL);
                                        entity->declaration.type = bitfield_type;
                                        handle_entity_attributes(attributes, entity);
                                } else {
                                        type_t *orig_type = entity->declaration.type;
                                        type_t *type      = skip_typeref(orig_type);
                                        if (is_type_function(type)) {
                                                errorf(&entity->base.source_position,
                                                       "compound member '%Y' must not have function type '%T'",
                                                                entity->base.symbol, orig_type);
                                        } else if (is_type_incomplete(type)) {
                                                /* §6.7.2.1:16 flexible array member */
                                                if (!is_type_array(type)       ||
                                                                token.type          != ';' ||
                                                                look_ahead(1)->type != '}') {
                                                        errorf(&entity->base.source_position,
                                                               "compound member '%Y' has incomplete type '%T'",
                                                                        entity->base.symbol, orig_type);
                                                }
                                        }
                                }

                                append_entity(&compound->members, entity);
                        }
                }
        } while (next_if(','));
        expect(';', end_error);

end_error:
        anonymous_entity = NULL;
}

static void parse_compound_type_entries(compound_t *compound)
{
        eat('{');
        add_anchor_token('}');

        while (token.type != '}') {
                if (token.type == T_EOF) {
                        errorf(HERE, "EOF while parsing struct");
                        break;
                }
                declaration_specifiers_t specifiers;
                memset(&specifiers, 0, sizeof(specifiers));
                parse_declaration_specifiers(&specifiers);

                parse_compound_declarators(compound, &specifiers);
        }
        rem_anchor_token('}');
        next_token();

        /* §6.7.2.1:7 */
        compound->complete = true;
}

static type_t *parse_typename(void)
{
        declaration_specifiers_t specifiers;
        memset(&specifiers, 0, sizeof(specifiers));
        parse_declaration_specifiers(&specifiers);
        if (specifiers.storage_class != STORAGE_CLASS_NONE
                        || specifiers.thread_local) {
                /* TODO: improve error message, user does probably not know what a
                 * storage class is...
                 */
                errorf(HERE, "typename must not have a storage class");
        }

        type_t *result = parse_abstract_declarator(specifiers.type);

        return result;
}




typedef expression_t* (*parse_expression_function)(void);
typedef expression_t* (*parse_expression_infix_function)(expression_t *left);

typedef struct expression_parser_function_t expression_parser_function_t;
struct expression_parser_function_t {
        parse_expression_function        parser;
        precedence_t                     infix_precedence;
        parse_expression_infix_function  infix_parser;
};

expression_parser_function_t expression_parsers[T_LAST_TOKEN];

/**
 * Prints an error message if an expression was expected but not read
 */
static expression_t *expected_expression_error(void)
{
        /* skip the error message if the error token was read */
        if (token.type != T_ERROR) {
                errorf(HERE, "expected expression, got token %K", &token);
        }
        next_token();

        return create_invalid_expression();
}

static type_t *get_string_type(void)
{
        return warning.write_strings ? type_const_char_ptr : type_char_ptr;
}

static type_t *get_wide_string_type(void)
{
        return warning.write_strings ? type_const_wchar_t_ptr : type_wchar_t_ptr;
}

/**
 * Parse a string constant.
 */
static expression_t *parse_string_literal(void)
{
        source_position_t begin   = token.source_position;
        string_t          res     = token.literal;
        bool              is_wide = (token.type == T_WIDE_STRING_LITERAL);

        next_token();
        while (token.type == T_STRING_LITERAL
                        || token.type == T_WIDE_STRING_LITERAL) {
                warn_string_concat(&token.source_position);
                res = concat_strings(&res, &token.literal);
                next_token();
                is_wide |= token.type == T_WIDE_STRING_LITERAL;
        }

        expression_t *literal;
        if (is_wide) {
                literal = allocate_expression_zero(EXPR_WIDE_STRING_LITERAL);
                literal->base.type = get_wide_string_type();
        } else {
                literal = allocate_expression_zero(EXPR_STRING_LITERAL);
                literal->base.type = get_string_type();
        }
        literal->base.source_position = begin;
        literal->literal.value        = res;

        return literal;
}

/**
 * Parse a boolean constant.
 */
static expression_t *parse_boolean_literal(bool value)
{
        expression_t *literal = allocate_expression_zero(EXPR_LITERAL_BOOLEAN);
        literal->base.source_position = token.source_position;
        literal->base.type            = type_bool;
        literal->literal.value.begin  = value ? "true" : "false";
        literal->literal.value.size   = value ? 4 : 5;

        next_token();
        return literal;
}

static void warn_traditional_suffix(void)
{
        if (!warning.traditional)
                return;
        warningf(&token.source_position, "traditional C rejects the '%Y' suffix",
                 token.symbol);
}

static void check_integer_suffix(void)
{
        symbol_t *suffix = token.symbol;
        if (suffix == NULL)
                return;

        bool not_traditional = false;
        const char *c = suffix->string;
        if (*c == 'l' || *c == 'L') {
                ++c;
                if (*c == *(c-1)) {
                        not_traditional = true;
                        ++c;
                        if (*c == 'u' || *c == 'U') {
                                ++c;
                        }
                } else if (*c == 'u' || *c == 'U') {
                        not_traditional = true;
                        ++c;
                }
        } else if (*c == 'u' || *c == 'U') {
                not_traditional = true;
                ++c;
                if (*c == 'l' || *c == 'L') {
                        ++c;
                        if (*c == *(c-1)) {
                                ++c;
                        }
                }
        }
        if (*c != '\0') {
                errorf(&token.source_position,
                       "invalid suffix '%s' on integer constant", suffix->string);
        } else if (not_traditional) {
                warn_traditional_suffix();
        }
}

static type_t *check_floatingpoint_suffix(void)
{
        symbol_t *suffix = token.symbol;
        type_t   *type   = type_double;
        if (suffix == NULL)
                return type;

        bool not_traditional = false;
        const char *c = suffix->string;
        if (*c == 'f' || *c == 'F') {
                ++c;
                type = type_float;
        } else if (*c == 'l' || *c == 'L') {
                ++c;
                type = type_long_double;
        }
        if (*c != '\0') {
                errorf(&token.source_position,
                       "invalid suffix '%s' on floatingpoint constant", suffix->string);
        } else if (not_traditional) {
                warn_traditional_suffix();
        }

        return type;
}

/**
 * Parse an integer constant.
 */
static expression_t *parse_number_literal(void)
{
        expression_kind_t  kind;
        type_t            *type;

        switch (token.type) {
        case T_INTEGER:
                kind = EXPR_LITERAL_INTEGER;
                check_integer_suffix();
                type = type_int;
                break;
        case T_INTEGER_OCTAL:
                kind = EXPR_LITERAL_INTEGER_OCTAL;
                check_integer_suffix();
                type = type_int;
                break;
        case T_INTEGER_HEXADECIMAL:
                kind = EXPR_LITERAL_INTEGER_HEXADECIMAL;
                check_integer_suffix();
                type = type_int;
                break;
        case T_FLOATINGPOINT:
                kind = EXPR_LITERAL_FLOATINGPOINT;
                type = check_floatingpoint_suffix();
                break;
        case T_FLOATINGPOINT_HEXADECIMAL:
                kind = EXPR_LITERAL_FLOATINGPOINT_HEXADECIMAL;
                type = check_floatingpoint_suffix();
                break;
        default:
                panic("unexpected token type in parse_number_literal");
        }

        expression_t *literal = allocate_expression_zero(kind);
        literal->base.source_position = token.source_position;
        literal->base.type            = type;
        literal->literal.value        = token.literal;
        literal->literal.suffix       = token.symbol;
        next_token();

        /* integer type depends on the size of the number and the size
         * representable by the types. The backend/codegeneration has to determine
         * that
         */
        determine_literal_type(&literal->literal);
        return literal;
}

/**
 * Parse a character constant.
 */
static expression_t *parse_character_constant(void)
{
        expression_t *literal = allocate_expression_zero(EXPR_LITERAL_CHARACTER);
        literal->base.source_position = token.source_position;
        literal->base.type            = c_mode & _CXX ? type_char : type_int;
        literal->literal.value        = token.literal;

        size_t len = literal->literal.value.size;
        if (len != 1) {
                if (!GNU_MODE && !(c_mode & _C99)) {
                        errorf(HERE, "more than 1 character in character constant");
                } else if (warning.multichar) {
                        literal->base.type = type_int;
                        warningf(HERE, "multi-character character constant");
                }
        }

        next_token();
        return literal;
}

/**
 * Parse a wide character constant.
 */
static expression_t *parse_wide_character_constant(void)
{
        expression_t *literal = allocate_expression_zero(EXPR_LITERAL_WIDE_CHARACTER);
        literal->base.source_position = token.source_position;
        literal->base.type            = type_int;
        literal->literal.value        = token.literal;

        size_t len = wstrlen(&literal->literal.value);
        if (len != 1) {
                warningf(HERE, "multi-character character constant");
        }

        next_token();
        return literal;
}

static entity_t *create_implicit_function(symbol_t *symbol,
                const source_position_t *source_position)
{
        type_t *ntype                          = allocate_type_zero(TYPE_FUNCTION);
        ntype->function.return_type            = type_int;
        ntype->function.unspecified_parameters = true;
        ntype->function.linkage                = LINKAGE_C;
        type_t *type                           = identify_new_type(ntype);

        entity_t *entity = allocate_entity_zero(ENTITY_FUNCTION);
        entity->declaration.storage_class          = STORAGE_CLASS_EXTERN;
        entity->declaration.declared_storage_class = STORAGE_CLASS_EXTERN;
        entity->declaration.type                   = type;
        entity->declaration.implicit               = true;
        entity->base.symbol                        = symbol;
        entity->base.source_position               = *source_position;

        if (current_scope != NULL) {
                bool strict_prototypes_old = warning.strict_prototypes;
                warning.strict_prototypes  = false;
                record_entity(entity, false);
                warning.strict_prototypes = strict_prototypes_old;
        }

        return entity;
}

/**
 * Performs automatic type cast as described in §6.3.2.1.
 *
 * @param orig_type  the original type
 */
static type_t *automatic_type_conversion(type_t *orig_type)
{
        type_t *type = skip_typeref(orig_type);
        if (is_type_array(type)) {
                array_type_t *array_type   = &type->array;
                type_t       *element_type = array_type->element_type;
                unsigned      qualifiers   = array_type->base.qualifiers;

                return make_pointer_type(element_type, qualifiers);
        }

        if (is_type_function(type)) {
                return make_pointer_type(orig_type, TYPE_QUALIFIER_NONE);
        }

        return orig_type;
}

/**
 * reverts the automatic casts of array to pointer types and function
 * to function-pointer types as defined §6.3.2.1
 */
type_t *revert_automatic_type_conversion(const expression_t *expression)
{
        switch (expression->kind) {
        case EXPR_REFERENCE: {
                entity_t *entity = expression->reference.entity;
                if (is_declaration(entity)) {
                        return entity->declaration.type;
                } else if (entity->kind == ENTITY_ENUM_VALUE) {
                        return entity->enum_value.enum_type;
                } else {
                        panic("no declaration or enum in reference");
                }
        }

        case EXPR_SELECT: {
                entity_t *entity = expression->select.compound_entry;
                assert(is_declaration(entity));
                type_t   *type   = entity->declaration.type;
                return get_qualified_type(type,
                                expression->base.type->base.qualifiers);
        }

        case EXPR_UNARY_DEREFERENCE: {
                const expression_t *const value = expression->unary.value;
                type_t             *const type  = skip_typeref(value->base.type);
                if (!is_type_pointer(type))
                        return type_error_type;
                return type->pointer.points_to;
        }

        case EXPR_ARRAY_ACCESS: {
                const expression_t *array_ref = expression->array_access.array_ref;
                type_t             *type_left = skip_typeref(array_ref->base.type);
                if (!is_type_pointer(type_left))
                        return type_error_type;
                return type_left->pointer.points_to;
        }

        case EXPR_STRING_LITERAL: {
                size_t size = expression->string_literal.value.size;
                return make_array_type(type_char, size, TYPE_QUALIFIER_NONE);
        }

        case EXPR_WIDE_STRING_LITERAL: {
                size_t size = wstrlen(&expression->string_literal.value);
                return make_array_type(type_wchar_t, size, TYPE_QUALIFIER_NONE);
        }

        case EXPR_COMPOUND_LITERAL:
                return expression->compound_literal.type;

        default:
                break;
        }
        return expression->base.type;
}

/**
 * Find an entity matching a symbol in a scope.
 * Uses current scope if scope is NULL
 */
static entity_t *lookup_entity(const scope_t *scope, symbol_t *symbol,
                               namespace_tag_t namespc)
{
        if (scope == NULL) {
                return get_entity(symbol, namespc);
        }

        /* we should optimize here, if scope grows above a certain size we should
           construct a hashmap here... */
        entity_t *entity = scope->entities;
        for ( ; entity != NULL; entity = entity->base.next) {
                if (entity->base.symbol == symbol && entity->base.namespc == namespc)
                        break;
        }

        return entity;
}

static entity_t *parse_qualified_identifier(void)
{
        /* namespace containing the symbol */
        symbol_t          *symbol;
        source_position_t  pos;
        const scope_t     *lookup_scope = NULL;

        if (next_if(T_COLONCOLON))
                lookup_scope = &unit->scope;

        entity_t *entity;
        while (true) {
                if (token.type != T_IDENTIFIER) {
                        parse_error_expected("while parsing identifier", T_IDENTIFIER, NULL);
                        return create_error_entity(sym_anonymous, ENTITY_VARIABLE);
                }
                symbol = token.symbol;
                pos    = *HERE;
                next_token();

                /* lookup entity */
                entity = lookup_entity(lookup_scope, symbol, NAMESPACE_NORMAL);

                if (!next_if(T_COLONCOLON))
                        break;

                switch (entity->kind) {
                case ENTITY_NAMESPACE:
                        lookup_scope = &entity->namespacee.members;
                        break;
                case ENTITY_STRUCT:
                case ENTITY_UNION:
                case ENTITY_CLASS:
                        lookup_scope = &entity->compound.members;
                        break;
                default:
                        errorf(&pos, "'%Y' must be a namespace, class, struct or union (but is a %s)",
                               symbol, get_entity_kind_name(entity->kind));
                        goto end_error;
                }
        }

        if (entity == NULL) {
                if (!strict_mode && token.type == '(') {
                        /* an implicitly declared function */
                        if (warning.error_implicit_function_declaration) {
                                errorf(&pos, "implicit declaration of function '%Y'", symbol);
                        } else if (warning.implicit_function_declaration) {
                                warningf(&pos, "implicit declaration of function '%Y'", symbol);
                        }

                        entity = create_implicit_function(symbol, &pos);
                } else {
                        errorf(&pos, "unknown identifier '%Y' found.", symbol);
                        entity = create_error_entity(symbol, ENTITY_VARIABLE);
                }
        }

        return entity;

end_error:
        /* skip further qualifications */
        while (next_if(T_IDENTIFIER) && next_if(T_COLONCOLON)) {}

        return create_error_entity(sym_anonymous, ENTITY_VARIABLE);
}

static expression_t *parse_reference(void)
{
        entity_t *entity = parse_qualified_identifier();

        type_t *orig_type;
        if (is_declaration(entity)) {
                orig_type = entity->declaration.type;
        } else if (entity->kind == ENTITY_ENUM_VALUE) {
                orig_type = entity->enum_value.enum_type;
        } else {
                panic("expected declaration or enum value in reference");
        }

        /* we always do the auto-type conversions; the & and sizeof parser contains
         * code to revert this! */
        type_t *type = automatic_type_conversion(orig_type);

        expression_kind_t kind = EXPR_REFERENCE;
        if (entity->kind == ENTITY_ENUM_VALUE)
                kind = EXPR_REFERENCE_ENUM_VALUE;

        expression_t *expression     = allocate_expression_zero(kind);
        expression->reference.entity = entity;
        expression->base.type        = type;

        /* this declaration is used */
        if (is_declaration(entity)) {
                entity->declaration.used = true;
        }

        if (entity->base.parent_scope != file_scope
                && (current_function != NULL
                        && entity->base.parent_scope->depth < current_function->parameters.depth)
                && (entity->kind == ENTITY_VARIABLE || entity->kind == ENTITY_PARAMETER)) {
                if (entity->kind == ENTITY_VARIABLE) {
                        /* access of a variable from an outer function */
                        entity->variable.address_taken = true;
                } else if (entity->kind == ENTITY_PARAMETER) {
                        entity->parameter.address_taken = true;
                }
                current_function->need_closure = true;
        }

        check_deprecated(HERE, entity);

        if (warning.init_self && entity == current_init_decl && !in_type_prop
            && entity->kind == ENTITY_VARIABLE) {
                current_init_decl = NULL;
                warningf(HERE, "variable '%#T' is initialized by itself",
                         entity->declaration.type, entity->base.symbol);
        }

        return expression;
}

static bool semantic_cast(expression_t *cast)
{
        expression_t            *expression      = cast->unary.value;
        type_t                  *orig_dest_type  = cast->base.type;
        type_t                  *orig_type_right = expression->base.type;
        type_t            const *dst_type        = skip_typeref(orig_dest_type);
        type_t            const *src_type        = skip_typeref(orig_type_right);
        source_position_t const *pos             = &cast->base.source_position;

        /* §6.5.4 A (void) cast is explicitly permitted, more for documentation than for utility. */
        if (dst_type == type_void)
                return true;

        /* only integer and pointer can be casted to pointer */
        if (is_type_pointer(dst_type)  &&
            !is_type_pointer(src_type) &&
            !is_type_integer(src_type) &&
            is_type_valid(src_type)) {
                errorf(pos, "cannot convert type '%T' to a pointer type", orig_type_right);
                return false;
        }

        if (!is_type_scalar(dst_type) && is_type_valid(dst_type)) {
                errorf(pos, "conversion to non-scalar type '%T' requested", orig_dest_type);
                return false;
        }

        if (!is_type_scalar(src_type) && is_type_valid(src_type)) {
                errorf(pos, "conversion from non-scalar type '%T' requested", orig_type_right);
                return false;
        }

        if (warning.cast_qual &&
            is_type_pointer(src_type) &&
            is_type_pointer(dst_type)) {
                type_t *src = skip_typeref(src_type->pointer.points_to);
                type_t *dst = skip_typeref(dst_type->pointer.points_to);
                unsigned missing_qualifiers =
                        src->base.qualifiers & ~dst->base.qualifiers;
                if (missing_qualifiers != 0) {
                        warningf(pos,
                                 "cast discards qualifiers '%Q' in pointer target type of '%T'",
                                 missing_qualifiers, orig_type_right);
                }
        }
        return true;
}

static expression_t *parse_compound_literal(type_t *type)
{
        expression_t *expression = allocate_expression_zero(EXPR_COMPOUND_LITERAL);

        parse_initializer_env_t env;
        env.type             = type;
        env.entity           = NULL;
        env.must_be_constant = false;
        initializer_t *initializer = parse_initializer(&env);
        type = env.type;

        expression->compound_literal.initializer = initializer;
        expression->compound_literal.type        = type;
        expression->base.type                    = automatic_type_conversion(type);

        return expression;
}

/**
 * Parse a cast expression.
 */
static expression_t *parse_cast(void)
{
        add_anchor_token(')');

        source_position_t source_position = token.source_position;

        type_t *type = parse_typename();

        rem_anchor_token(')');
        expect(')', end_error);

        if (token.type == '{') {
                return parse_compound_literal(type);
        }

        expression_t *cast = allocate_expression_zero(EXPR_UNARY_CAST);
        cast->base.source_position = source_position;

        expression_t *value = parse_subexpression(PREC_CAST);
        cast->base.type   = type;
        cast->unary.value = value;

        if (! semantic_cast(cast)) {
                /* TODO: record the error in the AST. else it is impossible to detect it */
        }

        return cast;
end_error:
        return create_invalid_expression();
}

/**
 * Parse a statement expression.
 */
static expression_t *parse_statement_expression(void)
{
        add_anchor_token(')');

        expression_t *expression = allocate_expression_zero(EXPR_STATEMENT);

        statement_t *statement          = parse_compound_statement(true);
        statement->compound.stmt_expr   = true;
        expression->statement.statement = statement;

        /* find last statement and use its type */
        type_t *type = type_void;
        const statement_t *stmt = statement->compound.statements;
        if (stmt != NULL) {
                while (stmt->base.next != NULL)
                        stmt = stmt->base.next;

                if (stmt->kind == STATEMENT_EXPRESSION) {
                        type = stmt->expression.expression->base.type;
                }
        } else if (warning.other) {
                warningf(&expression->base.source_position, "empty statement expression ({})");
        }
        expression->base.type = type;

        rem_anchor_token(')');
        expect(')', end_error);

end_error:
        return expression;
}

/**
 * Parse a parenthesized expression.
 */
static expression_t *parse_parenthesized_expression(void)
{
        eat('(');

        switch (token.type) {
        case '{':
                /* gcc extension: a statement expression */
                return parse_statement_expression();

        TYPE_QUALIFIERS
        TYPE_SPECIFIERS
                return parse_cast();
        case T_IDENTIFIER:
                if (is_typedef_symbol(token.symbol)) {
                        return parse_cast();
                }
        }

        add_anchor_token(')');
        expression_t *result = parse_expression();
        result->base.parenthesized = true;
        rem_anchor_token(')');
        expect(')', end_error);

end_error:
        return result;
}

static expression_t *parse_function_keyword(void)
{
        /* TODO */

        if (current_function == NULL) {
                errorf(HERE, "'__func__' used outside of a function");
        }

        expression_t *expression  = allocate_expression_zero(EXPR_FUNCNAME);
        expression->base.type     = type_char_ptr;
        expression->funcname.kind = FUNCNAME_FUNCTION;

        next_token();

        return expression;
}

static expression_t *parse_pretty_function_keyword(void)
{
        if (current_function == NULL) {
                errorf(HERE, "'__PRETTY_FUNCTION__' used outside of a function");
        }

        expression_t *expression  = allocate_expression_zero(EXPR_FUNCNAME);
        expression->base.type     = type_char_ptr;
        expression->funcname.kind = FUNCNAME_PRETTY_FUNCTION;

        eat(T___PRETTY_FUNCTION__);

        return expression;
}

static expression_t *parse_funcsig_keyword(void)
{
        if (current_function == NULL) {
                errorf(HERE, "'__FUNCSIG__' used outside of a function");
        }

        expression_t *expression  = allocate_expression_zero(EXPR_FUNCNAME);
        expression->base.type     = type_char_ptr;
        expression->funcname.kind = FUNCNAME_FUNCSIG;

        eat(T___FUNCSIG__);

        return expression;
}

static expression_t *parse_funcdname_keyword(void)
{
        if (current_function == NULL) {
                errorf(HERE, "'__FUNCDNAME__' used outside of a function");
        }

        expression_t *expression  = allocate_expression_zero(EXPR_FUNCNAME);
        expression->base.type     = type_char_ptr;
        expression->funcname.kind = FUNCNAME_FUNCDNAME;

        eat(T___FUNCDNAME__);

        return expression;
}

static designator_t *parse_designator(void)
{
        designator_t *result    = allocate_ast_zero(sizeof(result[0]));
        result->source_position = *HERE;

        if (token.type != T_IDENTIFIER) {
                parse_error_expected("while parsing member designator",
                                     T_IDENTIFIER, NULL);
                return NULL;
        }
        result->symbol = token.symbol;
        next_token();

        designator_t *last_designator = result;
        while (true) {
                if (next_if('.')) {
                        if (token.type != T_IDENTIFIER) {
                                parse_error_expected("while parsing member designator",
                                                     T_IDENTIFIER, NULL);
                                return NULL;
                        }
                        designator_t *designator    = allocate_ast_zero(sizeof(result[0]));
                        designator->source_position = *HERE;
                        designator->symbol          = token.symbol;
                        next_token();

                        last_designator->next = designator;
                        last_designator       = designator;
                        continue;
                }
                if (next_if('[')) {
                        add_anchor_token(']');
                        designator_t *designator    = allocate_ast_zero(sizeof(result[0]));
                        designator->source_position = *HERE;
                        designator->array_index     = parse_expression();
                        rem_anchor_token(']');
                        expect(']', end_error);
                        if (designator->array_index == NULL) {
                                return NULL;
                        }

                        last_designator->next = designator;
                        last_designator       = designator;
                        continue;
                }
                break;
        }

        return result;
end_error:
        return NULL;
}

/**
 * Parse the __builtin_offsetof() expression.
 */
static expression_t *parse_offsetof(void)
{
        expression_t *expression = allocate_expression_zero(EXPR_OFFSETOF);
        expression->base.type    = type_size_t;

        eat(T___builtin_offsetof);

        expect('(', end_error);
        add_anchor_token(',');
        type_t *type = parse_typename();
        rem_anchor_token(',');
        expect(',', end_error);
        add_anchor_token(')');
        designator_t *designator = parse_designator();
        rem_anchor_token(')');
        expect(')', end_error);

        expression->offsetofe.type       = type;
        expression->offsetofe.designator = designator;

        type_path_t path;
        memset(&path, 0, sizeof(path));
        path.top_type = type;
        path.path     = NEW_ARR_F(type_path_entry_t, 0);

        descend_into_subtype(&path);

        if (!walk_designator(&path, designator, true)) {
                return create_invalid_expression();
        }

        DEL_ARR_F(path.path);

        return expression;
end_error:
        return create_invalid_expression();
}

/**
 * Parses a _builtin_va_start() expression.
 */
static expression_t *parse_va_start(void)
{
        expression_t *expression = allocate_expression_zero(EXPR_VA_START);

        eat(T___builtin_va_start);

        expect('(', end_error);
        add_anchor_token(',');
        expression->va_starte.ap = parse_assignment_expression();
        rem_anchor_token(',');
        expect(',', end_error);
        expression_t *const expr = parse_assignment_expression();
        if (expr->kind == EXPR_REFERENCE) {
                entity_t *const entity = expr->reference.entity;
                if (!current_function->base.type->function.variadic) {
                        errorf(&expr->base.source_position,
                                        "'va_start' used in non-variadic function");
                } else if (entity->base.parent_scope != &current_function->parameters ||
                                entity->base.next != NULL ||
                                entity->kind != ENTITY_PARAMETER) {
                        errorf(&expr->base.source_position,
                               "second argument of 'va_start' must be last parameter of the current function");
                } else {
                        expression->va_starte.parameter = &entity->variable;
                }
                expect(')', end_error);
                return expression;
        }
        expect(')', end_error);
end_error:
        return create_invalid_expression();
}

/**
 * Parses a __builtin_va_arg() expression.
 */
static expression_t *parse_va_arg(void)
{
        expression_t *expression = allocate_expression_zero(EXPR_VA_ARG);

        eat(T___builtin_va_arg);

        expect('(', end_error);
        call_argument_t ap;
        ap.expression = parse_assignment_expression();
        expression->va_arge.ap = ap.expression;
        check_call_argument(type_valist, &ap, 1);

        expect(',', end_error);
        expression->base.type = parse_typename();
        expect(')', end_error);

        return expression;
end_error:
        return create_invalid_expression();
}

/**
 * Parses a __builtin_va_copy() expression.
 */
static expression_t *parse_va_copy(void)
{
        expression_t *expression = allocate_expression_zero(EXPR_VA_COPY);

        eat(T___builtin_va_copy);

        expect('(', end_error);
        expression_t *dst = parse_assignment_expression();
        assign_error_t error = semantic_assign(type_valist, dst);
        report_assign_error(error, type_valist, dst, "call argument 1",
                            &dst->base.source_position);
        expression->va_copye.dst = dst;

        expect(',', end_error);

        call_argument_t src;
        src.expression = parse_assignment_expression();
        check_call_argument(type_valist, &src, 2);
        expression->va_copye.src = src.expression;
        expect(')', end_error);

        return expression;
end_error:
        return create_invalid_expression();
}

/**
 * Parses a __builtin_constant_p() expression.
 */
static expression_t *parse_builtin_constant(void)
{
        expression_t *expression = allocate_expression_zero(EXPR_BUILTIN_CONSTANT_P);

        eat(T___builtin_constant_p);

        expect('(', end_error);
        add_anchor_token(')');
        expression->builtin_constant.value = parse_assignment_expression();
        rem_anchor_token(')');
        expect(')', end_error);
        expression->base.type = type_int;

        return expression;
end_error:
        return create_invalid_expression();
}

/**
 * Parses a __builtin_types_compatible_p() expression.
 */
static expression_t *parse_builtin_types_compatible(void)
{
        expression_t *expression = allocate_expression_zero(EXPR_BUILTIN_TYPES_COMPATIBLE_P);

        eat(T___builtin_types_compatible_p);

        expect('(', end_error);
        add_anchor_token(')');
        add_anchor_token(',');
        expression->builtin_types_compatible.left = parse_typename();
        rem_anchor_token(',');
        expect(',', end_error);
        expression->builtin_types_compatible.right = parse_typename();
        rem_anchor_token(')');
        expect(')', end_error);
        expression->base.type = type_int;

        return expression;
end_error:
        return create_invalid_expression();
}

/**
 * Parses a __builtin_is_*() compare expression.
 */
static expression_t *parse_compare_builtin(void)
{
        expression_t *expression;

        switch (token.type) {
        case T___builtin_isgreater:
                expression = allocate_expression_zero(EXPR_BINARY_ISGREATER);
                break;
        case T___builtin_isgreaterequal:
                expression = allocate_expression_zero(EXPR_BINARY_ISGREATEREQUAL);
                break;
        case T___builtin_isless:
                expression = allocate_expression_zero(EXPR_BINARY_ISLESS);
                break;
        case T___builtin_islessequal:
                expression = allocate_expression_zero(EXPR_BINARY_ISLESSEQUAL);
                break;
        case T___builtin_islessgreater:
                expression = allocate_expression_zero(EXPR_BINARY_ISLESSGREATER);
                break;
        case T___builtin_isunordered:
                expression = allocate_expression_zero(EXPR_BINARY_ISUNORDERED);
                break;
        default:
                internal_errorf(HERE, "invalid compare builtin found");
        }
        expression->base.source_position = *HERE;
        next_token();

        expect('(', end_error);
        expression->binary.left = parse_assignment_expression();
        expect(',', end_error);
        expression->binary.right = parse_assignment_expression();
        expect(')', end_error);

        type_t *const orig_type_left  = expression->binary.left->base.type;
        type_t *const orig_type_right = expression->binary.right->base.type;

        type_t *const type_left  = skip_typeref(orig_type_left);
        type_t *const type_right = skip_typeref(orig_type_right);
        if (!is_type_float(type_left) && !is_type_float(type_right)) {
                if (is_type_valid(type_left) && is_type_valid(type_right)) {
                        type_error_incompatible("invalid operands in comparison",
                                &expression->base.source_position, orig_type_left, orig_type_right);
                }
        } else {
                semantic_comparison(&expression->binary);
        }

        return expression;
end_error:
        return create_invalid_expression();
}

/**
 * Parses a MS assume() expression.
 */
static expression_t *parse_assume(void)
{
        expression_t *expression = allocate_expression_zero(EXPR_UNARY_ASSUME);

        eat(T__assume);

        expect('(', end_error);
        add_anchor_token(')');
        expression->unary.value = parse_assignment_expression();
        rem_anchor_token(')');
        expect(')', end_error);

        expression->base.type = type_void;
        return expression;
end_error:
        return create_invalid_expression();
}

/**
 * Return the declaration for a given label symbol or create a new one.
 *
 * @param symbol  the symbol of the label
 */
static label_t *get_label(symbol_t *symbol)
{
        entity_t *label;
        assert(current_function != NULL);

        label = get_entity(symbol, NAMESPACE_LABEL);
        /* if we found a local label, we already created the declaration */
        if (label != NULL && label->kind == ENTITY_LOCAL_LABEL) {
                if (label->base.parent_scope != current_scope) {
                        assert(label->base.parent_scope->depth < current_scope->depth);
                        current_function->goto_to_outer = true;
                }
                return &label->label;
        }

        label = get_entity(symbol, NAMESPACE_LABEL);
        /* if we found a label in the same function, then we already created the
         * declaration */
        if (label != NULL
                        && label->base.parent_scope == &current_function->parameters) {
                return &label->label;
        }

        /* otherwise we need to create a new one */
        label               = allocate_entity_zero(ENTITY_LABEL);
        label->base.namespc = NAMESPACE_LABEL;
        label->base.symbol  = symbol;

        label_push(label);

        return &label->label;
}

/**
 * Parses a GNU && label address expression.
 */
static expression_t *parse_label_address(void)
{
        source_position_t source_position = token.source_position;
        eat(T_ANDAND);
        if (token.type != T_IDENTIFIER) {
                parse_error_expected("while parsing label address", T_IDENTIFIER, NULL);
                goto end_error;
        }
        symbol_t *symbol = token.symbol;
        next_token();

        label_t *label       = get_label(symbol);
        label->used          = true;
        label->address_taken = true;

        expression_t *expression = allocate_expression_zero(EXPR_LABEL_ADDRESS);
        expression->base.source_position = source_position;

        /* label address is threaten as a void pointer */
        expression->base.type           = type_void_ptr;
        expression->label_address.label = label;
        return expression;
end_error:
        return create_invalid_expression();
}

/**
 * Parse a microsoft __noop expression.
 */
static expression_t *parse_noop_expression(void)
{
        /* the result is a (int)0 */
        expression_t *literal = allocate_expression_zero(EXPR_LITERAL_MS_NOOP);
        literal->base.type            = type_int;
        literal->base.source_position = token.source_position;
        literal->literal.value.begin  = "__noop";
        literal->literal.value.size   = 6;

        eat(T___noop);

        if (token.type == '(') {
                /* parse arguments */
                eat('(');
                add_anchor_token(')');
                add_anchor_token(',');

                if (token.type != ')') do {
                        (void)parse_assignment_expression();
                } while (next_if(','));
        }
        rem_anchor_token(',');
        rem_anchor_token(')');
        expect(')', end_error);

end_error:
        return literal;
}

/**
 * Parses a primary expression.
 */
static expression_t *parse_primary_expression(void)
{
        switch (token.type) {
        case T_false:                        return parse_boolean_literal(false);
        case T_true:                         return parse_boolean_literal(true);
        case T_INTEGER:
        case T_INTEGER_OCTAL:
        case T_INTEGER_HEXADECIMAL:
        case T_FLOATINGPOINT:
        case T_FLOATINGPOINT_HEXADECIMAL:    return parse_number_literal();
        case T_CHARACTER_CONSTANT:           return parse_character_constant();
        case T_WIDE_CHARACTER_CONSTANT:      return parse_wide_character_constant();
        case T_STRING_LITERAL:
        case T_WIDE_STRING_LITERAL:          return parse_string_literal();
        case T___FUNCTION__:
        case T___func__:                     return parse_function_keyword();
        case T___PRETTY_FUNCTION__:          return parse_pretty_function_keyword();
        case T___FUNCSIG__:                  return parse_funcsig_keyword();
        case T___FUNCDNAME__:                return parse_funcdname_keyword();
        case T___builtin_offsetof:           return parse_offsetof();
        case T___builtin_va_start:           return parse_va_start();
        case T___builtin_va_arg:             return parse_va_arg();
        case T___builtin_va_copy:            return parse_va_copy();
        case T___builtin_isgreater:
        case T___builtin_isgreaterequal:
        case T___builtin_isless:
        case T___builtin_islessequal:
        case T___builtin_islessgreater:
        case T___builtin_isunordered:        return parse_compare_builtin();
        case T___builtin_constant_p:         return parse_builtin_constant();
        case T___builtin_types_compatible_p: return parse_builtin_types_compatible();
        case T__assume:                      return parse_assume();
        case T_ANDAND:
                if (GNU_MODE)
                        return parse_label_address();
                break;

        case '(':                            return parse_parenthesized_expression();
        case T___noop:                       return parse_noop_expression();

        /* Gracefully handle type names while parsing expressions. */
        case T_COLONCOLON:
                return parse_reference();
        case T_IDENTIFIER:
                if (!is_typedef_symbol(token.symbol)) {
                        return parse_reference();
                }
                /* FALLTHROUGH */
        TYPENAME_START {
                source_position_t  const pos  = *HERE;
                type_t const      *const type = parse_typename();
                errorf(&pos, "encountered type '%T' while parsing expression", type);
                return create_invalid_expression();
        }
        }

        errorf(HERE, "unexpected token %K, expected an expression", &token);
        return create_invalid_expression();
}

/**
 * Check if the expression has the character type and issue a warning then.
 */
static void check_for_char_index_type(const expression_t *expression)
{
        type_t       *const type      = expression->base.type;
        const type_t *const base_type = skip_typeref(type);

        if (is_type_atomic(base_type, ATOMIC_TYPE_CHAR) &&
                        warning.char_subscripts) {
                warningf(&expression->base.source_position,
                         "array subscript has type '%T'", type);
        }
}

static expression_t *parse_array_expression(expression_t *left)
{
        expression_t *expression = allocate_expression_zero(EXPR_ARRAY_ACCESS);

        eat('[');
        add_anchor_token(']');

        expression_t *inside = parse_expression();

        type_t *const orig_type_left   = left->base.type;
        type_t *const orig_type_inside = inside->base.type;

        type_t *const type_left   = skip_typeref(orig_type_left);
        type_t *const type_inside = skip_typeref(orig_type_inside);

        type_t                    *return_type;
        array_access_expression_t *array_access = &expression->array_access;
        if (is_type_pointer(type_left)) {
                return_type             = type_left->pointer.points_to;
                array_access->array_ref = left;
                array_access->index     = inside;
                check_for_char_index_type(inside);
        } else if (is_type_pointer(type_inside)) {
                return_type             = type_inside->pointer.points_to;
                array_access->array_ref = inside;
                array_access->index     = left;
                array_access->flipped   = true;
                check_for_char_index_type(left);
        } else {
                if (is_type_valid(type_left) && is_type_valid(type_inside)) {
                        errorf(HERE,
                                "array access on object with non-pointer types '%T', '%T'",
                                orig_type_left, orig_type_inside);
                }
                return_type             = type_error_type;
                array_access->array_ref = left;
                array_access->index     = inside;
        }

        expression->base.type = automatic_type_conversion(return_type);

        rem_anchor_token(']');
        expect(']', end_error);
end_error:
        return expression;
}

static expression_t *parse_typeprop(expression_kind_t const kind)
{
        expression_t  *tp_expression = allocate_expression_zero(kind);
        tp_expression->base.type     = type_size_t;

        eat(kind == EXPR_SIZEOF ? T_sizeof : T___alignof__);

        /* we only refer to a type property, mark this case */
        bool old     = in_type_prop;
        in_type_prop = true;

        type_t       *orig_type;
        expression_t *expression;
        if (token.type == '(' && is_declaration_specifier(look_ahead(1), true)) {
                next_token();
                add_anchor_token(')');
                orig_type = parse_typename();
                rem_anchor_token(')');
                expect(')', end_error);

                if (token.type == '{') {
                        /* It was not sizeof(type) after all.  It is sizeof of an expression
                         * starting with a compound literal */
                        expression = parse_compound_literal(orig_type);
                        goto typeprop_expression;
                }
        } else {
                expression = parse_subexpression(PREC_UNARY);

typeprop_expression:
                tp_expression->typeprop.tp_expression = expression;

                orig_type = revert_automatic_type_conversion(expression);
                expression->base.type = orig_type;
        }

        tp_expression->typeprop.type   = orig_type;
        type_t const* const type       = skip_typeref(orig_type);
        char   const* const wrong_type =
                GNU_MODE && is_type_atomic(type, ATOMIC_TYPE_VOID) ? NULL                  :
                is_type_incomplete(type)                           ? "incomplete"          :
                type->kind == TYPE_FUNCTION                        ? "function designator" :
                type->kind == TYPE_BITFIELD                        ? "bitfield"            :
                NULL;
        if (wrong_type != NULL) {
                char const* const what = kind == EXPR_SIZEOF ? "sizeof" : "alignof";
                errorf(&tp_expression->base.source_position,
                                "operand of %s expression must not be of %s type '%T'",
                                what, wrong_type, orig_type);
        }

end_error:
        in_type_prop = old;
        return tp_expression;
}

static expression_t *parse_sizeof(void)
{
        return parse_typeprop(EXPR_SIZEOF);
}

static expression_t *parse_alignof(void)
{
        return parse_typeprop(EXPR_ALIGNOF);
}

static expression_t *parse_select_expression(expression_t *addr)
{
        assert(token.type == '.' || token.type == T_MINUSGREATER);
        bool select_left_arrow = (token.type == T_MINUSGREATER);
        next_token();

        if (token.type != T_IDENTIFIER) {
                parse_error_expected("while parsing select", T_IDENTIFIER, NULL);
                return create_invalid_expression();
        }
        symbol_t *symbol = token.symbol;
        next_token();

        type_t *const orig_type = addr->base.type;
        type_t *const type      = skip_typeref(orig_type);

        type_t *type_left;
        bool    saw_error = false;
        if (is_type_pointer(type)) {
                if (!select_left_arrow) {
                        errorf(HERE,
                               "request for member '%Y' in something not a struct or union, but '%T'",
                               symbol, orig_type);
                        saw_error = true;
                }
                type_left = skip_typeref(type->pointer.points_to);
        } else {
                if (select_left_arrow && is_type_valid(type)) {
                        errorf(HERE, "left hand side of '->' is not a pointer, but '%T'", orig_type);
                        saw_error = true;
                }
                type_left = type;
        }

        if (type_left->kind != TYPE_COMPOUND_STRUCT &&
            type_left->kind != TYPE_COMPOUND_UNION) {

                if (is_type_valid(type_left) && !saw_error) {
                        errorf(HERE,
                               "request for member '%Y' in something not a struct or union, but '%T'",
                               symbol, type_left);
                }
                return create_invalid_expression();
        }

        compound_t *compound = type_left->compound.compound;
        if (!compound->complete) {
                errorf(HERE, "request for member '%Y' in incomplete type '%T'",
                       symbol, type_left);
                return create_invalid_expression();
        }

        type_qualifiers_t  qualifiers = type_left->base.qualifiers;
        expression_t      *result
                = find_create_select(HERE, addr, qualifiers, compound, symbol);

        if (result == NULL) {
                errorf(HERE, "'%T' has no member named '%Y'", orig_type, symbol);
                return create_invalid_expression();
        }

        return result;
}

static void check_call_argument(type_t          *expected_type,
                                call_argument_t *argument, unsigned pos)
{
        type_t         *expected_type_skip = skip_typeref(expected_type);
        assign_error_t  error              = ASSIGN_ERROR_INCOMPATIBLE;
        expression_t   *arg_expr           = argument->expression;
        type_t         *arg_type           = skip_typeref(arg_expr->base.type);

        /* handle transparent union gnu extension */
        if (is_type_union(expected_type_skip)
                        && (get_type_modifiers(expected_type) & DM_TRANSPARENT_UNION)) {
                compound_t *union_decl  = expected_type_skip->compound.compound;
                type_t     *best_type   = NULL;
                entity_t   *entry       = union_decl->members.entities;
                for ( ; entry != NULL; entry = entry->base.next) {
                        assert(is_declaration(entry));
                        type_t *decl_type = entry->declaration.type;
                        error = semantic_assign(decl_type, arg_expr);
                        if (error == ASSIGN_ERROR_INCOMPATIBLE
                                || error == ASSIGN_ERROR_POINTER_QUALIFIER_MISSING)
                                continue;

                        if (error == ASSIGN_SUCCESS) {
                                best_type = decl_type;
                        } else if (best_type == NULL) {
                                best_type = decl_type;
                        }
                }

                if (best_type != NULL) {
                        expected_type = best_type;
                }
        }

        error                = semantic_assign(expected_type, arg_expr);
        argument->expression = create_implicit_cast(arg_expr, expected_type);

        if (error != ASSIGN_SUCCESS) {
                /* report exact scope in error messages (like "in argument 3") */
                char buf[64];
                snprintf(buf, sizeof(buf), "call argument %u", pos);
                report_assign_error(error, expected_type, arg_expr,     buf,
                                                        &arg_expr->base.source_position);
        } else if (warning.traditional || warning.conversion) {
                type_t *const promoted_type = get_default_promoted_type(arg_type);
                if (!types_compatible(expected_type_skip, promoted_type) &&
                    !types_compatible(expected_type_skip, type_void_ptr) &&
                    !types_compatible(type_void_ptr,      promoted_type)) {
                        /* Deliberately show the skipped types in this warning */
                        warningf(&arg_expr->base.source_position,
                                "passing call argument %u as '%T' rather than '%T' due to prototype",
                                pos, expected_type_skip, promoted_type);
                }
        }
}

/**
 * Handle the semantic restrictions of builtin calls
 */
static void handle_builtin_argument_restrictions(call_expression_t *call) {
        switch (call->function->reference.entity->function.btk) {
                case bk_gnu_builtin_return_address:
                case bk_gnu_builtin_frame_address: {
                        /* argument must be constant */
                        call_argument_t *argument = call->arguments;

                        if (! is_constant_expression(argument->expression)) {
                                errorf(&call->base.source_position,
                                       "argument of '%Y' must be a constant expression",
                                       call->function->reference.entity->base.symbol);
                        }
                        break;
                }
                case bk_gnu_builtin_object_size:
                        if (call->arguments == NULL)
                                break;

                        call_argument_t *arg = call->arguments->next;
                        if (arg != NULL && ! is_constant_expression(arg->expression)) {
                                errorf(&call->base.source_position,
                                           "second argument of '%Y' must be a constant expression",
                                           call->function->reference.entity->base.symbol);
                        }
                        break;
                case bk_gnu_builtin_prefetch:
                        /* second and third argument must be constant if existent */
                        if (call->arguments == NULL)
                                break;
                        call_argument_t *rw = call->arguments->next;
                        call_argument_t *locality = NULL;

                        if (rw != NULL) {
                                if (! is_constant_expression(rw->expression)) {
                                        errorf(&call->base.source_position,
                                               "second argument of '%Y' must be a constant expression",
                                               call->function->reference.entity->base.symbol);
                                }
                                locality = rw->next;
                        }
                        if (locality != NULL) {
                                if (! is_constant_expression(locality->expression)) {
                                        errorf(&call->base.source_position,
                                               "third argument of '%Y' must be a constant expression",
                                               call->function->reference.entity->base.symbol);
                                }
                                locality = rw->next;
                        }
                        break;
                default:
                        break;
        }
}

/**
 * Parse a call expression, ie. expression '( ... )'.
 *
 * @param expression  the function address
 */
static expression_t *parse_call_expression(expression_t *expression)
{
        expression_t      *result = allocate_expression_zero(EXPR_CALL);
        call_expression_t *call   = &result->call;
        call->function            = expression;

        type_t *const orig_type = expression->base.type;
        type_t *const type      = skip_typeref(orig_type);

        function_type_t *function_type = NULL;
        if (is_type_pointer(type)) {
                type_t *const to_type = skip_typeref(type->pointer.points_to);

                if (is_type_function(to_type)) {
                        function_type   = &to_type->function;
                        call->base.type = function_type->return_type;
                }
        }

        if (function_type == NULL && is_type_valid(type)) {
                errorf(HERE,
                       "called object '%E' (type '%T') is not a pointer to a function",
                       expression, orig_type);
        }

        /* parse arguments */
        eat('(');
        add_anchor_token(')');
        add_anchor_token(',');

        if (token.type != ')') {
                call_argument_t **anchor = &call->arguments;
                do {
                        call_argument_t *argument = allocate_ast_zero(sizeof(*argument));
                        argument->expression = parse_assignment_expression();

                        *anchor = argument;
                        anchor  = &argument->next;
                } while (next_if(','));
        }
        rem_anchor_token(',');
        rem_anchor_token(')');
        expect(')', end_error);

        if (function_type == NULL)
                return result;

        /* check type and count of call arguments */
        function_parameter_t *parameter = function_type->parameters;
        call_argument_t      *argument  = call->arguments;
        if (!function_type->unspecified_parameters) {
                for (unsigned pos = 0; parameter != NULL && argument != NULL;
                                parameter = parameter->next, argument = argument->next) {
                        check_call_argument(parameter->type, argument, ++pos);
                }

                if (parameter != NULL) {
                        errorf(HERE, "too few arguments to function '%E'", expression);
                } else if (argument != NULL && !function_type->variadic) {
                        errorf(HERE, "too many arguments to function '%E'", expression);
                }
        }

        /* do default promotion for other arguments */
        for (; argument != NULL; argument = argument->next) {
                type_t *type = argument->expression->base.type;
                if (!is_type_object(skip_typeref(type))) {
                        errorf(&argument->expression->base.source_position,
                               "call argument '%E' must not be void", argument->expression);
                }

                type = get_default_promoted_type(type);

                argument->expression
                        = create_implicit_cast(argument->expression, type);
        }

        check_format(&result->call);

        if (warning.aggregate_return &&
            is_type_compound(skip_typeref(function_type->return_type))) {
                warningf(&result->base.source_position,
                         "function call has aggregate value");
        }

        if (call->function->kind == EXPR_REFERENCE) {
                reference_expression_t *reference = &call->function->reference;
                if (reference->entity->kind == ENTITY_FUNCTION &&
                    reference->entity->function.btk != bk_none)
                        handle_builtin_argument_restrictions(call);
        }

end_error:
        return result;
}

static type_t *semantic_arithmetic(type_t *type_left, type_t *type_right);

static bool same_compound_type(const type_t *type1, const type_t *type2)
{
        return
                is_type_compound(type1) &&
                type1->kind == type2->kind &&
                type1->compound.compound == type2->compound.compound;
}

static expression_t const *get_reference_address(expression_t const *expr)
{
        bool regular_take_address = true;
        for (;;) {
                if (expr->kind == EXPR_UNARY_TAKE_ADDRESS) {
                        expr = expr->unary.value;
                } else {
                        regular_take_address = false;
                }

                if (expr->kind != EXPR_UNARY_DEREFERENCE)
                        break;

                expr = expr->unary.value;
        }

        if (expr->kind != EXPR_REFERENCE)
                return NULL;

        /* special case for functions which are automatically converted to a
         * pointer to function without an extra TAKE_ADDRESS operation */
        if (!regular_take_address &&
                        expr->reference.entity->kind != ENTITY_FUNCTION) {
                return NULL;
        }

        return expr;
}

static void warn_reference_address_as_bool(expression_t const* expr)
{
        if (!warning.address)
                return;

        expr = get_reference_address(expr);
        if (expr != NULL) {
                warningf(&expr->base.source_position,
                         "the address of '%Y' will always evaluate as 'true'",
                         expr->reference.entity->base.symbol);
        }
}

static void warn_assignment_in_condition(const expression_t *const expr)
{
        if (!warning.parentheses)
                return;
        if (expr->base.kind != EXPR_BINARY_ASSIGN)
                return;
        if (expr->base.parenthesized)
                return;
        warningf(&expr->base.source_position,
                        "suggest parentheses around assignment used as truth value");
}

static void semantic_condition(expression_t const *const expr,
                               char const *const context)
{
        type_t *const type = skip_typeref(expr->base.type);
        if (is_type_scalar(type)) {
                warn_reference_address_as_bool(expr);
                warn_assignment_in_condition(expr);
        } else if (is_type_valid(type)) {
                errorf(&expr->base.source_position,
                                "%s must have scalar type", context);
        }
}

/**
 * Parse a conditional expression, ie. 'expression ? ... : ...'.
 *
 * @param expression  the conditional expression
 */
static expression_t *parse_conditional_expression(expression_t *expression)
{
        expression_t *result = allocate_expression_zero(EXPR_CONDITIONAL);

        conditional_expression_t *conditional = &result->conditional;
        conditional->condition                = expression;

        eat('?');
        add_anchor_token(':');

        /* §6.5.15:2  The first operand shall have scalar type. */
        semantic_condition(expression, "condition of conditional operator");

        expression_t *true_expression = expression;
        bool          gnu_cond = false;
        if (GNU_MODE && token.type == ':') {
                gnu_cond = true;
        } else {
                true_expression = parse_expression();
        }
        rem_anchor_token(':');
        expect(':', end_error);
end_error:;
        expression_t *false_expression =
                parse_subexpression(c_mode & _CXX ? PREC_ASSIGNMENT : PREC_CONDITIONAL);

        type_t *const orig_true_type  = true_expression->base.type;
        type_t *const orig_false_type = false_expression->base.type;
        type_t *const true_type       = skip_typeref(orig_true_type);
        type_t *const false_type      = skip_typeref(orig_false_type);

        /* 6.5.15.3 */
        type_t *result_type;
        if (is_type_atomic(true_type,  ATOMIC_TYPE_VOID) ||
                        is_type_atomic(false_type, ATOMIC_TYPE_VOID)) {
                /* ISO/IEC 14882:1998(E) §5.16:2 */
                if (true_expression->kind == EXPR_UNARY_THROW) {
                        result_type = false_type;
                } else if (false_expression->kind == EXPR_UNARY_THROW) {
                        result_type = true_type;
                } else {
                        if (warning.other && (
                                                !is_type_atomic(true_type,  ATOMIC_TYPE_VOID) ||
                                                !is_type_atomic(false_type, ATOMIC_TYPE_VOID)
                                        )) {
                                warningf(&conditional->base.source_position,
                                                "ISO C forbids conditional expression with only one void side");
                        }
                        result_type = type_void;
                }
        } else if (is_type_arithmetic(true_type)
                   && is_type_arithmetic(false_type)) {
                result_type = semantic_arithmetic(true_type, false_type);
        } else if (same_compound_type(true_type, false_type)) {
                /* just take 1 of the 2 types */
                result_type = true_type;
        } else if (is_type_pointer(true_type) || is_type_pointer(false_type)) {
                type_t *pointer_type;
                type_t *other_type;
                expression_t *other_expression;
                if (is_type_pointer(true_type) &&
                                (!is_type_pointer(false_type) || is_null_pointer_constant(false_expression))) {
                        pointer_type     = true_type;
                        other_type       = false_type;
                        other_expression = false_expression;
                } else {
                        pointer_type     = false_type;
                        other_type       = true_type;
                        other_expression = true_expression;
                }

                if (is_null_pointer_constant(other_expression)) {
                        result_type = pointer_type;
                } else if (is_type_pointer(other_type)) {
                        type_t *to1 = skip_typeref(pointer_type->pointer.points_to);
                        type_t *to2 = skip_typeref(other_type->pointer.points_to);

                        type_t *to;
                        if (is_type_atomic(to1, ATOMIC_TYPE_VOID) ||
                            is_type_atomic(to2, ATOMIC_TYPE_VOID)) {
                                to = type_void;
                        } else if (types_compatible(get_unqualified_type(to1),
                                                    get_unqualified_type(to2))) {
                                to = to1;
                        } else {
                                if (warning.other) {
                                        warningf(&conditional->base.source_position,
                                                        "pointer types '%T' and '%T' in conditional expression are incompatible",
                                                        true_type, false_type);
                                }
                                to = type_void;
                        }

                        type_t *const type =
                                get_qualified_type(to, to1->base.qualifiers | to2->base.qualifiers);
                        result_type = make_pointer_type(type, TYPE_QUALIFIER_NONE);
                } else if (is_type_integer(other_type)) {
                        if (warning.other) {
                                warningf(&conditional->base.source_position,
                                                "pointer/integer type mismatch in conditional expression ('%T' and '%T')", true_type, false_type);
                        }
                        result_type = pointer_type;
                } else {
                        if (is_type_valid(other_type)) {
                                type_error_incompatible("while parsing conditional",
                                                &expression->base.source_position, true_type, false_type);
                        }
                        result_type = type_error_type;
                }
        } else {
                if (is_type_valid(true_type) && is_type_valid(false_type)) {
                        type_error_incompatible("while parsing conditional",
                                                &conditional->base.source_position, true_type,
                                                false_type);
                }
                result_type = type_error_type;
        }

        conditional->true_expression
                = gnu_cond ? NULL : create_implicit_cast(true_expression, result_type);
        conditional->false_expression
                = create_implicit_cast(false_expression, result_type);
        conditional->base.type = result_type;
        return result;
}

/**
 * Parse an extension expression.
 */
static expression_t *parse_extension(void)
{
        eat(T___extension__);

        bool old_gcc_extension   = in_gcc_extension;
        in_gcc_extension         = true;
        expression_t *expression = parse_subexpression(PREC_UNARY);
        in_gcc_extension         = old_gcc_extension;
        return expression;
}

/**
 * Parse a __builtin_classify_type() expression.
 */
static expression_t *parse_builtin_classify_type(void)
{
        expression_t *result = allocate_expression_zero(EXPR_CLASSIFY_TYPE);
        result->base.type    = type_int;

        eat(T___builtin_classify_type);

        expect('(', end_error);
        add_anchor_token(')');
        expression_t *expression = parse_expression();
        rem_anchor_token(')');
        expect(')', end_error);
        result->classify_type.type_expression = expression;

        return result;
end_error:
        return create_invalid_expression();
}

/**
 * Parse a delete expression
 * ISO/IEC 14882:1998(E) §5.3.5
 */
static expression_t *parse_delete(void)
{
        expression_t *const result = allocate_expression_zero(EXPR_UNARY_DELETE);
        result->base.type          = type_void;

        eat(T_delete);

        if (next_if('[')) {
                result->kind = EXPR_UNARY_DELETE_ARRAY;
                expect(']', end_error);
end_error:;
        }

        expression_t *const value = parse_subexpression(PREC_CAST);
        result->unary.value = value;

        type_t *const type = skip_typeref(value->base.type);
        if (!is_type_pointer(type)) {
                if (is_type_valid(type)) {
                        errorf(&value->base.source_position,
                                        "operand of delete must have pointer type");
                }
        } else if (warning.other &&
                        is_type_atomic(skip_typeref(type->pointer.points_to), ATOMIC_TYPE_VOID)) {
                warningf(&value->base.source_position,
                                "deleting 'void*' is undefined");
        }

        return result;
}

/**
 * Parse a throw expression
 * ISO/IEC 14882:1998(E) §15:1
 */
static expression_t *parse_throw(void)
{
        expression_t *const result = allocate_expression_zero(EXPR_UNARY_THROW);
        result->base.type          = type_void;

        eat(T_throw);

        expression_t *value = NULL;
        switch (token.type) {
                EXPRESSION_START {
                        value = parse_assignment_expression();
                        /* ISO/IEC 14882:1998(E) §15.1:3 */
                        type_t *const orig_type = value->base.type;
                        type_t *const type      = skip_typeref(orig_type);
                        if (is_type_incomplete(type)) {
                                errorf(&value->base.source_position,
                                                "cannot throw object of incomplete type '%T'", orig_type);
                        } else if (is_type_pointer(type)) {
                                type_t *const points_to = skip_typeref(type->pointer.points_to);
                                if (is_type_incomplete(points_to) &&
                                                !is_type_atomic(points_to, ATOMIC_TYPE_VOID)) {
                                        errorf(&value->base.source_position,
                                                        "cannot throw pointer to incomplete type '%T'", orig_type);
                                }
                        }
                }

                default:
                        break;
        }
        result->unary.value = value;

        return result;
}

static bool check_pointer_arithmetic(const source_position_t *source_position,
                                     type_t *pointer_type,
                                     type_t *orig_pointer_type)
{
        type_t *points_to = pointer_type->pointer.points_to;
        points_to = skip_typeref(points_to);

        if (is_type_incomplete(points_to)) {
                if (!GNU_MODE || !is_type_atomic(points_to, ATOMIC_TYPE_VOID)) {
                        errorf(source_position,
                               "arithmetic with pointer to incomplete type '%T' not allowed",
                               orig_pointer_type);
                        return false;
                } else if (warning.pointer_arith) {
                        warningf(source_position,
                                 "pointer of type '%T' used in arithmetic",
                                 orig_pointer_type);
                }
        } else if (is_type_function(points_to)) {
                if (!GNU_MODE) {
                        errorf(source_position,
                               "arithmetic with pointer to function type '%T' not allowed",
                               orig_pointer_type);
                        return false;
                } else if (warning.pointer_arith) {
                        warningf(source_position,
                                 "pointer to a function '%T' used in arithmetic",
                                 orig_pointer_type);
                }
        }
        return true;
}

static bool is_lvalue(const expression_t *expression)
{
        /* TODO: doesn't seem to be consistent with §6.3.2.1:1 */
        switch (expression->kind) {
        case EXPR_ARRAY_ACCESS:
        case EXPR_COMPOUND_LITERAL:
        case EXPR_REFERENCE:
        case EXPR_SELECT:
        case EXPR_UNARY_DEREFERENCE:
                return true;

        default: {
                type_t *type = skip_typeref(expression->base.type);
                return
                        /* ISO/IEC 14882:1998(E) §3.10:3 */
                        is_type_reference(type) ||
                        /* Claim it is an lvalue, if the type is invalid.  There was a parse
                         * error before, which maybe prevented properly recognizing it as
                         * lvalue. */
                        !is_type_valid(type);
        }
        }
}

static void semantic_incdec(unary_expression_t *expression)
{
        type_t *const orig_type = expression->value->base.type;
        type_t *const type      = skip_typeref(orig_type);
        if (is_type_pointer(type)) {
                if (!check_pointer_arithmetic(&expression->base.source_position,
                                              type, orig_type)) {
                        return;
                }
        } else if (!is_type_real(type) && is_type_valid(type)) {
                /* TODO: improve error message */
                errorf(&expression->base.source_position,
                       "operation needs an arithmetic or pointer type");
                return;
        }
        if (!is_lvalue(expression->value)) {
                /* TODO: improve error message */
                errorf(&expression->base.source_position, "lvalue required as operand");
        }
        expression->base.type = orig_type;
}

static void semantic_unexpr_arithmetic(unary_expression_t *expression)
{
        type_t *const orig_type = expression->value->base.type;
        type_t *const type      = skip_typeref(orig_type);
        if (!is_type_arithmetic(type)) {
                if (is_type_valid(type)) {
                        /* TODO: improve error message */
                        errorf(&expression->base.source_position,
                                "operation needs an arithmetic type");
                }
                return;
        }

        expression->base.type = orig_type;
}

static void semantic_unexpr_plus(unary_expression_t *expression)
{
        semantic_unexpr_arithmetic(expression);
        if (warning.traditional)
                warningf(&expression->base.source_position,
                        "traditional C rejects the unary plus operator");
}

static void semantic_not(unary_expression_t *expression)
{
        /* §6.5.3.3:1  The operand [...] of the ! operator, scalar type. */
        semantic_condition(expression->value, "operand of !");
        expression->base.type = c_mode & _CXX ? type_bool : type_int;
}

static void semantic_unexpr_integer(unary_expression_t *expression)
{
        type_t *const orig_type = expression->value->base.type;
        type_t *const type      = skip_typeref(orig_type);
        if (!is_type_integer(type)) {
                if (is_type_valid(type)) {
                        errorf(&expression->base.source_position,
                               "operand of ~ must be of integer type");
                }
                return;
        }

        expression->base.type = orig_type;
}

static void semantic_dereference(unary_expression_t *expression)
{
        type_t *const orig_type = expression->value->base.type;
        type_t *const type      = skip_typeref(orig_type);
        if (!is_type_pointer(type)) {
                if (is_type_valid(type)) {
                        errorf(&expression->base.source_position,
                               "Unary '*' needs pointer or array type, but type '%T' given", orig_type);
                }
                return;
        }

        type_t *result_type   = type->pointer.points_to;
        result_type           = automatic_type_conversion(result_type);
        expression->base.type = result_type;
}

/**
 * Record that an address is taken (expression represents an lvalue).
 *
 * @param expression       the expression
 * @param may_be_register  if true, the expression might be an register
 */
static void set_address_taken(expression_t *expression, bool may_be_register)
{
        if (expression->kind != EXPR_REFERENCE)
                return;

        entity_t *const entity = expression->reference.entity;

        if (entity->kind != ENTITY_VARIABLE && entity->kind != ENTITY_PARAMETER)
                return;

        if (entity->declaration.storage_class == STORAGE_CLASS_REGISTER
                        && !may_be_register) {
                errorf(&expression->base.source_position,
                                "address of register %s '%Y' requested",
                                get_entity_kind_name(entity->kind),     entity->base.symbol);
        }

        if (entity->kind == ENTITY_VARIABLE) {
                entity->variable.address_taken = true;
        } else {
                assert(entity->kind == ENTITY_PARAMETER);
                entity->parameter.address_taken = true;
        }
}

/**
 * Check the semantic of the address taken expression.
 */
static void semantic_take_addr(unary_expression_t *expression)
{
        expression_t *value = expression->value;
        value->base.type    = revert_automatic_type_conversion(value);

        type_t *orig_type = value->base.type;
        type_t *type      = skip_typeref(orig_type);
        if (!is_type_valid(type))
                return;

        /* §6.5.3.2 */
        if (!is_lvalue(value)) {
                errorf(&expression->base.source_position, "'&' requires an lvalue");
        }
        if (type->kind == TYPE_BITFIELD) {
                errorf(&expression->base.source_position,
                       "'&' not allowed on object with bitfield type '%T'",
                       type);
        }

        set_address_taken(value, false);

        expression->base.type = make_pointer_type(orig_type, TYPE_QUALIFIER_NONE);
}

#define CREATE_UNARY_EXPRESSION_PARSER(token_type, unexpression_type, sfunc) \
static expression_t *parse_##unexpression_type(void)                         \
{                                                                            \
        expression_t *unary_expression                                           \
                = allocate_expression_zero(unexpression_type);                       \
        eat(token_type);                                                         \
        unary_expression->unary.value = parse_subexpression(PREC_UNARY);         \
                                                                                 \
        sfunc(&unary_expression->unary);                                         \
                                                                                 \
        return unary_expression;                                                 \
}

CREATE_UNARY_EXPRESSION_PARSER('-', EXPR_UNARY_NEGATE,
                               semantic_unexpr_arithmetic)
CREATE_UNARY_EXPRESSION_PARSER('+', EXPR_UNARY_PLUS,
                               semantic_unexpr_plus)
CREATE_UNARY_EXPRESSION_PARSER('!', EXPR_UNARY_NOT,
                               semantic_not)
CREATE_UNARY_EXPRESSION_PARSER('*', EXPR_UNARY_DEREFERENCE,
                               semantic_dereference)
CREATE_UNARY_EXPRESSION_PARSER('&', EXPR_UNARY_TAKE_ADDRESS,
                               semantic_take_addr)
CREATE_UNARY_EXPRESSION_PARSER('~', EXPR_UNARY_BITWISE_NEGATE,
                               semantic_unexpr_integer)
CREATE_UNARY_EXPRESSION_PARSER(T_PLUSPLUS,   EXPR_UNARY_PREFIX_INCREMENT,
                               semantic_incdec)
CREATE_UNARY_EXPRESSION_PARSER(T_MINUSMINUS, EXPR_UNARY_PREFIX_DECREMENT,
                               semantic_incdec)

#define CREATE_UNARY_POSTFIX_EXPRESSION_PARSER(token_type, unexpression_type, \
                                               sfunc)                         \
static expression_t *parse_##unexpression_type(expression_t *left)            \
{                                                                             \
        expression_t *unary_expression                                            \
                = allocate_expression_zero(unexpression_type);                        \
        eat(token_type);                                                          \
        unary_expression->unary.value = left;                                     \
                                                                                  \
        sfunc(&unary_expression->unary);                                          \
                                                                              \
        return unary_expression;                                                  \
}

CREATE_UNARY_POSTFIX_EXPRESSION_PARSER(T_PLUSPLUS,
                                       EXPR_UNARY_POSTFIX_INCREMENT,
                                       semantic_incdec)
CREATE_UNARY_POSTFIX_EXPRESSION_PARSER(T_MINUSMINUS,
                                       EXPR_UNARY_POSTFIX_DECREMENT,
                                       semantic_incdec)

static type_t *semantic_arithmetic(type_t *type_left, type_t *type_right)
{
        /* TODO: handle complex + imaginary types */

        type_left  = get_unqualified_type(type_left);
        type_right = get_unqualified_type(type_right);

        /* §6.3.1.8 Usual arithmetic conversions */
        if (type_left == type_long_double || type_right == type_long_double) {
                return type_long_double;
        } else if (type_left == type_double || type_right == type_double) {
                return type_double;
        } else if (type_left == type_float || type_right == type_float) {
                return type_float;
        }

        type_left  = promote_integer(type_left);
        type_right = promote_integer(type_right);

        if (type_left == type_right)
                return type_left;

        bool const signed_left  = is_type_signed(type_left);
        bool const signed_right = is_type_signed(type_right);
        int const  rank_left    = get_rank(type_left);
        int const  rank_right   = get_rank(type_right);

        if (signed_left == signed_right)
                return rank_left >= rank_right ? type_left : type_right;

        int     s_rank;
        int     u_rank;
        type_t *s_type;
        type_t *u_type;
        if (signed_left) {
                s_rank = rank_left;
                s_type = type_left;
                u_rank = rank_right;
                u_type = type_right;
        } else {
                s_rank = rank_right;
                s_type = type_right;
                u_rank = rank_left;
                u_type = type_left;
        }

        if (u_rank >= s_rank)
                return u_type;

        /* casting rank to atomic_type_kind is a bit hacky, but makes things
         * easier here... */
        if (get_atomic_type_size((atomic_type_kind_t) s_rank)
                        > get_atomic_type_size((atomic_type_kind_t) u_rank))
                return s_type;

        switch (s_rank) {
                case ATOMIC_TYPE_INT:      return type_unsigned_int;
                case ATOMIC_TYPE_LONG:     return type_unsigned_long;
                case ATOMIC_TYPE_LONGLONG: return type_unsigned_long_long;

                default: panic("invalid atomic type");
        }
}

/**
 * Check the semantic restrictions for a binary expression.
 */
static void semantic_binexpr_arithmetic(binary_expression_t *expression)
{
        expression_t *const left            = expression->left;
        expression_t *const right           = expression->right;
        type_t       *const orig_type_left  = left->base.type;
        type_t       *const orig_type_right = right->base.type;
        type_t       *const type_left       = skip_typeref(orig_type_left);
        type_t       *const type_right      = skip_typeref(orig_type_right);

        if (!is_type_arithmetic(type_left) || !is_type_arithmetic(type_right)) {
                /* TODO: improve error message */
                if (is_type_valid(type_left) && is_type_valid(type_right)) {
                        errorf(&expression->base.source_position,
                               "operation needs arithmetic types");
                }
                return;
        }

        type_t *arithmetic_type = semantic_arithmetic(type_left, type_right);
        expression->left      = create_implicit_cast(left, arithmetic_type);
        expression->right     = create_implicit_cast(right, arithmetic_type);
        expression->base.type = arithmetic_type;
}

static void warn_div_by_zero(binary_expression_t const *const expression)
{
        if (!warning.div_by_zero ||
            !is_type_integer(expression->base.type))
                return;

        expression_t const *const right = expression->right;
        /* The type of the right operand can be different for /= */
        if (is_type_integer(right->base.type) &&
            is_constant_expression(right)     &&
            !fold_constant_to_bool(right)) {
                warningf(&expression->base.source_position, "division by zero");
        }
}

/**
 * Check the semantic restrictions for a div/mod expression.
 */
static void semantic_divmod_arithmetic(binary_expression_t *expression)
{
        semantic_binexpr_arithmetic(expression);
        warn_div_by_zero(expression);
}

static void warn_addsub_in_shift(const expression_t *const expr)
{
        if (expr->base.parenthesized)
                return;

        char op;
        switch (expr->kind) {
                case EXPR_BINARY_ADD: op = '+'; break;
                case EXPR_BINARY_SUB: op = '-'; break;
                default:              return;
        }

        warningf(&expr->base.source_position,
                        "suggest parentheses around '%c' inside shift", op);
}

static bool semantic_shift(binary_expression_t *expression)
{
        expression_t *const left            = expression->left;
        expression_t *const right           = expression->right;
        type_t       *const orig_type_left  = left->base.type;
        type_t       *const orig_type_right = right->base.type;
        type_t       *      type_left       = skip_typeref(orig_type_left);
        type_t       *      type_right      = skip_typeref(orig_type_right);

        if (!is_type_integer(type_left) || !is_type_integer(type_right)) {
                /* TODO: improve error message */
                if (is_type_valid(type_left) && is_type_valid(type_right)) {
                        errorf(&expression->base.source_position,
                               "operands of shift operation must have integer types");
                }
                return false;
        }

        type_left = promote_integer(type_left);

        if (is_constant_expression(right)) {
                long count = fold_constant_to_int(right);
                if (count < 0) {
                        warningf(&right->base.source_position,
                                        "shift count must be non-negative");
                } else if ((unsigned long)count >=
                                get_atomic_type_size(type_left->atomic.akind) * 8) {
                        warningf(&right->base.source_position,
                                        "shift count must be less than type width");
                }
        }

        type_right        = promote_integer(type_right);
        expression->right = create_implicit_cast(right, type_right);

        return true;
}

static void semantic_shift_op(binary_expression_t *expression)
{
        expression_t *const left  = expression->left;
        expression_t *const right = expression->right;

        if (!semantic_shift(expression))
                return;

        if (warning.parentheses) {
                warn_addsub_in_shift(left);
                warn_addsub_in_shift(right);
        }

        type_t *const orig_type_left = left->base.type;
        type_t *      type_left      = skip_typeref(orig_type_left);

        type_left             = promote_integer(type_left);
        expression->left      = create_implicit_cast(left, type_left);
        expression->base.type = type_left;
}

static void semantic_add(binary_expression_t *expression)
{
        expression_t *const left            = expression->left;
        expression_t *const right           = expression->right;
        type_t       *const orig_type_left  = left->base.type;
        type_t       *const orig_type_right = right->base.type;
        type_t       *const type_left       = skip_typeref(orig_type_left);
        type_t       *const type_right      = skip_typeref(orig_type_right);

        /* §6.5.6 */
        if (is_type_arithmetic(type_left) && is_type_arithmetic(type_right)) {
                type_t *arithmetic_type = semantic_arithmetic(type_left, type_right);
                expression->left  = create_implicit_cast(left, arithmetic_type);
                expression->right = create_implicit_cast(right, arithmetic_type);
                expression->base.type = arithmetic_type;
        } else if (is_type_pointer(type_left) && is_type_integer(type_right)) {
                check_pointer_arithmetic(&expression->base.source_position,
                                         type_left, orig_type_left);
                expression->base.type = type_left;
        } else if (is_type_pointer(type_right) && is_type_integer(type_left)) {
                check_pointer_arithmetic(&expression->base.source_position,
                                         type_right, orig_type_right);
                expression->base.type = type_right;
        } else if (is_type_valid(type_left) && is_type_valid(type_right)) {
                errorf(&expression->base.source_position,
                       "invalid operands to binary + ('%T', '%T')",
                       orig_type_left, orig_type_right);
        }
}

static void semantic_sub(binary_expression_t *expression)
{
        expression_t            *const left            = expression->left;
        expression_t            *const right           = expression->right;
        type_t                  *const orig_type_left  = left->base.type;
        type_t                  *const orig_type_right = right->base.type;
        type_t                  *const type_left       = skip_typeref(orig_type_left);
        type_t                  *const type_right      = skip_typeref(orig_type_right);
        source_position_t const *const pos             = &expression->base.source_position;

        /* §5.6.5 */
        if (is_type_arithmetic(type_left) && is_type_arithmetic(type_right)) {
                type_t *arithmetic_type = semantic_arithmetic(type_left, type_right);
                expression->left        = create_implicit_cast(left, arithmetic_type);
                expression->right       = create_implicit_cast(right, arithmetic_type);
                expression->base.type =  arithmetic_type;
        } else if (is_type_pointer(type_left) && is_type_integer(type_right)) {
                check_pointer_arithmetic(&expression->base.source_position,
                                         type_left, orig_type_left);
                expression->base.type = type_left;
        } else if (is_type_pointer(type_left) && is_type_pointer(type_right)) {
                type_t *const unqual_left  = get_unqualified_type(skip_typeref(type_left->pointer.points_to));
                type_t *const unqual_right = get_unqualified_type(skip_typeref(type_right->pointer.points_to));
                if (!types_compatible(unqual_left, unqual_right)) {
                        errorf(pos,
                               "subtracting pointers to incompatible types '%T' and '%T'",
                               orig_type_left, orig_type_right);
                } else if (!is_type_object(unqual_left)) {
                        if (!is_type_atomic(unqual_left, ATOMIC_TYPE_VOID)) {
                                errorf(pos, "subtracting pointers to non-object types '%T'",
                                       orig_type_left);
                        } else if (warning.other) {
                                warningf(pos, "subtracting pointers to void");
                        }
                }
                expression->base.type = type_ptrdiff_t;
        } else if (is_type_valid(type_left) && is_type_valid(type_right)) {
                errorf(pos, "invalid operands of types '%T' and '%T' to binary '-'",
                       orig_type_left, orig_type_right);
        }
}

static void warn_string_literal_address(expression_t const* expr)
{
        while (expr->kind == EXPR_UNARY_TAKE_ADDRESS) {
                expr = expr->unary.value;
                if (expr->kind != EXPR_UNARY_DEREFERENCE)
                        return;
                expr = expr->unary.value;
        }

        if (expr->kind == EXPR_STRING_LITERAL
                        || expr->kind == EXPR_WIDE_STRING_LITERAL) {
                warningf(&expr->base.source_position,
                        "comparison with string literal results in unspecified behaviour");
        }
}

static void warn_comparison_in_comparison(const expression_t *const expr)
{
        if (expr->base.parenthesized)
                return;
        switch (expr->base.kind) {
                case EXPR_BINARY_LESS:
                case EXPR_BINARY_GREATER:
                case EXPR_BINARY_LESSEQUAL:
                case EXPR_BINARY_GREATEREQUAL:
                case EXPR_BINARY_NOTEQUAL:
                case EXPR_BINARY_EQUAL:
                        warningf(&expr->base.source_position,
                                        "comparisons like 'x <= y < z' do not have their mathematical meaning");
                        break;
                default:
                        break;
        }
}

static bool maybe_negative(expression_t const *const expr)
{
        return
                !is_constant_expression(expr) ||
                fold_constant_to_int(expr) < 0;
}

/**
 * Check the semantics of comparison expressions.
 *
 * @param expression   The expression to check.
 */
static void semantic_comparison(binary_expression_t *expression)
{
        expression_t *left  = expression->left;
        expression_t *right = expression->right;

        if (warning.address) {
                warn_string_literal_address(left);
                warn_string_literal_address(right);

                expression_t const* const func_left = get_reference_address(left);
                if (func_left != NULL && is_null_pointer_constant(right)) {
                        warningf(&expression->base.source_position,
                                 "the address of '%Y' will never be NULL",
                                 func_left->reference.entity->base.symbol);
                }

                expression_t const* const func_right = get_reference_address(right);
                if (func_right != NULL && is_null_pointer_constant(right)) {
                        warningf(&expression->base.source_position,
                                 "the address of '%Y' will never be NULL",
                                 func_right->reference.entity->base.symbol);
                }
        }

        if (warning.parentheses) {
                warn_comparison_in_comparison(left);
                warn_comparison_in_comparison(right);
        }

        type_t *orig_type_left  = left->base.type;
        type_t *orig_type_right = right->base.type;
        type_t *type_left       = skip_typeref(orig_type_left);
        type_t *type_right      = skip_typeref(orig_type_right);

        /* TODO non-arithmetic types */
        if (is_type_arithmetic(type_left) && is_type_arithmetic(type_right)) {
                type_t *arithmetic_type = semantic_arithmetic(type_left, type_right);

                /* test for signed vs unsigned compares */
                if (warning.sign_compare && is_type_integer(arithmetic_type)) {
                        bool const signed_left  = is_type_signed(type_left);
                        bool const signed_right = is_type_signed(type_right);
                        if (signed_left != signed_right) {
                                /* FIXME long long needs better const folding magic */
                                /* TODO check whether constant value can be represented by other type */
                                if ((signed_left  && maybe_negative(left)) ||
                                                (signed_right && maybe_negative(right))) {
                                        warningf(&expression->base.source_position,
                                                        "comparison between signed and unsigned");
                                }
                        }
                }

                expression->left        = create_implicit_cast(left, arithmetic_type);
                expression->right       = create_implicit_cast(right, arithmetic_type);
                expression->base.type   = arithmetic_type;
                if (warning.float_equal &&
                    (expression->base.kind == EXPR_BINARY_EQUAL ||
                     expression->base.kind == EXPR_BINARY_NOTEQUAL) &&
                    is_type_float(arithmetic_type)) {
                        warningf(&expression->base.source_position,
                                 "comparing floating point with == or != is unsafe");
                }
        } else if (is_type_pointer(type_left) && is_type_pointer(type_right)) {
                /* TODO check compatibility */
        } else if (is_type_pointer(type_left)) {
                expression->right = create_implicit_cast(right, type_left);
        } else if (is_type_pointer(type_right)) {
                expression->left = create_implicit_cast(left, type_right);
        } else if (is_type_valid(type_left) && is_type_valid(type_right)) {
                type_error_incompatible("invalid operands in comparison",
                                        &expression->base.source_position,
                                        type_left, type_right);
        }
        expression->base.type = c_mode & _CXX ? type_bool : type_int;
}

/**
 * Checks if a compound type has constant fields.
 */
static bool has_const_fields(const compound_type_t *type)
{
        compound_t *compound = type->compound;
        entity_t   *entry    = compound->members.entities;

        for (; entry != NULL; entry = entry->base.next) {
                if (!is_declaration(entry))
                        continue;

                const type_t *decl_type = skip_typeref(entry->declaration.type);
                if (decl_type->base.qualifiers & TYPE_QUALIFIER_CONST)
                        return true;
        }

        return false;
}

static bool is_valid_assignment_lhs(expression_t const* const left)
{
        type_t *const orig_type_left = revert_automatic_type_conversion(left);
        type_t *const type_left      = skip_typeref(orig_type_left);

        if (!is_lvalue(left)) {
                errorf(HERE, "left hand side '%E' of assignment is not an lvalue",
                       left);
                return false;
        }

        if (left->kind == EXPR_REFERENCE
                        && left->reference.entity->kind == ENTITY_FUNCTION) {
                errorf(HERE, "cannot assign to function '%E'", left);
                return false;
        }

        if (is_type_array(type_left)) {
                errorf(HERE, "cannot assign to array '%E'", left);
                return false;
        }
        if (type_left->base.qualifiers & TYPE_QUALIFIER_CONST) {
                errorf(HERE, "assignment to readonly location '%E' (type '%T')", left,
                       orig_type_left);
                return false;
        }
        if (is_type_incomplete(type_left)) {
                errorf(HERE, "left-hand side '%E' of assignment has incomplete type '%T'",
                       left, orig_type_left);
                return false;
        }
        if (is_type_compound(type_left) && has_const_fields(&type_left->compound)) {
                errorf(HERE, "cannot assign to '%E' because compound type '%T' has readonly fields",
                       left, orig_type_left);
                return false;
        }

        return true;
}

static void semantic_arithmetic_assign(binary_expression_t *expression)
{
        expression_t *left            = expression->left;
        expression_t *right           = expression->right;
        type_t       *orig_type_left  = left->base.type;
        type_t       *orig_type_right = right->base.type;

        if (!is_valid_assignment_lhs(left))
                return;

        type_t *type_left  = skip_typeref(orig_type_left);
        type_t *type_right = skip_typeref(orig_type_right);

        if (!is_type_arithmetic(type_left) || !is_type_arithmetic(type_right)) {
                /* TODO: improve error message */
                if (is_type_valid(type_left) && is_type_valid(type_right)) {
                        errorf(&expression->base.source_position,
                               "operation needs arithmetic types");
                }
                return;
        }

        /* combined instructions are tricky. We can't create an implicit cast on
         * the left side, because we need the uncasted form for the store.
         * The ast2firm pass has to know that left_type must be right_type
         * for the arithmetic operation and create a cast by itself */
        type_t *arithmetic_type = semantic_arithmetic(type_left, type_right);
        expression->right       = create_implicit_cast(right, arithmetic_type);
        expression->base.type   = type_left;
}

static void semantic_divmod_assign(binary_expression_t *expression)
{
        semantic_arithmetic_assign(expression);
        warn_div_by_zero(expression);
}

static void semantic_arithmetic_addsubb_assign(binary_expression_t *expression)
{
        expression_t *const left            = expression->left;
        expression_t *const right           = expression->right;
        type_t       *const orig_type_left  = left->base.type;
        type_t       *const orig_type_right = right->base.type;
        type_t       *const type_left       = skip_typeref(orig_type_left);
        type_t       *const type_right      = skip_typeref(orig_type_right);

        if (!is_valid_assignment_lhs(left))
                return;

        if (is_type_arithmetic(type_left) && is_type_arithmetic(type_right)) {
                /* combined instructions are tricky. We can't create an implicit cast on
                 * the left side, because we need the uncasted form for the store.
                 * The ast2firm pass has to know that left_type must be right_type
                 * for the arithmetic operation and create a cast by itself */
                type_t *const arithmetic_type = semantic_arithmetic(type_left, type_right);
                expression->right     = create_implicit_cast(right, arithmetic_type);
                expression->base.type = type_left;
        } else if (is_type_pointer(type_left) && is_type_integer(type_right)) {
                check_pointer_arithmetic(&expression->base.source_position,
                                         type_left, orig_type_left);
                expression->base.type = type_left;
        } else if (is_type_valid(type_left) && is_type_valid(type_right)) {
                errorf(&expression->base.source_position,
                       "incompatible types '%T' and '%T' in assignment",
                       orig_type_left, orig_type_right);
        }
}

static void semantic_integer_assign(binary_expression_t *expression)
{
        expression_t *left            = expression->left;
        expression_t *right           = expression->right;
        type_t       *orig_type_left  = left->base.type;
        type_t       *orig_type_right = right->base.type;

        if (!is_valid_assignment_lhs(left))
                return;

        type_t *type_left  = skip_typeref(orig_type_left);
        type_t *type_right = skip_typeref(orig_type_right);

        if (!is_type_integer(type_left) || !is_type_integer(type_right)) {
                /* TODO: improve error message */
                if (is_type_valid(type_left) && is_type_valid(type_right)) {
                        errorf(&expression->base.source_position,
                               "operation needs integer types");
                }
                return;
        }

        /* combined instructions are tricky. We can't create an implicit cast on
         * the left side, because we need the uncasted form for the store.
         * The ast2firm pass has to know that left_type must be right_type
         * for the arithmetic operation and create a cast by itself */
        type_t *arithmetic_type = semantic_arithmetic(type_left, type_right);
        expression->right       = create_implicit_cast(right, arithmetic_type);
        expression->base.type   = type_left;
}

static void semantic_shift_assign(binary_expression_t *expression)
{
        expression_t *left           = expression->left;

        if (!is_valid_assignment_lhs(left))
                return;

        if (!semantic_shift(expression))
                return;

        expression->base.type = skip_typeref(left->base.type);
}

static void warn_logical_and_within_or(const expression_t *const expr)
{
        if (expr->base.kind != EXPR_BINARY_LOGICAL_AND)
                return;
        if (expr->base.parenthesized)
                return;
        warningf(&expr->base.source_position,
                        "suggest parentheses around && within ||");
}

/**
 * Check the semantic restrictions of a logical expression.
 */
static void semantic_logical_op(binary_expression_t *expression)
{
        /* §6.5.13:2  Each of the operands shall have scalar type.
         * §6.5.14:2  Each of the operands shall have scalar type. */
        semantic_condition(expression->left,   "left operand of logical operator");
        semantic_condition(expression->right, "right operand of logical operator");
        if (expression->base.kind == EXPR_BINARY_LOGICAL_OR &&
                        warning.parentheses) {
                warn_logical_and_within_or(expression->left);
                warn_logical_and_within_or(expression->right);
        }
        expression->base.type = c_mode & _CXX ? type_bool : type_int;
}

/**
 * Check the semantic restrictions of a binary assign expression.
 */
static void semantic_binexpr_assign(binary_expression_t *expression)
{
        expression_t *left           = expression->left;
        type_t       *orig_type_left = left->base.type;

        if (!is_valid_assignment_lhs(left))
                return;

        assign_error_t error = semantic_assign(orig_type_left, expression->right);
        report_assign_error(error, orig_type_left, expression->right,
                        "assignment", &left->base.source_position);
        expression->right = create_implicit_cast(expression->right, orig_type_left);
        expression->base.type = orig_type_left;
}

/**
 * Determine if the outermost operation (or parts thereof) of the given
 * expression has no effect in order to generate a warning about this fact.
 * Therefore in some cases this only examines some of the operands of the
 * expression (see comments in the function and examples below).
 * Examples:
 *   f() + 23;    // warning, because + has no effect
 *   x || f();    // no warning, because x controls execution of f()
 *   x ? y : f(); // warning, because y has no effect
 *   (void)x;     // no warning to be able to suppress the warning
 * This function can NOT be used for an "expression has definitely no effect"-
 * analysis. */
static bool expression_has_effect(const expression_t *const expr)
{
        switch (expr->kind) {
                case EXPR_UNKNOWN:                    break;
                case EXPR_INVALID:                    return true; /* do NOT warn */
                case EXPR_REFERENCE:                  return false;
                case EXPR_REFERENCE_ENUM_VALUE:       return false;
                case EXPR_LABEL_ADDRESS:              return false;

                /* suppress the warning for microsoft __noop operations */
                case EXPR_LITERAL_MS_NOOP:            return true;
                case EXPR_LITERAL_BOOLEAN:
                case EXPR_LITERAL_CHARACTER:
                case EXPR_LITERAL_WIDE_CHARACTER:
                case EXPR_LITERAL_INTEGER:
                case EXPR_LITERAL_INTEGER_OCTAL:
                case EXPR_LITERAL_INTEGER_HEXADECIMAL:
                case EXPR_LITERAL_FLOATINGPOINT:
                case EXPR_LITERAL_FLOATINGPOINT_HEXADECIMAL: return false;
                case EXPR_STRING_LITERAL:             return false;
                case EXPR_WIDE_STRING_LITERAL:        return false;

                case EXPR_CALL: {
                        const call_expression_t *const call = &expr->call;
                        if (call->function->kind != EXPR_REFERENCE)
                                return true;

                        switch (call->function->reference.entity->function.btk) {
                                /* FIXME: which builtins have no effect? */
                                default:                      return true;
                        }
                }

                /* Generate the warning if either the left or right hand side of a
                 * conditional expression has no effect */
                case EXPR_CONDITIONAL: {
                        conditional_expression_t const *const cond = &expr->conditional;
                        expression_t             const *const t    = cond->true_expression;
                        return
                                (t == NULL || expression_has_effect(t)) &&
                                expression_has_effect(cond->false_expression);
                }

                case EXPR_SELECT:                     return false;
                case EXPR_ARRAY_ACCESS:               return false;
                case EXPR_SIZEOF:                     return false;
                case EXPR_CLASSIFY_TYPE:              return false;
                case EXPR_ALIGNOF:                    return false;

                case EXPR_FUNCNAME:                   return false;
                case EXPR_BUILTIN_CONSTANT_P:         return false;
                case EXPR_BUILTIN_TYPES_COMPATIBLE_P: return false;
                case EXPR_OFFSETOF:                   return false;
                case EXPR_VA_START:                   return true;
                case EXPR_VA_ARG:                     return true;
                case EXPR_VA_COPY:                    return true;
                case EXPR_STATEMENT:                  return true; // TODO
                case EXPR_COMPOUND_LITERAL:           return false;

                case EXPR_UNARY_NEGATE:               return false;
                case EXPR_UNARY_PLUS:                 return false;
                case EXPR_UNARY_BITWISE_NEGATE:       return false;
                case EXPR_UNARY_NOT:                  return false;
                case EXPR_UNARY_DEREFERENCE:          return false;
                case EXPR_UNARY_TAKE_ADDRESS:         return false;
                case EXPR_UNARY_POSTFIX_INCREMENT:    return true;
                case EXPR_UNARY_POSTFIX_DECREMENT:    return true;
                case EXPR_UNARY_PREFIX_INCREMENT:     return true;
                case EXPR_UNARY_PREFIX_DECREMENT:     return true;

                /* Treat void casts as if they have an effect in order to being able to
                 * suppress the warning */
                case EXPR_UNARY_CAST: {
                        type_t *const type = skip_typeref(expr->base.type);
                        return is_type_atomic(type, ATOMIC_TYPE_VOID);
                }

                case EXPR_UNARY_CAST_IMPLICIT:        return true;
                case EXPR_UNARY_ASSUME:               return true;
                case EXPR_UNARY_DELETE:               return true;
                case EXPR_UNARY_DELETE_ARRAY:         return true;
                case EXPR_UNARY_THROW:                return true;

                case EXPR_BINARY_ADD:                 return false;
                case EXPR_BINARY_SUB:                 return false;
                case EXPR_BINARY_MUL:                 return false;
                case EXPR_BINARY_DIV:                 return false;
                case EXPR_BINARY_MOD:                 return false;
                case EXPR_BINARY_EQUAL:               return false;
                case EXPR_BINARY_NOTEQUAL:            return false;
                case EXPR_BINARY_LESS:                return false;
                case EXPR_BINARY_LESSEQUAL:           return false;
                case EXPR_BINARY_GREATER:             return false;
                case EXPR_BINARY_GREATEREQUAL:        return false;
                case EXPR_BINARY_BITWISE_AND:         return false;
                case EXPR_BINARY_BITWISE_OR:          return false;
                case EXPR_BINARY_BITWISE_XOR:         return false;
                case EXPR_BINARY_SHIFTLEFT:           return false;
                case EXPR_BINARY_SHIFTRIGHT:          return false;
                case EXPR_BINARY_ASSIGN:              return true;
                case EXPR_BINARY_MUL_ASSIGN:          return true;
                case EXPR_BINARY_DIV_ASSIGN:          return true;
                case EXPR_BINARY_MOD_ASSIGN:          return true;
                case EXPR_BINARY_ADD_ASSIGN:          return true;
                case EXPR_BINARY_SUB_ASSIGN:          return true;
                case EXPR_BINARY_SHIFTLEFT_ASSIGN:    return true;
                case EXPR_BINARY_SHIFTRIGHT_ASSIGN:   return true;
                case EXPR_BINARY_BITWISE_AND_ASSIGN:  return true;
                case EXPR_BINARY_BITWISE_XOR_ASSIGN:  return true;
                case EXPR_BINARY_BITWISE_OR_ASSIGN:   return true;

                /* Only examine the right hand side of && and ||, because the left hand
                 * side already has the effect of controlling the execution of the right
                 * hand side */
                case EXPR_BINARY_LOGICAL_AND:
                case EXPR_BINARY_LOGICAL_OR:
                /* Only examine the right hand side of a comma expression, because the left
                 * hand side has a separate warning */
                case EXPR_BINARY_COMMA:
                        return expression_has_effect(expr->binary.right);

                case EXPR_BINARY_ISGREATER:           return false;
                case EXPR_BINARY_ISGREATEREQUAL:      return false;
                case EXPR_BINARY_ISLESS:              return false;
                case EXPR_BINARY_ISLESSEQUAL:         return false;
                case EXPR_BINARY_ISLESSGREATER:       return false;
                case EXPR_BINARY_ISUNORDERED:         return false;
        }

        internal_errorf(HERE, "unexpected expression");
}

static void semantic_comma(binary_expression_t *expression)
{
        if (warning.unused_value) {
                const expression_t *const left = expression->left;
                if (!expression_has_effect(left)) {
                        warningf(&left->base.source_position,
                                 "left-hand operand of comma expression has no effect");
                }
        }
        expression->base.type = expression->right->base.type;
}

/**
 * @param prec_r precedence of the right operand
 */
#define CREATE_BINEXPR_PARSER(token_type, binexpression_type, prec_r, sfunc) \
static expression_t *parse_##binexpression_type(expression_t *left)          \
{                                                                            \
        expression_t *binexpr = allocate_expression_zero(binexpression_type);    \
        binexpr->binary.left  = left;                                            \
        eat(token_type);                                                         \
                                                                             \
        expression_t *right = parse_subexpression(prec_r);                       \
                                                                             \
        binexpr->binary.right = right;                                           \
        sfunc(&binexpr->binary);                                                 \
                                                                             \
        return binexpr;                                                          \
}

CREATE_BINEXPR_PARSER('*',                    EXPR_BINARY_MUL,                PREC_CAST,           semantic_binexpr_arithmetic)
CREATE_BINEXPR_PARSER('/',                    EXPR_BINARY_DIV,                PREC_CAST,           semantic_divmod_arithmetic)
CREATE_BINEXPR_PARSER('%',                    EXPR_BINARY_MOD,                PREC_CAST,           semantic_divmod_arithmetic)
CREATE_BINEXPR_PARSER('+',                    EXPR_BINARY_ADD,                PREC_MULTIPLICATIVE, semantic_add)
CREATE_BINEXPR_PARSER('-',                    EXPR_BINARY_SUB,                PREC_MULTIPLICATIVE, semantic_sub)
CREATE_BINEXPR_PARSER(T_LESSLESS,             EXPR_BINARY_SHIFTLEFT,          PREC_ADDITIVE,       semantic_shift_op)
CREATE_BINEXPR_PARSER(T_GREATERGREATER,       EXPR_BINARY_SHIFTRIGHT,         PREC_ADDITIVE,       semantic_shift_op)
CREATE_BINEXPR_PARSER('<',                    EXPR_BINARY_LESS,               PREC_SHIFT,          semantic_comparison)
CREATE_BINEXPR_PARSER('>',                    EXPR_BINARY_GREATER,            PREC_SHIFT,          semantic_comparison)
CREATE_BINEXPR_PARSER(T_LESSEQUAL,            EXPR_BINARY_LESSEQUAL,          PREC_SHIFT,          semantic_comparison)
CREATE_BINEXPR_PARSER(T_GREATEREQUAL,         EXPR_BINARY_GREATEREQUAL,       PREC_SHIFT,          semantic_comparison)
CREATE_BINEXPR_PARSER(T_EXCLAMATIONMARKEQUAL, EXPR_BINARY_NOTEQUAL,           PREC_RELATIONAL,     semantic_comparison)
CREATE_BINEXPR_PARSER(T_EQUALEQUAL,           EXPR_BINARY_EQUAL,              PREC_RELATIONAL,     semantic_comparison)
CREATE_BINEXPR_PARSER('&',                    EXPR_BINARY_BITWISE_AND,        PREC_EQUALITY,       semantic_binexpr_arithmetic)
CREATE_BINEXPR_PARSER('^',                    EXPR_BINARY_BITWISE_XOR,        PREC_AND,            semantic_binexpr_arithmetic)
CREATE_BINEXPR_PARSER('|',                    EXPR_BINARY_BITWISE_OR,         PREC_XOR,            semantic_binexpr_arithmetic)
CREATE_BINEXPR_PARSER(T_ANDAND,               EXPR_BINARY_LOGICAL_AND,        PREC_OR,             semantic_logical_op)
CREATE_BINEXPR_PARSER(T_PIPEPIPE,             EXPR_BINARY_LOGICAL_OR,         PREC_LOGICAL_AND,    semantic_logical_op)
CREATE_BINEXPR_PARSER('=',                    EXPR_BINARY_ASSIGN,             PREC_ASSIGNMENT,     semantic_binexpr_assign)
CREATE_BINEXPR_PARSER(T_PLUSEQUAL,            EXPR_BINARY_ADD_ASSIGN,         PREC_ASSIGNMENT,     semantic_arithmetic_addsubb_assign)
CREATE_BINEXPR_PARSER(T_MINUSEQUAL,           EXPR_BINARY_SUB_ASSIGN,         PREC_ASSIGNMENT,     semantic_arithmetic_addsubb_assign)
CREATE_BINEXPR_PARSER(T_ASTERISKEQUAL,        EXPR_BINARY_MUL_ASSIGN,         PREC_ASSIGNMENT,     semantic_arithmetic_assign)
CREATE_BINEXPR_PARSER(T_SLASHEQUAL,           EXPR_BINARY_DIV_ASSIGN,         PREC_ASSIGNMENT,     semantic_divmod_assign)
CREATE_BINEXPR_PARSER(T_PERCENTEQUAL,         EXPR_BINARY_MOD_ASSIGN,         PREC_ASSIGNMENT,     semantic_divmod_assign)
CREATE_BINEXPR_PARSER(T_LESSLESSEQUAL,        EXPR_BINARY_SHIFTLEFT_ASSIGN,   PREC_ASSIGNMENT,     semantic_shift_assign)
CREATE_BINEXPR_PARSER(T_GREATERGREATEREQUAL,  EXPR_BINARY_SHIFTRIGHT_ASSIGN,  PREC_ASSIGNMENT,     semantic_shift_assign)
CREATE_BINEXPR_PARSER(T_ANDEQUAL,             EXPR_BINARY_BITWISE_AND_ASSIGN, PREC_ASSIGNMENT,     semantic_integer_assign)
CREATE_BINEXPR_PARSER(T_PIPEEQUAL,            EXPR_BINARY_BITWISE_OR_ASSIGN,  PREC_ASSIGNMENT,     semantic_integer_assign)
CREATE_BINEXPR_PARSER(T_CARETEQUAL,           EXPR_BINARY_BITWISE_XOR_ASSIGN, PREC_ASSIGNMENT,     semantic_integer_assign)
CREATE_BINEXPR_PARSER(',',                    EXPR_BINARY_COMMA,              PREC_ASSIGNMENT,     semantic_comma)


static expression_t *parse_subexpression(precedence_t precedence)
{
        if (token.type < 0) {
                return expected_expression_error();
        }

        expression_parser_function_t *parser
                = &expression_parsers[token.type];
        source_position_t             source_position = token.source_position;
        expression_t                 *left;

        if (parser->parser != NULL) {
                left = parser->parser();
        } else {
                left = parse_primary_expression();
        }
        assert(left != NULL);
        left->base.source_position = source_position;

        while (true) {
                if (token.type < 0) {
                        return expected_expression_error();
                }

                parser = &expression_parsers[token.type];
                if (parser->infix_parser == NULL)
                        break;
                if (parser->infix_precedence < precedence)
                        break;

                left = parser->infix_parser(left);

                assert(left != NULL);
                assert(left->kind != EXPR_UNKNOWN);
                left->base.source_position = source_position;
        }

        return left;
}

/**
 * Parse an expression.
 */
static expression_t *parse_expression(void)
{
        return parse_subexpression(PREC_EXPRESSION);
}

/**
 * Register a parser for a prefix-like operator.
 *
 * @param parser      the parser function
 * @param token_type  the token type of the prefix token
 */
static void register_expression_parser(parse_expression_function parser,
                                       int token_type)
{
        expression_parser_function_t *entry = &expression_parsers[token_type];

        if (entry->parser != NULL) {
                diagnosticf("for token '%k'\n", (token_type_t)token_type);
                panic("trying to register multiple expression parsers for a token");
        }
        entry->parser = parser;
}

/**
 * Register a parser for an infix operator with given precedence.
 *
 * @param parser      the parser function
 * @param token_type  the token type of the infix operator
 * @param precedence  the precedence of the operator
 */
static void register_infix_parser(parse_expression_infix_function parser,
                int token_type, precedence_t precedence)
{
        expression_parser_function_t *entry = &expression_parsers[token_type];

        if (entry->infix_parser != NULL) {
                diagnosticf("for token '%k'\n", (token_type_t)token_type);
                panic("trying to register multiple infix expression parsers for a "
                      "token");
        }
        entry->infix_parser     = parser;
        entry->infix_precedence = precedence;
}

/**
 * Initialize the expression parsers.
 */
static void init_expression_parsers(void)
{
        memset(&expression_parsers, 0, sizeof(expression_parsers));

        register_infix_parser(parse_array_expression,               '[',                    PREC_POSTFIX);
        register_infix_parser(parse_call_expression,                '(',                    PREC_POSTFIX);
        register_infix_parser(parse_select_expression,              '.',                    PREC_POSTFIX);
        register_infix_parser(parse_select_expression,              T_MINUSGREATER,         PREC_POSTFIX);
        register_infix_parser(parse_EXPR_UNARY_POSTFIX_INCREMENT,   T_PLUSPLUS,             PREC_POSTFIX);
        register_infix_parser(parse_EXPR_UNARY_POSTFIX_DECREMENT,   T_MINUSMINUS,           PREC_POSTFIX);
        register_infix_parser(parse_EXPR_BINARY_MUL,                '*',                    PREC_MULTIPLICATIVE);
        register_infix_parser(parse_EXPR_BINARY_DIV,                '/',                    PREC_MULTIPLICATIVE);
        register_infix_parser(parse_EXPR_BINARY_MOD,                '%',                    PREC_MULTIPLICATIVE);
        register_infix_parser(parse_EXPR_BINARY_ADD,                '+',                    PREC_ADDITIVE);
        register_infix_parser(parse_EXPR_BINARY_SUB,                '-',                    PREC_ADDITIVE);
        register_infix_parser(parse_EXPR_BINARY_SHIFTLEFT,          T_LESSLESS,             PREC_SHIFT);
        register_infix_parser(parse_EXPR_BINARY_SHIFTRIGHT,         T_GREATERGREATER,       PREC_SHIFT);
        register_infix_parser(parse_EXPR_BINARY_LESS,               '<',                    PREC_RELATIONAL);
        register_infix_parser(parse_EXPR_BINARY_GREATER,            '>',                    PREC_RELATIONAL);
        register_infix_parser(parse_EXPR_BINARY_LESSEQUAL,          T_LESSEQUAL,            PREC_RELATIONAL);
        register_infix_parser(parse_EXPR_BINARY_GREATEREQUAL,       T_GREATEREQUAL,         PREC_RELATIONAL);
        register_infix_parser(parse_EXPR_BINARY_EQUAL,              T_EQUALEQUAL,           PREC_EQUALITY);
        register_infix_parser(parse_EXPR_BINARY_NOTEQUAL,           T_EXCLAMATIONMARKEQUAL, PREC_EQUALITY);
        register_infix_parser(parse_EXPR_BINARY_BITWISE_AND,        '&',                    PREC_AND);
        register_infix_parser(parse_EXPR_BINARY_BITWISE_XOR,        '^',                    PREC_XOR);
        register_infix_parser(parse_EXPR_BINARY_BITWISE_OR,         '|',                    PREC_OR);
        register_infix_parser(parse_EXPR_BINARY_LOGICAL_AND,        T_ANDAND,               PREC_LOGICAL_AND);
        register_infix_parser(parse_EXPR_BINARY_LOGICAL_OR,         T_PIPEPIPE,             PREC_LOGICAL_OR);
        register_infix_parser(parse_conditional_expression,         '?',                    PREC_CONDITIONAL);
        register_infix_parser(parse_EXPR_BINARY_ASSIGN,             '=',                    PREC_ASSIGNMENT);
        register_infix_parser(parse_EXPR_BINARY_ADD_ASSIGN,         T_PLUSEQUAL,            PREC_ASSIGNMENT);
        register_infix_parser(parse_EXPR_BINARY_SUB_ASSIGN,         T_MINUSEQUAL,           PREC_ASSIGNMENT);
        register_infix_parser(parse_EXPR_BINARY_MUL_ASSIGN,         T_ASTERISKEQUAL,        PREC_ASSIGNMENT);
        register_infix_parser(parse_EXPR_BINARY_DIV_ASSIGN,         T_SLASHEQUAL,           PREC_ASSIGNMENT);
        register_infix_parser(parse_EXPR_BINARY_MOD_ASSIGN,         T_PERCENTEQUAL,         PREC_ASSIGNMENT);
        register_infix_parser(parse_EXPR_BINARY_SHIFTLEFT_ASSIGN,   T_LESSLESSEQUAL,        PREC_ASSIGNMENT);
        register_infix_parser(parse_EXPR_BINARY_SHIFTRIGHT_ASSIGN,  T_GREATERGREATEREQUAL,  PREC_ASSIGNMENT);
        register_infix_parser(parse_EXPR_BINARY_BITWISE_AND_ASSIGN, T_ANDEQUAL,             PREC_ASSIGNMENT);
        register_infix_parser(parse_EXPR_BINARY_BITWISE_OR_ASSIGN,  T_PIPEEQUAL,            PREC_ASSIGNMENT);
        register_infix_parser(parse_EXPR_BINARY_BITWISE_XOR_ASSIGN, T_CARETEQUAL,           PREC_ASSIGNMENT);
        register_infix_parser(parse_EXPR_BINARY_COMMA,              ',',                    PREC_EXPRESSION);

        register_expression_parser(parse_EXPR_UNARY_NEGATE,           '-');
        register_expression_parser(parse_EXPR_UNARY_PLUS,             '+');
        register_expression_parser(parse_EXPR_UNARY_NOT,              '!');
        register_expression_parser(parse_EXPR_UNARY_BITWISE_NEGATE,   '~');
        register_expression_parser(parse_EXPR_UNARY_DEREFERENCE,      '*');
        register_expression_parser(parse_EXPR_UNARY_TAKE_ADDRESS,     '&');
        register_expression_parser(parse_EXPR_UNARY_PREFIX_INCREMENT, T_PLUSPLUS);
        register_expression_parser(parse_EXPR_UNARY_PREFIX_DECREMENT, T_MINUSMINUS);
        register_expression_parser(parse_sizeof,                      T_sizeof);
        register_expression_parser(parse_alignof,                     T___alignof__);
        register_expression_parser(parse_extension,                   T___extension__);
        register_expression_parser(parse_builtin_classify_type,       T___builtin_classify_type);
        register_expression_parser(parse_delete,                      T_delete);
        register_expression_parser(parse_throw,                       T_throw);
}

/**
 * Parse a asm statement arguments specification.
 */
static asm_argument_t *parse_asm_arguments(bool is_out)
{
        asm_argument_t  *result = NULL;
        asm_argument_t **anchor = &result;

        while (token.type == T_STRING_LITERAL || token.type == '[') {
                asm_argument_t *argument = allocate_ast_zero(sizeof(argument[0]));
                memset(argument, 0, sizeof(argument[0]));

                if (next_if('[')) {
                        if (token.type != T_IDENTIFIER) {
                                parse_error_expected("while parsing asm argument",
                                                     T_IDENTIFIER, NULL);
                                return NULL;
                        }
                        argument->symbol = token.symbol;

                        expect(']', end_error);
                }

                argument->constraints = parse_string_literals();
                expect('(', end_error);
                add_anchor_token(')');
                expression_t *expression = parse_expression();
                rem_anchor_token(')');
                if (is_out) {
                        /* Ugly GCC stuff: Allow lvalue casts.  Skip casts, when they do not
                         * change size or type representation (e.g. int -> long is ok, but
                         * int -> float is not) */
                        if (expression->kind == EXPR_UNARY_CAST) {
                                type_t      *const type = expression->base.type;
                                type_kind_t  const kind = type->kind;
                                if (kind == TYPE_ATOMIC || kind == TYPE_POINTER) {
                                        unsigned flags;
                                        unsigned size;
                                        if (kind == TYPE_ATOMIC) {
                                                atomic_type_kind_t const akind = type->atomic.akind;
                                                flags = get_atomic_type_flags(akind) & ~ATOMIC_TYPE_FLAG_SIGNED;
                                                size  = get_atomic_type_size(akind);
                                        } else {
                                                flags = ATOMIC_TYPE_FLAG_INTEGER | ATOMIC_TYPE_FLAG_ARITHMETIC;
                                                size  = get_atomic_type_size(get_intptr_kind());
                                        }

                                        do {
                                                expression_t *const value      = expression->unary.value;
                                                type_t       *const value_type = value->base.type;
                                                type_kind_t   const value_kind = value_type->kind;

                                                unsigned value_flags;
                                                unsigned value_size;
                                                if (value_kind == TYPE_ATOMIC) {
                                                        atomic_type_kind_t const value_akind = value_type->atomic.akind;
                                                        value_flags = get_atomic_type_flags(value_akind) & ~ATOMIC_TYPE_FLAG_SIGNED;
                                                        value_size  = get_atomic_type_size(value_akind);
                                                } else if (value_kind == TYPE_POINTER) {
                                                        value_flags = ATOMIC_TYPE_FLAG_INTEGER | ATOMIC_TYPE_FLAG_ARITHMETIC;
                                                        value_size  = get_atomic_type_size(get_intptr_kind());
                                                } else {
                                                        break;
                                                }

                                                if (value_flags != flags || value_size != size)
                                                        break;

                                                expression = value;
                                        } while (expression->kind == EXPR_UNARY_CAST);
                                }
                        }

                        if (!is_lvalue(expression)) {
                                errorf(&expression->base.source_position,
                                       "asm output argument is not an lvalue");
                        }

                        if (argument->constraints.begin[0] == '=')
                                determine_lhs_ent(expression, NULL);
                        else
                                mark_vars_read(expression, NULL);
                } else {
                        mark_vars_read(expression, NULL);
                }
                argument->expression = expression;
                expect(')', end_error);

                set_address_taken(expression, true);

                *anchor = argument;
                anchor  = &argument->next;

                if (!next_if(','))
                        break;
        }

        return result;
end_error:
        return NULL;
}

/**
 * Parse a asm statement clobber specification.
 */
static asm_clobber_t *parse_asm_clobbers(void)
{
        asm_clobber_t *result  = NULL;
        asm_clobber_t **anchor = &result;

        while (token.type == T_STRING_LITERAL) {
                asm_clobber_t *clobber = allocate_ast_zero(sizeof(clobber[0]));
                clobber->clobber       = parse_string_literals();

                *anchor = clobber;
                anchor  = &clobber->next;

                if (!next_if(','))
                        break;
        }

        return result;
}

/**
 * Parse an asm statement.
 */
static statement_t *parse_asm_statement(void)
{
        statement_t     *statement     = allocate_statement_zero(STATEMENT_ASM);
        asm_statement_t *asm_statement = &statement->asms;

        eat(T_asm);

        if (next_if(T_volatile))
                asm_statement->is_volatile = true;

        expect('(', end_error);
        add_anchor_token(')');
        if (token.type != T_STRING_LITERAL) {
                parse_error_expected("after asm(", T_STRING_LITERAL, NULL);
                goto end_of_asm;
        }
        asm_statement->asm_text = parse_string_literals();

        add_anchor_token(':');
        if (!next_if(':')) {
                rem_anchor_token(':');
                goto end_of_asm;
        }

        asm_statement->outputs = parse_asm_arguments(true);
        if (!next_if(':')) {
                rem_anchor_token(':');
                goto end_of_asm;
        }

        asm_statement->inputs = parse_asm_arguments(false);
        if (!next_if(':')) {
                rem_anchor_token(':');
                goto end_of_asm;
        }
        rem_anchor_token(':');

        asm_statement->clobbers = parse_asm_clobbers();

end_of_asm:
        rem_anchor_token(')');
        expect(')', end_error);
        expect(';', end_error);

        if (asm_statement->outputs == NULL) {
                /* GCC: An 'asm' instruction without any output operands will be treated
                 * identically to a volatile 'asm' instruction. */
                asm_statement->is_volatile = true;
        }

        return statement;
end_error:
        return create_invalid_statement();
}

static statement_t *parse_label_inner_statement(char const *const label, bool const eat_empty_stmt)
{
        statement_t *inner_stmt;
        switch (token.type) {
                case '}':
                        errorf(HERE, "%s at end of compound statement", label);
                        inner_stmt = create_invalid_statement();
                        break;

                case ';':
                        if (eat_empty_stmt) {
                                /* Eat an empty statement here, to avoid the warning about an empty
                                 * statement after a label.  label:; is commonly used to have a label
                                 * before a closing brace. */
                                inner_stmt = create_empty_statement();
                                next_token();
                                break;
                        }
                        /* FALLTHROUGH */

                default:
                        inner_stmt = parse_statement();
                        if (inner_stmt->kind == STATEMENT_DECLARATION) {
                                errorf(&inner_stmt->base.source_position, "declaration after %s", label);
                        }
                        break;
        }
        return inner_stmt;
}

/**
 * Parse a case statement.
 */
static statement_t *parse_case_statement(void)
{
        statement_t       *const statement = allocate_statement_zero(STATEMENT_CASE_LABEL);
        source_position_t *const pos       = &statement->base.source_position;

        eat(T_case);

        expression_t *const expression   = parse_expression();
        statement->case_label.expression = expression;
        if (!is_constant_expression(expression)) {
                /* This check does not prevent the error message in all cases of an
                 * prior error while parsing the expression.  At least it catches the
                 * common case of a mistyped enum entry. */
                if (is_type_valid(skip_typeref(expression->base.type))) {
                        errorf(pos, "case label does not reduce to an integer constant");
                }
                statement->case_label.is_bad = true;
        } else {
                long const val = fold_constant_to_int(expression);
                statement->case_label.first_case = val;
                statement->case_label.last_case  = val;
        }

        if (GNU_MODE) {
                if (next_if(T_DOTDOTDOT)) {
                        expression_t *const end_range   = parse_expression();
                        statement->case_label.end_range = end_range;
                        if (!is_constant_expression(end_range)) {
                                /* This check does not prevent the error message in all cases of an
                                 * prior error while parsing the expression.  At least it catches the
                                 * common case of a mistyped enum entry. */
                                if (is_type_valid(skip_typeref(end_range->base.type))) {
                                        errorf(pos, "case range does not reduce to an integer constant");
                                }
                                statement->case_label.is_bad = true;
                        } else {
                                long const val = fold_constant_to_int(end_range);
                                statement->case_label.last_case = val;

                                if (warning.other && val < statement->case_label.first_case) {
                                        statement->case_label.is_empty_range = true;
                                        warningf(pos, "empty range specified");
                                }
                        }
                }
        }

        PUSH_PARENT(statement);

        expect(':', end_error);
end_error:

        if (current_switch != NULL) {
                if (! statement->case_label.is_bad) {
                        /* Check for duplicate case values */
                        case_label_statement_t *c = &statement->case_label;
                        for (case_label_statement_t *l = current_switch->first_case; l != NULL; l = l->next) {
                                if (l->is_bad || l->is_empty_range || l->expression == NULL)
                                        continue;

                                if (c->last_case < l->first_case || c->first_case > l->last_case)
                                        continue;

                                errorf(pos, "duplicate case value (previously used %P)",
                                       &l->base.source_position);
                                break;
                        }
                }
                /* link all cases into the switch statement */
                if (current_switch->last_case == NULL) {
                        current_switch->first_case      = &statement->case_label;
                } else {
                        current_switch->last_case->next = &statement->case_label;
                }
                current_switch->last_case = &statement->case_label;
        } else {
                errorf(pos, "case label not within a switch statement");
        }

        statement->case_label.statement = parse_label_inner_statement("case label", false);

        POP_PARENT;
        return statement;
}

/**
 * Parse a default statement.
 */
static statement_t *parse_default_statement(void)
{
        statement_t *statement = allocate_statement_zero(STATEMENT_CASE_LABEL);

        eat(T_default);

        PUSH_PARENT(statement);

        expect(':', end_error);
end_error:

        if (current_switch != NULL) {
                const case_label_statement_t *def_label = current_switch->default_label;
                if (def_label != NULL) {
                        errorf(HERE, "multiple default labels in one switch (previous declared %P)",
                               &def_label->base.source_position);
                } else {
                        current_switch->default_label = &statement->case_label;

                        /* link all cases into the switch statement */
                        if (current_switch->last_case == NULL) {
                                current_switch->first_case      = &statement->case_label;
                        } else {
                                current_switch->last_case->next = &statement->case_label;
                        }
                        current_switch->last_case = &statement->case_label;
                }
        } else {
                errorf(&statement->base.source_position,
                        "'default' label not within a switch statement");
        }

        statement->case_label.statement = parse_label_inner_statement("default label", false);

        POP_PARENT;
        return statement;
}

/**
 * Parse a label statement.
 */
static statement_t *parse_label_statement(void)
{
        assert(token.type == T_IDENTIFIER);
        symbol_t *symbol = token.symbol;
        label_t  *label  = get_label(symbol);

        statement_t *const statement = allocate_statement_zero(STATEMENT_LABEL);
        statement->label.label       = label;

        next_token();

        PUSH_PARENT(statement);

        /* if statement is already set then the label is defined twice,
         * otherwise it was just mentioned in a goto/local label declaration so far
         */
        if (label->statement != NULL) {
                errorf(HERE, "duplicate label '%Y' (declared %P)",
                       symbol, &label->base.source_position);
        } else {
                label->base.source_position = token.source_position;
                label->statement            = statement;
        }

        eat(':');

        statement->label.statement = parse_label_inner_statement("label", true);

        /* remember the labels in a list for later checking */
        *label_anchor = &statement->label;
        label_anchor  = &statement->label.next;

        POP_PARENT;
        return statement;
}

/**
 * Parse an if statement.
 */
static statement_t *parse_if(void)
{
        statement_t *statement = allocate_statement_zero(STATEMENT_IF);

        eat(T_if);

        PUSH_PARENT(statement);

        add_anchor_token('{');

        expect('(', end_error);
        add_anchor_token(')');
        expression_t *const expr = parse_expression();
        statement->ifs.condition = expr;
        /* §6.8.4.1:1  The controlling expression of an if statement shall have
         *             scalar type. */
        semantic_condition(expr, "condition of 'if'-statment");
        mark_vars_read(expr, NULL);
        rem_anchor_token(')');
        expect(')', end_error);

end_error:
        rem_anchor_token('{');

        add_anchor_token(T_else);
        statement_t *const true_stmt = parse_statement();
        statement->ifs.true_statement = true_stmt;
        rem_anchor_token(T_else);

        if (next_if(T_else)) {
                statement->ifs.false_statement = parse_statement();
        } else if (warning.parentheses &&
                        true_stmt->kind == STATEMENT_IF &&
                        true_stmt->ifs.false_statement != NULL) {
                warningf(&true_stmt->base.source_position,
                                "suggest explicit braces to avoid ambiguous 'else'");
        }

        POP_PARENT;
        return statement;
}

/**
 * Check that all enums are handled in a switch.
 *
 * @param statement  the switch statement to check
 */
static void check_enum_cases(const switch_statement_t *statement)
{
        const type_t *type = skip_typeref(statement->expression->base.type);
        if (! is_type_enum(type))
                return;
        const enum_type_t *enumt = &type->enumt;

        /* if we have a default, no warnings */
        if (statement->default_label != NULL)
                return;

        /* FIXME: calculation of value should be done while parsing */
        /* TODO: quadratic algorithm here. Change to an n log n one */
        long            last_value = -1;
        const entity_t *entry      = enumt->enume->base.next;
        for (; entry != NULL && entry->kind == ENTITY_ENUM_VALUE;
             entry = entry->base.next) {
                const expression_t *expression = entry->enum_value.value;
                long                value      = expression != NULL ? fold_constant_to_int(expression) : last_value + 1;
                bool                found      = false;
                for (const case_label_statement_t *l = statement->first_case; l != NULL; l = l->next) {
                        if (l->expression == NULL)
                                continue;
                        if (l->first_case <= value && value <= l->last_case) {
                                found = true;
                                break;
                        }
                }
                if (! found) {
                        warningf(&statement->base.source_position,
                                 "enumeration value '%Y' not handled in switch",
                                 entry->base.symbol);
                }
                last_value = value;
        }
}

/**
 * Parse a switch statement.
 */
static statement_t *parse_switch(void)
{
        statement_t *statement = allocate_statement_zero(STATEMENT_SWITCH);

        eat(T_switch);

        PUSH_PARENT(statement);

        expect('(', end_error);
        add_anchor_token(')');
        expression_t *const expr = parse_expression();
        mark_vars_read(expr, NULL);
        type_t       *      type = skip_typeref(expr->base.type);
        if (is_type_integer(type)) {
                type = promote_integer(type);
                if (warning.traditional) {
                        if (get_rank(type) >= get_akind_rank(ATOMIC_TYPE_LONG)) {
                                warningf(&expr->base.source_position,
                                        "'%T' switch expression not converted to '%T' in ISO C",
                                        type, type_int);
                        }
                }
        } else if (is_type_valid(type)) {
                errorf(&expr->base.source_position,
                       "switch quantity is not an integer, but '%T'", type);
                type = type_error_type;
        }
        statement->switchs.expression = create_implicit_cast(expr, type);
        expect(')', end_error);
        rem_anchor_token(')');

        switch_statement_t *rem = current_switch;
        current_switch          = &statement->switchs;
        statement->switchs.body = parse_statement();
        current_switch          = rem;

        if (warning.switch_default &&
            statement->switchs.default_label == NULL) {
                warningf(&statement->base.source_position, "switch has no default case");
        }
        if (warning.switch_enum)
                check_enum_cases(&statement->switchs);

        POP_PARENT;
        return statement;
end_error:
        POP_PARENT;
        return create_invalid_statement();
}

static statement_t *parse_loop_body(statement_t *const loop)
{
        statement_t *const rem = current_loop;
        current_loop = loop;

        statement_t *const body = parse_statement();

        current_loop = rem;
        return body;
}

/**
 * Parse a while statement.
 */
static statement_t *parse_while(void)
{
        statement_t *statement = allocate_statement_zero(STATEMENT_WHILE);

        eat(T_while);

        PUSH_PARENT(statement);

        expect('(', end_error);
        add_anchor_token(')');
        expression_t *const cond = parse_expression();
        statement->whiles.condition = cond;
        /* §6.8.5:2    The controlling expression of an iteration statement shall
         *             have scalar type. */
        semantic_condition(cond, "condition of 'while'-statement");
        mark_vars_read(cond, NULL);
        rem_anchor_token(')');
        expect(')', end_error);

        statement->whiles.body = parse_loop_body(statement);

        POP_PARENT;
        return statement;
end_error:
        POP_PARENT;
        return create_invalid_statement();
}

/**
 * Parse a do statement.
 */
static statement_t *parse_do(void)
{
        statement_t *statement = allocate_statement_zero(STATEMENT_DO_WHILE);

        eat(T_do);

        PUSH_PARENT(statement);

        add_anchor_token(T_while);
        statement->do_while.body = parse_loop_body(statement);
        rem_anchor_token(T_while);

        expect(T_while, end_error);
        expect('(', end_error);
        add_anchor_token(')');
        expression_t *const cond = parse_expression();
        statement->do_while.condition = cond;
        /* §6.8.5:2    The controlling expression of an iteration statement shall
         *             have scalar type. */
        semantic_condition(cond, "condition of 'do-while'-statement");
        mark_vars_read(cond, NULL);
        rem_anchor_token(')');
        expect(')', end_error);
        expect(';', end_error);

        POP_PARENT;
        return statement;
end_error:
        POP_PARENT;
        return create_invalid_statement();
}

/**
 * Parse a for statement.
 */
static statement_t *parse_for(void)
{
        statement_t *statement = allocate_statement_zero(STATEMENT_FOR);

        eat(T_for);

        expect('(', end_error1);
        add_anchor_token(')');

        PUSH_PARENT(statement);

        size_t const  top       = environment_top();
        scope_t      *old_scope = scope_push(&statement->fors.scope);

        bool old_gcc_extension = in_gcc_extension;
        while (next_if(T___extension__)) {
                in_gcc_extension = true;
        }

        if (next_if(';')) {
        } else if (is_declaration_specifier(&token, false)) {
                parse_declaration(record_entity, DECL_FLAGS_NONE);
        } else {
                add_anchor_token(';');
                expression_t *const init = parse_expression();
                statement->fors.initialisation = init;
                mark_vars_read(init, ENT_ANY);
                if (warning.unused_value && !expression_has_effect(init)) {
                        warningf(&init->base.source_position,
                                        "initialisation of 'for'-statement has no effect");
                }
                rem_anchor_token(';');
                expect(';', end_error2);
        }
        in_gcc_extension = old_gcc_extension;

        if (token.type != ';') {
                add_anchor_token(';');
                expression_t *const cond = parse_expression();
                statement->fors.condition = cond;
                /* §6.8.5:2    The controlling expression of an iteration statement
                 *             shall have scalar type. */
                semantic_condition(cond, "condition of 'for'-statement");
                mark_vars_read(cond, NULL);
                rem_anchor_token(';');
        }
        expect(';', end_error2);
        if (token.type != ')') {
                expression_t *const step = parse_expression();
                statement->fors.step = step;
                mark_vars_read(step, ENT_ANY);
                if (warning.unused_value && !expression_has_effect(step)) {
                        warningf(&step->base.source_position,
                                 "step of 'for'-statement has no effect");
                }
        }
        expect(')', end_error2);
        rem_anchor_token(')');
        statement->fors.body = parse_loop_body(statement);

        assert(current_scope == &statement->fors.scope);
        scope_pop(old_scope);
        environment_pop_to(top);

        POP_PARENT;
        return statement;

end_error2:
        POP_PARENT;
        rem_anchor_token(')');
        assert(current_scope == &statement->fors.scope);
        scope_pop(old_scope);
        environment_pop_to(top);
        /* fallthrough */

end_error1:
        return create_invalid_statement();
}

/**
 * Parse a goto statement.
 */
static statement_t *parse_goto(void)
{
        statement_t *statement = allocate_statement_zero(STATEMENT_GOTO);
        eat(T_goto);

        if (GNU_MODE && next_if('*')) {
                expression_t *expression = parse_expression();
                mark_vars_read(expression, NULL);

                /* Argh: although documentation says the expression must be of type void*,
                 * gcc accepts anything that can be casted into void* without error */
                type_t *type = expression->base.type;

                if (type != type_error_type) {
                        if (!is_type_pointer(type) && !is_type_integer(type)) {
                                errorf(&expression->base.source_position,
                                        "cannot convert to a pointer type");
                        } else if (warning.other && type != type_void_ptr) {
                                warningf(&expression->base.source_position,
                                        "type of computed goto expression should be 'void*' not '%T'", type);
                        }
                        expression = create_implicit_cast(expression, type_void_ptr);
                }

                statement->gotos.expression = expression;
        } else if (token.type == T_IDENTIFIER) {
                symbol_t *symbol = token.symbol;
                next_token();
                statement->gotos.label = get_label(symbol);
        } else {
                if (GNU_MODE)
                        parse_error_expected("while parsing goto", T_IDENTIFIER, '*', NULL);
                else
                        parse_error_expected("while parsing goto", T_IDENTIFIER, NULL);
                eat_until_anchor();
                return create_invalid_statement();
        }

        /* remember the goto's in a list for later checking */
        *goto_anchor = &statement->gotos;
        goto_anchor  = &statement->gotos.next;

        expect(';', end_error);

end_error:
        return statement;
}

/**
 * Parse a continue statement.
 */
static statement_t *parse_continue(void)
{
        if (current_loop == NULL) {
                errorf(HERE, "continue statement not within loop");
        }

        statement_t *statement = allocate_statement_zero(STATEMENT_CONTINUE);

        eat(T_continue);
        expect(';', end_error);

end_error:
        return statement;
}

/**
 * Parse a break statement.
 */
static statement_t *parse_break(void)
{
        if (current_switch == NULL && current_loop == NULL) {
                errorf(HERE, "break statement not within loop or switch");
        }

        statement_t *statement = allocate_statement_zero(STATEMENT_BREAK);

        eat(T_break);
        expect(';', end_error);

end_error:
        return statement;
}

/**
 * Parse a __leave statement.
 */
static statement_t *parse_leave_statement(void)
{
        if (current_try == NULL) {
                errorf(HERE, "__leave statement not within __try");
        }

        statement_t *statement = allocate_statement_zero(STATEMENT_LEAVE);

        eat(T___leave);
        expect(';', end_error);

end_error:
        return statement;
}

/**
 * Check if a given entity represents a local variable.
 */
static bool is_local_variable(const entity_t *entity)
{
        if (entity->kind != ENTITY_VARIABLE)
                return false;

        switch ((storage_class_tag_t) entity->declaration.storage_class) {
        case STORAGE_CLASS_AUTO:
        case STORAGE_CLASS_REGISTER: {
                const type_t *type = skip_typeref(entity->declaration.type);
                if (is_type_function(type)) {
                        return false;
                } else {
                        return true;
                }
        }
        default:
                return false;
        }
}

/**
 * Check if a given expression represents a local variable.
 */
static bool expression_is_local_variable(const expression_t *expression)
{
        if (expression->base.kind != EXPR_REFERENCE) {
                return false;
        }
        const entity_t *entity = expression->reference.entity;
        return is_local_variable(entity);
}

/**
 * Check if a given expression represents a local variable and
 * return its declaration then, else return NULL.
 */
entity_t *expression_is_variable(const expression_t *expression)
{
        if (expression->base.kind != EXPR_REFERENCE) {
                return NULL;
        }
        entity_t *entity = expression->reference.entity;
        if (entity->kind != ENTITY_VARIABLE)
                return NULL;

        return entity;
}

/**
 * Parse a return statement.
 */
static statement_t *parse_return(void)
{
        eat(T_return);

        statement_t *statement = allocate_statement_zero(STATEMENT_RETURN);

        expression_t *return_value = NULL;
        if (token.type != ';') {
                return_value = parse_expression();
                mark_vars_read(return_value, NULL);
        }

        const type_t *const func_type = skip_typeref(current_function->base.type);
        assert(is_type_function(func_type));
        type_t *const return_type = skip_typeref(func_type->function.return_type);

        source_position_t const *const pos = &statement->base.source_position;
        if (return_value != NULL) {
                type_t *return_value_type = skip_typeref(return_value->base.type);

                if (is_type_atomic(return_type, ATOMIC_TYPE_VOID)) {
                        if (is_type_atomic(return_value_type, ATOMIC_TYPE_VOID)) {
                                /* ISO/IEC 14882:1998(E) §6.6.3:2 */
                                /* Only warn in C mode, because GCC does the same */
                                if (c_mode & _CXX || strict_mode) {
                                        errorf(pos,
                                                        "'return' with a value, in function returning 'void'");
                                } else if (warning.other) {
                                        warningf(pos,
                                                        "'return' with a value, in function returning 'void'");
                                }
                        } else if (!(c_mode & _CXX)) { /* ISO/IEC 14882:1998(E) §6.6.3:3 */
                                /* Only warn in C mode, because GCC does the same */
                                if (strict_mode) {
                                        errorf(pos,
                                                        "'return' with expression in function returning 'void'");
                                } else if (warning.other) {
                                        warningf(pos,
                                                        "'return' with expression in function returning 'void'");
                                }
                        }
                } else {
                        assign_error_t error = semantic_assign(return_type, return_value);
                        report_assign_error(error, return_type, return_value, "'return'",
                                        pos);
                }
                return_value = create_implicit_cast(return_value, return_type);
                /* check for returning address of a local var */
                if (warning.other && return_value != NULL
                                && return_value->base.kind == EXPR_UNARY_TAKE_ADDRESS) {
                        const expression_t *expression = return_value->unary.value;
                        if (expression_is_local_variable(expression)) {
                                warningf(pos, "function returns address of local variable");
                        }
                }
        } else if (warning.other && !is_type_atomic(return_type, ATOMIC_TYPE_VOID)) {
                /* ISO/IEC 14882:1998(E) §6.6.3:3 */
                if (c_mode & _CXX || strict_mode) {
                        errorf(pos,
                                        "'return' without value, in function returning non-void");
                } else {
                        warningf(pos,
                                        "'return' without value, in function returning non-void");
                }
        }
        statement->returns.value = return_value;

        expect(';', end_error);

end_error:
        return statement;
}

/**
 * Parse a declaration statement.
 */
static statement_t *parse_declaration_statement(void)
{
        statement_t *statement = allocate_statement_zero(STATEMENT_DECLARATION);

        entity_t *before = current_scope->last_entity;
        if (GNU_MODE) {
                parse_external_declaration();
        } else {
                parse_declaration(record_entity, DECL_FLAGS_NONE);
        }

        declaration_statement_t *const decl  = &statement->declaration;
        entity_t                *const begin =
                before != NULL ? before->base.next : current_scope->entities;
        decl->declarations_begin = begin;
        decl->declarations_end   = begin != NULL ? current_scope->last_entity : NULL;

        return statement;
}

/**
 * Parse an expression statement, ie. expr ';'.
 */
static statement_t *parse_expression_statement(void)
{
        statement_t *statement = allocate_statement_zero(STATEMENT_EXPRESSION);

        expression_t *const expr         = parse_expression();
        statement->expression.expression = expr;
        mark_vars_read(expr, ENT_ANY);

        expect(';', end_error);

end_error:
        return statement;
}

/**
 * Parse a microsoft __try { } __finally { } or
 * __try{ } __except() { }
 */
static statement_t *parse_ms_try_statment(void)
{
        statement_t *statement = allocate_statement_zero(STATEMENT_MS_TRY);
        eat(T___try);

        PUSH_PARENT(statement);

        ms_try_statement_t *rem = current_try;
        current_try = &statement->ms_try;
        statement->ms_try.try_statement = parse_compound_statement(false);
        current_try = rem;

        POP_PARENT;

        if (next_if(T___except)) {
                expect('(', end_error);
                add_anchor_token(')');
                expression_t *const expr = parse_expression();
                mark_vars_read(expr, NULL);
                type_t       *      type = skip_typeref(expr->base.type);
                if (is_type_integer(type)) {
                        type = promote_integer(type);
                } else if (is_type_valid(type)) {
                        errorf(&expr->base.source_position,
                               "__expect expression is not an integer, but '%T'", type);
                        type = type_error_type;
                }
                statement->ms_try.except_expression = create_implicit_cast(expr, type);
                rem_anchor_token(')');
                expect(')', end_error);
                statement->ms_try.final_statement = parse_compound_statement(false);
        } else if (next_if(T__finally)) {
                statement->ms_try.final_statement = parse_compound_statement(false);
        } else {
                parse_error_expected("while parsing __try statement", T___except, T___finally, NULL);
                return create_invalid_statement();
        }
        return statement;
end_error:
        return create_invalid_statement();
}

static statement_t *parse_empty_statement(void)
{
        if (warning.empty_statement) {
                warningf(HERE, "statement is empty");
        }
        statement_t *const statement = create_empty_statement();
        eat(';');
        return statement;
}

static statement_t *parse_local_label_declaration(void)
{
        statement_t *statement = allocate_statement_zero(STATEMENT_DECLARATION);

        eat(T___label__);

        entity_t *begin   = NULL;
        entity_t *end     = NULL;
        entity_t **anchor = &begin;
        do {
                if (token.type != T_IDENTIFIER) {
                        parse_error_expected("while parsing local label declaration",
                                T_IDENTIFIER, NULL);
                        goto end_error;
                }
                symbol_t *symbol = token.symbol;
                entity_t *entity = get_entity(symbol, NAMESPACE_LABEL);
                if (entity != NULL && entity->base.parent_scope == current_scope) {
                        errorf(HERE, "multiple definitions of '__label__ %Y' (previous definition %P)",
                               symbol, &entity->base.source_position);
                } else {
                        entity = allocate_entity_zero(ENTITY_LOCAL_LABEL);

                        entity->base.parent_scope    = current_scope;
                        entity->base.namespc         = NAMESPACE_LABEL;
                        entity->base.source_position = token.source_position;
                        entity->base.symbol          = symbol;

                        *anchor = entity;
                        anchor  = &entity->base.next;
                        end     = entity;

                        environment_push(entity);
                }
                next_token();
        } while (next_if(','));
        expect(';', end_error);
end_error:
        statement->declaration.declarations_begin = begin;
        statement->declaration.declarations_end   = end;
        return statement;
}

static void parse_namespace_definition(void)
{
        eat(T_namespace);

        entity_t *entity = NULL;
        symbol_t *symbol = NULL;

        if (token.type == T_IDENTIFIER) {
                symbol = token.symbol;
                next_token();

                entity = get_entity(symbol, NAMESPACE_NORMAL);
                if (entity != NULL
                                && entity->kind != ENTITY_NAMESPACE
                                && entity->base.parent_scope == current_scope) {
                        if (!is_error_entity(entity)) {
                                error_redefined_as_different_kind(&token.source_position,
                                                entity, ENTITY_NAMESPACE);
                        }
                        entity = NULL;
                }
        }

        if (entity == NULL) {
                entity                       = allocate_entity_zero(ENTITY_NAMESPACE);
                entity->base.symbol          = symbol;
                entity->base.source_position = token.source_position;
                entity->base.namespc         = NAMESPACE_NORMAL;
                entity->base.parent_scope    = current_scope;
        }

        if (token.type == '=') {
                /* TODO: parse namespace alias */
                panic("namespace alias definition not supported yet");
        }

        environment_push(entity);
        append_entity(current_scope, entity);

        size_t const  top       = environment_top();
        scope_t      *old_scope = scope_push(&entity->namespacee.members);

        entity_t     *old_current_entity = current_entity;
        current_entity = entity;

        expect('{', end_error);
        parse_externals();
        expect('}', end_error);

end_error:
        assert(current_scope == &entity->namespacee.members);
        assert(current_entity == entity);
        current_entity = old_current_entity;
        scope_pop(old_scope);
        environment_pop_to(top);
}

/**
 * Parse a statement.
 * There's also parse_statement() which additionally checks for
 * "statement has no effect" warnings
 */
static statement_t *intern_parse_statement(void)
{
        statement_t *statement = NULL;

        /* declaration or statement */
        add_anchor_token(';');
        switch (token.type) {
        case T_IDENTIFIER: {
                token_type_t la1_type = (token_type_t)look_ahead(1)->type;
                if (la1_type == ':') {
                        statement = parse_label_statement();
                } else if (is_typedef_symbol(token.symbol)) {
                        statement = parse_declaration_statement();
                } else {
                        /* it's an identifier, the grammar says this must be an
                         * expression statement. However it is common that users mistype
                         * declaration types, so we guess a bit here to improve robustness
                         * for incorrect programs */
                        switch (la1_type) {
                        case '&':
                        case '*':
                                if (get_entity(token.symbol, NAMESPACE_NORMAL) != NULL) {
                        default:
                                        statement = parse_expression_statement();
                                } else {
                        DECLARATION_START
                        case T_IDENTIFIER:
                                        statement = parse_declaration_statement();
                                }
                                break;
                        }
                }
                break;
        }

        case T___extension__:
                /* This can be a prefix to a declaration or an expression statement.
                 * We simply eat it now and parse the rest with tail recursion. */
                while (next_if(T___extension__)) {}
                bool old_gcc_extension = in_gcc_extension;
                in_gcc_extension       = true;
                statement = intern_parse_statement();
                in_gcc_extension = old_gcc_extension;
                break;

        DECLARATION_START
                statement = parse_declaration_statement();
                break;

        case T___label__:
                statement = parse_local_label_declaration();
                break;

        case ';':         statement = parse_empty_statement();         break;
        case '{':         statement = parse_compound_statement(false); break;
        case T___leave:   statement = parse_leave_statement();         break;
        case T___try:     statement = parse_ms_try_statment();         break;
        case T_asm:       statement = parse_asm_statement();           break;
        case T_break:     statement = parse_break();                   break;
        case T_case:      statement = parse_case_statement();          break;
        case T_continue:  statement = parse_continue();                break;
        case T_default:   statement = parse_default_statement();       break;
        case T_do:        statement = parse_do();                      break;
        case T_for:       statement = parse_for();                     break;
        case T_goto:      statement = parse_goto();                    break;
        case T_if:        statement = parse_if();                      break;
        case T_return:    statement = parse_return();                  break;
        case T_switch:    statement = parse_switch();                  break;
        case T_while:     statement = parse_while();                   break;

        EXPRESSION_START
                statement = parse_expression_statement();
                break;

        default:
                errorf(HERE, "unexpected token %K while parsing statement", &token);
                statement = create_invalid_statement();
                if (!at_anchor())
                        next_token();
                break;
        }
        rem_anchor_token(';');

        assert(statement != NULL
                        && statement->base.source_position.input_name != NULL);

        return statement;
}

/**
 * parse a statement and emits "statement has no effect" warning if needed
 * (This is really a wrapper around intern_parse_statement with check for 1
 *  single warning. It is needed, because for statement expressions we have
 *  to avoid the warning on the last statement)
 */
static statement_t *parse_statement(void)
{
        statement_t *statement = intern_parse_statement();

        if (statement->kind == STATEMENT_EXPRESSION && warning.unused_value) {
                expression_t *expression = statement->expression.expression;
                if (!expression_has_effect(expression)) {
                        warningf(&expression->base.source_position,
                                        "statement has no effect");
                }
        }

        return statement;
}

/**
 * Parse a compound statement.
 */
static statement_t *parse_compound_statement(bool inside_expression_statement)
{
        statement_t *statement = allocate_statement_zero(STATEMENT_COMPOUND);

        PUSH_PARENT(statement);

        eat('{');
        add_anchor_token('}');
        /* tokens, which can start a statement */
        /* TODO MS, __builtin_FOO */
        add_anchor_token('!');
        add_anchor_token('&');
        add_anchor_token('(');
        add_anchor_token('*');
        add_anchor_token('+');
        add_anchor_token('-');
        add_anchor_token('{');
        add_anchor_token('~');
        add_anchor_token(T_CHARACTER_CONSTANT);
        add_anchor_token(T_COLONCOLON);
        add_anchor_token(T_FLOATINGPOINT);
        add_anchor_token(T_IDENTIFIER);
        add_anchor_token(T_INTEGER);
        add_anchor_token(T_MINUSMINUS);
        add_anchor_token(T_PLUSPLUS);
        add_anchor_token(T_STRING_LITERAL);
        add_anchor_token(T_WIDE_CHARACTER_CONSTANT);
        add_anchor_token(T_WIDE_STRING_LITERAL);
        add_anchor_token(T__Bool);
        add_anchor_token(T__Complex);
        add_anchor_token(T__Imaginary);
        add_anchor_token(T___FUNCTION__);
        add_anchor_token(T___PRETTY_FUNCTION__);
        add_anchor_token(T___alignof__);
        add_anchor_token(T___attribute__);
        add_anchor_token(T___builtin_va_start);
        add_anchor_token(T___extension__);
        add_anchor_token(T___func__);
        add_anchor_token(T___imag__);
        add_anchor_token(T___label__);
        add_anchor_token(T___real__);
        add_anchor_token(T___thread);
        add_anchor_token(T_asm);
        add_anchor_token(T_auto);
        add_anchor_token(T_bool);
        add_anchor_token(T_break);
        add_anchor_token(T_case);
        add_anchor_token(T_char);
        add_anchor_token(T_class);
        add_anchor_token(T_const);
        add_anchor_token(T_const_cast);
        add_anchor_token(T_continue);
        add_anchor_token(T_default);
        add_anchor_token(T_delete);
        add_anchor_token(T_double);
        add_anchor_token(T_do);
        add_anchor_token(T_dynamic_cast);
        add_anchor_token(T_enum);
        add_anchor_token(T_extern);
        add_anchor_token(T_false);
        add_anchor_token(T_float);
        add_anchor_token(T_for);
        add_anchor_token(T_goto);
        add_anchor_token(T_if);
        add_anchor_token(T_inline);
        add_anchor_token(T_int);
        add_anchor_token(T_long);
        add_anchor_token(T_new);
        add_anchor_token(T_operator);
        add_anchor_token(T_register);
        add_anchor_token(T_reinterpret_cast);
        add_anchor_token(T_restrict);
        add_anchor_token(T_return);
        add_anchor_token(T_short);
        add_anchor_token(T_signed);
        add_anchor_token(T_sizeof);
        add_anchor_token(T_static);
        add_anchor_token(T_static_cast);
        add_anchor_token(T_struct);
        add_anchor_token(T_switch);
        add_anchor_token(T_template);
        add_anchor_token(T_this);
        add_anchor_token(T_throw);
        add_anchor_token(T_true);
        add_anchor_token(T_try);
        add_anchor_token(T_typedef);
        add_anchor_token(T_typeid);
        add_anchor_token(T_typename);
        add_anchor_token(T_typeof);
        add_anchor_token(T_union);
        add_anchor_token(T_unsigned);
        add_anchor_token(T_using);
        add_anchor_token(T_void);
        add_anchor_token(T_volatile);
        add_anchor_token(T_wchar_t);
        add_anchor_token(T_while);

        size_t const  top       = environment_top();
        scope_t      *old_scope = scope_push(&statement->compound.scope);

        statement_t **anchor            = &statement->compound.statements;
        bool          only_decls_so_far = true;
        while (token.type != '}') {
                if (token.type == T_EOF) {
                        errorf(&statement->base.source_position,
                               "EOF while parsing compound statement");
                        break;
                }
                statement_t *sub_statement = intern_parse_statement();
                if (is_invalid_statement(sub_statement)) {
                        /* an error occurred. if we are at an anchor, return */
                        if (at_anchor())
                                goto end_error;
                        continue;
                }

                if (warning.declaration_after_statement) {
                        if (sub_statement->kind != STATEMENT_DECLARATION) {
                                only_decls_so_far = false;
                        } else if (!only_decls_so_far) {
                                warningf(&sub_statement->base.source_position,
                                         "ISO C90 forbids mixed declarations and code");
                        }
                }

                *anchor = sub_statement;

                while (sub_statement->base.next != NULL)
                        sub_statement = sub_statement->base.next;

                anchor = &sub_statement->base.next;
        }
        next_token();

        /* look over all statements again to produce no effect warnings */
        if (warning.unused_value) {
                statement_t *sub_statement = statement->compound.statements;
                for (; sub_statement != NULL; sub_statement = sub_statement->base.next) {
                        if (sub_statement->kind != STATEMENT_EXPRESSION)
                                continue;
                        /* don't emit a warning for the last expression in an expression
                         * statement as it has always an effect */
                        if (inside_expression_statement && sub_statement->base.next == NULL)
                                continue;

                        expression_t *expression = sub_statement->expression.expression;
                        if (!expression_has_effect(expression)) {
                                warningf(&expression->base.source_position,
                                         "statement has no effect");
                        }
                }
        }

end_error:
        rem_anchor_token(T_while);
        rem_anchor_token(T_wchar_t);
        rem_anchor_token(T_volatile);
        rem_anchor_token(T_void);
        rem_anchor_token(T_using);
        rem_anchor_token(T_unsigned);
        rem_anchor_token(T_union);
        rem_anchor_token(T_typeof);
        rem_anchor_token(T_typename);
        rem_anchor_token(T_typeid);
        rem_anchor_token(T_typedef);
        rem_anchor_token(T_try);
        rem_anchor_token(T_true);
        rem_anchor_token(T_throw);
        rem_anchor_token(T_this);
        rem_anchor_token(T_template);
        rem_anchor_token(T_switch);
        rem_anchor_token(T_struct);
        rem_anchor_token(T_static_cast);
        rem_anchor_token(T_static);
        rem_anchor_token(T_sizeof);
        rem_anchor_token(T_signed);
        rem_anchor_token(T_short);
        rem_anchor_token(T_return);
        rem_anchor_token(T_restrict);
        rem_anchor_token(T_reinterpret_cast);
        rem_anchor_token(T_register);
        rem_anchor_token(T_operator);
        rem_anchor_token(T_new);
        rem_anchor_token(T_long);
        rem_anchor_token(T_int);
        rem_anchor_token(T_inline);
        rem_anchor_token(T_if);
        rem_anchor_token(T_goto);
        rem_anchor_token(T_for);
        rem_anchor_token(T_float);
        rem_anchor_token(T_false);
        rem_anchor_token(T_extern);
        rem_anchor_token(T_enum);
        rem_anchor_token(T_dynamic_cast);
        rem_anchor_token(T_do);
        rem_anchor_token(T_double);
        rem_anchor_token(T_delete);
        rem_anchor_token(T_default);
        rem_anchor_token(T_continue);
        rem_anchor_token(T_const_cast);
        rem_anchor_token(T_const);
        rem_anchor_token(T_class);
        rem_anchor_token(T_char);
        rem_anchor_token(T_case);
        rem_anchor_token(T_break);
        rem_anchor_token(T_bool);
        rem_anchor_token(T_auto);
        rem_anchor_token(T_asm);
        rem_anchor_token(T___thread);
        rem_anchor_token(T___real__);
        rem_anchor_token(T___label__);
        rem_anchor_token(T___imag__);
        rem_anchor_token(T___func__);
        rem_anchor_token(T___extension__);
        rem_anchor_token(T___builtin_va_start);
        rem_anchor_token(T___attribute__);
        rem_anchor_token(T___alignof__);
        rem_anchor_token(T___PRETTY_FUNCTION__);
        rem_anchor_token(T___FUNCTION__);
        rem_anchor_token(T__Imaginary);
        rem_anchor_token(T__Complex);
        rem_anchor_token(T__Bool);
        rem_anchor_token(T_WIDE_STRING_LITERAL);
        rem_anchor_token(T_WIDE_CHARACTER_CONSTANT);
        rem_anchor_token(T_STRING_LITERAL);
        rem_anchor_token(T_PLUSPLUS);
        rem_anchor_token(T_MINUSMINUS);
        rem_anchor_token(T_INTEGER);
        rem_anchor_token(T_IDENTIFIER);
        rem_anchor_token(T_FLOATINGPOINT);
        rem_anchor_token(T_COLONCOLON);
        rem_anchor_token(T_CHARACTER_CONSTANT);
        rem_anchor_token('~');
        rem_anchor_token('{');
        rem_anchor_token('-');
        rem_anchor_token('+');
        rem_anchor_token('*');
        rem_anchor_token('(');
        rem_anchor_token('&');
        rem_anchor_token('!');
        rem_anchor_token('}');
        assert(current_scope == &statement->compound.scope);
        scope_pop(old_scope);
        environment_pop_to(top);

        POP_PARENT;
        return statement;
}

/**
 * Check for unused global static functions and variables
 */
static void check_unused_globals(void)
{
        if (!warning.unused_function && !warning.unused_variable)
                return;

        for (const entity_t *entity = file_scope->entities; entity != NULL;
             entity = entity->base.next) {
                if (!is_declaration(entity))
                        continue;

                const declaration_t *declaration = &entity->declaration;
                if (declaration->used                  ||
                    declaration->modifiers & DM_UNUSED ||
                    declaration->modifiers & DM_USED   ||
                    declaration->storage_class != STORAGE_CLASS_STATIC)
                        continue;

                type_t *const type = declaration->type;
                const char *s;
                if (entity->kind == ENTITY_FUNCTION) {
                        /* inhibit warning for static inline functions */
                        if (entity->function.is_inline)
                                continue;

                        s = entity->function.statement != NULL ? "defined" : "declared";
                } else {
                        s = "defined";
                }

                warningf(&declaration->base.source_position, "'%#T' %s but not used",
                        type, declaration->base.symbol, s);
        }
}

static void parse_global_asm(void)
{
        statement_t *statement = allocate_statement_zero(STATEMENT_ASM);

        eat(T_asm);
        expect('(', end_error);

        statement->asms.asm_text = parse_string_literals();
        statement->base.next     = unit->global_asm;
        unit->global_asm         = statement;

        expect(')', end_error);
        expect(';', end_error);

end_error:;
}

static void parse_linkage_specification(void)
{
        eat(T_extern);
        assert(token.type == T_STRING_LITERAL);

        const char *linkage = parse_string_literals().begin;

        linkage_kind_t old_linkage = current_linkage;
        linkage_kind_t new_linkage;
        if (strcmp(linkage, "C") == 0) {
                new_linkage = LINKAGE_C;
        } else if (strcmp(linkage, "C++") == 0) {
                new_linkage = LINKAGE_CXX;
        } else {
                errorf(HERE, "linkage string \"%s\" not recognized", linkage);
                new_linkage = LINKAGE_INVALID;
        }
        current_linkage = new_linkage;

        if (next_if('{')) {
                parse_externals();
                expect('}', end_error);
        } else {
                parse_external();
        }

end_error:
        assert(current_linkage == new_linkage);
        current_linkage = old_linkage;
}

static void parse_external(void)
{
        switch (token.type) {
                DECLARATION_START_NO_EXTERN
                case T_IDENTIFIER:
                case T___extension__:
                /* tokens below are for implicit int */
                case '&': /* & x; -> int& x; (and error later, because C++ has no
                             implicit int) */
                case '*': /* * x; -> int* x; */
                case '(': /* (x); -> int (x); */
                        parse_external_declaration();
                        return;

                case T_extern:
                        if (look_ahead(1)->type == T_STRING_LITERAL) {
                                parse_linkage_specification();
                        } else {
                                parse_external_declaration();
                        }
                        return;

                case T_asm:
                        parse_global_asm();
                        return;

                case T_namespace:
                        parse_namespace_definition();
                        return;

                case ';':
                        if (!strict_mode) {
                                if (warning.other)
                                        warningf(HERE, "stray ';' outside of function");
                                next_token();
                                return;
                        }
                        /* FALLTHROUGH */

                default:
                        errorf(HERE, "stray %K outside of function", &token);
                        if (token.type == '(' || token.type == '{' || token.type == '[')
                                eat_until_matching_token(token.type);
                        next_token();
                        return;
        }
}

static void parse_externals(void)
{
        add_anchor_token('}');
        add_anchor_token(T_EOF);

#ifndef NDEBUG
        unsigned char token_anchor_copy[T_LAST_TOKEN];
        memcpy(token_anchor_copy, token_anchor_set, sizeof(token_anchor_copy));
#endif

        while (token.type != T_EOF && token.type != '}') {
#ifndef NDEBUG
                bool anchor_leak = false;
                for (int i = 0; i != T_LAST_TOKEN; ++i) {
                        unsigned char count = token_anchor_set[i] - token_anchor_copy[i];
                        if (count != 0) {
                                errorf(HERE, "Leaked anchor token %k %d times", i, count);
                                anchor_leak = true;
                        }
                }
                if (in_gcc_extension) {
                        errorf(HERE, "Leaked __extension__");
                        anchor_leak = true;
                }

                if (anchor_leak)
                        abort();
#endif

                parse_external();
        }

        rem_anchor_token(T_EOF);
        rem_anchor_token('}');
}

/**
 * Parse a translation unit.
 */
static void parse_translation_unit(void)
{
        add_anchor_token(T_EOF);

        while (true) {
                parse_externals();

                if (token.type == T_EOF)
                        break;

                errorf(HERE, "stray %K outside of function", &token);
                if (token.type == '(' || token.type == '{' || token.type == '[')
                        eat_until_matching_token(token.type);
                next_token();
        }
}

/**
 * Parse the input.
 *
 * @return  the translation unit or NULL if errors occurred.
 */
void start_parsing(void)
{
        environment_stack = NEW_ARR_F(stack_entry_t, 0);
        label_stack       = NEW_ARR_F(stack_entry_t, 0);
        diagnostic_count  = 0;
        error_count       = 0;
        warning_count     = 0;

        print_to_file(stderr);

        assert(unit == NULL);
        unit = allocate_ast_zero(sizeof(unit[0]));

        assert(file_scope == NULL);
        file_scope = &unit->scope;

        assert(current_scope == NULL);
        scope_push(&unit->scope);

        create_gnu_builtins();
        if (c_mode & _MS)
                create_microsoft_intrinsics();
}

translation_unit_t *finish_parsing(void)
{
        assert(current_scope == &unit->scope);
        scope_pop(NULL);

        assert(file_scope == &unit->scope);
        check_unused_globals();
        file_scope = NULL;

        DEL_ARR_F(environment_stack);
        DEL_ARR_F(label_stack);

        translation_unit_t *result = unit;
        unit = NULL;
        return result;
}

/* §6.9.2:2 and §6.9.2:5: At the end of the translation incomplete arrays
 * are given length one. */
static void complete_incomplete_arrays(void)
{
        size_t n = ARR_LEN(incomplete_arrays);
        for (size_t i = 0; i != n; ++i) {
                declaration_t *const decl      = incomplete_arrays[i];
                type_t        *const orig_type = decl->type;
                type_t        *const type      = skip_typeref(orig_type);

                if (!is_type_incomplete(type))
                        continue;

                if (warning.other) {
                        warningf(&decl->base.source_position,
                                        "array '%#T' assumed to have one element",
                                        orig_type, decl->base.symbol);
                }

                type_t *const new_type = duplicate_type(type);
                new_type->array.size_constant     = true;
                new_type->array.has_implicit_size = true;
                new_type->array.size              = 1;

                type_t *const result = identify_new_type(new_type);

                decl->type = result;
        }
}

void prepare_main_collect2(entity_t *entity)
{
        // create call to __main
        symbol_t *symbol         = symbol_table_insert("__main");
        entity_t *subsubmain_ent
                = create_implicit_function(symbol, &builtin_source_position);

        expression_t *ref         = allocate_expression_zero(EXPR_REFERENCE);
        type_t       *ftype       = subsubmain_ent->declaration.type;
        ref->base.source_position = builtin_source_position;
        ref->base.type            = make_pointer_type(ftype, TYPE_QUALIFIER_NONE);
        ref->reference.entity     = subsubmain_ent;

        expression_t *call = allocate_expression_zero(EXPR_CALL);
        call->base.source_position = builtin_source_position;
        call->base.type            = type_void;
        call->call.function        = ref;

        statement_t *expr_statement = allocate_statement_zero(STATEMENT_EXPRESSION);
        expr_statement->base.source_position  = builtin_source_position;
        expr_statement->expression.expression = call;

        statement_t *statement = entity->function.statement;
        assert(statement->kind == STATEMENT_COMPOUND);
        compound_statement_t *compounds = &statement->compound;

        expr_statement->base.next = compounds->statements;
        compounds->statements     = expr_statement;
}

void parse(void)
{
        lookahead_bufpos = 0;
        for (int i = 0; i < MAX_LOOKAHEAD + 2; ++i) {
                next_token();
        }
        current_linkage   = c_mode & _CXX ? LINKAGE_CXX : LINKAGE_C;
        incomplete_arrays = NEW_ARR_F(declaration_t*, 0);
        parse_translation_unit();
        complete_incomplete_arrays();
        DEL_ARR_F(incomplete_arrays);
        incomplete_arrays = NULL;
}

/**
 * Initialize the parser.
 */
void init_parser(void)
{
        sym_anonymous = symbol_table_insert("<anonymous>");

        memset(token_anchor_set, 0, sizeof(token_anchor_set));

        init_expression_parsers();
        obstack_init(&temp_obst);

        symbol_t *const va_list_sym = symbol_table_insert("__builtin_va_list");
        type_valist = create_builtin_type(va_list_sym, type_void_ptr);
}

/**
 * Terminate the parser.
 */
void exit_parser(void)
{
        obstack_free(&temp_obst, NULL);
}