Slightly simplify stack_pop_to().

[cparser] / parser.c

/*
 * This file is part of cparser.
 * Copyright (C) 2007-2008 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 "lang_features.h"
#include "warning.h"
#include "adt/bitfiddle.h"
#include "adt/error.h"
#include "adt/array.h"

/** if wchar_t is equal to unsigned short. */
bool opt_short_wchar_t =
#ifdef _WIN32
        true;
#else
        false;
#endif

//#define PRINT_TOKENS
#define MAX_LOOKAHEAD 2

typedef struct {
        declaration_t *old_declaration;
        symbol_t      *symbol;
        unsigned short namespc;
} stack_entry_t;

typedef struct argument_list_t argument_list_t;
struct argument_list_t {
        long              argument;
        argument_list_t  *next;
};

typedef struct gnu_attribute_t gnu_attribute_t;
struct gnu_attribute_t {
        gnu_attribute_kind_t kind;           /**< The kind of the GNU attribute. */
        gnu_attribute_t     *next;
        bool                 invalid;        /**< Set if this attribute had argument errors, */
        bool                 have_arguments; /**< True, if this attribute has arguments. */
        union {
                size_t              value;
                string_t            string;
                atomic_type_kind_t  akind;
                long                argument;  /**< Single argument. */
                argument_list_t    *arguments; /**< List of argument expressions. */
        } u;
};

typedef struct declaration_specifiers_t  declaration_specifiers_t;
struct declaration_specifiers_t {
        source_position_t  source_position;
        unsigned char      declared_storage_class;
        unsigned char      alignment;         /**< Alignment, 0 if not set. */
        unsigned int       is_inline : 1;
        unsigned int       deprecated : 1;
        decl_modifiers_t   modifiers;         /**< declaration modifiers */
        gnu_attribute_t   *gnu_attributes;    /**< list of GNU attributes */
        const char        *deprecated_string; /**< can be set if declaration was marked deprecated. */
        symbol_t          *get_property_sym;  /**< the name of the get property if set. */
        symbol_t          *put_property_sym;  /**< the name of the put property if set. */
        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. */
        declaration_t *declaration; /**< the declaration that is initialized if any */
        bool           must_be_constant;
} parse_initializer_env_t;

typedef declaration_t* (*parsed_declaration_func) (declaration_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 int                 lookahead_bufpos;
static stack_entry_t      *environment_stack = NULL;
static stack_entry_t      *label_stack       = NULL;
static stack_entry_t      *local_label_stack = NULL;
/** The global file scope. */
static scope_t            *global_scope      = NULL;
/** The current scope. */
static scope_t            *scope             = NULL;
static declaration_t      *last_declaration  = NULL;
/** Point to the current function declaration if inside a function. */
static declaration_t      *current_function  = NULL;
static declaration_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 goto_statement_t   *goto_first        = NULL;
static goto_statement_t   *goto_last         = NULL;
static label_statement_t  *label_first       = NULL;
static label_statement_t  *label_last        = 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 in we are in a __extension__ context. */
static bool                in_gcc_extension  = false;
static struct obstack      temp_obst;


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

static source_position_t null_position = { NULL, 0 };

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

/* symbols for Microsoft extended-decl-modifier */
static const symbol_t *sym_align      = NULL;
static const symbol_t *sym_allocate   = NULL;
static const symbol_t *sym_dllimport  = NULL;
static const symbol_t *sym_dllexport  = NULL;
static const symbol_t *sym_naked      = NULL;
static const symbol_t *sym_noinline   = NULL;
static const symbol_t *sym_noreturn   = NULL;
static const symbol_t *sym_nothrow    = NULL;
static const symbol_t *sym_novtable   = NULL;
static const symbol_t *sym_property   = NULL;
static const symbol_t *sym_get        = NULL;
static const symbol_t *sym_put        = NULL;
static const symbol_t *sym_selectany  = NULL;
static const symbol_t *sym_thread     = NULL;
static const symbol_t *sym_uuid       = NULL;
static const symbol_t *sym_deprecated = NULL;
static const symbol_t *sym_restrict   = NULL;
static const symbol_t *sym_noalias    = 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 type_t *type_valist;

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

static expression_t *parse_sub_expression(unsigned precedence);
static expression_t *parse_expression(void);
static type_t       *parse_typename(void);

static void parse_compound_type_entries(declaration_t *compound_declaration);
static declaration_t *parse_declarator(
                const declaration_specifiers_t *specifiers, bool may_be_abstract);
static declaration_t *record_declaration(declaration_t *declaration, bool is_definition);

static void semantic_comparison(binary_expression_t *expression);

#define STORAGE_CLASSES     \
        case T_typedef:         \
        case T_extern:          \
        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__:

#ifdef PROVIDE_COMPLEX
#define COMPLEX_SPECIFIERS  \
        case T__Complex:
#define IMAGINARY_SPECIFIERS \
        case T__Imaginary:
#else
#define COMPLEX_SPECIFIERS
#define IMAGINARY_SPECIFIERS
#endif

#define TYPE_SPECIFIERS       \
        case T_void:              \
        case T_char:              \
        case T_short:             \
        case T_int:               \
        case T_long:              \
        case T_float:             \
        case T_double:            \
        case T_signed:            \
        case T_unsigned:          \
        case T__Bool:             \
        case T_struct:            \
        case T_union:             \
        case T_enum:              \
        case T___typeof__:        \
        case T___builtin_va_list: \
        case T__declspec:         \
        COMPLEX_SPECIFIERS        \
        IMAGINARY_SPECIFIERS

#define DECLARATION_START   \
        STORAGE_CLASSES         \
        TYPE_QUALIFIERS         \
        TYPE_SPECIFIERS

#define TYPENAME_START      \
        TYPE_QUALIFIERS         \
        TYPE_SPECIFIERS

/**
 * Allocate an AST node with given size and
 * initialize all fields with zero.
 */
static void *allocate_ast_zero(size_t size)
{
        void *res = allocate_ast(size);
        memset(res, 0, size);
        return res;
}

static declaration_t *allocate_declaration_zero(void)
{
        declaration_t *declaration = allocate_ast_zero(sizeof(declaration_t));
        declaration->type      = type_error_type;
        declaration->alignment = 0;
        return declaration;
}

/**
 * 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 <= sizeof(sizes) / sizeof(sizes[0]));
        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_CONST]                   = sizeof(const_expression_t),
                [EXPR_CHARACTER_CONSTANT]      = sizeof(const_expression_t),
                [EXPR_WIDE_CHARACTER_CONSTANT] = sizeof(const_expression_t),
                [EXPR_STRING_LITERAL]          = sizeof(string_literal_expression_t),
                [EXPR_WIDE_STRING_LITERAL]     = sizeof(wide_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_SYMBOL]          = sizeof(builtin_symbol_expression_t),
                [EXPR_BUILTIN_CONSTANT_P]      = sizeof(builtin_constant_expression_t),
                [EXPR_BUILTIN_PREFETCH]        = sizeof(builtin_prefetch_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_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 <= sizeof(sizes) / sizeof(sizes[0]));
        assert(sizes[kind] != 0);
        return sizes[kind];
}

/**
 * Allocate a statement node of given kind and initialize all
 * fields with zero.
 */
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;
        return res;
}

/**
 * Allocate an expression node of given kind and initialize all
 * fields with zero.
 */
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;
        return res;
}

/**
 * Creates a new invalid expression.
 */
static expression_t *create_invalid_expression(void)
{
        expression_t *expression         = allocate_expression_zero(EXPR_INVALID);
        expression->base.source_position = token.source_position;
        return expression;
}

/**
 * Creates a new invalid statement.
 */
static statement_t *create_invalid_statement(void)
{
        statement_t *statement          = allocate_statement_zero(STATEMENT_INVALID);
        statement->base.source_position = token.source_position;
        return statement;
}

/**
 * Allocate a new empty statement.
 */
static statement_t *create_empty_statement(void)
{
        statement_t *statement          = allocate_statement_zero(STATEMENT_EMPTY);
        statement->base.source_position = token.source_position;
        return statement;
}

/**
 * Returns the size of a type node.
 *
 * @param kind  the type kind
 */
static size_t get_type_struct_size(type_kind_t kind)
{
        static const size_t sizes[] = {
                [TYPE_ATOMIC]          = sizeof(atomic_type_t),
                [TYPE_COMPLEX]         = sizeof(complex_type_t),
                [TYPE_IMAGINARY]       = sizeof(imaginary_type_t),
                [TYPE_BITFIELD]        = sizeof(bitfield_type_t),
                [TYPE_COMPOUND_STRUCT] = sizeof(compound_type_t),
                [TYPE_COMPOUND_UNION]  = sizeof(compound_type_t),
                [TYPE_ENUM]            = sizeof(enum_type_t),
                [TYPE_FUNCTION]        = sizeof(function_type_t),
                [TYPE_POINTER]         = sizeof(pointer_type_t),
                [TYPE_ARRAY]           = sizeof(array_type_t),
                [TYPE_BUILTIN]         = sizeof(builtin_type_t),
                [TYPE_TYPEDEF]         = sizeof(typedef_type_t),
                [TYPE_TYPEOF]          = sizeof(typeof_type_t),
        };
        assert(sizeof(sizes) / sizeof(sizes[0]) == (int) TYPE_TYPEOF + 1);
        assert(kind <= TYPE_TYPEOF);
        assert(sizes[kind] != 0);
        return sizes[kind];
}

/**
 * Allocate a type node of given kind and initialize all
 * fields with zero.
 *
 * @param kind             type kind to allocate
 * @param source_position  the source position of the type definition
 */
static type_t *allocate_type_zero(type_kind_t kind, const source_position_t *source_position)
{
        size_t  size = get_type_struct_size(kind);
        type_t *res  = obstack_alloc(type_obst, size);
        memset(res, 0, size);

        res->base.kind            = kind;
        res->base.source_position = *source_position;
        return res;
}

/**
 * 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 < sizeof(sizes) / sizeof(*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;
}

/**
 * Free a type from the type obstack.
 */
static void free_type(void *type)
{
        obstack_free(type_obst, type);
}

/**
 * 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);
}

/**
 * Returns the index of the top element of the local label stack.
 */
static size_t local_label_top(void)
{
        return ARR_LEN(local_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
}

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

/**
 * Adds a token to the token 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];
}

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;
}

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 from the token 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];
}

static bool at_anchor(void)
{
        if (token.type < 0)
                return false;
        return token_anchor_set[token.type];
}

/**
 * Eat tokens until a matching token 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)
{
        if (token.type == T_EOF)
                return;
        while (token_anchor_set[token.type] == 0) {
                if (token.type == '(' || token.type == '{' || token.type == '[')
                        eat_until_matching_token(token.type);
                if (token.type == T_EOF)
                        break;
                next_token();
        }
}

static void eat_block(void)
{
        eat_until_matching_token('{');
        if (token.type == '}')
                next_token();
}

#define eat(token_type)  do { assert(token.type == token_type); next_token(); } while (0)

/**
 * 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 a type error.
 */
static void type_error(const char *msg, const source_position_t *source_position,
                       type_t *type)
{
        errorf(source_position, "%s, but found type '%T'", msg, type);
}

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

static void scope_push(scope_t *new_scope)
{
        if (scope != NULL) {
                scope->last_declaration = last_declaration;
                new_scope->depth        = scope->depth + 1;
        }
        new_scope->parent = scope;
        scope             = new_scope;

        last_declaration = new_scope->last_declaration;
}

static void scope_pop(void)
{
        scope->last_declaration = last_declaration;
        scope = scope->parent;
        last_declaration = scope->last_declaration;
}

/**
 * Search a symbol in a given namespace and returns its declaration or
 * NULL if this symbol was not found.
 */
static declaration_t *get_declaration(const symbol_t *const symbol,
                                      const namespace_t namespc)
{
        declaration_t *declaration = symbol->declaration;
        for( ; declaration != NULL; declaration = declaration->symbol_next) {
                if (declaration->namespc == namespc)
                        return declaration;
        }

        return NULL;
}

/**
 * pushs an environment_entry on the environment stack and links the
 * corresponding symbol to the new entry
 */
static void stack_push(stack_entry_t **stack_ptr, declaration_t *declaration)
{
        symbol_t    *symbol  = declaration->symbol;
        namespace_t  namespc = (namespace_t) declaration->namespc;

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

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

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

/**
 * Push a declaration on the environment stack.
 *
 * @param declaration  the declaration
 */
static void environment_push(declaration_t *declaration)
{
        assert(declaration->source_position.input_name != NULL);
        assert(declaration->parent_scope != NULL);
        stack_push(&environment_stack, declaration);
}

/**
 * Push a declaration on the global label stack.
 *
 * @param declaration  the declaration
 */
static void label_push(declaration_t *declaration)
{
        declaration->parent_scope = &current_function->scope;
        stack_push(&label_stack, declaration);
}

/**
 * Push a declaration of the local label stack.
 *
 * @param declaration  the declaration
 */
static void local_label_push(declaration_t *declaration)
{
        assert(declaration->parent_scope != NULL);
        stack_push(&local_label_stack, declaration);
}

/**
 * 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];

                declaration_t *old_declaration = entry->old_declaration;
                symbol_t      *symbol          = entry->symbol;
                namespace_t    namespc         = (namespace_t)entry->namespc;

                /* replace/remove declaration */
                declaration_t **anchor;
                declaration_t  *iter;
                for (anchor = &symbol->declaration;; anchor = &iter->symbol_next) {
                        iter = *anchor;
                        assert(iter != NULL);
                        /* replace an entry? */
                        if (iter->namespc == namespc)
                                break;
                }

                /* Because of scopes and appending other namespaces to the end of
                 * the list, this must hold. */
                assert((old_declaration != NULL ? old_declaration->symbol_next : NULL) == iter->symbol_next);
                *anchor = old_declaration;
        }

        ARR_SHRINKLEN(*stack_ptr, (int) 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);
}

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


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

static int get_rank(const type_t *type)
{
        assert(!is_typeref(type));
        /* The C-standard allows promoting enums to int or unsigned int (see § 7.2.2
         * and esp. footnote 108). However we can't fold constants (yet), so we
         * can't decide whether unsigned int is possible, while int always works.
         * (unsigned int would be preferable when possible... for stuff like
         *  struct { enum { ... } bla : 4; } ) */
        if (type->kind == TYPE_ENUM)
                return get_akind_rank(ATOMIC_TYPE_INT);

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

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 the 0 pointer constant.
 */
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) {
                expression = expression->unary.value;
        }

        /* TODO: not correct yet, should be any constant integer expression
         * which evaluates to 0 */
        if (expression->kind != EXPR_CONST)
                return false;

        type_t *const type = skip_typeref(expression->base.type);
        if (!is_type_integer(type))
                return false;

        return expression->conste.v.int_value == 0;
}

/**
 * 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: {
                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:
                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:
                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:
                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) ||
                                        is_type_atomic(points_to_right, ATOMIC_TYPE_VOID)) {
                                return 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)
{
        /* start parsing at precedence 7 (conditional expression) */
        expression_t *result = parse_sub_expression(7);

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

        return result;
}

static expression_t *parse_assignment_expression(void)
{
        /* start parsing at precedence 2 (assignment expression) */
        return parse_sub_expression(2);
}

static type_t *make_global_typedef(const char *name, type_t *type)
{
        symbol_t *const symbol       = symbol_table_insert(name);

        declaration_t *const declaration = allocate_declaration_zero();
        declaration->namespc                = NAMESPACE_NORMAL;
        declaration->storage_class          = STORAGE_CLASS_TYPEDEF;
        declaration->declared_storage_class = STORAGE_CLASS_TYPEDEF;
        declaration->type                   = type;
        declaration->symbol                 = symbol;
        declaration->source_position        = builtin_source_position;
        declaration->implicit               = true;

        record_declaration(declaration, false);

        type_t *typedef_type               = allocate_type_zero(TYPE_TYPEDEF, &builtin_source_position);
        typedef_type->typedeft.declaration = declaration;

        return typedef_type;
}

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

        next_token();

        while (token.type == T_STRING_LITERAL) {
                result = concat_strings(&result, &token.v.string);
                next_token();
        }

        return result;
}

static const char *const gnu_attribute_names[GNU_AK_LAST] = {
        [GNU_AK_CONST]                  = "const",
        [GNU_AK_VOLATILE]               = "volatile",
        [GNU_AK_CDECL]                  = "cdecl",
        [GNU_AK_STDCALL]                = "stdcall",
        [GNU_AK_FASTCALL]               = "fastcall",
        [GNU_AK_DEPRECATED]             = "deprecated",
        [GNU_AK_NOINLINE]               = "noinline",
        [GNU_AK_NORETURN]               = "noreturn",
        [GNU_AK_NAKED]                  = "naked",
        [GNU_AK_PURE]                   = "pure",
        [GNU_AK_ALWAYS_INLINE]          = "always_inline",
        [GNU_AK_MALLOC]                 = "malloc",
        [GNU_AK_WEAK]                   = "weak",
        [GNU_AK_CONSTRUCTOR]            = "constructor",
        [GNU_AK_DESTRUCTOR]             = "destructor",
        [GNU_AK_NOTHROW]                = "nothrow",
        [GNU_AK_TRANSPARENT_UNION]      = "transparent_union",
        [GNU_AK_COMMON]                 = "common",
        [GNU_AK_NOCOMMON]               = "nocommon",
        [GNU_AK_PACKED]                 = "packed",
        [GNU_AK_SHARED]                 = "shared",
        [GNU_AK_NOTSHARED]              = "notshared",
        [GNU_AK_USED]                   = "used",
        [GNU_AK_UNUSED]                 = "unused",
        [GNU_AK_NO_INSTRUMENT_FUNCTION] = "no_instrument_function",
        [GNU_AK_WARN_UNUSED_RESULT]     = "warn_unused_result",
        [GNU_AK_LONGCALL]               = "longcall",
        [GNU_AK_SHORTCALL]              = "shortcall",
        [GNU_AK_LONG_CALL]              = "long_call",
        [GNU_AK_SHORT_CALL]             = "short_call",
        [GNU_AK_FUNCTION_VECTOR]        = "function_vector",
        [GNU_AK_INTERRUPT]              = "interrupt",
        [GNU_AK_INTERRUPT_HANDLER]      = "interrupt_handler",
        [GNU_AK_NMI_HANDLER]            = "nmi_handler",
        [GNU_AK_NESTING]                = "nesting",
        [GNU_AK_NEAR]                   = "near",
        [GNU_AK_FAR]                    = "far",
        [GNU_AK_SIGNAL]                 = "signal",
        [GNU_AK_EIGTHBIT_DATA]          = "eightbit_data",
        [GNU_AK_TINY_DATA]              = "tiny_data",
        [GNU_AK_SAVEALL]                = "saveall",
        [GNU_AK_FLATTEN]                = "flatten",
        [GNU_AK_SSEREGPARM]             = "sseregparm",
        [GNU_AK_EXTERNALLY_VISIBLE]     = "externally_visible",
        [GNU_AK_RETURN_TWICE]           = "return_twice",
        [GNU_AK_MAY_ALIAS]              = "may_alias",
        [GNU_AK_MS_STRUCT]              = "ms_struct",
        [GNU_AK_GCC_STRUCT]             = "gcc_struct",
        [GNU_AK_DLLIMPORT]              = "dllimport",
        [GNU_AK_DLLEXPORT]              = "dllexport",
        [GNU_AK_ALIGNED]                = "aligned",
        [GNU_AK_ALIAS]                  = "alias",
        [GNU_AK_SECTION]                = "section",
        [GNU_AK_FORMAT]                 = "format",
        [GNU_AK_FORMAT_ARG]             = "format_arg",
        [GNU_AK_WEAKREF]                = "weakref",
        [GNU_AK_NONNULL]                = "nonnull",
        [GNU_AK_TLS_MODEL]              = "tls_model",
        [GNU_AK_VISIBILITY]             = "visibility",
        [GNU_AK_REGPARM]                = "regparm",
        [GNU_AK_MODE]                   = "mode",
        [GNU_AK_MODEL]                  = "model",
        [GNU_AK_TRAP_EXIT]              = "trap_exit",
        [GNU_AK_SP_SWITCH]              = "sp_switch",
        [GNU_AK_SENTINEL]               = "sentinel"
};

/**
 * 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);
}

/**
 * Allocate a new gnu temporal attribute.
 */
static gnu_attribute_t *allocate_gnu_attribute(gnu_attribute_kind_t kind)
{
        gnu_attribute_t *attribute = obstack_alloc(&temp_obst, sizeof(*attribute));
        attribute->kind            = kind;
        attribute->next            = NULL;
        attribute->invalid         = false;
        attribute->have_arguments  = false;

        return attribute;
}

/**
 * parse one constant expression argument.
 */
static void parse_gnu_attribute_const_arg(gnu_attribute_t *attribute)
{
        expression_t *expression;
        add_anchor_token(')');
        expression = parse_constant_expression();
        rem_anchor_token(')');
        expect(')');
        attribute->u.argument = fold_constant(expression);
        return;
end_error:
        attribute->invalid = true;
}

/**
 * parse a list of constant expressions arguments.
 */
static void parse_gnu_attribute_const_arg_list(gnu_attribute_t *attribute)
{
        argument_list_t **list = &attribute->u.arguments;
        argument_list_t  *entry;
        expression_t     *expression;
        add_anchor_token(')');
        add_anchor_token(',');
        while (true) {
                expression = parse_constant_expression();
                entry = obstack_alloc(&temp_obst, sizeof(entry));
                entry->argument = fold_constant(expression);
                entry->next     = NULL;
                *list = entry;
                list = &entry->next;
                if (token.type != ',')
                        break;
                next_token();
        }
        rem_anchor_token(',');
        rem_anchor_token(')');
        expect(')');
        return;
end_error:
        attribute->invalid = true;
}

/**
 * parse one string literal argument.
 */
static void parse_gnu_attribute_string_arg(gnu_attribute_t *attribute,
                                           string_t *string)
{
        add_anchor_token('(');
        if (token.type != T_STRING_LITERAL) {
                parse_error_expected("while parsing attribute directive",
                                     T_STRING_LITERAL, NULL);
                goto end_error;
        }
        *string = parse_string_literals();
        rem_anchor_token('(');
        expect(')');
        return;
end_error:
        attribute->invalid = true;
}

/**
 * parse one tls model.
 */
static void parse_gnu_attribute_tls_model_arg(gnu_attribute_t *attribute)
{
        static const char *const tls_models[] = {
                "global-dynamic",
                "local-dynamic",
                "initial-exec",
                "local-exec"
        };
        string_t string = { NULL, 0 };
        parse_gnu_attribute_string_arg(attribute, &string);
        if (string.begin != NULL) {
                for(size_t i = 0; i < 4; ++i) {
                        if (strcmp(tls_models[i], string.begin) == 0) {
                                attribute->u.value = i;
                                return;
                        }
                }
                errorf(HERE, "'%s' is an unrecognized tls model", string.begin);
        }
        attribute->invalid = true;
}

/**
 * parse one tls model.
 */
static void parse_gnu_attribute_visibility_arg(gnu_attribute_t *attribute)
{
        static const char *const visibilities[] = {
                "default",
                "protected",
                "hidden",
                "internal"
        };
        string_t string = { NULL, 0 };
        parse_gnu_attribute_string_arg(attribute, &string);
        if (string.begin != NULL) {
                for(size_t i = 0; i < 4; ++i) {
                        if (strcmp(visibilities[i], string.begin) == 0) {
                                attribute->u.value = i;
                                return;
                        }
                }
                errorf(HERE, "'%s' is an unrecognized visibility", string.begin);
        }
        attribute->invalid = true;
}

/**
 * parse one (code) model.
 */
static void parse_gnu_attribute_model_arg(gnu_attribute_t *attribute)
{
        static const char *const visibilities[] = {
                "small",
                "medium",
                "large"
        };
        string_t string = { NULL, 0 };
        parse_gnu_attribute_string_arg(attribute, &string);
        if (string.begin != NULL) {
                for(int i = 0; i < 3; ++i) {
                        if (strcmp(visibilities[i], string.begin) == 0) {
                                attribute->u.value = i;
                                return;
                        }
                }
                errorf(HERE, "'%s' is an unrecognized model", string.begin);
        }
        attribute->invalid = true;
}

static void parse_gnu_attribute_mode_arg(gnu_attribute_t *attribute)
{
        /* TODO: find out what is allowed here... */

        /* at least: byte, word, pointer, list of machine modes
         * __XXX___ is interpreted as XXX */
        add_anchor_token(')');

        if (token.type != T_IDENTIFIER) {
                expect(T_IDENTIFIER);
        }

        /* This isn't really correct, the backend should provide a list of machine
         * specific modes (according to gcc philosophy that is...) */
        const char *symbol_str = token.v.symbol->string;
        if (strcmp_underscore("QI",   symbol_str) == 0 ||
            strcmp_underscore("byte", symbol_str) == 0) {
                attribute->u.akind = ATOMIC_TYPE_CHAR;
        } else if (strcmp_underscore("HI", symbol_str) == 0) {
                attribute->u.akind = ATOMIC_TYPE_SHORT;
        } else if (strcmp_underscore("SI",      symbol_str) == 0
                || strcmp_underscore("word",    symbol_str) == 0
                || strcmp_underscore("pointer", symbol_str) == 0) {
                attribute->u.akind = ATOMIC_TYPE_INT;
        } else if (strcmp_underscore("DI", symbol_str) == 0) {
                attribute->u.akind = ATOMIC_TYPE_LONGLONG;
        } else {
                warningf(HERE, "ignoring unknown mode '%s'", symbol_str);
                attribute->invalid = true;
        }
        next_token();

        rem_anchor_token(')');
        expect(')');
        return;
end_error:
        attribute->invalid = true;
}

/**
 * parse one interrupt argument.
 */
static void parse_gnu_attribute_interrupt_arg(gnu_attribute_t *attribute)
{
        static const char *const interrupts[] = {
                "IRQ",
                "FIQ",
                "SWI",
                "ABORT",
                "UNDEF"
        };
        string_t string = { NULL, 0 };
        parse_gnu_attribute_string_arg(attribute, &string);
        if (string.begin != NULL) {
                for(size_t i = 0; i < 5; ++i) {
                        if (strcmp(interrupts[i], string.begin) == 0) {
                                attribute->u.value = i;
                                return;
                        }
                }
                errorf(HERE, "'%s' is not an interrupt", string.begin);
        }
        attribute->invalid = true;
}

/**
 * parse ( identifier, const expression, const expression )
 */
static void parse_gnu_attribute_format_args(gnu_attribute_t *attribute)
{
        static const char *const format_names[] = {
                "printf",
                "scanf",
                "strftime",
                "strfmon"
        };
        int i;

        if (token.type != T_IDENTIFIER) {
                parse_error_expected("while parsing format attribute directive", T_IDENTIFIER, NULL);
                goto end_error;
        }
        const char *name = token.v.symbol->string;
        for(i = 0; i < 4; ++i) {
                if (strcmp_underscore(format_names[i], name) == 0)
                        break;
        }
        if (i >= 4) {
                if (warning.attribute)
                        warningf(HERE, "'%s' is an unrecognized format function type", name);
        }
        next_token();

        expect(',');
        add_anchor_token(')');
        add_anchor_token(',');
        parse_constant_expression();
        rem_anchor_token(',');
        rem_anchor_token(')');

        expect(',');
        add_anchor_token(')');
        parse_constant_expression();
        rem_anchor_token(')');
        expect(')');
        return;
end_error:
        attribute->u.value = true;
}

static void check_no_argument(gnu_attribute_t *attribute, const char *name)
{
        if (!attribute->have_arguments)
                return;

        /* should have no arguments */
        errorf(HERE, "wrong number of arguments specified for '%s' attribute", name);
        eat_until_matching_token('(');
        /* we have already consumed '(', so we stop before ')', eat it */
        eat(')');
        attribute->invalid = true;
}

/**
 * Parse one GNU attribute.
 *
 * Note that attribute names can be specified WITH or WITHOUT
 * double underscores, ie const or __const__.
 *
 * The following attributes are parsed without arguments
 *  const
 *  volatile
 *  cdecl
 *  stdcall
 *  fastcall
 *  deprecated
 *  noinline
 *  noreturn
 *  naked
 *  pure
 *  always_inline
 *  malloc
 *  weak
 *  constructor
 *  destructor
 *  nothrow
 *  transparent_union
 *  common
 *  nocommon
 *  packed
 *  shared
 *  notshared
 *  used
 *  unused
 *  no_instrument_function
 *  warn_unused_result
 *  longcall
 *  shortcall
 *  long_call
 *  short_call
 *  function_vector
 *  interrupt_handler
 *  nmi_handler
 *  nesting
 *  near
 *  far
 *  signal
 *  eightbit_data
 *  tiny_data
 *  saveall
 *  flatten
 *  sseregparm
 *  externally_visible
 *  return_twice
 *  may_alias
 *  ms_struct
 *  gcc_struct
 *  dllimport
 *  dllexport
 *
 * The following attributes are parsed with arguments
 *  aligned( const expression )
 *  alias( string literal )
 *  section( string literal )
 *  format( identifier, const expression, const expression )
 *  format_arg( const expression )
 *  tls_model( string literal )
 *  visibility( string literal )
 *  regparm( const expression )
 *  model( string leteral )
 *  trap_exit( const expression )
 *  sp_switch( string literal )
 *
 * The following attributes might have arguments
 *  weak_ref( string literal )
 *  non_null( const expression // ',' )
 *  interrupt( string literal )
 *  sentinel( constant expression )
 */
static decl_modifiers_t parse_gnu_attribute(gnu_attribute_t **attributes)
{
        gnu_attribute_t *head      = *attributes;
        gnu_attribute_t *last      = *attributes;
        decl_modifiers_t modifiers = 0;
        gnu_attribute_t *attribute;

        eat(T___attribute__);
        expect('(');
        expect('(');

        if (token.type != ')') {
                /* find the end of the list */
                if (last != NULL) {
                        while (last->next != NULL)
                                last = last->next;
                }

                /* non-empty attribute list */
                while (true) {
                        const char *name;
                        if (token.type == T_const) {
                                name = "const";
                        } else if (token.type == T_volatile) {
                                name = "volatile";
                        } else if (token.type == T_cdecl) {
                                /* __attribute__((cdecl)), WITH ms mode */
                                name = "cdecl";
                        } else if (token.type == T_IDENTIFIER) {
                                const symbol_t *sym = token.v.symbol;
                                name = sym->string;
                        } else {
                                parse_error_expected("while parsing GNU attribute", T_IDENTIFIER, NULL);
                                break;
                        }

                        next_token();

                        int i;
                        for(i = 0; i < GNU_AK_LAST; ++i) {
                                if (strcmp_underscore(gnu_attribute_names[i], name) == 0)
                                        break;
                        }
                        gnu_attribute_kind_t kind = (gnu_attribute_kind_t)i;

                        attribute = NULL;
                        if (kind == GNU_AK_LAST) {
                                if (warning.attribute)
                                        warningf(HERE, "'%s' attribute directive ignored", name);

                                /* skip possible arguments */
                                if (token.type == '(') {
                                        eat_until_matching_token(')');
                                }
                        } else {
                                /* check for arguments */
                                attribute = allocate_gnu_attribute(kind);
                                if (token.type == '(') {
                                        next_token();
                                        if (token.type == ')') {
                                                /* empty args are allowed */
                                                next_token();
                                        } else
                                                attribute->have_arguments = true;
                                }

                                switch(kind) {
                                case GNU_AK_CONST:
                                case GNU_AK_VOLATILE:
                                case GNU_AK_NAKED:
                                case GNU_AK_MALLOC:
                                case GNU_AK_WEAK:
                                case GNU_AK_COMMON:
                                case GNU_AK_NOCOMMON:
                                case GNU_AK_SHARED:
                                case GNU_AK_NOTSHARED:
                                case GNU_AK_NO_INSTRUMENT_FUNCTION:
                                case GNU_AK_WARN_UNUSED_RESULT:
                                case GNU_AK_LONGCALL:
                                case GNU_AK_SHORTCALL:
                                case GNU_AK_LONG_CALL:
                                case GNU_AK_SHORT_CALL:
                                case GNU_AK_FUNCTION_VECTOR:
                                case GNU_AK_INTERRUPT_HANDLER:
                                case GNU_AK_NMI_HANDLER:
                                case GNU_AK_NESTING:
                                case GNU_AK_NEAR:
                                case GNU_AK_FAR:
                                case GNU_AK_SIGNAL:
                                case GNU_AK_EIGTHBIT_DATA:
                                case GNU_AK_TINY_DATA:
                                case GNU_AK_SAVEALL:
                                case GNU_AK_FLATTEN:
                                case GNU_AK_SSEREGPARM:
                                case GNU_AK_EXTERNALLY_VISIBLE:
                                case GNU_AK_RETURN_TWICE:
                                case GNU_AK_MAY_ALIAS:
                                case GNU_AK_MS_STRUCT:
                                case GNU_AK_GCC_STRUCT:
                                        goto no_arg;

                                case GNU_AK_CDECL:             modifiers |= DM_CDECL;             goto no_arg;
                                case GNU_AK_FASTCALL:          modifiers |= DM_FASTCALL;          goto no_arg;
                                case GNU_AK_STDCALL:           modifiers |= DM_STDCALL;           goto no_arg;
                                case GNU_AK_UNUSED:            modifiers |= DM_UNUSED;            goto no_arg;
                                case GNU_AK_USED:              modifiers |= DM_USED;              goto no_arg;
                                case GNU_AK_PURE:              modifiers |= DM_PURE;              goto no_arg;
                                case GNU_AK_ALWAYS_INLINE:     modifiers |= DM_FORCEINLINE;       goto no_arg;
                                case GNU_AK_DLLIMPORT:         modifiers |= DM_DLLIMPORT;         goto no_arg;
                                case GNU_AK_DLLEXPORT:         modifiers |= DM_DLLEXPORT;         goto no_arg;
                                case GNU_AK_PACKED:            modifiers |= DM_PACKED;            goto no_arg;
                                case GNU_AK_NOINLINE:          modifiers |= DM_NOINLINE;          goto no_arg;
                                case GNU_AK_NORETURN:          modifiers |= DM_NORETURN;          goto no_arg;
                                case GNU_AK_NOTHROW:           modifiers |= DM_NOTHROW;           goto no_arg;
                                case GNU_AK_TRANSPARENT_UNION: modifiers |= DM_TRANSPARENT_UNION; goto no_arg;
                                case GNU_AK_CONSTRUCTOR:       modifiers |= DM_CONSTRUCTOR;       goto no_arg;
                                case GNU_AK_DESTRUCTOR:        modifiers |= DM_DESTRUCTOR;        goto no_arg;
                                case GNU_AK_DEPRECATED:        modifiers |= DM_DEPRECATED;        goto no_arg;

                                case GNU_AK_ALIGNED:
                                        /* __align__ may be used without an argument */
                                        if (attribute->have_arguments) {
                                                parse_gnu_attribute_const_arg(attribute);
                                        }
                                        break;

                                case GNU_AK_FORMAT_ARG:
                                case GNU_AK_REGPARM:
                                case GNU_AK_TRAP_EXIT:
                                        if (!attribute->have_arguments) {
                                                /* should have arguments */
                                                errorf(HERE, "wrong number of arguments specified for '%s' attribute", name);
                                                attribute->invalid = true;
                                        } else
                                                parse_gnu_attribute_const_arg(attribute);
                                        break;
                                case GNU_AK_ALIAS:
                                case GNU_AK_SECTION:
                                case GNU_AK_SP_SWITCH:
                                        if (!attribute->have_arguments) {
                                                /* should have arguments */
                                                errorf(HERE, "wrong number of arguments specified for '%s' attribute", name);
                                                attribute->invalid = true;
                                        } else
                                                parse_gnu_attribute_string_arg(attribute, &attribute->u.string);
                                        break;
                                case GNU_AK_FORMAT:
                                        if (!attribute->have_arguments) {
                                                /* should have arguments */
                                                errorf(HERE, "wrong number of arguments specified for '%s' attribute", name);
                                                attribute->invalid = true;
                                        } else
                                                parse_gnu_attribute_format_args(attribute);
                                        break;
                                case GNU_AK_WEAKREF:
                                        /* may have one string argument */
                                        if (attribute->have_arguments)
                                                parse_gnu_attribute_string_arg(attribute, &attribute->u.string);
                                        break;
                                case GNU_AK_NONNULL:
                                        if (attribute->have_arguments)
                                                parse_gnu_attribute_const_arg_list(attribute);
                                        break;
                                case GNU_AK_TLS_MODEL:
                                        if (!attribute->have_arguments) {
                                                /* should have arguments */
                                                errorf(HERE, "wrong number of arguments specified for '%s' attribute", name);
                                        } else
                                                parse_gnu_attribute_tls_model_arg(attribute);
                                        break;
                                case GNU_AK_VISIBILITY:
                                        if (!attribute->have_arguments) {
                                                /* should have arguments */
                                                errorf(HERE, "wrong number of arguments specified for '%s' attribute", name);
                                        } else
                                                parse_gnu_attribute_visibility_arg(attribute);
                                        break;
                                case GNU_AK_MODEL:
                                        if (!attribute->have_arguments) {
                                                /* should have arguments */
                                                errorf(HERE, "wrong number of arguments specified for '%s' attribute", name);
                                        } else {
                                                parse_gnu_attribute_model_arg(attribute);
                                        }
                                        break;
                                case GNU_AK_MODE:
                                        if (!attribute->have_arguments) {
                                                /* should have arguments */
                                                errorf(HERE, "wrong number of arguments specified for '%s' attribute", name);
                                        } else {
                                                parse_gnu_attribute_mode_arg(attribute);
                                        }
                                        break;
                                case GNU_AK_INTERRUPT:
                                        /* may have one string argument */
                                        if (attribute->have_arguments)
                                                parse_gnu_attribute_interrupt_arg(attribute);
                                        break;
                                case GNU_AK_SENTINEL:
                                        /* may have one string argument */
                                        if (attribute->have_arguments)
                                                parse_gnu_attribute_const_arg(attribute);
                                        break;
                                case GNU_AK_LAST:
                                        /* already handled */
                                        break;

no_arg:
                                        check_no_argument(attribute, name);
                                }
                        }
                        if (attribute != NULL) {
                                if (last != NULL) {
                                        last->next = attribute;
                                        last       = attribute;
                                } else {
                                        head = last = attribute;
                                }
                        }

                        if (token.type != ',')
                                break;
                        next_token();
                }
        }
        expect(')');
        expect(')');
end_error:
        *attributes = head;

        return modifiers;
}

/**
 * Parse GNU attributes.
 */
static decl_modifiers_t parse_attributes(gnu_attribute_t **attributes)
{
        decl_modifiers_t modifiers = 0;

        while (true) {
                switch(token.type) {
                case T___attribute__:
                        modifiers |= parse_gnu_attribute(attributes);
                        continue;

                case T_asm:
                        next_token();
                        expect('(');
                        if (token.type != T_STRING_LITERAL) {
                                parse_error_expected("while parsing assembler attribute",
                                                     T_STRING_LITERAL, NULL);
                                eat_until_matching_token('(');
                                break;
                        } else {
                                parse_string_literals();
                        }
                        expect(')');
                        continue;

                case T_cdecl:     modifiers |= DM_CDECL;    break;
                case T__fastcall: modifiers |= DM_FASTCALL; break;
                case T__stdcall:  modifiers |= DM_STDCALL;  break;

                case T___thiscall:
                        /* TODO record modifier */
                        warningf(HERE, "Ignoring declaration modifier %K", &token);
                        break;

end_error:
                default: return modifiers;
                }

                next_token();
        }
}

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

        while (true) {
                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(']');
                        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.v.symbol;
                        next_token();
                        break;
                default:
                        expect('=');
                        return result;
                }

                assert(designator != NULL);
                if (last != NULL) {
                        last->next = designator;
                } else {
                        result = designator;
                }
                last = designator;
        }
end_error:
        return NULL;
}

static initializer_t *initializer_from_string(array_type_t *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,
                                                   wide_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.value);
                                        }

                                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->wide_string.value);
                                        }
                                }

                                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 (token.type == '{') {
                warningf(HERE, "extra curly braces around scalar initializer");
                do {
                        ++braces;
                        next_token();
                } while (token.type == '{');
        }

        expression_t *expression = parse_assignment_expression();
        if (must_be_constant && !is_initializer_constant(expression)) {
                errorf(&expression->base.source_position,
                       "Initialisation expression '%E' is not constant\n",
                       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) {
                if (token.type == ',') {
                        next_token();
                }
                if (token.type != '}') {
                        if (!additional_warning_displayed) {
                                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->symbol->string);
                } else if (is_type_array(type)) {
                        fprintf(stderr, "[%zu]", 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)) {
                declaration_t *declaration = top_type->compound.declaration;
                declaration_t *entry       = declaration->scope.declarations;
                top->v.compound_entry      = entry;

                if (entry != NULL) {
                        path->top_type         = entry->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);
                                }
                                goto failed;
                        }

                        declaration_t *declaration = type->compound.declaration;
                        declaration_t *iter        = declaration->scope.declarations;
                        for( ; iter != NULL; iter = iter->next) {
                                if (iter->symbol == symbol) {
                                        break;
                                }
                        }
                        if (iter == NULL) {
                                errorf(&designator->source_position,
                                       "'%T' has no member named '%Y'", orig_type, symbol);
                                goto failed;
                        }
                        if (used_in_offsetof) {
                                type_t *real_type = skip_typeref(iter->type);
                                if (real_type->kind == TYPE_BITFIELD) {
                                        errorf(&designator->source_position,
                                               "offsetof designator '%Y' may not specify bitfield",
                                               symbol);
                                        goto failed;
                                }
                        }

                        top->type             = orig_type;
                        top->v.compound_entry = iter;
                        orig_type             = iter->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;
                        }
                        if (!is_type_valid(array_index->base.type)) {
                                goto failed;
                        }

                        long index = fold_constant(array_index);
                        if (!used_in_offsetof) {
                                if (index < 0) {
                                        errorf(&designator->source_position,
                                               "array index [%E] must be positive", array_index);
                                        goto failed;
                                }
                                if (type->array.size_constant == true) {
                                        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);
                                                goto failed;
                                        }
                                }
                        }

                        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;

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

                top->v.index++;

                if (!type->array.size_constant || top->v.index < type->array.size) {
                        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 until token is found.
 */
static void skip_until(int type)
{
        while (token.type != type) {
                if (token.type == T_EOF)
                        return;
                next_token();
        }
}

/**
 * skip any {...} blocks until a closing bracket is reached.
 */
static void skip_initializers(void)
{
        if (token.type == '{')
                next_token();

        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);

                /* we can't do usefull stuff if we didn't even parse the type. Skip the
                 * initializers in this case. */
                if (!is_type_valid(type)) {
                        skip_initializers();
                        return create_empty_initializer();
                }
        }

        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.v.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->declaration != NULL) {
                                                errorf(HERE, "extra brace group at end of initializer for '%Y'",
                                                       env->declaration->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('}');
                                } else {
                                        expect('}');
                                        goto error_parse_next;
                                }
                        }
                } else {
                        /* must be an expression */
                        expression_t *expression = parse_assignment_expression();

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

                        if (type == NULL) {
                                /* we are already outside, ... */
                                if (is_type_compound(outer_type) &&
                                    !outer_type->compound.declaration->init.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) {
                                        if (token.type == ',') {
                                                next_token();
                                        }
                                        if (token.type != '}') {
                                                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 (env->declaration != NULL)
                                warningf(HERE, "excess elements in struct initializer for '%Y'",
                                 env->declaration->symbol);
                        else
                                warningf(HERE, "excess elements in struct initializer");
                }

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

/**
 * 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);
        initializer_t *result = NULL;
        size_t         max_index;

        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('}');
        } 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);
        }

        /* § 6.7.5 (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:
                        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");
                }

                expression_t *cnst       = allocate_expression_zero(EXPR_CONST);
                cnst->base.type          = type_size_t;
                cnst->conste.v.int_value = size;

                type_t *new_type = duplicate_type(type);

                new_type->array.size_expression = cnst;
                new_type->array.size_constant   = true;
                new_type->array.size            = size;
                env->type = new_type;
        }

        return result;
end_error:
        return NULL;
}

static declaration_t *append_declaration(declaration_t *declaration);

static declaration_t *parse_compound_type_specifier(bool is_struct)
{
        gnu_attribute_t  *attributes = NULL;
        decl_modifiers_t  modifiers  = 0;
        if (is_struct) {
                eat(T_struct);
        } else {
                eat(T_union);
        }

        symbol_t      *symbol      = NULL;
        declaration_t *declaration = NULL;

        if (token.type == T___attribute__) {
                modifiers |= parse_attributes(&attributes);
        }

        if (token.type == T_IDENTIFIER) {
                symbol = token.v.symbol;
                next_token();

                namespace_t const namespc =
                        is_struct ? NAMESPACE_STRUCT : NAMESPACE_UNION;
                declaration = get_declaration(symbol, namespc);
                if (declaration != NULL) {
                        if (declaration->parent_scope != scope &&
                            (token.type == '{' || token.type == ';')) {
                                declaration = NULL;
                        } else if (declaration->init.complete &&
                                   token.type == '{') {
                                assert(symbol != NULL);
                                errorf(HERE, "multiple definitions of '%s %Y' (previous definition at %P)",
                                       is_struct ? "struct" : "union", symbol,
                                       &declaration->source_position);
                                declaration->scope.declarations = 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 (declaration == NULL) {
                declaration = allocate_declaration_zero();
                declaration->namespc         =
                        (is_struct ? NAMESPACE_STRUCT : NAMESPACE_UNION);
                declaration->source_position = token.source_position;
                declaration->symbol          = symbol;
                declaration->parent_scope    = scope;
                if (symbol != NULL) {
                        environment_push(declaration);
                }
                append_declaration(declaration);
        }

        if (token.type == '{') {
                declaration->init.complete = true;

                parse_compound_type_entries(declaration);
                modifiers |= parse_attributes(&attributes);
        }

        declaration->modifiers |= modifiers;
        return declaration;
}

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

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

                declaration_t *const entry = allocate_declaration_zero();
                entry->storage_class   = STORAGE_CLASS_ENUM_ENTRY;
                entry->type            = enum_type;
                entry->symbol          = token.v.symbol;
                entry->source_position = token.source_position;
                next_token();

                if (token.type == '=') {
                        next_token();
                        expression_t *value = parse_constant_expression();

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

                        /* TODO semantic */
                }

                record_declaration(entry, false);

                if (token.type != ',')
                        break;
                next_token();
        } while (token.type != '}');
        rem_anchor_token('}');

        expect('}');

end_error:
        ;
}

static type_t *parse_enum_specifier(void)
{
        gnu_attribute_t *attributes = NULL;
        declaration_t   *declaration;
        symbol_t        *symbol;

        eat(T_enum);
        if (token.type == T_IDENTIFIER) {
                symbol = token.v.symbol;
                next_token();

                declaration = get_declaration(symbol, NAMESPACE_ENUM);
        } else if (token.type != '{') {
                parse_error_expected("while parsing enum type specifier",
                                     T_IDENTIFIER, '{', NULL);
                return NULL;
        } else {
                declaration = NULL;
                symbol      = NULL;
        }

        if (declaration == NULL) {
                declaration = allocate_declaration_zero();
                declaration->namespc         = NAMESPACE_ENUM;
                declaration->source_position = token.source_position;
                declaration->symbol          = symbol;
                declaration->parent_scope  = scope;
        }

        type_t *const type      = allocate_type_zero(TYPE_ENUM, &declaration->source_position);
        type->enumt.declaration = declaration;

        if (token.type == '{') {
                if (declaration->init.complete) {
                        errorf(HERE, "multiple definitions of enum %Y", symbol);
                }
                if (symbol != NULL) {
                        environment_push(declaration);
                }
                append_declaration(declaration);
                declaration->init.complete = true;

                parse_enum_entries(type);
                parse_attributes(&attributes);
        }

        return type;
}

/**
 * if a symbol is a typedef to another type, return true
 */
static bool is_typedef_symbol(symbol_t *symbol)
{
        const declaration_t *const declaration =
                get_declaration(symbol, NAMESPACE_NORMAL);
        return
                declaration != NULL &&
                declaration->storage_class == STORAGE_CLASS_TYPEDEF;
}

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

        type_t *type;

        expect('(');
        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 (token.type == T___extension__) {
                /* This can be a prefix to a typename or an expression. */
                next_token();
                in_gcc_extension = true;
        }
        switch (token.type) {
        case T_IDENTIFIER:
                if (is_typedef_symbol(token.v.symbol)) {
                        type = parse_typename();
                } else {
                        expression = parse_expression();
                        type       = expression->base.type;
                }
                break;

        TYPENAME_START
                type = parse_typename();
                break;

        default:
                expression = parse_expression();
                type       = expression->base.type;
                break;
        }
        in_type_prop     = old_type_prop;
        in_gcc_extension = old_gcc_extension;

        rem_anchor_token(')');
        expect(')');

        type_t *typeof_type              = allocate_type_zero(TYPE_TYPEOF, &expression->base.source_position);
        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_SHORT     = 1 << 6,
        SPECIFIER_LONG_LONG = 1 << 7,
        SPECIFIER_FLOAT     = 1 << 8,
        SPECIFIER_BOOL      = 1 << 9,
        SPECIFIER_VOID      = 1 << 10,
        SPECIFIER_INT8      = 1 << 11,
        SPECIFIER_INT16     = 1 << 12,
        SPECIFIER_INT32     = 1 << 13,
        SPECIFIER_INT64     = 1 << 14,
        SPECIFIER_INT128    = 1 << 15,
        SPECIFIER_COMPLEX   = 1 << 16,
        SPECIFIER_IMAGINARY = 1 << 17,
} 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, &builtin_source_position);
        type->builtin.symbol    = symbol;
        type->builtin.real_type = real_type;

        type_t *result = typehash_insert(type);
        if (type != result) {
                free_type(type);
        }

        return result;
}

static type_t *get_typedef_type(symbol_t *symbol)
{
        declaration_t *declaration = get_declaration(symbol, NAMESPACE_NORMAL);
        if (declaration == NULL ||
           declaration->storage_class != STORAGE_CLASS_TYPEDEF)
                return NULL;

        type_t *type               = allocate_type_zero(TYPE_TYPEDEF, &declaration->source_position);
        type->typedeft.declaration = declaration;

        return type;
}

/**
 * check for the allowed MS alignment values.
 */
static bool check_alignment_value(long long intvalue)
{
        if (intvalue < 1 || intvalue > 8192) {
                errorf(HERE, "illegal alignment value");
                return false;
        }
        unsigned v = (unsigned)intvalue;
        for (unsigned i = 1; i <= 8192; i += i) {
                if (i == v)
                        return true;
        }
        errorf(HERE, "alignment must be power of two");
        return false;
}

#define DET_MOD(name, tag) do { \
        if (*modifiers & tag) warningf(HERE, #name " used more than once"); \
        *modifiers |= tag; \
} while (0)

static void parse_microsoft_extended_decl_modifier(declaration_specifiers_t *specifiers)
{
        decl_modifiers_t *modifiers = &specifiers->modifiers;

        while (true) {
                if (token.type == T_restrict) {
                        next_token();
                        DET_MOD(restrict, DM_RESTRICT);
                        goto end_loop;
                } else if (token.type != T_IDENTIFIER)
                        break;
                symbol_t *symbol = token.v.symbol;
                if (symbol == sym_align) {
                        next_token();
                        expect('(');
                        if (token.type != T_INTEGER)
                                goto end_error;
                        if (check_alignment_value(token.v.intvalue)) {
                                if (specifiers->alignment != 0)
                                        warningf(HERE, "align used more than once");
                                specifiers->alignment = (unsigned char)token.v.intvalue;
                        }
                        next_token();
                        expect(')');
                } else if (symbol == sym_allocate) {
                        next_token();
                        expect('(');
                        if (token.type != T_IDENTIFIER)
                                goto end_error;
                        (void)token.v.symbol;
                        expect(')');
                } else if (symbol == sym_dllimport) {
                        next_token();
                        DET_MOD(dllimport, DM_DLLIMPORT);
                } else if (symbol == sym_dllexport) {
                        next_token();
                        DET_MOD(dllexport, DM_DLLEXPORT);
                } else if (symbol == sym_thread) {
                        next_token();
                        DET_MOD(thread, DM_THREAD);
                } else if (symbol == sym_naked) {
                        next_token();
                        DET_MOD(naked, DM_NAKED);
                } else if (symbol == sym_noinline) {
                        next_token();
                        DET_MOD(noinline, DM_NOINLINE);
                } else if (symbol == sym_noreturn) {
                        next_token();
                        DET_MOD(noreturn, DM_NORETURN);
                } else if (symbol == sym_nothrow) {
                        next_token();
                        DET_MOD(nothrow, DM_NOTHROW);
                } else if (symbol == sym_novtable) {
                        next_token();
                        DET_MOD(novtable, DM_NOVTABLE);
                } else if (symbol == sym_property) {
                        next_token();
                        expect('(');
                        for (;;) {
                                bool is_get = false;
                                if (token.type != T_IDENTIFIER)
                                        goto end_error;
                                if (token.v.symbol == sym_get) {
                                        is_get = true;
                                } else if (token.v.symbol == sym_put) {
                                } else {
                                        errorf(HERE, "Bad property name '%Y'", token.v.symbol);
                                        goto end_error;
                                }
                                next_token();
                                expect('=');
                                if (token.type != T_IDENTIFIER)
                                        goto end_error;
                                if (is_get) {
                                        if (specifiers->get_property_sym != NULL) {
                                                errorf(HERE, "get property name already specified");
                                        } else {
                                                specifiers->get_property_sym = token.v.symbol;
                                        }
                                } else {
                                        if (specifiers->put_property_sym != NULL) {
                                                errorf(HERE, "put property name already specified");
                                        } else {
                                                specifiers->put_property_sym = token.v.symbol;
                                        }
                                }
                                next_token();
                                if (token.type == ',') {
                                        next_token();
                                        continue;
                                }
                                break;
                        }
                        expect(')');
                } else if (symbol == sym_selectany) {
                        next_token();
                        DET_MOD(selectany, DM_SELECTANY);
                } else if (symbol == sym_uuid) {
                        next_token();
                        expect('(');
                        if (token.type != T_STRING_LITERAL)
                                goto end_error;
                        next_token();
                        expect(')');
                } else if (symbol == sym_deprecated) {
                        next_token();
                        if (specifiers->deprecated != 0)
                                warningf(HERE, "deprecated used more than once");
                        specifiers->deprecated = 1;
                        if (token.type == '(') {
                                next_token();
                                if (token.type == T_STRING_LITERAL) {
                                        specifiers->deprecated_string = token.v.string.begin;
                                        next_token();
                                } else {
                                        errorf(HERE, "string literal expected");
                                }
                                expect(')');
                        }
                } else if (symbol == sym_noalias) {
                        next_token();
                        DET_MOD(noalias, DM_NOALIAS);
                } else {
                        warningf(HERE, "Unknown modifier %Y ignored", token.v.symbol);
                        next_token();
                        if (token.type == '(')
                                skip_until(')');
                }
end_loop:
                if (token.type == ',')
                        next_token();
        }
end_error:
        return;
}

static declaration_t *create_error_declaration(symbol_t *symbol, storage_class_tag_t storage_class)
{
        declaration_t *const decl    = allocate_declaration_zero();
        decl->source_position        = *HERE;
        decl->declared_storage_class = storage_class;
        decl->storage_class          =
                storage_class != STORAGE_CLASS_NONE || scope == global_scope ?
                        storage_class : STORAGE_CLASS_AUTO;
        decl->symbol                 = symbol;
        decl->implicit               = true;
        record_declaration(decl, false);
        return decl;
}

/**
 * Finish the construction of a struct type by calculating
 * its size, offsets, alignment.
 */
static void finish_struct_type(compound_type_t *type) {
        if (type->declaration == NULL)
                return;
        declaration_t *struct_decl = type->declaration;
        if (! struct_decl->init.complete)
                return;

        il_size_t      size           = 0;
        il_size_t      offset;
        il_alignment_t alignment      = 1;
        bool           need_pad       = false;

        declaration_t *entry = struct_decl->scope.declarations;
        for (; entry != NULL; entry = entry->next) {
                if (entry->namespc != NAMESPACE_NORMAL)
                        continue;

                type_t *m_type = skip_typeref(entry->type);
                if (! is_type_valid(m_type)) {
                        /* simply ignore errors here */
                        continue;
                }
                il_alignment_t m_alignment = m_type->base.alignment;
                if (m_alignment > alignment)
                        alignment = m_alignment;

                offset = (size + m_alignment - 1) & -m_alignment;

                if (offset > size)
                        need_pad = true;
                entry->offset = offset;
                size = offset + m_type->base.size;
        }
        if (type->base.alignment != 0) {
                alignment = type->base.alignment;
        }

        offset = (size + alignment - 1) & -alignment;
        if (offset > size)
                need_pad = true;

        if (warning.padded && need_pad) {
                warningf(&struct_decl->source_position,
                        "'%#T' needs padding", type, struct_decl->symbol);
        }
        if (warning.packed && !need_pad) {
                warningf(&struct_decl->source_position,
                        "superfluous packed attribute on '%#T'",
                        type, struct_decl->symbol);
        }

        type->base.size      = offset;
        type->base.alignment = alignment;
}

/**
 * Finish the construction of an union type by calculating
 * its size and alignment.
 */
static void finish_union_type(compound_type_t *type) {
        if (type->declaration == NULL)
                return;
        declaration_t *union_decl = type->declaration;
        if (! union_decl->init.complete)
                return;

        il_size_t      size      = 0;
        il_alignment_t alignment = 1;

        declaration_t *entry = union_decl->scope.declarations;
        for (; entry != NULL; entry = entry->next) {
                if (entry->namespc != NAMESPACE_NORMAL)
                        continue;

                type_t *m_type = skip_typeref(entry->type);
                if (! is_type_valid(m_type))
                        continue;

                entry->offset = 0;
                if (m_type->base.size > size)
                        size = m_type->base.size;
                if (m_type->base.alignment > alignment)
                        alignment = m_type->base.alignment;
        }
        if (type->base.alignment != 0) {
                alignment = type->base.alignment;
        }
        size = (size + alignment - 1) & -alignment;
        type->base.size      = size;
        type->base.alignment = alignment;
}

static void parse_declaration_specifiers(declaration_specifiers_t *specifiers)
{
        type_t            *type              = NULL;
        type_qualifiers_t  qualifiers        = TYPE_QUALIFIER_NONE;
        type_modifiers_t   modifiers         = TYPE_MODIFIER_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->modifiers
                        |= parse_attributes(&specifiers->gnu_attributes);
                if (specifiers->modifiers & DM_TRANSPARENT_UNION)
                        modifiers |= TYPE_MODIFIER_TRANSPARENT_UNION;

                switch (token.type) {

                /* storage class */
#define MATCH_STORAGE_CLASS(token, class)                                  \
                case token:                                                        \
                        if (specifiers->declared_storage_class != STORAGE_CLASS_NONE) { \
                                errorf(HERE, "multiple storage classes in declaration specifiers"); \
                        }                                                              \
                        specifiers->declared_storage_class = 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:
                        next_token();
                        expect('(');
                        add_anchor_token(')');
                        parse_microsoft_extended_decl_modifier(specifiers);
                        rem_anchor_token(')');
                        expect(')');
                        break;

                case T___thread:
                        switch (specifiers->declared_storage_class) {
                        case STORAGE_CLASS_NONE:
                                specifiers->declared_storage_class = STORAGE_CLASS_THREAD;
                                break;

                        case STORAGE_CLASS_EXTERN:
                                specifiers->declared_storage_class = STORAGE_CLASS_THREAD_EXTERN;
                                break;

                        case STORAGE_CLASS_STATIC:
                                specifiers->declared_storage_class = STORAGE_CLASS_THREAD_STATIC;
                                break;

                        default:
                                errorf(HERE, "multiple storage classes in declaration specifiers");
                                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:                                                     \
                        next_token();                                               \
                        if (type_specifiers & specifier) {                           \
                                errorf(HERE, "multiple " name " type specifiers given"); \
                        } else {                                                    \
                                type_specifiers |= specifier;                           \
                        }                                                           \
                        break

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

                case T__forceinline:
                        /* only in microsoft mode */
                        specifiers->modifiers |= DM_FORCEINLINE;
                        /* FALLTHROUGH */

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

                case T_long:
                        next_token();
                        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;
                        }
                        break;

                case T_struct: {
                        type = allocate_type_zero(TYPE_COMPOUND_STRUCT, HERE);

                        type->compound.declaration = parse_compound_type_specifier(true);
                        finish_struct_type(&type->compound);
                        break;
                }
                case T_union: {
                        type = allocate_type_zero(TYPE_COMPOUND_UNION, HERE);
                        type->compound.declaration = parse_compound_type_specifier(false);
                        if (type->compound.declaration->modifiers & DM_TRANSPARENT_UNION)
                                modifiers |= TYPE_MODIFIER_TRANSPARENT_UNION;
                        break;
                        finish_union_type(&type->compound);
                }
                case T_enum:
                        type = parse_enum_specifier();
                        break;
                case T___typeof__:
                        type = parse_typeof();
                        break;
                case T___builtin_va_list:
                        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 '*':
                                                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.v.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 '*': {
                                                errorf(HERE, "%K does not name a type", &token);

                                                declaration_t *const decl =
                                                        create_error_declaration(token.v.symbol, STORAGE_CLASS_TYPEDEF);

                                                type = allocate_type_zero(TYPE_TYPEDEF, HERE);
                                                type->typedeft.declaration = decl;

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

                                        default:
                                                goto finish_specifiers;
                                }
                        }

                        next_token();
                        type = typedef_type;
                        break;
                }

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

finish_specifiers:
        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_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;

                                if (!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, &builtin_source_position);
                        type->complex.akind = atomic_type;
                } else if (type_specifiers & SPECIFIER_IMAGINARY) {
                        type                  = allocate_type_zero(TYPE_IMAGINARY, &builtin_source_position);
                        type->imaginary.akind = atomic_type;
                } else {
                        type               = allocate_type_zero(TYPE_ATOMIC, &builtin_source_position);
                        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;
        type->base.modifiers  = modifiers;

        type_t *result = typehash_insert(type);
        if (newtype && result != type) {
                free_type(type);
        }

        specifiers->type = result;
        return;

end_error:
        specifiers->type = type_error_type;
        return;
}

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 and return a list of declarations.
 *
 * @param last  points to the last declaration in the list
 * @return the list of declarations
 */
static declaration_t *parse_identifier_list(declaration_t **last)
{
        declaration_t *declarations     = NULL;
        declaration_t *last_declaration = NULL;
        do {
                declaration_t *const declaration = allocate_declaration_zero();
                declaration->type            = NULL; /* a K&R parameter list has no types, yet */
                declaration->source_position = token.source_position;
                declaration->symbol          = token.v.symbol;
                next_token();

                if (last_declaration != NULL) {
                        last_declaration->next = declaration;
                } else {
                        declarations = declaration;
                }
                last_declaration = declaration;

                if (token.type != ',') {
                        break;
                }
                next_token();
        } while (token.type == T_IDENTIFIER);

        *last = last_declaration;
        return declarations;
}

static type_t *automatic_type_conversion(type_t *orig_type);

static void semantic_parameter(declaration_t *declaration)
{
        /* TODO: improve error messages */
        source_position_t const* const pos = &declaration->source_position;

        switch (declaration->declared_storage_class) {
                case STORAGE_CLASS_TYPEDEF:
                        errorf(pos, "typedef not allowed in parameter list");
                        break;

                /* Allowed storage classes */
                case STORAGE_CLASS_NONE:
                case STORAGE_CLASS_REGISTER:
                        break;

                default:
                        errorf(pos, "parameter may only have none or register storage class");
                        break;
        }

        type_t *const orig_type = declaration->type;
        /* §6.7.5.3(7): Array as last part of a parameter type is just syntactic
         * sugar.  Turn it into a pointer.
         * §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_t *const type = automatic_type_conversion(orig_type);
        declaration->type = type;

        if (is_type_incomplete(skip_typeref(type))) {
                errorf(pos, "parameter '%#T' is of incomplete type",
                       orig_type, declaration->symbol);
        }
}

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

        parse_declaration_specifiers(&specifiers);

        declaration_t *declaration = parse_declarator(&specifiers, /*may_be_abstract=*/true);

        return declaration;
}

/**
 * Parses a function type parameter list and return a list of declarations.
 *
 * @param last  point to the last element of the list
 * @return the parameter list
 */
static declaration_t *parse_parameters(function_type_t *type, declaration_t **last)
{
        declaration_t *declarations = NULL;

        eat('(');
        add_anchor_token(')');
        int saved_comma_state = save_and_reset_anchor_state(',');

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

        if (token.type == ')') {
                type->unspecified_parameters = 1;
                goto parameters_finished;
        }

        declaration_t        *declaration;
        declaration_t        *last_declaration = NULL;
        function_parameter_t *parameter;
        function_parameter_t *last_parameter = NULL;

        while (true) {
                switch(token.type) {
                case T_DOTDOTDOT:
                        next_token();
                        type->variadic = 1;
                        goto parameters_finished;

                case T_IDENTIFIER:
                case T___extension__:
                DECLARATION_START
                        declaration = parse_parameter();

                        /* func(void) is not a parameter */
                        if (last_parameter == NULL
                                        && token.type == ')'
                                        && declaration->symbol == NULL
                                        && skip_typeref(declaration->type) == type_void) {
                                goto parameters_finished;
                        }
                        semantic_parameter(declaration);

                        parameter       = obstack_alloc(type_obst, sizeof(parameter[0]));
                        memset(parameter, 0, sizeof(parameter[0]));
                        parameter->type = declaration->type;

                        if (last_parameter != NULL) {
                                last_declaration->next = declaration;
                                last_parameter->next   = parameter;
                        } else {
                                type->parameters = parameter;
                                declarations     = declaration;
                        }
                        last_parameter   = parameter;
                        last_declaration = declaration;
                        break;

                default:
                        goto parameters_finished;
                }
                if (token.type != ',') {
                        goto parameters_finished;
                }
                next_token();
        }


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

        restore_anchor_state(',', saved_comma_state);
        *last = last_declaration;
        return declarations;

end_error:
        restore_anchor_state(',', saved_comma_state);
        *last = NULL;
        return NULL;
}

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

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

typedef struct parsed_pointer_t parsed_pointer_t;
struct parsed_pointer_t {
        construct_type_t  construct_type;
        type_qualifiers_t type_qualifiers;
};

typedef struct construct_function_type_t construct_function_type_t;
struct construct_function_type_t {
        construct_type_t  construct_type;
        type_t           *function_type;
};

typedef struct parsed_array_t parsed_array_t;
struct parsed_array_t {
        construct_type_t  construct_type;
        type_qualifiers_t type_qualifiers;
        bool              is_static;
        bool              is_variable;
        expression_t     *size;
};

typedef struct construct_base_type_t construct_base_type_t;
struct construct_base_type_t {
        construct_type_t  construct_type;
        type_t           *type;
};

static construct_type_t *parse_pointer_declarator(void)
{
        eat('*');

        parsed_pointer_t *pointer = obstack_alloc(&temp_obst, sizeof(pointer[0]));
        memset(pointer, 0, sizeof(pointer[0]));
        pointer->construct_type.kind = CONSTRUCT_POINTER;
        pointer->type_qualifiers     = parse_type_qualifiers();

        return (construct_type_t*) pointer;
}

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

        parsed_array_t *array = obstack_alloc(&temp_obst, sizeof(array[0]));
        memset(array, 0, sizeof(array[0]));
        array->construct_type.kind = CONSTRUCT_ARRAY;

        if (token.type == T_static) {
                array->is_static = true;
                next_token();
        }

        type_qualifiers_t type_qualifiers = parse_type_qualifiers();
        if (type_qualifiers != 0) {
                if (token.type == T_static) {
                        array->is_static = true;
                        next_token();
                }
        }
        array->type_qualifiers = type_qualifiers;

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

        rem_anchor_token(']');
        expect(']');

end_error:
        return (construct_type_t*) array;
}

static construct_type_t *parse_function_declarator(declaration_t *declaration)
{
        type_t *type;
        if (declaration != NULL) {
                type = allocate_type_zero(TYPE_FUNCTION, &declaration->source_position);

                unsigned mask = declaration->modifiers & (DM_CDECL|DM_STDCALL|DM_FASTCALL|DM_THISCALL);

                if (mask & (mask-1)) {
                        const char *first = NULL, *second = NULL;

                        /* more than one calling convention set */
                        if (declaration->modifiers & DM_CDECL) {
                                if (first == NULL)       first = "cdecl";
                                else if (second == NULL) second = "cdecl";
                        }
                        if (declaration->modifiers & DM_STDCALL) {
                                if (first == NULL)       first = "stdcall";
                                else if (second == NULL) second = "stdcall";
                        }
                        if (declaration->modifiers & DM_FASTCALL) {
                                if (first == NULL)       first = "fastcall";
                                else if (second == NULL) second = "fastcall";
                        }
                        if (declaration->modifiers & DM_THISCALL) {
                                if (first == NULL)       first = "thiscall";
                                else if (second == NULL) second = "thiscall";
                        }
                        errorf(&declaration->source_position, "%s and %s attributes are not compatible", first, second);
                }

                if (declaration->modifiers & DM_CDECL)
                        type->function.calling_convention = CC_CDECL;
                else if (declaration->modifiers & DM_STDCALL)
                        type->function.calling_convention = CC_STDCALL;
                else if (declaration->modifiers & DM_FASTCALL)
                        type->function.calling_convention = CC_FASTCALL;
                else if (declaration->modifiers & DM_THISCALL)
                        type->function.calling_convention = CC_THISCALL;
        } else {
                type = allocate_type_zero(TYPE_FUNCTION, HERE);
        }

        declaration_t *last;
        declaration_t *parameters = parse_parameters(&type->function, &last);
        if (declaration != NULL) {
                declaration->scope.declarations     = parameters;
                declaration->scope.last_declaration = last;
                declaration->scope.is_parameter     = true;
        }

        construct_function_type_t *construct_function_type =
                obstack_alloc(&temp_obst, sizeof(construct_function_type[0]));
        memset(construct_function_type, 0, sizeof(construct_function_type[0]));
        construct_function_type->construct_type.kind = CONSTRUCT_FUNCTION;
        construct_function_type->function_type       = type;

        return &construct_function_type->construct_type;
}

static void fix_declaration_type(declaration_t *declaration)
{
        decl_modifiers_t declaration_modifiers = declaration->modifiers;
        type_modifiers_t type_modifiers        = declaration->type->base.modifiers;

        if (declaration_modifiers & DM_TRANSPARENT_UNION)
                type_modifiers |= TYPE_MODIFIER_TRANSPARENT_UNION;

        if (declaration->type->base.modifiers == type_modifiers)
                return;

        type_t *copy = duplicate_type(declaration->type);
        copy->base.modifiers = type_modifiers;

        type_t *result = typehash_insert(copy);
        if (result != copy) {
                obstack_free(type_obst, copy);
        }

        declaration->type = result;
}

static construct_type_t *parse_inner_declarator(declaration_t *declaration,
                bool may_be_abstract)
{
        /* 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 *last  = NULL;
        gnu_attribute_t  *attributes = NULL;

        decl_modifiers_t modifiers = parse_attributes(&attributes);

        /* pointers */
        while (token.type == '*') {
                construct_type_t *type = parse_pointer_declarator();

                if (last == NULL) {
                        first = type;
                        last  = type;
                } else {
                        last->next = type;
                        last       = type;
                }

                /* TODO: find out if this is correct */
                modifiers |= parse_attributes(&attributes);
        }

        if (declaration != NULL)
                declaration->modifiers |= modifiers;

        construct_type_t *inner_types = NULL;

        switch(token.type) {
        case T_IDENTIFIER:
                if (declaration == NULL) {
                        errorf(HERE, "no identifier expected in typename");
                } else {
                        declaration->symbol          = token.v.symbol;
                        declaration->source_position = token.source_position;
                }
                next_token();
                break;
        case '(':
                next_token();
                add_anchor_token(')');
                inner_types = parse_inner_declarator(declaration, may_be_abstract);
                if (inner_types != NULL) {
                        /* All later declarators only modify the return type, not declaration */
                        declaration = NULL;
                }
                rem_anchor_token(')');
                expect(')');
                break;
        default:
                if (may_be_abstract)
                        break;
                parse_error_expected("while parsing declarator", T_IDENTIFIER, '(', NULL);
                eat_until_anchor();
                return NULL;
        }

        construct_type_t *p = last;

        while(true) {
                construct_type_t *type;
                switch(token.type) {
                case '(':
                        type = parse_function_declarator(declaration);
                        break;
                case '[':
                        type = parse_array_declarator();
                        break;
                default:
                        goto declarator_finished;
                }

                /* insert in the middle of the list (behind p) */
                if (p != NULL) {
                        type->next = p->next;
                        p->next    = type;
                } else {
                        type->next = first;
                        first      = type;
                }
                if (last == p) {
                        last = type;
                }
        }

declarator_finished:
        /* append inner_types at the end of the list, we don't to set last anymore
         * as it's not needed anymore */
        if (last == NULL) {
                assert(first == NULL);
                first = inner_types;
        } else {
                last->next = inner_types;
        }

        return first;
end_error:
        return NULL;
}

static void parse_declaration_attributes(declaration_t *declaration)
{
        gnu_attribute_t  *attributes = NULL;
        decl_modifiers_t  modifiers  = parse_attributes(&attributes);

        if (declaration == NULL)
                return;

        declaration->modifiers |= modifiers;
        /* check if we have these stupid mode attributes... */
        type_t *old_type = declaration->type;
        if (old_type == NULL)
                return;

        gnu_attribute_t *attribute = attributes;
        for ( ; attribute != NULL; attribute = attribute->next) {
                if (attribute->kind != GNU_AK_MODE || attribute->invalid)
                        continue;

                atomic_type_kind_t  akind = attribute->u.akind;
                if (!is_type_signed(old_type)) {
                        switch(akind) {
                        case ATOMIC_TYPE_CHAR: akind = ATOMIC_TYPE_UCHAR; break;
                        case ATOMIC_TYPE_SHORT: akind = ATOMIC_TYPE_USHORT; break;
                        case ATOMIC_TYPE_INT: akind = ATOMIC_TYPE_UINT; break;
                        case ATOMIC_TYPE_LONGLONG: akind = ATOMIC_TYPE_ULONGLONG; break;
                        default:
                                panic("invalid akind in mode attribute");
                        }
                }
                declaration->type
                        = make_atomic_type(akind, old_type->base.qualifiers);
        }
}

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->next) {
                switch(iter->kind) {
                case CONSTRUCT_INVALID:
                        internal_errorf(HERE, "invalid type construction found");
                case CONSTRUCT_FUNCTION: {
                        construct_function_type_t *construct_function_type
                                = (construct_function_type_t*) iter;

                        type_t *function_type = construct_function_type->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) {
                                        warningf(HERE,
                                                "type qualifiers in return type of function type are meaningless");
                                }
                        }

                        type = function_type;
                        break;
                }

                case CONSTRUCT_POINTER: {
                        parsed_pointer_t *parsed_pointer = (parsed_pointer_t*) iter;
                        type_t           *pointer_type   = allocate_type_zero(TYPE_POINTER, &null_position);
                        pointer_type->pointer.points_to  = type;
                        pointer_type->base.qualifiers    = parsed_pointer->type_qualifiers;

                        type = pointer_type;
                        break;
                }

                case CONSTRUCT_ARRAY: {
                        parsed_array_t *parsed_array  = (parsed_array_t*) iter;
                        type_t         *array_type    = allocate_type_zero(TYPE_ARRAY, &null_position);

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

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

                        if (size_expression != NULL) {
                                if (is_constant_expression(size_expression)) {
                                        array_type->array.size_constant = true;
                                        array_type->array.size
                                                = fold_constant(size_expression);
                                } 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 = array_type;
                        break;
                }
                }

                type_t *hashed_type = typehash_insert(type);
                if (hashed_type != type) {
                        /* the function type was constructed earlier freeing it here will
                         * destroy other types... */
                        if (iter->kind != CONSTRUCT_FUNCTION) {
                                free_type(type);
                        }
                        type = hashed_type;
                }
        }

        return type;
}

static declaration_t *parse_declarator(
                const declaration_specifiers_t *specifiers, bool may_be_abstract)
{
        declaration_t *const declaration    = allocate_declaration_zero();
        declaration->source_position        = specifiers->source_position;
        declaration->declared_storage_class = specifiers->declared_storage_class;
        declaration->modifiers              = specifiers->modifiers;
        declaration->deprecated_string      = specifiers->deprecated_string;
        declaration->get_property_sym       = specifiers->get_property_sym;
        declaration->put_property_sym       = specifiers->put_property_sym;
        declaration->is_inline              = specifiers->is_inline;

        declaration->storage_class          = specifiers->declared_storage_class;
        if (declaration->storage_class == STORAGE_CLASS_NONE
                        && scope != global_scope) {
                declaration->storage_class = STORAGE_CLASS_AUTO;
        }

        if (specifiers->alignment != 0) {
                /* TODO: add checks here */
                declaration->alignment = specifiers->alignment;
        }

        construct_type_t *construct_type
                = parse_inner_declarator(declaration, may_be_abstract);
        type_t *const type = specifiers->type;
        declaration->type = construct_declarator_type(construct_type, type);

        parse_declaration_attributes(declaration);

        fix_declaration_type(declaration);

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

        return declaration;
}

static type_t *parse_abstract_declarator(type_t *base_type)
{
        construct_type_t *construct_type = parse_inner_declarator(NULL, 1);

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

        return result;
}

static declaration_t *append_declaration(declaration_t* const declaration)
{
        if (last_declaration != NULL) {
                last_declaration->next = declaration;
        } else {
                scope->declarations = declaration;
        }
        last_declaration = declaration;
        return declaration;
}

/**
 * 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_type_of_main(const declaration_t *const decl, const function_type_t *const func_type)
{
        if (decl->storage_class == STORAGE_CLASS_STATIC) {
                warningf(&decl->source_position,
                         "'main' is normally a non-static function");
        }
        if (!types_compatible(skip_typeref(func_type->return_type), type_int)) {
                warningf(&decl->source_position,
                         "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(&decl->source_position,
                                 "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(&decl->source_position,
                                         "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(&decl->source_position,
                                                 "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(&decl->source_position, "'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 declaration_t *record_declaration(
        declaration_t *const declaration,
        const bool is_definition)
{
        const symbol_t *const symbol  = declaration->symbol;
        const namespace_t     namespc = (namespace_t)declaration->namespc;

        assert(symbol != NULL);
        declaration_t *previous_declaration = get_declaration(symbol, namespc);

        type_t *const orig_type = declaration->type;
        type_t *const type      = skip_typeref(orig_type);
        if (is_type_function(type) &&
                        type->function.unspecified_parameters &&
                        warning.strict_prototypes &&
                        previous_declaration == NULL) {
                warningf(&declaration->source_position,
                         "function declaration '%#T' is not a prototype",
                         orig_type, symbol);
        }

        if (warning.main && is_type_function(type) && is_sym_main(symbol)) {
                check_type_of_main(declaration, &type->function);
        }

        if (warning.nested_externs                             &&
            declaration->storage_class == STORAGE_CLASS_EXTERN &&
            scope                      != global_scope) {
                warningf(&declaration->source_position,
                         "nested extern declaration of '%#T'", declaration->type, symbol);
        }

        assert(declaration != previous_declaration);
        if (previous_declaration != NULL &&
            previous_declaration->parent_scope->is_parameter &&
            scope->depth == previous_declaration->parent_scope->depth + 1) {
                errorf(&declaration->source_position,
                        "declaration '%#T' redeclares the parameter '%#T' (declared %P)",
                        orig_type, symbol, previous_declaration->type, symbol,
                        &previous_declaration->source_position);
                goto finish;
        }
        if (previous_declaration != NULL &&
            previous_declaration->parent_scope == scope) {
                /* can happen for K&R style declarations */
                if (previous_declaration->type == NULL) {
                        previous_declaration->type = declaration->type;
                }

                const type_t *prev_type = skip_typeref(previous_declaration->type);
                if (!types_compatible(type, prev_type)) {
                        errorf(&declaration->source_position,
                                   "declaration '%#T' is incompatible with '%#T' (declared %P)",
                                   orig_type, symbol, previous_declaration->type, symbol,
                                   &previous_declaration->source_position);
                } else {
                        unsigned old_storage_class = previous_declaration->storage_class;
                        if (old_storage_class == STORAGE_CLASS_ENUM_ENTRY) {
                                errorf(&declaration->source_position,
                                           "redeclaration of enum entry '%Y' (declared %P)",
                                           symbol, &previous_declaration->source_position);
                                return previous_declaration;
                        }

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

                        unsigned new_storage_class = declaration->storage_class;

                        if (is_type_incomplete(prev_type)) {
                                previous_declaration->type = type;
                                prev_type                  = type;
                        }

                        /* pretend no storage class means extern for function
                         * declarations (except if the previous declaration is neither
                         * none nor extern) */
                        if (is_type_function(type)) {
                                if (prev_type->function.unspecified_parameters) {
                                        previous_declaration->type = type;
                                        prev_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(&declaration->source_position,
                                                                         "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;
                                }
                        }

                        if (old_storage_class == STORAGE_CLASS_EXTERN &&
                                        new_storage_class == STORAGE_CLASS_EXTERN) {
warn_redundant_declaration:
                                if (!is_definition           &&
                                    warning.redundant_decls  &&
                                    is_type_valid(prev_type) &&
                                    strcmp(previous_declaration->source_position.input_name, "<builtin>") != 0) {
                                        warningf(&declaration->source_position,
                                                 "redundant declaration for '%Y' (declared %P)",
                                                 symbol, &previous_declaration->source_position);
                                }
                        } else if (current_function == NULL) {
                                if (old_storage_class != STORAGE_CLASS_STATIC &&
                                    new_storage_class == STORAGE_CLASS_STATIC) {
                                        errorf(&declaration->source_position,
                                               "static declaration of '%Y' follows non-static declaration (declared %P)",
                                               symbol, &previous_declaration->source_position);
                                } else if (old_storage_class == STORAGE_CLASS_EXTERN) {
                                        previous_declaration->storage_class          = STORAGE_CLASS_NONE;
                                        previous_declaration->declared_storage_class = STORAGE_CLASS_NONE;
                                } else {
                                        goto warn_redundant_declaration;
                                }
                        } else if (is_type_valid(prev_type)) {
                                if (old_storage_class == new_storage_class) {
                                        errorf(&declaration->source_position,
                                               "redeclaration of '%Y' (declared %P)",
                                               symbol, &previous_declaration->source_position);
                                } else {
                                        errorf(&declaration->source_position,
                                               "redeclaration of '%Y' with different linkage (declared %P)",
                                               symbol, &previous_declaration->source_position);
                                }
                        }
                }

                previous_declaration->modifiers |= declaration->modifiers;
                previous_declaration->is_inline |= declaration->is_inline;
                return previous_declaration;
        } else if (is_type_function(type)) {
                if (is_definition &&
                    declaration->storage_class != STORAGE_CLASS_STATIC) {
                        if (warning.missing_prototypes && !is_sym_main(symbol)) {
                                warningf(&declaration->source_position,
                                         "no previous prototype for '%#T'", orig_type, symbol);
                        } else if (warning.missing_declarations && !is_sym_main(symbol)) {
                                warningf(&declaration->source_position,
                                         "no previous declaration for '%#T'", orig_type,
                                         symbol);
                        }
                }
        } else {
                if (warning.missing_declarations &&
                    scope == global_scope && (
                      declaration->storage_class == STORAGE_CLASS_NONE ||
                      declaration->storage_class == STORAGE_CLASS_THREAD
                    )) {
                        warningf(&declaration->source_position,
                                 "no previous declaration for '%#T'", orig_type, symbol);
                }
        }
finish:
        assert(declaration->parent_scope == NULL);
        assert(scope != NULL);

        declaration->parent_scope = scope;

        environment_push(declaration);
        return append_declaration(declaration);
}

static void parser_error_multiple_definition(declaration_t *declaration,
                const source_position_t *source_position)
{
        errorf(source_position, "multiple definition of symbol '%Y' (declared %P)",
               declaration->symbol, &declaration->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->v.symbol);

                case T___extension__:
                STORAGE_CLASSES
                        return !only_specifiers_qualifiers;

                default:
                        return false;
        }
}

static void parse_init_declarator_rest(declaration_t *declaration)
{
        eat('=');

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

        if (declaration->init.initializer != NULL) {
                parser_error_multiple_definition(declaration, HERE);
        }

        bool must_be_constant = false;
        if (declaration->storage_class == STORAGE_CLASS_STATIC
                        || declaration->storage_class == STORAGE_CLASS_THREAD_STATIC
                        || declaration->parent_scope == global_scope) {
                must_be_constant = true;
        }

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

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

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

        if (!is_type_function(type)) {
                /* § 6.7.5 (22)  array initializers for arrays with unknown size determine
                 * the array type size */
                declaration->type             = env.type;
                declaration->init.initializer = initializer;
        }
}

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

        if (specifiers->declared_storage_class != STORAGE_CLASS_NONE) {
                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.declaration->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;
        }

#ifdef RECORD_EMPTY_DECLARATIONS
        declaration_t *const declaration    = allocate_declaration_zero();
        declaration->type                   = specifiers->type;
        declaration->declared_storage_class = specifiers->declared_storage_class;
        declaration->source_position        = specifiers->source_position;
        declaration->modifiers              = specifiers->modifiers;
        declaration->storage_class          = STORAGE_CLASS_NONE;

        append_declaration(declaration);
#endif
}

static void parse_declaration_rest(declaration_t *ndeclaration,
                const declaration_specifiers_t *specifiers,
                parsed_declaration_func finished_declaration)
{
        add_anchor_token(';');
        add_anchor_token(',');
        while(true) {
                declaration_t *declaration =
                        finished_declaration(ndeclaration, token.type == '=');

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

                if (type->kind != TYPE_FUNCTION &&
                    declaration->is_inline &&
                    is_type_valid(type)) {
                        warningf(&declaration->source_position,
                                 "variable '%Y' declared 'inline'\n", declaration->symbol);
                }

                if (token.type == '=') {
                        parse_init_declarator_rest(declaration);
                }

                if (token.type != ',')
                        break;
                eat(',');

                add_anchor_token('=');
                ndeclaration = parse_declarator(specifiers, /*may_be_abstract=*/false);
                rem_anchor_token('=');
        }
        expect(';');

end_error:
        rem_anchor_token(';');
        rem_anchor_token(',');
}

static declaration_t *finished_kr_declaration(declaration_t *declaration, bool is_definition)
{
        symbol_t *symbol  = declaration->symbol;
        if (symbol == NULL) {
                errorf(HERE, "anonymous declaration not valid as function parameter");
                return declaration;
        }
        namespace_t namespc = (namespace_t) declaration->namespc;
        if (namespc != NAMESPACE_NORMAL) {
                return record_declaration(declaration, false);
        }

        declaration_t *previous_declaration = get_declaration(symbol, namespc);
        if (previous_declaration == NULL ||
                        previous_declaration->parent_scope != scope) {
                errorf(HERE, "expected declaration of a function parameter, found '%Y'",
                       symbol);
                return declaration;
        }

        if (is_definition) {
                errorf(HERE, "parameter %Y is initialised", declaration->symbol);
        }

        if (previous_declaration->type == NULL) {
                previous_declaration->type          = declaration->type;
                previous_declaration->declared_storage_class = declaration->declared_storage_class;
                previous_declaration->storage_class = declaration->storage_class;
                previous_declaration->parent_scope  = scope;
                return previous_declaration;
        } else {
                return record_declaration(declaration, false);
        }
}

static void parse_declaration(parsed_declaration_func finished_declaration)
{
        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 {
                declaration_t *declaration = parse_declarator(&specifiers, /*may_be_abstract=*/false);
                parse_declaration_rest(declaration, &specifiers, finished_declaration);
        }
}

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 (type == type_float) {
                result = type_double;
        }

        return result;
}

static void parse_kr_declaration_list(declaration_t *declaration)
{
        type_t *type = skip_typeref(declaration->type);
        if (!is_type_function(type))
                return;

        if (!type->function.kr_style_parameters)
                return;

        add_anchor_token('{');

        /* push function parameters */
        size_t const top = environment_top();
        scope_push(&declaration->scope);

        declaration_t *parameter = declaration->scope.declarations;
        for ( ; parameter != NULL; parameter = parameter->next) {
                assert(parameter->parent_scope == NULL);
                parameter->parent_scope = scope;
                environment_push(parameter);
        }

        /* parse declaration list */
        while (is_declaration_specifier(&token, false)) {
                parse_declaration(finished_kr_declaration);
        }

        /* pop function parameters */
        assert(scope == &declaration->scope);
        scope_pop();
        environment_pop_to(top);

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

        function_parameter_t *parameters     = NULL;
        function_parameter_t *last_parameter = NULL;

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

                semantic_parameter(parameter_declaration);
                parameter_type = parameter_declaration->type;

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

                function_parameter_t *function_parameter
                        = obstack_alloc(type_obst, sizeof(function_parameter[0]));
                memset(function_parameter, 0, sizeof(function_parameter[0]));

                function_parameter->type = parameter_type;
                if (last_parameter != NULL) {
                        last_parameter->next = function_parameter;
                } else {
                        parameters = function_parameter;
                }
                last_parameter = function_parameter;
        }

        /* § 6.9.1.7: A K&R style parameter list does NOT act as a function
         * prototype */
        new_type->function.parameters             = parameters;
        new_type->function.unspecified_parameters = true;

        type = typehash_insert(new_type);
        if (type != new_type) {
                obstack_free(type_obst, new_type);
        }

        declaration->type = 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->source_position.input_name,
                        current_function->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;

                declaration_t *label = goto_statement->label;

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

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

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

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

                if (is_sym_main(current_function->symbol)) {
                        /* do not issue unused warnings for main */
                        return;
                }
                const declaration_t *parameter = scope->declarations;
                for (; parameter != NULL; parameter = parameter->next) {
                        if (! parameter->used) {
                                print_in_function();
                                warningf(&parameter->source_position,
                                         "unused parameter '%Y'", parameter->symbol);
                        }
                }
        }
        if (warning.unused_variable) {
        }
}

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

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_DECLARATION:
                case STATEMENT_ASM:
                        next = stmt->base.next;
                        break;

                case STATEMENT_COMPOUND:
                        next = stmt->compound.statements;
                        break;

                case STATEMENT_RETURN:
                        noreturn_candidate = false;
                        return;

                case STATEMENT_IF: {
                        if_statement_t const* const ifs = &stmt->ifs;
                        int            const        val = determine_truth(ifs->condition);

                        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 (is_constant_expression(expr)) {
                                long                    const val      = fold_constant(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 (expr->kind == EXPR_CALL) {
                                expression_t const *const func = expr->call.function;
                                if (func->kind == EXPR_REFERENCE) {
                                        declaration_t const *const decl = func->reference.declaration;
                                        if (decl != NULL && decl->modifiers & DM_NORETURN) {
                                                return;
                                        }
                                }
                        }

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

                case STATEMENT_CONTINUE: {
                        statement_t *parent = stmt;
                        for (;;) {
                                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: {
                        statement_t *parent = stmt;
                        for (;;) {
                                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) {
                                statement_t *parent = stmt->base.parent;
                                if (parent == NULL) /* top level goto */
                                        return;
                                next = parent;
                        } else {
                                next = stmt->gotos.label->init.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;
                        int                      const val    = determine_truth(whiles->condition);

                        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          const        val  =
                                cond == NULL ? 1 : determine_truth(cond);

                        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;
                }
        }

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

                        type_t *const type = current_function->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->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:
                        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;
                                int                      const val    = determine_truth(whiles->condition);

                                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;
                                int                  const        val = determine_truth(dw->condition);

                                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          const        val  =
                                        cond == NULL ? 1 : determine_truth(cond);

                                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;
                }
        }

        if (next == NULL) {
                next = stmt->base.parent;
                if (next == NULL) {
                        warningf(&stmt->base.source_position,
                                 "control reaches end of non-void function");
                }
        }

        check_reachable(next);
}

static void check_unreachable(statement_t const* const stmt)
{
        if (!stmt->base.reachable            &&
            stmt->kind != STATEMENT_DO_WHILE &&
            stmt->kind != STATEMENT_FOR      &&
            (stmt->kind != STATEMENT_COMPOUND || stmt->compound.statements == NULL)) {
                warningf(&stmt->base.source_position, "statement is unreachable");
        }

        switch (stmt->kind) {
                case STATEMENT_INVALID:
                case STATEMENT_EMPTY:
                case STATEMENT_RETURN:
                case STATEMENT_DECLARATION:
                case STATEMENT_EXPRESSION:
                case STATEMENT_CONTINUE:
                case STATEMENT_BREAK:
                case STATEMENT_GOTO:
                case STATEMENT_ASM:
                case STATEMENT_LEAVE:
                        break;

                case STATEMENT_COMPOUND:
                        if (stmt->compound.statements)
                                check_unreachable(stmt->compound.statements);
                        break;

                case STATEMENT_IF:
                        check_unreachable(stmt->ifs.true_statement);
                        if (stmt->ifs.false_statement != NULL)
                                check_unreachable(stmt->ifs.false_statement);
                        break;

                case STATEMENT_SWITCH:
                        check_unreachable(stmt->switchs.body);
                        break;

                case STATEMENT_LABEL:
                        check_unreachable(stmt->label.statement);
                        break;

                case STATEMENT_CASE_LABEL:
                        check_unreachable(stmt->case_label.statement);
                        break;

                case STATEMENT_WHILE:
                        check_unreachable(stmt->whiles.body);
                        break;

                case STATEMENT_DO_WHILE:
                        check_unreachable(stmt->do_while.body);
                        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");
                                }
                        }
                        break;

                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");
                                }
                        }

                        check_unreachable(fors->body);
                        break;
                }

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

        if (stmt->base.next)
                check_unreachable(stmt->base.next);
}

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 */
        declaration_t *ndeclaration = parse_declarator(&specifiers, /*may_be_abstract=*/false);

        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_declaration);
                        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;
        }

        type_t *type = ndeclaration->type;

        /* note that we don't skip typerefs: the standard doesn't allow them here
         * (so we can't use is_type_function here) */
        if (type->kind != TYPE_FUNCTION) {
                if (is_type_valid(type)) {
                        errorf(HERE, "declarator '%#T' has a body but is not a function type",
                               type, ndeclaration->symbol);
                }
                eat_block();
                return;
        }

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

                type = typehash_insert(duplicate);
                if (type != duplicate) {
                        obstack_free(type_obst, duplicate);
                }
                ndeclaration->type = type;
        }

        declaration_t *const declaration = record_declaration(ndeclaration, true);
        if (ndeclaration != declaration) {
                declaration->scope = ndeclaration->scope;
        }
        type = skip_typeref(declaration->type);

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

        declaration_t *parameter = declaration->scope.declarations;
        for( ; parameter != NULL; parameter = parameter->next) {
                if (parameter->parent_scope == &ndeclaration->scope) {
                        parameter->parent_scope = scope;
                }
                assert(parameter->parent_scope == NULL
                                || parameter->parent_scope == scope);
                parameter->parent_scope = scope;
                if (parameter->symbol == NULL) {
                        errorf(&parameter->source_position, "parameter name omitted");
                        continue;
                }
                environment_push(parameter);
        }

        if (declaration->init.statement != NULL) {
                parser_error_multiple_definition(declaration, HERE);
                eat_block();
        } else {
                /* parse function body */
                int            label_stack_top      = label_top();
                declaration_t *old_current_function = current_function;
                current_function                    = declaration;
                current_parent                      = NULL;

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

                assert(current_parent   == NULL);
                assert(current_function == declaration);
                current_function = old_current_function;
                label_pop_to(label_stack_top);
        }

        assert(scope == &declaration->scope);
        scope_pop();
        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, source_position);

        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 = skipped_type->base.size * 8;
        }

        if (is_constant_expression(size)) {
                long v = fold_constant(size);

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

        return type;
}

static declaration_t *find_compound_entry(declaration_t *compound_declaration,
                                          symbol_t *symbol)
{
        declaration_t *iter = compound_declaration->scope.declarations;
        for( ; iter != NULL; iter = iter->next) {
                if (iter->namespc != NAMESPACE_NORMAL)
                        continue;

                if (iter->symbol == NULL) {
                        type_t *type = skip_typeref(iter->type);
                        if (is_type_compound(type)) {
                                declaration_t *result
                                        = find_compound_entry(type->compound.declaration, symbol);
                                if (result != NULL)
                                        return result;
                        }
                        continue;
                }

                if (iter->symbol == symbol) {
                        return iter;
                }
        }

        return NULL;
}

static void parse_compound_declarators(declaration_t *struct_declaration,
                const declaration_specifiers_t *specifiers)
{
        declaration_t *last_declaration = struct_declaration->scope.declarations;
        if (last_declaration != NULL) {
                while (last_declaration->next != NULL) {
                        last_declaration = last_declaration->next;
                }
        }

        while (true) {
                declaration_t *declaration;

                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, sym_anonymous);

                        declaration                         = allocate_declaration_zero();
                        declaration->namespc                = NAMESPACE_NORMAL;
                        declaration->declared_storage_class = STORAGE_CLASS_NONE;
                        declaration->storage_class          = STORAGE_CLASS_NONE;
                        declaration->source_position        = source_position;
                        declaration->modifiers              = specifiers->modifiers;
                        declaration->type                   = type;
                } else {
                        declaration = parse_declarator(specifiers,/*may_be_abstract=*/true);

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

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

                                type_t *bitfield_type = make_bitfield_type(orig_type, size,
                                                &source_position, declaration->symbol);
                                declaration->type = bitfield_type;
                        } else {
                                /* TODO we ignore arrays for now... what is missing is a check
                                 * that they're at the end of the struct */
                                if (is_type_incomplete(type) && !is_type_array(type)) {
                                        errorf(HERE,
                                               "compound member '%Y' has incomplete type '%T'",
                                               declaration->symbol, orig_type);
                                } else if (is_type_function(type)) {
                                        errorf(HERE, "compound member '%Y' must not have function type '%T'",
                                               declaration->symbol, orig_type);
                                }
                        }
                }

                /* make sure we don't define a symbol multiple times */
                symbol_t *symbol = declaration->symbol;
                if (symbol != NULL) {
                        declaration_t *prev_decl
                                = find_compound_entry(struct_declaration, symbol);

                        if (prev_decl != NULL) {
                                assert(prev_decl->symbol == symbol);
                                errorf(&declaration->source_position,
                                       "multiple declarations of symbol '%Y' (declared %P)",
                                       symbol, &prev_decl->source_position);
                        }
                }

                /* append declaration */
                if (last_declaration != NULL) {
                        last_declaration->next = declaration;
                } else {
                        struct_declaration->scope.declarations = declaration;
                }
                last_declaration = declaration;

                if (token.type != ',')
                        break;
                next_token();
        }
        expect(';');

end_error:
        ;
}

static void parse_compound_type_entries(declaration_t *compound_declaration)
{
        eat('{');
        add_anchor_token('}');

        while (token.type != '}' && token.type != T_EOF) {
                declaration_specifiers_t specifiers;
                memset(&specifiers, 0, sizeof(specifiers));
                parse_declaration_specifiers(&specifiers);

                parse_compound_declarators(compound_declaration, &specifiers);
        }
        rem_anchor_token('}');

        if (token.type == T_EOF) {
                errorf(HERE, "EOF while parsing struct");
        }
        next_token();
}

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

        type_t *result = parse_abstract_declarator(specifiers.type);

        return result;
}




typedef expression_t* (*parse_expression_function) (unsigned precedence);
typedef expression_t* (*parse_expression_infix_function) (unsigned precedence,
                                                          expression_t *left);

typedef struct expression_parser_function_t expression_parser_function_t;
struct expression_parser_function_t {
        unsigned                         precedence;
        parse_expression_function        parser;
        unsigned                         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();
}

/**
 * Parse a string constant.
 */
static expression_t *parse_string_const(void)
{
        wide_string_t wres;
        if (token.type == T_STRING_LITERAL) {
                string_t res = token.v.string;
                next_token();
                while (token.type == T_STRING_LITERAL) {
                        res = concat_strings(&res, &token.v.string);
                        next_token();
                }
                if (token.type != T_WIDE_STRING_LITERAL) {
                        expression_t *const cnst = allocate_expression_zero(EXPR_STRING_LITERAL);
                        /* note: that we use type_char_ptr here, which is already the
                         * automatic converted type. revert_automatic_type_conversion
                         * will construct the array type */
                        cnst->base.type    = warning.write_strings ? type_const_char_ptr : type_char_ptr;
                        cnst->string.value = res;
                        return cnst;
                }

                wres = concat_string_wide_string(&res, &token.v.wide_string);
        } else {
                wres = token.v.wide_string;
        }
        next_token();

        for (;;) {
                switch (token.type) {
                        case T_WIDE_STRING_LITERAL:
                                wres = concat_wide_strings(&wres, &token.v.wide_string);
                                break;

                        case T_STRING_LITERAL:
                                wres = concat_wide_string_string(&wres, &token.v.string);
                                break;

                        default: {
                                expression_t *const cnst = allocate_expression_zero(EXPR_WIDE_STRING_LITERAL);
                                cnst->base.type         = warning.write_strings ? type_const_wchar_t_ptr : type_wchar_t_ptr;
                                cnst->wide_string.value = wres;
                                return cnst;
                        }
                }
                next_token();
        }
}

/**
 * Parse an integer constant.
 */
static expression_t *parse_int_const(void)
{
        expression_t *cnst         = allocate_expression_zero(EXPR_CONST);
        cnst->base.source_position = *HERE;
        cnst->base.type            = token.datatype;
        cnst->conste.v.int_value   = token.v.intvalue;

        next_token();

        return cnst;
}

/**
 * Parse a character constant.
 */
static expression_t *parse_character_constant(void)
{
        expression_t *cnst = allocate_expression_zero(EXPR_CHARACTER_CONSTANT);

        cnst->base.source_position = *HERE;
        cnst->base.type            = token.datatype;
        cnst->conste.v.character   = token.v.string;

        if (cnst->conste.v.character.size != 1) {
                if (warning.multichar && GNU_MODE) {
                        warningf(HERE, "multi-character character constant");
                } else {
                        errorf(HERE, "more than 1 characters in character constant");
                }
        }
        next_token();

        return cnst;
}

/**
 * Parse a wide character constant.
 */
static expression_t *parse_wide_character_constant(void)
{
        expression_t *cnst = allocate_expression_zero(EXPR_WIDE_CHARACTER_CONSTANT);

        cnst->base.source_position    = *HERE;
        cnst->base.type               = token.datatype;
        cnst->conste.v.wide_character = token.v.wide_string;

        if (cnst->conste.v.wide_character.size != 1) {
                if (warning.multichar && GNU_MODE) {
                        warningf(HERE, "multi-character character constant");
                } else {
                        errorf(HERE, "more than 1 characters in character constant");
                }
        }
        next_token();

        return cnst;
}

/**
 * Parse a float constant.
 */
static expression_t *parse_float_const(void)
{
        expression_t *cnst         = allocate_expression_zero(EXPR_CONST);
        cnst->base.type            = token.datatype;
        cnst->conste.v.float_value = token.v.floatvalue;

        next_token();

        return cnst;
}

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

        type_t *type = typehash_insert(ntype);
        if (type != ntype) {
                free_type(ntype);
        }

        declaration_t *const declaration    = allocate_declaration_zero();
        declaration->storage_class          = STORAGE_CLASS_EXTERN;
        declaration->declared_storage_class = STORAGE_CLASS_EXTERN;
        declaration->type                   = type;
        declaration->symbol                 = symbol;
        declaration->source_position        = *source_position;
        declaration->implicit               = true;

        bool strict_prototypes_old = warning.strict_prototypes;
        warning.strict_prototypes  = false;
        record_declaration(declaration, false);
        warning.strict_prototypes = strict_prototypes_old;

        return declaration;
}

/**
 * Creates a return_type (func)(argument_type) function type if not
 * already exists.
 */
static type_t *make_function_2_type(type_t *return_type, type_t *argument_type1,
                                    type_t *argument_type2)
{
        function_parameter_t *parameter2
                = obstack_alloc(type_obst, sizeof(parameter2[0]));
        memset(parameter2, 0, sizeof(parameter2[0]));
        parameter2->type = argument_type2;

        function_parameter_t *parameter1
                = obstack_alloc(type_obst, sizeof(parameter1[0]));
        memset(parameter1, 0, sizeof(parameter1[0]));
        parameter1->type = argument_type1;
        parameter1->next = parameter2;

        type_t *type               = allocate_type_zero(TYPE_FUNCTION, &builtin_source_position);
        type->function.return_type = return_type;
        type->function.parameters  = parameter1;

        type_t *result = typehash_insert(type);
        if (result != type) {
                free_type(type);
        }

        return result;
}

/**
 * Creates a return_type (func)(argument_type) function type if not
 * already exists.
 *
 * @param return_type    the return type
 * @param argument_type  the argument type
 */
static type_t *make_function_1_type(type_t *return_type, type_t *argument_type)
{
        function_parameter_t *parameter
                = obstack_alloc(type_obst, sizeof(parameter[0]));
        memset(parameter, 0, sizeof(parameter[0]));
        parameter->type = argument_type;

        type_t *type               = allocate_type_zero(TYPE_FUNCTION, &builtin_source_position);
        type->function.return_type = return_type;
        type->function.parameters  = parameter;

        type_t *result = typehash_insert(type);
        if (result != type) {
                free_type(type);
        }

        return result;
}

static type_t *make_function_0_type(type_t *return_type)
{
        type_t *type               = allocate_type_zero(TYPE_FUNCTION, &builtin_source_position);
        type->function.return_type = return_type;
        type->function.parameters  = NULL;

        type_t *result = typehash_insert(type);
        if (result != type) {
                free_type(type);
        }

        return result;
}

/**
 * Creates a function type for some function like builtins.
 *
 * @param symbol   the symbol describing the builtin
 */
static type_t *get_builtin_symbol_type(symbol_t *symbol)
{
        switch(symbol->ID) {
        case T___builtin_alloca:
                return make_function_1_type(type_void_ptr, type_size_t);
        case T___builtin_huge_val:
                return make_function_0_type(type_double);
        case T___builtin_nan:
                return make_function_1_type(type_double, type_char_ptr);
        case T___builtin_nanf:
                return make_function_1_type(type_float, type_char_ptr);
        case T___builtin_nand:
                return make_function_1_type(type_long_double, type_char_ptr);
        case T___builtin_va_end:
                return make_function_1_type(type_void, type_valist);
        case T___builtin_expect:
                return make_function_2_type(type_long, type_long, type_long);
        default:
                internal_errorf(HERE, "not implemented builtin symbol found");
        }
}

/**
 * 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: return expression->reference.declaration->type;

                case EXPR_SELECT:
                        return get_qualified_type(expression->select.compound_entry->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);
                        assert(is_type_pointer(type));
                        return type->pointer.points_to;
                }

                case EXPR_BUILTIN_SYMBOL:
                        return get_builtin_symbol_type(expression->builtin_symbol.symbol);

                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_valid(type_left))
                                return type_left;
                        assert(is_type_pointer(type_left));
                        return type_left->pointer.points_to;
                }

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

                case EXPR_WIDE_STRING_LITERAL: {
                        size_t size = expression->wide_string.value.size;
                        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;
}

static expression_t *parse_reference(void)
{
        expression_t *expression = allocate_expression_zero(EXPR_REFERENCE);

        reference_expression_t *ref = &expression->reference;
        symbol_t *const symbol = token.v.symbol;

        declaration_t *declaration = get_declaration(symbol, NAMESPACE_NORMAL);

        if (declaration == NULL) {
                if (!strict_mode && look_ahead(1)->type == '(') {
                        /* an implicitly declared function */
                        if (warning.implicit_function_declaration) {
                                warningf(HERE, "implicit declaration of function '%Y'",
                                        symbol);
                        }

                        declaration = create_implicit_function(symbol, HERE);
                } else {
                        errorf(HERE, "unknown symbol '%Y' found.", symbol);
                        declaration = create_error_declaration(symbol, STORAGE_CLASS_NONE);
                }
        }

        type_t *orig_type = declaration->type;

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

        ref->declaration = declaration;
        ref->base.type   = type;

        /* this declaration is used */
        declaration->used = true;

        if (declaration->parent_scope != global_scope &&
            declaration->parent_scope->depth < current_function->scope.depth &&
            is_type_valid(orig_type) && !is_type_function(orig_type)) {
                /* access of a variable from an outer function */
                declaration->address_taken     = true;
                ref->is_outer_ref              = true;
                current_function->need_closure = true;
        }

        /* check for deprecated functions */
        if (warning.deprecated_declarations &&
            declaration->modifiers & DM_DEPRECATED) {
                char const *const prefix = is_type_function(declaration->type) ?
                        "function" : "variable";

                if (declaration->deprecated_string != NULL) {
                        warningf(HERE, "%s '%Y' is deprecated (declared %P): \"%s\"",
                                prefix, declaration->symbol, &declaration->source_position,
                                declaration->deprecated_string);
                } else {
                        warningf(HERE, "%s '%Y' is deprecated (declared %P)", prefix,
                                declaration->symbol, &declaration->source_position);
                }
        }
        if (warning.init_self && declaration == current_init_decl && !in_type_prop) {
                current_init_decl = NULL;
                warningf(HERE, "variable '%#T' is initialized by itself",
                        declaration->type, declaration->symbol);
        }

        next_token();
        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.declaration      = 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(')');

        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_sub_expression(20);
        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);
        expression->statement.statement  = statement;
        expression->base.source_position = statement->base.source_position;

        /* 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 {
                warningf(&expression->base.source_position, "empty statement expression ({})");
        }
        expression->base.type = type;

        rem_anchor_token(')');
        expect(')');

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.v.symbol)) {
                        return parse_cast();
                }
        }

        add_anchor_token(')');
        expression_t *result = parse_expression();
        rem_anchor_token(')');
        expect(')');

end_error:
        return result;
}

static expression_t *parse_function_keyword(void)
{
        next_token();
        /* 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;

        return expression;
}

static expression_t *parse_pretty_function_keyword(void)
{
        eat(T___PRETTY_FUNCTION__);

        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;

        return expression;
}

static expression_t *parse_funcsig_keyword(void)
{
        eat(T___FUNCSIG__);

        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;

        return expression;
}

static expression_t *parse_funcdname_keyword(void)
{
        eat(T___FUNCDNAME__);

        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;

        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.v.symbol;
        next_token();

        designator_t *last_designator = result;
        while(true) {
                if (token.type == '.') {
                        next_token();
                        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.v.symbol;
                        next_token();

                        last_designator->next = designator;
                        last_designator       = designator;
                        continue;
                }
                if (token.type == '[') {
                        next_token();
                        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(']');
                        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)
{
        eat(T___builtin_offsetof);

        expression_t *expression = allocate_expression_zero(EXPR_OFFSETOF);
        expression->base.type    = type_size_t;

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

        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)
{
        eat(T___builtin_va_start);

        expression_t *expression = allocate_expression_zero(EXPR_VA_START);

        expect('(');
        add_anchor_token(',');
        expression->va_starte.ap = parse_assignment_expression();
        rem_anchor_token(',');
        expect(',');
        expression_t *const expr = parse_assignment_expression();
        if (expr->kind == EXPR_REFERENCE) {
                declaration_t *const decl = expr->reference.declaration;
                if (decl->parent_scope != &current_function->scope || decl->next != NULL) {
                        errorf(&expr->base.source_position,
                               "second argument of 'va_start' must be last parameter of the current function");
                }
                expression->va_starte.parameter = decl;
                expect(')');
                return expression;
        }
        expect(')');
end_error:
        return create_invalid_expression();
}

/**
 * Parses a _builtin_va_arg() expression.
 */
static expression_t *parse_va_arg(void)
{
        eat(T___builtin_va_arg);

        expression_t *expression = allocate_expression_zero(EXPR_VA_ARG);

        expect('(');
        expression->va_arge.ap = parse_assignment_expression();
        expect(',');
        expression->base.type = parse_typename();
        expect(')');

        return expression;
end_error:
        return create_invalid_expression();
}

static expression_t *parse_builtin_symbol(void)
{
        expression_t *expression = allocate_expression_zero(EXPR_BUILTIN_SYMBOL);

        symbol_t *symbol = token.v.symbol;

        expression->builtin_symbol.symbol = symbol;
        next_token();

        type_t *type = get_builtin_symbol_type(symbol);
        type = automatic_type_conversion(type);

        expression->base.type = type;
        return expression;
}

/**
 * Parses a __builtin_constant() expression.
 */
static expression_t *parse_builtin_constant(void)
{
        eat(T___builtin_constant_p);

        expression_t *expression = allocate_expression_zero(EXPR_BUILTIN_CONSTANT_P);

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

        return expression;
end_error:
        return create_invalid_expression();
}

/**
 * Parses a __builtin_prefetch() expression.
 */
static expression_t *parse_builtin_prefetch(void)
{
        eat(T___builtin_prefetch);

        expression_t *expression = allocate_expression_zero(EXPR_BUILTIN_PREFETCH);

        expect('(');
        add_anchor_token(')');
        expression->builtin_prefetch.adr = parse_assignment_expression();
        if (token.type == ',') {
                next_token();
                expression->builtin_prefetch.rw = parse_assignment_expression();
        }
        if (token.type == ',') {
                next_token();
                expression->builtin_prefetch.locality = parse_assignment_expression();
        }
        rem_anchor_token(')');
        expect(')');
        expression->base.type = type_void;

        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");
                break;
        }
        expression->base.source_position = *HERE;
        next_token();

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

        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();
}

#if 0
/**
 * Parses a __builtin_expect() expression.
 */
static expression_t *parse_builtin_expect(void)
{
        eat(T___builtin_expect);

        expression_t *expression
                = allocate_expression_zero(EXPR_BINARY_BUILTIN_EXPECT);

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

        expression->base.type = expression->binary.left->base.type;

        return expression;
end_error:
        return create_invalid_expression();
}
#endif

/**
 * Parses a MS assume() expression.
 */
static expression_t *parse_assume(void)
{
        eat(T__assume);

        expression_t *expression
                = allocate_expression_zero(EXPR_UNARY_ASSUME);

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

        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 declaration_t *get_label(symbol_t *symbol)
{
        declaration_t *candidate;
        assert(current_function != NULL);

        candidate = get_declaration(symbol, NAMESPACE_LOCAL_LABEL);
        /* if we found a local label, we already created the declaration */
        if (candidate != NULL) {
                if (candidate->parent_scope != scope) {
                        assert(candidate->parent_scope->depth < scope->depth);
                        current_function->goto_to_outer = true;
                }
                return candidate;
        }

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

        /* otherwise we need to create a new one */
        declaration_t *const declaration = allocate_declaration_zero();
        declaration->namespc       = NAMESPACE_LABEL;
        declaration->symbol        = symbol;

        label_push(declaration);

        return declaration;
}

/**
 * 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.v.symbol;
        next_token();

        declaration_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.declaration = label;
        return expression;
end_error:
        return create_invalid_expression();
}

/**
 * Parse a microsoft __noop expression.
 */
static expression_t *parse_noop_expression(void)
{
        source_position_t source_position = *HERE;
        eat(T___noop);

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

                if (token.type != ')') {
                        while(true) {
                                (void)parse_assignment_expression();
                                if (token.type != ',')
                                        break;
                                next_token();
                        }
                }
        }
        rem_anchor_token(',');
        rem_anchor_token(')');
        expect(')');

        /* the result is a (int)0 */
        expression_t *cnst         = allocate_expression_zero(EXPR_CONST);
        cnst->base.source_position = source_position;
        cnst->base.type            = type_int;
        cnst->conste.v.int_value   = 0;
        cnst->conste.is_ms_noop    = true;

        return cnst;

end_error:
        return create_invalid_expression();
}

/**
 * Parses a primary expression.
 */
static expression_t *parse_primary_expression(void)
{
        switch (token.type) {
                case T_INTEGER:                  return parse_int_const();
                case T_CHARACTER_CONSTANT:       return parse_character_constant();
                case T_WIDE_CHARACTER_CONSTANT:  return parse_wide_character_constant();
                case T_FLOATINGPOINT:            return parse_float_const();
                case T_STRING_LITERAL:
                case T_WIDE_STRING_LITERAL:      return parse_string_const();
                case T_IDENTIFIER:               return parse_reference();
                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_expect:
                case T___builtin_alloca:
                case T___builtin_nan:
                case T___builtin_nand:
                case T___builtin_nanf:
                case T___builtin_huge_val:
                case T___builtin_va_end:         return parse_builtin_symbol();
                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_prefetch:       return parse_builtin_prefetch();
                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();
        }

        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(unsigned precedence,
                                            expression_t *left)
{
        (void) precedence;

        eat('[');
        add_anchor_token(']');

        expression_t *inside = parse_expression();

        expression_t *expression = allocate_expression_zero(EXPR_ARRAY_ACCESS);

        array_access_expression_t *array_access = &expression->array_access;

        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;
        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(']');
        if (token.type == ']') {
                next_token();
        } else {
                parse_error_expected("Problem while parsing array access", ']', NULL);
        }
        return expression;
}

static expression_t *parse_typeprop(expression_kind_t const kind,
                                    source_position_t const pos,
                                    unsigned const precedence)
{
        expression_t  *tp_expression = allocate_expression_zero(kind);
        tp_expression->base.type            = type_size_t;
        tp_expression->base.source_position = pos;

        char const* const what = kind == EXPR_SIZEOF ? "sizeof" : "alignof";

        /* we only refer to a type property, mark this case */
        bool old     = in_type_prop;
        in_type_prop = true;
        if (token.type == '(' && is_declaration_specifier(look_ahead(1), true)) {
                next_token();
                add_anchor_token(')');
                type_t* const orig_type = parse_typename();
                tp_expression->typeprop.type = orig_type;

                type_t const* const type = skip_typeref(orig_type);
                char const* const wrong_type =
                        is_type_incomplete(type)    ? "incomplete"          :
                        type->kind == TYPE_FUNCTION ? "function designator" :
                        type->kind == TYPE_BITFIELD ? "bitfield"            :
                        NULL;
                if (wrong_type != NULL) {
                        errorf(&pos, "operand of %s expression must not be %s type '%T'",
                               what, wrong_type, type);
                }

                rem_anchor_token(')');
                expect(')');
        } else {
                expression_t *expression = parse_sub_expression(precedence);

                type_t* const orig_type = revert_automatic_type_conversion(expression);
                expression->base.type = orig_type;

                type_t const* const type = skip_typeref(orig_type);
                char const* const wrong_type =
                        is_type_incomplete(type)    ? "incomplete"          :
                        type->kind == TYPE_FUNCTION ? "function designator" :
                        type->kind == TYPE_BITFIELD ? "bitfield"            :
                        NULL;
                if (wrong_type != NULL) {
                        errorf(&pos, "operand of %s expression must not be expression of %s type '%T'", what, wrong_type, type);
                }

                tp_expression->typeprop.type          = expression->base.type;
                tp_expression->typeprop.tp_expression = expression;
        }

end_error:
        in_type_prop = old;
        return tp_expression;
}

static expression_t *parse_sizeof(unsigned precedence)
{
        source_position_t pos = *HERE;
        eat(T_sizeof);
        return parse_typeprop(EXPR_SIZEOF, pos, precedence);
}

static expression_t *parse_alignof(unsigned precedence)
{
        source_position_t pos = *HERE;
        eat(T___alignof__);
        return parse_typeprop(EXPR_ALIGNOF, pos, precedence);
}

static expression_t *parse_select_expression(unsigned precedence,
                                             expression_t *compound)
{
        (void) precedence;
        assert(token.type == '.' || token.type == T_MINUSGREATER);

        bool is_pointer = (token.type == T_MINUSGREATER);
        next_token();

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

        if (token.type != T_IDENTIFIER) {
                parse_error_expected("while parsing select", T_IDENTIFIER, NULL);
                return select;
        }
        symbol_t *symbol = token.v.symbol;
        next_token();

        type_t *const orig_type = compound->base.type;
        type_t *const type      = skip_typeref(orig_type);

        type_t *type_left;
        bool    saw_error = false;
        if (is_type_pointer(type)) {
                if (!is_pointer) {
                        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 (is_pointer && is_type_valid(type)) {
                        errorf(HERE, "left hand side of '->' is not a pointer, but '%T'", orig_type);
                        saw_error = true;
                }
                type_left = type;
        }

        declaration_t *entry;
        if (type_left->kind == TYPE_COMPOUND_STRUCT ||
            type_left->kind == TYPE_COMPOUND_UNION) {
                declaration_t *const declaration = type_left->compound.declaration;

                if (!declaration->init.complete) {
                        errorf(HERE, "request for member '%Y' of incomplete type '%T'",
                               symbol, type_left);
                        goto create_error_entry;
                }

                entry = find_compound_entry(declaration, symbol);
                if (entry == NULL) {
                        errorf(HERE, "'%T' has no member named '%Y'", orig_type, symbol);
                        goto create_error_entry;
                }
        } else {
                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);
                }
create_error_entry:
                entry         = allocate_declaration_zero();
                entry->symbol = symbol;
        }

        select->select.compound_entry = entry;

        type_t *const res_type =
                get_qualified_type(entry->type, type_left->base.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);

        type_t *skipped = skip_typeref(res_type);
        if (skipped->kind == TYPE_BITFIELD) {
                select->base.type = skipped->bitfield.base_type;
        }

        return select;
}

static void check_call_argument(const function_parameter_t *parameter,
                                call_argument_t *argument, unsigned pos)
{
        type_t         *expected_type      = parameter->type;
        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)
                        && (expected_type_skip->base.modifiers
                                & TYPE_MODIFIER_TRANSPARENT_UNION)) {
                declaration_t  *union_decl = expected_type_skip->compound.declaration;

                declaration_t *declaration = union_decl->scope.declarations;
                type_t        *best_type   = NULL;
                for ( ; declaration != NULL; declaration = declaration->next) {
                        type_t *decl_type = 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(argument->expression,
                                                    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);
                }
        }
}

/**
 * Parse a call expression, ie. expression '( ... )'.
 *
 * @param expression  the function address
 */
static expression_t *parse_call_expression(unsigned precedence,
                                           expression_t *expression)
{
        (void) precedence;
        expression_t *result = allocate_expression_zero(EXPR_CALL);
        result->base.source_position = expression->base.source_position;

        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 *last_argument = NULL;

                while (true) {
                        call_argument_t *argument = allocate_ast_zero(sizeof(argument[0]));

                        argument->expression = parse_assignment_expression();
                        if (last_argument == NULL) {
                                call->arguments = argument;
                        } else {
                                last_argument->next = argument;
                        }
                        last_argument = argument;

                        if (token.type != ',')
                                break;
                        next_token();
                }
        }
        rem_anchor_token(',');
        rem_anchor_token(')');
        expect(')');

        if (function_type == NULL)
                return result;

        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, 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( ; argument != NULL; argument = argument->next) {
                type_t *type = argument->expression->base.type;

                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");
        }

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.declaration == type2->compound.declaration;
}

/**
 * Parse a conditional expression, ie. 'expression ? ... : ...'.
 *
 * @param expression  the conditional expression
 */
static expression_t *parse_conditional_expression(unsigned precedence,
                                                  expression_t *expression)
{
        expression_t *result = allocate_expression_zero(EXPR_CONDITIONAL);

        conditional_expression_t *conditional = &result->conditional;
        conditional->base.source_position = *HERE;
        conditional->condition            = expression;

        eat('?');
        add_anchor_token(':');

        /* 6.5.15.2 */
        type_t *const condition_type_orig = expression->base.type;
        type_t *const condition_type      = skip_typeref(condition_type_orig);
        if (!is_type_scalar(condition_type) && is_type_valid(condition_type)) {
                type_error("expected a scalar type in conditional condition",
                           &expression->base.source_position, condition_type_orig);
        }

        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(':');
        expression_t *false_expression = parse_sub_expression(precedence);

        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)) {
                if (!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);

                true_expression  = create_implicit_cast(true_expression, result_type);
                false_expression = create_implicit_cast(false_expression, result_type);

                conditional->true_expression  = true_expression;
                conditional->false_expression = false_expression;
                conditional->base.type        = result_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 {
                                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)) {
                        warningf(&conditional->base.source_position,
                                        "pointer/integer type mismatch in conditional expression ('%T' and '%T')", true_type, false_type);
                        result_type = pointer_type;
                } else {
                        type_error_incompatible("while parsing conditional",
                                        &expression->base.source_position, true_type, false_type);
                        result_type = type_error_type;
                }
        } else {
                /* TODO: one pointer to void*, other some pointer */

                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;
end_error:
        return create_invalid_expression();
}

/**
 * Parse an extension expression.
 */
static expression_t *parse_extension(unsigned precedence)
{
        eat(T___extension__);

        bool old_gcc_extension   = in_gcc_extension;
        in_gcc_extension         = true;
        expression_t *expression = parse_sub_expression(precedence);
        in_gcc_extension         = old_gcc_extension;
        return expression;
}

/**
 * Parse a __builtin_classify_type() expression.
 */
static expression_t *parse_builtin_classify_type(const unsigned precedence)
{
        eat(T___builtin_classify_type);

        expression_t *result = allocate_expression_zero(EXPR_CLASSIFY_TYPE);
        result->base.type    = type_int;

        expect('(');
        add_anchor_token(')');
        expression_t *expression = parse_sub_expression(precedence);
        rem_anchor_token(')');
        expect(')');
        result->classify_type.type_expression = expression;

        return result;
end_error:
        return create_invalid_expression();
}

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)
{
        switch (expression->kind) {
        case EXPR_REFERENCE:
        case EXPR_ARRAY_ACCESS:
        case EXPR_SELECT:
        case EXPR_UNARY_DEREFERENCE:
                return true;

        default:
                return false;
        }
}

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 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;

        if (!regular_take_address &&
            !is_type_function(skip_typeref(expr->reference.declaration->type))) {
                return NULL;
        }

        return expr;
}

static void warn_function_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.declaration->symbol);
        }
}

static void semantic_not(unary_expression_t *expression)
{
        type_t *const orig_type = expression->value->base.type;
        type_t *const type      = skip_typeref(orig_type);
        if (!is_type_scalar(type) && is_type_valid(type)) {
                errorf(&expression->base.source_position,
                       "operand of ! must be of scalar type");
        }

        warn_function_address_as_bool(expression->value);

        expression->base.type = 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;

        declaration_t *const declaration = expression->reference.declaration;
        /* happens for parse errors */
        if (declaration == NULL)
                return;

        if (declaration->storage_class == STORAGE_CLASS_REGISTER && !may_be_register) {
                errorf(&expression->base.source_position,
                                "address of register variable '%Y' requested",
                                declaration->symbol);
        } else {
                declaration->address_taken = 1;
        }
}

/**
 * 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;
        if (!is_type_valid(orig_type))
                return;

        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(unsigned precedence)            \
{                                                                              \
        expression_t *unary_expression                                             \
                = allocate_expression_zero(unexpression_type);                         \
        unary_expression->base.source_position = *HERE;                            \
        eat(token_type);                                                           \
        unary_expression->unary.value = parse_sub_expression(precedence);          \
                                                                                   \
        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(unsigned precedence,           \
                                               expression_t *left)            \
{                                                                             \
        (void) precedence;                                                        \
                                                                              \
        expression_t *unary_expression                                            \
                = allocate_expression_zero(unexpression_type);                        \
        unary_expression->base.source_position = *HERE;                           \
        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(right) == 0) {
                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 semantic_shift_op(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;
        }

        type_left  = promote_integer(type_left);
        type_right = promote_integer(type_right);

        expression->left      = create_implicit_cast(left, type_left);
        expression->right     = create_implicit_cast(right, type_right);
        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;
                return;
        } 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;
                return;
        } 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)) {
                                warningf(pos, "subtracting pointers to void");
                        } else {
                                errorf(pos, "subtracting pointers to non-object types '%T'",
                                       orig_type_left);
                        }
                }
                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");
        }
}

/**
 * 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.declaration->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.declaration->symbol);
                }
        }

        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)) {
                /* test for signed vs unsigned compares */
                if (warning.sign_compare &&
                    (expression->base.kind != EXPR_BINARY_EQUAL &&
                     expression->base.kind != EXPR_BINARY_NOTEQUAL) &&
                    (is_type_signed(type_left) != is_type_signed(type_right))) {

                        /* check if 1 of the operands is a constant, in this case we just
                         * check wether we can safely represent the resulting constant in
                         * the type of the other operand. */
                        expression_t *const_expr = NULL;
                        expression_t *other_expr = NULL;

                        if (is_constant_expression(left)) {
                                const_expr = left;
                                other_expr = right;
                        } else if (is_constant_expression(right)) {
                                const_expr = right;
                                other_expr = left;
                        }

                        if (const_expr != NULL) {
                                type_t *other_type = skip_typeref(other_expr->base.type);
                                long    val        = fold_constant(const_expr);
                                /* TODO: check if val can be represented by other_type */
                                (void) other_type;
                                (void) val;
                        }
                        warningf(&expression->base.source_position,
                                 "comparison between signed and unsigned");
                }
                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;
                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 = type_int;
}

/**
 * Checks if a compound type has constant fields.
 */
static bool has_const_fields(const compound_type_t *type)
{
        const scope_t       *scope       = &type->declaration->scope;
        const declaration_t *declaration = scope->declarations;

        for (; declaration != NULL; declaration = declaration->next) {
                if (declaration->namespc != NAMESPACE_NORMAL)
                        continue;

                const type_t *decl_type = skip_typeref(declaration->type);
                if (decl_type->base.qualifiers & TYPE_QUALIFIER_CONST)
                        return true;
        }
        /* TODO */
        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 (is_type_array(type_left)) {
                errorf(HERE, "cannot assign to arrays ('%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);
        }
}

/**
 * Check the semantic restrictions of a logical expression.
 */
static void semantic_logical_op(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);

        warn_function_address_as_bool(left);
        warn_function_address_as_bool(right);

        if (!is_type_scalar(type_left) || !is_type_scalar(type_right)) {
                /* TODO: improve error message */
                if (is_type_valid(type_left) && is_type_valid(type_right)) {
                        errorf(&expression->base.source_position,
                               "operation needs scalar types");
                }
                return;
        }

        expression->base.type = 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;
                /* suppress the warning for microsoft __noop operations */
                case EXPR_CONST:                     return expr->conste.is_ms_noop;
                case EXPR_CHARACTER_CONSTANT:        return false;
                case EXPR_WIDE_CHARACTER_CONSTANT:   return false;
                case EXPR_STRING_LITERAL:            return false;
                case EXPR_WIDE_STRING_LITERAL:       return false;
                case EXPR_LABEL_ADDRESS:             return false;

                case EXPR_CALL: {
                        const call_expression_t *const call = &expr->call;
                        if (call->function->kind != EXPR_BUILTIN_SYMBOL)
                                return true;

                        switch (call->function->builtin_symbol.symbol->ID) {
                                case T___builtin_va_end: return true;
                                default:                 return false;
                        }
                }

                /* Generate the warning if either the left or right hand side of a
                 * conditional expression has no effect */
                case EXPR_CONDITIONAL: {
                        const conditional_expression_t *const cond = &expr->conditional;
                        return
                                expression_has_effect(cond->true_expression) &&
                                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_SYMBOL:            break; /* handled in EXPR_CALL */
                case EXPR_BUILTIN_CONSTANT_P:        return false;
                case EXPR_BUILTIN_PREFETCH:          return true;
                case EXPR_OFFSETOF:                  return false;
                case EXPR_VA_START:                  return true;
                case EXPR_VA_ARG:                    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_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_BUILTIN_EXPECT:     return true;
                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;
}

#define CREATE_BINEXPR_PARSER(token_type, binexpression_type, sfunc, lr)  \
static expression_t *parse_##binexpression_type(unsigned precedence,      \
                                                expression_t *left)       \
{                                                                         \
        expression_t *binexpr = allocate_expression_zero(binexpression_type); \
        binexpr->base.source_position = *HERE;                                \
        binexpr->binary.left          = left;                                 \
        eat(token_type);                                                      \
                                                                          \
        expression_t *right = parse_sub_expression(precedence + lr);          \
                                                                          \
        binexpr->binary.right = right;                                        \
        sfunc(&binexpr->binary);                                              \
                                                                          \
        return binexpr;                                                       \
}

CREATE_BINEXPR_PARSER(',', EXPR_BINARY_COMMA,    semantic_comma, 1)
CREATE_BINEXPR_PARSER('*', EXPR_BINARY_MUL,      semantic_binexpr_arithmetic, 1)
CREATE_BINEXPR_PARSER('/', EXPR_BINARY_DIV,      semantic_divmod_arithmetic, 1)
CREATE_BINEXPR_PARSER('%', EXPR_BINARY_MOD,      semantic_divmod_arithmetic, 1)
CREATE_BINEXPR_PARSER('+', EXPR_BINARY_ADD,      semantic_add, 1)
CREATE_BINEXPR_PARSER('-', EXPR_BINARY_SUB,      semantic_sub, 1)
CREATE_BINEXPR_PARSER('<', EXPR_BINARY_LESS,     semantic_comparison, 1)
CREATE_BINEXPR_PARSER('>', EXPR_BINARY_GREATER,  semantic_comparison, 1)
CREATE_BINEXPR_PARSER('=', EXPR_BINARY_ASSIGN,   semantic_binexpr_assign, 0)

CREATE_BINEXPR_PARSER(T_EQUALEQUAL,           EXPR_BINARY_EQUAL,
                      semantic_comparison, 1)
CREATE_BINEXPR_PARSER(T_EXCLAMATIONMARKEQUAL, EXPR_BINARY_NOTEQUAL,
                      semantic_comparison, 1)
CREATE_BINEXPR_PARSER(T_LESSEQUAL,            EXPR_BINARY_LESSEQUAL,
                      semantic_comparison, 1)
CREATE_BINEXPR_PARSER(T_GREATEREQUAL,         EXPR_BINARY_GREATEREQUAL,
                      semantic_comparison, 1)

CREATE_BINEXPR_PARSER('&', EXPR_BINARY_BITWISE_AND,
                      semantic_binexpr_arithmetic, 1)
CREATE_BINEXPR_PARSER('|', EXPR_BINARY_BITWISE_OR,
                      semantic_binexpr_arithmetic, 1)
CREATE_BINEXPR_PARSER('^', EXPR_BINARY_BITWISE_XOR,
                      semantic_binexpr_arithmetic, 1)
CREATE_BINEXPR_PARSER(T_ANDAND, EXPR_BINARY_LOGICAL_AND,
                      semantic_logical_op, 1)
CREATE_BINEXPR_PARSER(T_PIPEPIPE, EXPR_BINARY_LOGICAL_OR,
                      semantic_logical_op, 1)
CREATE_BINEXPR_PARSER(T_LESSLESS, EXPR_BINARY_SHIFTLEFT,
                      semantic_shift_op, 1)
CREATE_BINEXPR_PARSER(T_GREATERGREATER, EXPR_BINARY_SHIFTRIGHT,
                      semantic_shift_op, 1)
CREATE_BINEXPR_PARSER(T_PLUSEQUAL, EXPR_BINARY_ADD_ASSIGN,
                      semantic_arithmetic_addsubb_assign, 0)
CREATE_BINEXPR_PARSER(T_MINUSEQUAL, EXPR_BINARY_SUB_ASSIGN,
                      semantic_arithmetic_addsubb_assign, 0)
CREATE_BINEXPR_PARSER(T_ASTERISKEQUAL, EXPR_BINARY_MUL_ASSIGN,
                      semantic_arithmetic_assign, 0)
CREATE_BINEXPR_PARSER(T_SLASHEQUAL, EXPR_BINARY_DIV_ASSIGN,
                      semantic_divmod_assign, 0)
CREATE_BINEXPR_PARSER(T_PERCENTEQUAL, EXPR_BINARY_MOD_ASSIGN,
                      semantic_divmod_assign, 0)
CREATE_BINEXPR_PARSER(T_LESSLESSEQUAL, EXPR_BINARY_SHIFTLEFT_ASSIGN,
                      semantic_arithmetic_assign, 0)
CREATE_BINEXPR_PARSER(T_GREATERGREATEREQUAL, EXPR_BINARY_SHIFTRIGHT_ASSIGN,
                      semantic_arithmetic_assign, 0)
CREATE_BINEXPR_PARSER(T_ANDEQUAL, EXPR_BINARY_BITWISE_AND_ASSIGN,
                      semantic_arithmetic_assign, 0)
CREATE_BINEXPR_PARSER(T_PIPEEQUAL, EXPR_BINARY_BITWISE_OR_ASSIGN,
                      semantic_arithmetic_assign, 0)
CREATE_BINEXPR_PARSER(T_CARETEQUAL, EXPR_BINARY_BITWISE_XOR_ASSIGN,
                      semantic_arithmetic_assign, 0)

static expression_t *parse_sub_expression(unsigned 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(parser->precedence);
        } 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(parser->infix_precedence, 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_sub_expression(1);
}

/**
 * Register a parser for a prefix-like operator with given precedence.
 *
 * @param parser      the parser function
 * @param token_type  the token type of the prefix token
 * @param precedence  the precedence of the operator
 */
static void register_expression_parser(parse_expression_function parser,
                                       int token_type, unsigned precedence)
{
        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;
        entry->precedence = precedence;
}

/**
 * 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, unsigned 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,         '[',              30);
        register_infix_parser(parse_call_expression,          '(',              30);
        register_infix_parser(parse_select_expression,        '.',              30);
        register_infix_parser(parse_select_expression,        T_MINUSGREATER,   30);
        register_infix_parser(parse_EXPR_UNARY_POSTFIX_INCREMENT,
                                                              T_PLUSPLUS,       30);
        register_infix_parser(parse_EXPR_UNARY_POSTFIX_DECREMENT,
                                                              T_MINUSMINUS,     30);

        register_infix_parser(parse_EXPR_BINARY_MUL,          '*',              17);
        register_infix_parser(parse_EXPR_BINARY_DIV,          '/',              17);
        register_infix_parser(parse_EXPR_BINARY_MOD,          '%',              17);
        register_infix_parser(parse_EXPR_BINARY_ADD,          '+',              16);
        register_infix_parser(parse_EXPR_BINARY_SUB,          '-',              16);
        register_infix_parser(parse_EXPR_BINARY_SHIFTLEFT,    T_LESSLESS,       15);
        register_infix_parser(parse_EXPR_BINARY_SHIFTRIGHT,   T_GREATERGREATER, 15);
        register_infix_parser(parse_EXPR_BINARY_LESS,         '<',              14);
        register_infix_parser(parse_EXPR_BINARY_GREATER,      '>',              14);
        register_infix_parser(parse_EXPR_BINARY_LESSEQUAL,    T_LESSEQUAL,      14);
        register_infix_parser(parse_EXPR_BINARY_GREATEREQUAL, T_GREATEREQUAL,   14);
        register_infix_parser(parse_EXPR_BINARY_EQUAL,        T_EQUALEQUAL,     13);
        register_infix_parser(parse_EXPR_BINARY_NOTEQUAL,
                                                    T_EXCLAMATIONMARKEQUAL, 13);
        register_infix_parser(parse_EXPR_BINARY_BITWISE_AND,  '&',              12);
        register_infix_parser(parse_EXPR_BINARY_BITWISE_XOR,  '^',              11);
        register_infix_parser(parse_EXPR_BINARY_BITWISE_OR,   '|',              10);
        register_infix_parser(parse_EXPR_BINARY_LOGICAL_AND,  T_ANDAND,          9);
        register_infix_parser(parse_EXPR_BINARY_LOGICAL_OR,   T_PIPEPIPE,        8);
        register_infix_parser(parse_conditional_expression,   '?',               7);
        register_infix_parser(parse_EXPR_BINARY_ASSIGN,       '=',               2);
        register_infix_parser(parse_EXPR_BINARY_ADD_ASSIGN,   T_PLUSEQUAL,       2);
        register_infix_parser(parse_EXPR_BINARY_SUB_ASSIGN,   T_MINUSEQUAL,      2);
        register_infix_parser(parse_EXPR_BINARY_MUL_ASSIGN,   T_ASTERISKEQUAL,   2);
        register_infix_parser(parse_EXPR_BINARY_DIV_ASSIGN,   T_SLASHEQUAL,      2);
        register_infix_parser(parse_EXPR_BINARY_MOD_ASSIGN,   T_PERCENTEQUAL,    2);
        register_infix_parser(parse_EXPR_BINARY_SHIFTLEFT_ASSIGN,
                                                                T_LESSLESSEQUAL, 2);
        register_infix_parser(parse_EXPR_BINARY_SHIFTRIGHT_ASSIGN,
                                                          T_GREATERGREATEREQUAL, 2);
        register_infix_parser(parse_EXPR_BINARY_BITWISE_AND_ASSIGN,
                                                                     T_ANDEQUAL, 2);
        register_infix_parser(parse_EXPR_BINARY_BITWISE_OR_ASSIGN,
                                                                    T_PIPEEQUAL, 2);
        register_infix_parser(parse_EXPR_BINARY_BITWISE_XOR_ASSIGN,
                                                                   T_CARETEQUAL, 2);

        register_infix_parser(parse_EXPR_BINARY_COMMA,        ',',               1);

        register_expression_parser(parse_EXPR_UNARY_NEGATE,           '-',      25);
        register_expression_parser(parse_EXPR_UNARY_PLUS,             '+',      25);
        register_expression_parser(parse_EXPR_UNARY_NOT,              '!',      25);
        register_expression_parser(parse_EXPR_UNARY_BITWISE_NEGATE,   '~',      25);
        register_expression_parser(parse_EXPR_UNARY_DEREFERENCE,      '*',      25);
        register_expression_parser(parse_EXPR_UNARY_TAKE_ADDRESS,     '&',      25);
        register_expression_parser(parse_EXPR_UNARY_PREFIX_INCREMENT,
                                                                  T_PLUSPLUS,   25);
        register_expression_parser(parse_EXPR_UNARY_PREFIX_DECREMENT,
                                                                  T_MINUSMINUS, 25);
        register_expression_parser(parse_sizeof,                      T_sizeof, 25);
        register_expression_parser(parse_alignof,                T___alignof__, 25);
        register_expression_parser(parse_extension,            T___extension__, 25);
        register_expression_parser(parse_builtin_classify_type,
                                                     T___builtin_classify_type, 25);
}

/**
 * Parse a asm statement arguments specification.
 */
static asm_argument_t *parse_asm_arguments(bool is_out)
{
        asm_argument_t *result = NULL;
        asm_argument_t *last   = NULL;

        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 (token.type == '[') {
                        eat('[');
                        if (token.type != T_IDENTIFIER) {
                                parse_error_expected("while parsing asm argument",
                                                     T_IDENTIFIER, NULL);
                                return NULL;
                        }
                        argument->symbol = token.v.symbol;

                        expect(']');
                }

                argument->constraints = parse_string_literals();
                expect('(');
                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");
                        }
                }
                argument->expression = expression;
                expect(')');

                set_address_taken(expression, true);

                if (last != NULL) {
                        last->next = argument;
                } else {
                        result = argument;
                }
                last = argument;

                if (token.type != ',')
                        break;
                eat(',');
        }

        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 *last   = NULL;

        while(token.type == T_STRING_LITERAL) {
                asm_clobber_t *clobber = allocate_ast_zero(sizeof(clobber[0]));
                clobber->clobber       = parse_string_literals();

                if (last != NULL) {
                        last->next = clobber;
                } else {
                        result = clobber;
                }
                last = clobber;

                if (token.type != ',')
                        break;
                eat(',');
        }

        return result;
}

/**
 * Parse an asm statement.
 */
static statement_t *parse_asm_statement(void)
{
        eat(T_asm);

        statement_t *statement          = allocate_statement_zero(STATEMENT_ASM);
        statement->base.source_position = token.source_position;

        asm_statement_t *asm_statement = &statement->asms;

        if (token.type == T_volatile) {
                next_token();
                asm_statement->is_volatile = true;
        }

        expect('(');
        add_anchor_token(')');
        add_anchor_token(':');
        asm_statement->asm_text = parse_string_literals();

        if (token.type != ':') {
                rem_anchor_token(':');
                goto end_of_asm;
        }
        eat(':');

        asm_statement->outputs = parse_asm_arguments(true);
        if (token.type != ':') {
                rem_anchor_token(':');
                goto end_of_asm;
        }
        eat(':');

        asm_statement->inputs = parse_asm_arguments(false);
        if (token.type != ':') {
                rem_anchor_token(':');
                goto end_of_asm;
        }
        rem_anchor_token(':');
        eat(':');

        asm_statement->clobbers = parse_asm_clobbers();

end_of_asm:
        rem_anchor_token(')');
        expect(')');
        expect(';');

        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();
}

/**
 * Parse a case statement.
 */
static statement_t *parse_case_statement(void)
{
        eat(T_case);

        statement_t       *const statement = allocate_statement_zero(STATEMENT_CASE_LABEL);
        source_position_t *const pos       = &statement->base.source_position;

        *pos                             = token.source_position;
        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(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(expression);
                statement->case_label.first_case = val;
                statement->case_label.last_case  = val;
        }

        if (GNU_MODE) {
                if (token.type == T_DOTDOTDOT) {
                        next_token();
                        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(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(end_range);
                                statement->case_label.last_case = val;

                                if (val < statement->case_label.first_case) {
                                        statement->case_label.is_empty_range = true;
                                        warningf(pos, "empty range specified");
                                }
                        }
                }
        }

        PUSH_PARENT(statement);

        expect(':');

        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_t *const inner_stmt = parse_statement();
        statement->case_label.statement = inner_stmt;
        if (inner_stmt->kind == STATEMENT_DECLARATION) {
                errorf(&inner_stmt->base.source_position, "declaration after case label");
        }

        POP_PARENT;
        return statement;
end_error:
        POP_PARENT;
        return create_invalid_statement();
}

/**
 * Parse a default statement.
 */
static statement_t *parse_default_statement(void)
{
        eat(T_default);

        statement_t *statement = allocate_statement_zero(STATEMENT_CASE_LABEL);
        statement->base.source_position = token.source_position;

        PUSH_PARENT(statement);

        expect(':');
        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_t *const inner_stmt = parse_statement();
        statement->case_label.statement = inner_stmt;
        if (inner_stmt->kind == STATEMENT_DECLARATION) {
                errorf(&inner_stmt->base.source_position, "declaration after default label");
        }

        POP_PARENT;
        return statement;
end_error:
        POP_PARENT;
        return create_invalid_statement();
}

/**
 * Parse a label statement.
 */
static statement_t *parse_label_statement(void)
{
        assert(token.type == T_IDENTIFIER);
        symbol_t *symbol = token.v.symbol;
        next_token();

        declaration_t *label = get_label(symbol);

        statement_t *const statement = allocate_statement_zero(STATEMENT_LABEL);
        statement->base.source_position = token.source_position;
        statement->label.label          = label;

        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->init.statement != NULL) {
                errorf(HERE, "duplicate label '%Y' (declared %P)",
                       symbol, &label->source_position);
        } else {
                label->source_position = token.source_position;
                label->init.statement  = statement;
        }

        eat(':');

        if (token.type == '}') {
                /* TODO only warn? */
                if (false) {
                        warningf(HERE, "label at end of compound statement");
                        statement->label.statement = create_empty_statement();
                } else {
                        errorf(HERE, "label at end of compound statement");
                        statement->label.statement = create_invalid_statement();
                }
        } else if (token.type == ';') {
                /* 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. */
                statement->label.statement = create_empty_statement();
                next_token();
        } else {
                statement_t *const inner_stmt = parse_statement();
                statement->label.statement = inner_stmt;
                if (inner_stmt->kind == STATEMENT_DECLARATION) {
                        errorf(&inner_stmt->base.source_position, "declaration after label");
                }
        }

        /* remember the labels in a list for later checking */
        if (label_last == NULL) {
                label_first = &statement->label;
        } else {
                label_last->next = &statement->label;
        }
        label_last = &statement->label;

        POP_PARENT;
        return statement;
}

/**
 * Parse an if statement.
 */
static statement_t *parse_if(void)
{
        eat(T_if);

        statement_t *statement          = allocate_statement_zero(STATEMENT_IF);
        statement->base.source_position = token.source_position;

        PUSH_PARENT(statement);

        expect('(');
        add_anchor_token(')');
        statement->ifs.condition = parse_expression();
        rem_anchor_token(')');
        expect(')');

        add_anchor_token(T_else);
        statement->ifs.true_statement = parse_statement();
        rem_anchor_token(T_else);

        if (token.type == T_else) {
                next_token();
                statement->ifs.false_statement = parse_statement();
        }

        POP_PARENT;
        return statement;
end_error:
        POP_PARENT;
        return create_invalid_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 */
        const declaration_t *declaration;
        long last_value = -1;
        for (declaration = enumt->declaration->next;
             declaration != NULL && declaration->storage_class == STORAGE_CLASS_ENUM_ENTRY;
                 declaration = declaration->next) {
                const expression_t *expression = declaration->init.enum_value;
                long                value      = expression != NULL ? fold_constant(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", declaration->symbol);
                }
                last_value = value;
        }
}

/**
 * Parse a switch statement.
 */
static statement_t *parse_switch(void)
{
        eat(T_switch);

        statement_t *statement          = allocate_statement_zero(STATEMENT_SWITCH);
        statement->base.source_position = token.source_position;

        PUSH_PARENT(statement);

        expect('(');
        add_anchor_token(')');
        expression_t *const expr = parse_expression();
        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(')');
        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)
{
        eat(T_while);

        statement_t *statement          = allocate_statement_zero(STATEMENT_WHILE);
        statement->base.source_position = token.source_position;

        PUSH_PARENT(statement);

        expect('(');
        add_anchor_token(')');
        statement->whiles.condition = parse_expression();
        rem_anchor_token(')');
        expect(')');

        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)
{
        eat(T_do);

        statement_t *statement = allocate_statement_zero(STATEMENT_DO_WHILE);
        statement->base.source_position = token.source_position;

        PUSH_PARENT(statement)

        add_anchor_token(T_while);
        statement->do_while.body = parse_loop_body(statement);
        rem_anchor_token(T_while);

        expect(T_while);
        expect('(');
        add_anchor_token(')');
        statement->do_while.condition = parse_expression();
        rem_anchor_token(')');
        expect(')');
        expect(';');

        POP_PARENT;
        return statement;
end_error:
        POP_PARENT;
        return create_invalid_statement();
}

/**
 * Parse a for statement.
 */
static statement_t *parse_for(void)
{
        eat(T_for);

        statement_t *statement          = allocate_statement_zero(STATEMENT_FOR);
        statement->base.source_position = token.source_position;

        PUSH_PARENT(statement);

        size_t const top = environment_top();
        scope_push(&statement->fors.scope);

        expect('(');
        add_anchor_token(')');

        if (token.type != ';') {
                if (is_declaration_specifier(&token, false)) {
                        parse_declaration(record_declaration);
                } else {
                        add_anchor_token(';');
                        expression_t *const init = parse_expression();
                        statement->fors.initialisation = init;
                        if (warning.unused_value && !expression_has_effect(init)) {
                                warningf(&init->base.source_position,
                                         "initialisation of 'for'-statement has no effect");
                        }
                        rem_anchor_token(';');
                        expect(';');
                }
        } else {
                expect(';');
        }

        if (token.type != ';') {
                add_anchor_token(';');
                statement->fors.condition = parse_expression();
                rem_anchor_token(';');
        }
        expect(';');
        if (token.type != ')') {
                expression_t *const step = parse_expression();
                statement->fors.step = step;
                if (warning.unused_value && !expression_has_effect(step)) {
                        warningf(&step->base.source_position,
                                 "step of 'for'-statement has no effect");
                }
        }
        rem_anchor_token(')');
        expect(')');
        statement->fors.body = parse_loop_body(statement);

        assert(scope == &statement->fors.scope);
        scope_pop();
        environment_pop_to(top);

        POP_PARENT;
        return statement;

end_error:
        POP_PARENT;
        rem_anchor_token(')');
        assert(scope == &statement->fors.scope);
        scope_pop();
        environment_pop_to(top);

        return create_invalid_statement();
}

/**
 * Parse a goto statement.
 */
static statement_t *parse_goto(void)
{
        source_position_t source_position = token.source_position;
        eat(T_goto);

        statement_t *statement;
        if (GNU_MODE && token.type == '*') {
                next_token();
                expression_t *expression = parse_expression();

                /* Argh: although documentation say the expression must be of type void *,
                 * gcc excepts 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(&source_position, "cannot convert to a pointer type");
                        } else if (type != type_void_ptr) {
                                warningf(&source_position,
                                        "type of computed goto expression should be 'void*' not '%T'", type);
                        }
                        expression = create_implicit_cast(expression, type_void_ptr);
                }

                statement                       = allocate_statement_zero(STATEMENT_GOTO);
                statement->base.source_position = source_position;
                statement->gotos.expression     = expression;
        } else {
                if (token.type != T_IDENTIFIER) {
                        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();
                        goto end_error;
                }
                symbol_t *symbol = token.v.symbol;
                next_token();

                statement                       = allocate_statement_zero(STATEMENT_GOTO);
                statement->base.source_position = source_position;
                statement->gotos.label          = get_label(symbol);

                if (statement->gotos.label->parent_scope->depth < current_function->scope.depth) {
                        statement->gotos.outer_fkt_jmp = true;
                }
        }

        /* remember the goto's in a list for later checking */
        if (goto_last == NULL) {
                goto_first = &statement->gotos;
        } else {
                goto_last->next = &statement->gotos;
        }
        goto_last = &statement->gotos;

        expect(';');

        return statement;
end_error:
        return create_invalid_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);
        statement->base.source_position = token.source_position;

        eat(T_continue);
        expect(';');

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);
        statement->base.source_position = token.source_position;

        eat(T_break);
        expect(';');

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);
        statement->base.source_position = token.source_position;

        eat(T___leave);
        expect(';');

end_error:
        return statement;
}

/**
 * Check if a given declaration represents a local variable.
 */
static bool is_local_var_declaration(const declaration_t *declaration)
{
        switch ((storage_class_tag_t) declaration->storage_class) {
        case STORAGE_CLASS_AUTO:
        case STORAGE_CLASS_REGISTER: {
                const type_t *type = skip_typeref(declaration->type);
                if (is_type_function(type)) {
                        return false;
                } else {
                        return true;
                }
        }
        default:
                return false;
        }
}

/**
 * Check if a given declaration represents a variable.
 */
static bool is_var_declaration(const declaration_t *declaration)
{
        if (declaration->storage_class == STORAGE_CLASS_TYPEDEF)
                return false;

        const type_t *type = skip_typeref(declaration->type);
        return !is_type_function(type);
}

/**
 * Check if a given expression represents a local variable.
 */
static bool is_local_variable(const expression_t *expression)
{
        if (expression->base.kind != EXPR_REFERENCE) {
                return false;
        }
        const declaration_t *declaration = expression->reference.declaration;
        return is_local_var_declaration(declaration);
}

/**
 * Check if a given expression represents a local variable and
 * return its declaration then, else return NULL.
 */
declaration_t *expr_is_variable(const expression_t *expression)
{
        if (expression->base.kind != EXPR_REFERENCE) {
                return NULL;
        }
        declaration_t *declaration = expression->reference.declaration;
        if (is_var_declaration(declaration))
                return declaration;
        return NULL;
}

/**
 * Parse a return statement.
 */
static statement_t *parse_return(void)
{
        statement_t *statement          = allocate_statement_zero(STATEMENT_RETURN);
        statement->base.source_position = token.source_position;

        eat(T_return);

        expression_t *return_value = NULL;
        if (token.type != ';') {
                return_value = parse_expression();
        }

        const type_t *const func_type = current_function->type;
        assert(is_type_function(func_type));
        type_t *const return_type = skip_typeref(func_type->function.return_type);

        if (return_value != NULL) {
                type_t *return_value_type = skip_typeref(return_value->base.type);

                if (is_type_atomic(return_type, ATOMIC_TYPE_VOID)
                                && !is_type_atomic(return_value_type, ATOMIC_TYPE_VOID)) {
                        warningf(&statement->base.source_position,
                                 "'return' with a value, in function returning void");
                        return_value = NULL;
                } else {
                        assign_error_t error = semantic_assign(return_type, return_value);
                        report_assign_error(error, return_type, return_value, "'return'",
                                            &statement->base.source_position);
                        return_value = create_implicit_cast(return_value, return_type);
                }
                /* check for returning address of a local var */
                if (return_value != NULL &&
                                return_value->base.kind == EXPR_UNARY_TAKE_ADDRESS) {
                        const expression_t *expression = return_value->unary.value;
                        if (is_local_variable(expression)) {
                                warningf(&statement->base.source_position,
                                         "function returns address of local variable");
                        }
                }
        } else {
                if (!is_type_atomic(return_type, ATOMIC_TYPE_VOID)) {
                        warningf(&statement->base.source_position,
                                 "'return' without value, in function returning non-void");
                }
        }
        statement->returns.value = return_value;

        expect(';');

end_error:
        return statement;
}

/**
 * Parse a declaration statement.
 */
static statement_t *parse_declaration_statement(void)
{
        statement_t *statement = allocate_statement_zero(STATEMENT_DECLARATION);

        statement->base.source_position = token.source_position;

        declaration_t *before = last_declaration;
        if (GNU_MODE)
                parse_external_declaration();
        else
                parse_declaration(record_declaration);

        if (before == NULL) {
                statement->declaration.declarations_begin = scope->declarations;
        } else {
                statement->declaration.declarations_begin = before->next;
        }
        statement->declaration.declarations_end = last_declaration;

        return statement;
}

/**
 * Parse an expression statement, ie. expr ';'.
 */
static statement_t *parse_expression_statement(void)
{
        statement_t *statement = allocate_statement_zero(STATEMENT_EXPRESSION);

        statement->base.source_position  = token.source_position;
        expression_t *const expr         = parse_expression();
        statement->expression.expression = expr;

        expect(';');

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);
        statement->base.source_position  = token.source_position;
        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 (token.type == T___except) {
                eat(T___except);
                expect('(');
                add_anchor_token(')');
                expression_t *const expr = parse_expression();
                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(')');
                statement->ms_try.final_statement = parse_compound_statement(false);
        } else if (token.type == T__finally) {
                eat(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);
        statement->base.source_position = token.source_position;

        eat(T___label__);

        declaration_t *begin = NULL, *end = NULL;

        while (true) {
                if (token.type != T_IDENTIFIER) {
                        parse_error_expected("while parsing local label declaration",
                                T_IDENTIFIER, NULL);
                        goto end_error;
                }
                symbol_t      *symbol      = token.v.symbol;
                declaration_t *declaration = get_declaration(symbol, NAMESPACE_LOCAL_LABEL);
                if (declaration != NULL) {
                        errorf(HERE, "multiple definitions of '__label__ %Y' (previous definition at %P)",
                                symbol, &declaration->source_position);
                } else {
                        declaration = allocate_declaration_zero();
                        declaration->namespc         = NAMESPACE_LOCAL_LABEL;
                        declaration->source_position = token.source_position;
                        declaration->symbol          = symbol;
                        declaration->parent_scope    = scope;
                        declaration->init.statement  = NULL;

                        if (end != NULL)
                                end->next = declaration;
                        end = declaration;
                        if (begin == NULL)
                                begin = declaration;

                        local_label_push(declaration);
                }
                next_token();

                if (token.type != ',')
                        break;
                next_token();
        }
        eat(';');
end_error:
        statement->declaration.declarations_begin = begin;
        statement->declaration.declarations_end   = end;
        return statement;
}

/**
 * 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.v.symbol)) {
                        statement = parse_declaration_statement();
                } else switch (la1_type) {
                        case '*':
                                if (get_declaration(token.v.symbol, NAMESPACE_NORMAL) != NULL)
                                        goto expression_statment;
                                /* FALLTHROUGH */

                        DECLARATION_START
                        case T_IDENTIFIER:
                                statement = parse_declaration_statement();
                                break;

                        default:
expression_statment:
                                statement = parse_expression_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. */
                do {
                        next_token();
                } while (token.type == T___extension__);
                bool old_gcc_extension = in_gcc_extension;
                in_gcc_extension       = true;
                statement = 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;

        case '!':
        case '&':
        case '(':
        case '*':
        case '+':
        case '-':
        case '~':
        case T_ANDAND:
        case T_CHARACTER_CONSTANT:
        case T_FLOATINGPOINT:
        case T_INTEGER:
        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___builtin_alloca:
        case T___builtin_classify_type:
        case T___builtin_constant_p:
        case T___builtin_expect:
        case T___builtin_huge_val:
        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_nan:
        case T___builtin_nand:
        case T___builtin_nanf:
        case T___builtin_offsetof:
        case T___builtin_prefetch:
        case T___builtin_va_arg:
        case T___builtin_va_end:
        case T___builtin_va_start:
        case T___func__:
        case T___noop:
        case T__assume:
                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);
        statement->base.source_position = token.source_position;

        PUSH_PARENT(statement);

        eat('{');
        add_anchor_token('}');

        size_t const top       = environment_top();
        size_t const top_local = local_label_top();
        scope_push(&statement->compound.scope);

        statement_t **anchor            = &statement->compound.statements;
        bool          only_decls_so_far = true;
        while (token.type != '}' && token.type != T_EOF) {
                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;
        }

        if (token.type == '}') {
                next_token();
        } else {
                errorf(&statement->base.source_position,
                       "end of file while looking for closing '}'");
        }

        /* 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('}');
        assert(scope == &statement->compound.scope);
        scope_pop();
        environment_pop_to(top);
        local_label_pop_to(top_local);

        POP_PARENT;
        return statement;
}

/**
 * Initialize builtin types.
 */
static void initialize_builtin_types(void)
{
        type_intmax_t    = make_global_typedef("__intmax_t__",      type_long_long);
        type_size_t      = make_global_typedef("__SIZE_TYPE__",     type_unsigned_long);
        type_ssize_t     = make_global_typedef("__SSIZE_TYPE__",    type_long);
        type_ptrdiff_t   = make_global_typedef("__PTRDIFF_TYPE__",  type_long);
        type_uintmax_t   = make_global_typedef("__uintmax_t__",     type_unsigned_long_long);
        type_uptrdiff_t  = make_global_typedef("__UPTRDIFF_TYPE__", type_unsigned_long);
        type_wchar_t     = make_global_typedef("__WCHAR_TYPE__",    opt_short_wchar_t ? type_unsigned_short : type_int);
        type_wint_t      = make_global_typedef("__WINT_TYPE__",     type_int);

        type_intmax_t_ptr  = make_pointer_type(type_intmax_t,  TYPE_QUALIFIER_NONE);
        type_ptrdiff_t_ptr = make_pointer_type(type_ptrdiff_t, TYPE_QUALIFIER_NONE);
        type_ssize_t_ptr   = make_pointer_type(type_ssize_t,   TYPE_QUALIFIER_NONE);
        type_wchar_t_ptr   = make_pointer_type(type_wchar_t,   TYPE_QUALIFIER_NONE);

        /* const version of wchar_t */
        type_const_wchar_t = allocate_type_zero(TYPE_TYPEDEF, &builtin_source_position);
        type_const_wchar_t->typedeft.declaration  = type_wchar_t->typedeft.declaration;
        type_const_wchar_t->base.qualifiers      |= TYPE_QUALIFIER_CONST;

        type_const_wchar_t_ptr = make_pointer_type(type_const_wchar_t, TYPE_QUALIFIER_NONE);
}

/**
 * Check for unused global static functions and variables
 */
static void check_unused_globals(void)
{
        if (!warning.unused_function && !warning.unused_variable)
                return;

        for (const declaration_t *decl = global_scope->declarations; decl != NULL; decl = decl->next) {
                if (decl->used                  ||
                    decl->modifiers & DM_UNUSED ||
                    decl->modifiers & DM_USED   ||
                    decl->storage_class != STORAGE_CLASS_STATIC)
                        continue;

                type_t *const type = decl->type;
                const char *s;
                if (is_type_function(skip_typeref(type))) {
                        if (!warning.unused_function || decl->is_inline)
                                continue;

                        s = (decl->init.statement != NULL ? "defined" : "declared");
                } else {
                        if (!warning.unused_variable)
                                continue;

                        s = "defined";
                }

                warningf(&decl->source_position, "'%#T' %s but not used",
                        type, decl->symbol, s);
        }
}

static void parse_global_asm(void)
{
        eat(T_asm);
        expect('(');

        statement_t *statement          = allocate_statement_zero(STATEMENT_ASM);
        statement->base.source_position = token.source_position;
        statement->asms.asm_text        = parse_string_literals();
        statement->base.next            = unit->global_asm;
        unit->global_asm                = statement;

        expect(')');
        expect(';');

end_error:;
}

/**
 * Parse a translation unit.
 */
static void parse_translation_unit(void)
{
        for (;;) {
#ifndef NDEBUG
                bool anchor_leak = false;
                for (int i = 0; i != T_LAST_TOKEN; ++i) {
                        unsigned char count = token_anchor_set[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

                switch (token.type) {
                        DECLARATION_START
                        case T_IDENTIFIER:
                        case T___extension__:
                                parse_external_declaration();
                                break;

                        case T_asm:
                                parse_global_asm();
                                break;

                        case T_EOF:
                                return;

                        case ';':
                                /* TODO error in strict mode */
                                warningf(HERE, "stray ';' outside of function");
                                next_token();
                                break;

                        default:
                                errorf(HERE, "stray %K outside of function", &token);
                                if (token.type == '(' || token.type == '{' || token.type == '[')
                                        eat_until_matching_token(token.type);
                                next_token();
                                break;
                }
        }
}

/**
 * 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);
        local_label_stack = NEW_ARR_F(stack_entry_t, 0);
        diagnostic_count  = 0;
        error_count       = 0;
        warning_count     = 0;

        type_set_output(stderr);
        ast_set_output(stderr);

        assert(unit == NULL);
        unit = allocate_ast_zero(sizeof(unit[0]));

        assert(global_scope == NULL);
        global_scope = &unit->scope;

        assert(scope == NULL);
        scope_push(&unit->scope);

        initialize_builtin_types();
}

translation_unit_t *finish_parsing(void)
{
        /* do NOT use scope_pop() here, this will crash, will it by hand */
        assert(scope == &unit->scope);
        scope            = NULL;
        last_declaration = NULL;

        assert(global_scope == &unit->scope);
        check_unused_globals();
        global_scope = NULL;

        DEL_ARR_F(environment_stack);
        DEL_ARR_F(label_stack);
        DEL_ARR_F(local_label_stack);

        translation_unit_t *result = unit;
        unit = NULL;
        return result;
}

void parse(void)
{
        lookahead_bufpos = 0;
        for (int i = 0; i < MAX_LOOKAHEAD + 2; ++i) {
                next_token();
        }
        parse_translation_unit();
}

/**
 * Initialize the parser.
 */
void init_parser(void)
{
        sym_anonymous = symbol_table_insert("<anonymous>");

        if (c_mode & _MS) {
                /* add predefined symbols for extended-decl-modifier */
                sym_align      = symbol_table_insert("align");
                sym_allocate   = symbol_table_insert("allocate");
                sym_dllimport  = symbol_table_insert("dllimport");
                sym_dllexport  = symbol_table_insert("dllexport");
                sym_naked      = symbol_table_insert("naked");
                sym_noinline   = symbol_table_insert("noinline");
                sym_noreturn   = symbol_table_insert("noreturn");
                sym_nothrow    = symbol_table_insert("nothrow");
                sym_novtable   = symbol_table_insert("novtable");
                sym_property   = symbol_table_insert("property");
                sym_get        = symbol_table_insert("get");
                sym_put        = symbol_table_insert("put");
                sym_selectany  = symbol_table_insert("selectany");
                sym_thread     = symbol_table_insert("thread");
                sym_uuid       = symbol_table_insert("uuid");
                sym_deprecated = symbol_table_insert("deprecated");
                sym_restrict   = symbol_table_insert("restrict");
                sym_noalias    = symbol_table_insert("noalias");
        }
        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);
}