[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"

//#define PRINT_TOKENS
#define MAX_LOOKAHEAD 2

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

typedef struct gnu_attribute_t gnu_attribute_t;
struct gnu_attribute_t {
        gnu_attribute_kind_t kind;
        gnu_attribute_t     *next;
        bool                 invalid;
        bool                 have_arguments;
        union {
                size_t   value;
                string_t string;
        } 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   decl_modifiers;    /**< MS __declspec extended modifier mask */
        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);

static token_t             token;
static token_t             lookahead_buffer[MAX_LOOKAHEAD];
static int                 lookahead_bufpos;
static stack_entry_t      *environment_stack = NULL;
static stack_entry_t      *label_stack       = NULL;
static scope_t            *global_scope      = NULL;
static scope_t            *scope             = NULL;
static declaration_t      *last_declaration  = NULL;
static declaration_t      *current_function  = NULL;
static switch_statement_t *current_switch    = NULL;
static statement_t        *current_loop      = 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;
static struct obstack      temp_obst;

static source_position_t null_position = { NULL, 0 };

/* 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

static type_t *type_valist;

static statement_t *parse_compound_statement(void);
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);

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:

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

#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),
        };
        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;
        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_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.
 */
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 label stack.
 */
static size_t label_top(void)
{
        return ARR_LEN(label_stack);
}

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

        lookahead_bufpos = (lookahead_bufpos+1) % MAX_LOOKAHEAD;

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

/**
 * 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];
}

/**
 * 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);
        --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) {
        unsigned parenthesis_count = 0;
        unsigned brace_count = 0;
        unsigned bracket_count = 0;
        int end_token = type;

        if(type == '(')
                end_token = ')';
        else if(type == '{')
                end_token = '}';
        else if(type == '[')
                end_token = ']';

        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;
                        break;
                case '}':
                        if(brace_count > 0)
                                --brace_count;
                        break;
                case ']':
                        if(bracket_count > 0)
                                --bracket_count;
                        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();
}

/**
 * eat all token until a ';' is reached
 * or a stop token is found.
 */
static void eat_statement(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 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), 0); \
                add_anchor_token(expected);                \
        eat_until_anchor();                        \
                rem_anchor_token(expected);                \
        goto end_error;                            \
    }                                              \
    next_token();                                  \
        } while(0)

static void set_scope(scope_t *new_scope)
{
        if(scope != NULL) {
                scope->last_declaration = last_declaration;
        }
        scope = new_scope;

        last_declaration = new_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 *iter = symbol->declaration;
        if (iter == NULL) {
                symbol->declaration = declaration;
        } else {
                declaration_t *iter_last = NULL;
                for( ; iter != NULL; iter_last = iter, iter = iter->symbol_next) {
                        /* replace an entry? */
                        if(iter->namespc == namespc) {
                                if(iter_last == NULL) {
                                        symbol->declaration = declaration;
                                } else {
                                        iter_last->symbol_next = declaration;
                                }
                                declaration->symbol_next = iter->symbol_next;
                                break;
                        }
                }
                if(iter == NULL) {
                        assert(iter_last->symbol_next == NULL);
                        iter_last->symbol_next = 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);
}

static void environment_push(declaration_t *declaration)
{
        assert(declaration->source_position.input_name != NULL);
        assert(declaration->parent_scope != NULL);
        stack_push(&environment_stack, declaration);
}

static void label_push(declaration_t *declaration)
{
        declaration->parent_scope = &current_function->scope;
        stack_push(&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 *declaration = symbol->declaration;
                assert(declaration != NULL);
                if(declaration->namespc == namespc) {
                        if(old_declaration == NULL) {
                                symbol->declaration = declaration->symbol_next;
                        } else {
                                symbol->declaration = old_declaration;
                        }
                } else {
                        declaration_t *iter_last = declaration;
                        declaration_t *iter      = declaration->symbol_next;
                        for( ; iter != NULL; iter_last = iter, iter = iter->symbol_next) {
                                /* replace an entry? */
                                if(iter->namespc == namespc) {
                                        assert(iter_last != NULL);
                                        iter_last->symbol_next = old_declaration;
                                        if(old_declaration != NULL) {
                                                old_declaration->symbol_next = iter->symbol_next;
                                        }
                                        break;
                                }
                        }
                        assert(iter != NULL);
                }
        }

        ARR_SHRINKLEN(*stack_ptr, (int) new_top);
}

static void environment_pop_to(size_t new_top)
{
        stack_pop_to(&environment_stack, new_top);
}

static void label_pop_to(size_t new_top)
{
        stack_pop_to(&label_stack, new_top);
}


static int get_rank(const type_t *type)
{
        assert(!is_typeref(type));
        /* The C-standard allows promoting 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 ATOMIC_TYPE_INT;

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

static type_t *promote_integer(type_t *type)
{
        if(type->kind == TYPE_BITFIELD)
                type = type->bitfield.base;

        if(get_rank(type) < 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);
}

/** Implements the rules from § 6.5.16.1 */
static type_t *semantic_assign(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);

        if(is_type_pointer(type_left)) {
                if(is_null_pointer_constant(right)) {
                        return orig_type_left;
                } 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);

                        /* 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) {
                                errorf(source_position,
                                                "destination type '%T' in %s from type '%T' lacks qualifiers '%Q' in pointed-to type", type_left, context, type_right, missing_qualifiers);
                                return orig_type_left;
                        }

                        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 orig_type_left;
                        }

                        if (!types_compatible(points_to_left, points_to_right)) {
                                warningf(source_position,
                                        "destination type '%T' in %s is incompatible with '%E' of type '%T'",
                                        orig_type_left, context, right, orig_type_right);
                        }

                        return orig_type_left;
                } else if(is_type_integer(type_right)) {
                        warningf(source_position,
                                        "%s makes pointer '%T' from integer '%T' without a cast",
                                        context, orig_type_left, orig_type_right);
                        return orig_type_left;
                }
        } 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 orig_type_left;
        } 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 orig_type_left;
                }
        } else if (is_type_integer(type_left) && is_type_pointer(type_right)) {
                warningf(source_position,
                                "%s makes integer '%T' from pointer '%T' without a cast",
                                context, orig_type_left, orig_type_right);
                return orig_type_left;
        }

        if (!is_type_valid(type_left))
                return type_left;

        if (!is_type_valid(type_right))
                return orig_type_right;

        return NULL;
}

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;

        record_declaration(declaration);

        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 *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]                 = "coommon",
        [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_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] == '_') {
                s2 += 2;
                size_t l1 = strlen(s1);
                if(l1 + 2 != strlen(s2)) {
                        /* not equal */
                        return 1;
                }
                return strncmp(s1, s2, l1);
        }
        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(')');
        (void)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) {
        expression_t *expression;
        add_anchor_token(')');
        add_anchor_token(',');
        while(true){
                expression = parse_constant_expression();
                if(token.type != ',')
                        break;
                next_token();
        }
        rem_anchor_token(',');
        rem_anchor_token(')');
        expect(')');
        (void)expression;
        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, 0);
                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 *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 *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 *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;
}

/**
 * parse one interrupt argument.
 */
static void parse_gnu_attribute_interrupt_arg(gnu_attribute_t *attribute) {
        static const char *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 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 *format_names[] = {
                "printf",
                "scanf",
                "strftime",
                "strfmon"
        };
        int i;

        if(token.type != T_IDENTIFIER) {
                parse_error_expected("while parsing format attribute directive", T_IDENTIFIER, 0);
                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;
}

/**
 * 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 void parse_gnu_attribute(gnu_attribute_t **attributes)
{
        gnu_attribute_t *head = *attributes;
        gnu_attribute_t *last = *attributes;
        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) {
                                parse_error_expected("while parsing GNU attribute", T_IDENTIFIER, 0);
                                break;
                        }
                        const symbol_t *sym = token.v.symbol;
                        name = sym->string;
                        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_CDECL:
                                case GNU_AK_STDCALL:
                                case GNU_AK_FASTCALL:
                                case GNU_AK_DEPRECATED:
                                case GNU_AK_NOINLINE:
                                case GNU_AK_NORETURN:
                                case GNU_AK_NAKED:
                                case GNU_AK_PURE:
                                case GNU_AK_ALWAYS_INLINE:
                                case GNU_AK_MALLOC:
                                case GNU_AK_WEAK:
                                case GNU_AK_CONSTRUCTOR:
                                case GNU_AK_DESTRUCTOR:
                                case GNU_AK_NOTHROW:
                                case GNU_AK_TRANSPARENT_UNION:
                                case GNU_AK_COMMON:
                                case GNU_AK_NOCOMMON:
                                case GNU_AK_PACKED:
                                case GNU_AK_SHARED:
                                case GNU_AK_NOTSHARED:
                                case GNU_AK_USED:
                                case GNU_AK_UNUSED:
                                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:
                                case GNU_AK_DLLIMPORT:
                                case GNU_AK_DLLEXPORT:
                                        if(attribute->have_arguments) {
                                                /* 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;
                                        }
                                        break;

                                case GNU_AK_ALIGNED:
                                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);
                                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;
                                }
                        }
                        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;
}

/**
 * Parse GNU attributes.
 */
static void parse_attributes(gnu_attribute_t **attributes)
{
        while(true) {
                switch(token.type) {
                case T___attribute__: {
                        parse_gnu_attribute(attributes);
                        break;
                }
                case T_asm:
                        next_token();
                        expect('(');
                        if(token.type != T_STRING_LITERAL) {
                                parse_error_expected("while parsing assembler attribute",
                                                     T_STRING_LITERAL, 0);
                                eat_until_matching_token('(');
                                break;
                        } else {
                                parse_string_literals();
                        }
                        expect(')');
                        break;
                default:
                        goto attributes_finished;
                }
        }

attributes_finished:
end_error:
        return;
}

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, 0);
                                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;
                        }
                }
        }

        type_t *const res_type = semantic_assign(type, expression, "initializer",
                                                 &expression->base.source_position);
        if (res_type == NULL)
                return NULL;

        initializer_t *const result = allocate_initializer_zero(INITIALIZER_VALUE);
        result->value.value = create_implicit_cast(expression, res_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;
        while(token.type == '{') {
                next_token();
                if(braces == 0) {
                        warningf(HERE, "extra curly braces around scalar initializer");
                }
                braces++;
        }

        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, "[%zd]", 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);

        assert(is_type_compound(top_type) || is_type_array(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 {
                assert(is_type_array(top_type));

                top->v.index   = 0;
                path->top_type = top_type->array.element_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 braket 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();

                        /* 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);
                }

                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, ... */
                                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);

        return result;

end_error:
        skip_initializers();
        DEL_ARR_F(initializers);
        ascend_to(path, top_path_level);
        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;

                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;
        if(is_struct) {
                eat(T_struct);
        } else {
                eat(T_union);
        }

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

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

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

                if(is_struct) {
                        declaration = get_declaration(symbol, NAMESPACE_STRUCT);
                } else {
                        declaration = get_declaration(symbol, NAMESPACE_UNION);
                }
        } else if(token.type != '{') {
                if(is_struct) {
                        parse_error_expected("while parsing struct type specifier",
                                             T_IDENTIFIER, '{', 0);
                } else {
                        parse_error_expected("while parsing union type specifier",
                                             T_IDENTIFIER, '{', 0);
                }

                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 == '{') {
                if(declaration->init.is_defined) {
                        assert(symbol != NULL);
                        errorf(HERE, "multiple definitions of '%s %Y'",
                               is_struct ? "struct" : "union", symbol);
                        declaration->scope.declarations = NULL;
                }
                declaration->init.is_defined = true;

                parse_compound_type_entries(declaration);
                parse_attributes(&attributes);
        }

        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, 0);
                        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);

                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, '{', 0);
                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.is_defined) {
                        errorf(HERE, "multiple definitions of enum %Y", symbol);
                }
                if (symbol != NULL) {
                        environment_push(declaration);
                }
                append_declaration(declaration);
                declaration->init.is_defined = 1;

                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;

restart:
        switch(token.type) {
        case T___extension__:
                /* this can be a prefix to a typename or an expression */
                /* we simply eat it now. */
                do {
                        next_token();
                } while(token.type == T___extension__);
                goto restart;

        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;
        }

        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 {
        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,
#ifdef PROVIDE_COMPLEX
        SPECIFIER_COMPLEX   = 1 << 16,
        SPECIFIER_IMAGINARY = 1 << 17,
#endif
} 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_elignment_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->decl_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_elignment_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 void parse_declaration_specifiers(declaration_specifiers_t *specifiers)
{
        type_t   *type            = NULL;
        unsigned  type_qualifiers = 0;
        unsigned  type_specifiers = 0;
        int       newtype         = 0;

        specifiers->source_position = token.source_position;

        while(true) {
                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:                                                     \
                        type_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__:
                        /* TODO */
                        next_token();
                        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")
#ifdef PROVIDE_COMPLEX
                MATCH_SPECIFIER(T__Complex,   SPECIFIER_COMPLEX,   "_Complex")
                MATCH_SPECIFIER(T__Imaginary, SPECIFIER_IMAGINARY, "_Imaginary")
#endif
                case T__forceinline:
                        /* only in microsoft mode */
                        specifiers->decl_modifiers |= DM_FORCEINLINE;

                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);
                        break;
                }
                case T_union: {
                        type = allocate_type_zero(TYPE_COMPOUND_UNION, HERE);

                        type->compound.declaration = parse_compound_type_specifier(false);
                        break;
                }
                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___attribute__:
                        parse_attributes(&specifiers->gnu_attributes);
                        break;

                case T_IDENTIFIER: {
                        /* only parse identifier if we haven't found a type yet */
                        if(type != NULL || type_specifiers != 0)
                                goto finish_specifiers;

                        type_t *typedef_type = get_typedef_type(token.v.symbol);

                        if(typedef_type == NULL)
                                goto finish_specifiers;

                        next_token();
                        type = typedef_type;
                        break;
                }

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

finish_specifiers:

        if(type == NULL) {
                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;
                        break;
                case SPECIFIER_UNSIGNED | SPECIFIER_LONG | SPECIFIER_LONG_LONG:
                case SPECIFIER_UNSIGNED | SPECIFIER_LONG | SPECIFIER_LONG_LONG
                        | SPECIFIER_INT:
                        atomic_type = ATOMIC_TYPE_ULONGLONG;
                        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;
#ifdef PROVIDE_COMPLEX
                case SPECIFIER_FLOAT | SPECIFIER_COMPLEX:
                        atomic_type = ATOMIC_TYPE_FLOAT_COMPLEX;
                        break;
                case SPECIFIER_DOUBLE | SPECIFIER_COMPLEX:
                        atomic_type = ATOMIC_TYPE_DOUBLE_COMPLEX;
                        break;
                case SPECIFIER_LONG | SPECIFIER_DOUBLE | SPECIFIER_COMPLEX:
                        atomic_type = ATOMIC_TYPE_LONG_DOUBLE_COMPLEX;
                        break;
                case SPECIFIER_FLOAT | SPECIFIER_IMAGINARY:
                        atomic_type = ATOMIC_TYPE_FLOAT_IMAGINARY;
                        break;
                case SPECIFIER_DOUBLE | SPECIFIER_IMAGINARY:
                        atomic_type = ATOMIC_TYPE_DOUBLE_IMAGINARY;
                        break;
                case SPECIFIER_LONG | SPECIFIER_DOUBLE | SPECIFIER_IMAGINARY:
                        atomic_type = ATOMIC_TYPE_LONG_DOUBLE_IMAGINARY;
                        break;
#endif
                default:
                        /* invalid specifier combination, give an error message */
                        if(type_specifiers == 0) {
                                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 gives");
                        } 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");
                        }
                        atomic_type = ATOMIC_TYPE_INVALID;
                }

                type               = allocate_type_zero(TYPE_ATOMIC, &builtin_source_position);
                type->atomic.akind = atomic_type;
                newtype            = 1;
        } else {
                if(type_specifiers != 0) {
                        errorf(HERE, "multiple datatypes in declaration");
                }
        }

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

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

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

static type_qualifiers_t parse_type_qualifiers(void)
{
        type_qualifiers_t type_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 type_qualifiers;
                }
        }
}

static declaration_t *parse_identifier_list(void)
{
        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);

        return declarations;
}

static void semantic_parameter(declaration_t *declaration)
{
        /* TODO: improve error messages */

        if(declaration->declared_storage_class == STORAGE_CLASS_TYPEDEF) {
                errorf(HERE, "typedef not allowed in parameter list");
        } else if(declaration->declared_storage_class != STORAGE_CLASS_NONE
                        && declaration->declared_storage_class != STORAGE_CLASS_REGISTER) {
                errorf(HERE, "parameter may only have none or register storage class");
        }

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

        /* Array as last part of a parameter type is just syntactic sugar.  Turn it
         * into a pointer. § 6.7.5.3 (7) */
        if (is_type_array(type)) {
                type_t *const element_type = type->array.element_type;

                type = make_pointer_type(element_type, type->base.qualifiers);

                declaration->type = type;
        }

        if(is_type_incomplete(type)) {
                errorf(HERE, "incomplete type '%T' not allowed for parameter '%Y'",
                       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);

        semantic_parameter(declaration);

        return declaration;
}

static declaration_t *parse_parameters(function_type_t *type)
{
        if(token.type == T_IDENTIFIER) {
                symbol_t *symbol = token.v.symbol;
                if(!is_typedef_symbol(symbol)) {
                        type->kr_style_parameters = true;
                        return parse_identifier_list();
                }
        }

        if(token.type == ')') {
                type->unspecified_parameters = 1;
                return NULL;
        }
        if(token.type == T_void && look_ahead(1)->type == ')') {
                next_token();
                return NULL;
        }

        declaration_t        *declarations = NULL;
        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;
                        return declarations;

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

                        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:
                        return declarations;
                }
                if(token.type != ',')
                        return declarations;
                next_token();
        }
}

typedef enum {
        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(']');

        return (construct_type_t*) array;
end_error:
        return NULL;
}

static construct_type_t *parse_function_declarator(declaration_t *declaration)
{
        eat('(');
        add_anchor_token(')');

        type_t *type;
        if(declaration != NULL) {
                type = allocate_type_zero(TYPE_FUNCTION, &declaration->source_position);
        } else {
                type = allocate_type_zero(TYPE_FUNCTION, HERE);
        }

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

        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;

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

end_error:
        return (construct_type_t*) construct_function_type;
}

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;

        /* 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 */
        parse_attributes(&attributes);

        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);
                rem_anchor_token(')');
                expect(')');
                break;
        default:
                if(may_be_abstract)
                        break;
                parse_error_expected("while parsing declarator", T_IDENTIFIER, '(', 0);
                /* avoid a loop in the outermost scope, because eat_statement doesn't
                 * eat '}' */
                if(token.type == '}' && current_function == NULL) {
                        next_token();
                } else {
                        eat_statement();
                }
                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:
        parse_attributes(&attributes);

        /* 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 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);
                        if (is_type_function(skipped_return_type)) {
                                errorf(HERE, "function returning function is not allowed");
                                type = type_error_type;
                        } else if (is_type_array(skipped_return_type)) {
                                errorf(HERE, "function returning array is not allowed");
                                type = type_error_type;
                        } else {
                                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);
                        if (is_type_atomic(skipped_type, ATOMIC_TYPE_VOID)) {
                                errorf(HERE, "array of void is not allowed");
                                type = type_error_type;
                        } else {
                                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->declared_storage_class = specifiers->declared_storage_class;
        declaration->modifiers              = specifiers->decl_modifiers;
        declaration->deprecated             = specifiers->deprecated;
        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);

        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 (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) {
                                        warningf(&decl->source_position, "'main' takes only zero, two or three arguments");
                                }
                        }
                } else {
                        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 *internal_record_declaration(
        declaration_t *const declaration,
        const bool is_function_definition)
{
        const symbol_t *const symbol  = declaration->symbol;
        const namespace_t     namespc = (namespace_t)declaration->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) {
                warningf(&declaration->source_position,
                         "function declaration '%#T' is not a prototype",
                         orig_type, declaration->symbol);
        }

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

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

        assert(declaration != previous_declaration);
        if (previous_declaration != NULL) {
                if (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;
                                }

                                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)) {
                                        switch (old_storage_class) {
                                                case STORAGE_CLASS_NONE:
                                                        old_storage_class = STORAGE_CLASS_EXTERN;

                                                case STORAGE_CLASS_EXTERN:
                                                        if (is_function_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 (warning.redundant_decls) {
                                                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 && !is_function_definition) {
                                                        goto warn_redundant_declaration;
                                                }
                                                if (new_storage_class == STORAGE_CLASS_NONE) {
                                                        previous_declaration->storage_class = STORAGE_CLASS_NONE;
                                                        previous_declaration->declared_storage_class = STORAGE_CLASS_NONE;
                                                }
                                        }
                                } else {
                                        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);
                                        }
                                }
                        }
                        return previous_declaration;
                }
        } else if (is_function_definition) {
                if (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 &&
            !is_type_function(type) && (
              declaration->storage_class == STORAGE_CLASS_NONE ||
              declaration->storage_class == STORAGE_CLASS_THREAD
            )) {
                warningf(&declaration->source_position,
                         "no previous declaration for '%#T'", orig_type, symbol);
        }

        assert(declaration->parent_scope == NULL);
        assert(scope != NULL);

        declaration->parent_scope = scope;

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

static declaration_t *record_declaration(declaration_t *declaration)
{
        return internal_record_declaration(declaration, false);
}

static declaration_t *record_function_definition(declaration_t *declaration)
{
        return internal_record_declaration(declaration, true);
}

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_type_specifiers)
{
        switch(token->type) {
                TYPE_SPECIFIERS
                        return true;
                case T_IDENTIFIER:
                        return is_typedef_symbol(token->v.symbol);

                case T___extension__:
                STORAGE_CLASSES
                TYPE_QUALIFIERS
                        return !only_type_specifiers;

                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;
        }

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

        initializer_t *initializer = parse_initializer(&env);

        if(env.type != orig_type) {
                orig_type         = env.type;
                type              = skip_typeref(orig_type);
                declaration->type = env.type;
        }

        if(is_type_function(type)) {
                errorf(&declaration->source_position,
                       "initializers not allowed for function types at declator '%Y' (type '%T')",
                       declaration->symbol, orig_type);
        } else {
                declaration->init.initializer = initializer;
        }
}

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

        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->decl_modifiers;

        if (declaration->declared_storage_class != STORAGE_CLASS_NONE) {
                warningf(&declaration->source_position,
                         "useless storage class in empty declaration");
        }
        declaration->storage_class = STORAGE_CLASS_NONE;

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

                case TYPE_ENUM:
                        break;

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

        finished_declaration(declaration);
}

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

                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(',');

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

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

static declaration_t *finished_kr_declaration(declaration_t *declaration)
{
        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);
        }

        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(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);
        }
}

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

        if(token.type == ';') {
                parse_anonymous_declaration_rest(&specifiers, append_declaration);
        } else {
                declaration_t *declaration = parse_declarator(&specifiers, /*may_be_abstract=*/false);
                parse_declaration_rest(declaration, &specifiers, finished_declaration);
        }
}

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;

        /* push function parameters */
        int       top        = environment_top();
        scope_t  *last_scope = scope;
        set_scope(&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);
        set_scope(last_scope);
        environment_pop_to(top);

        /* update function type */
        type_t *new_type = duplicate_type(type);
        new_type->function.kr_style_parameters = false;

        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;

                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;
        }
        new_type->function.parameters = parameters;

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

        declaration->type = type;
}

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) {
                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;

                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 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, append_declaration);
                return;
        }

        add_anchor_token(',');
        add_anchor_token('=');
        rem_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(';');

        /* must be a declaration */
        if(token.type == ',' || token.type == '=' || token.type == ';') {
                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", '{', 0);
                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;
        }

        /* § 6.7.5.3 (14) a function definition with () means no
         * parameters (and not unspecified parameters) */
        if(type->function.unspecified_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_function_definition(ndeclaration);
        if(ndeclaration != declaration) {
                declaration->scope = ndeclaration->scope;
        }
        type = skip_typeref(declaration->type);

        /* push function parameters and switch scope */
        int       top        = environment_top();
        scope_t  *last_scope = scope;
        set_scope(&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;
                environment_push(parameter);
        }

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

                declaration->init.statement = parse_compound_statement();
                first_err = true;
                check_labels();
                check_declarations();

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

end_of_parse_external_declaration:
        assert(scope == &declaration->scope);
        set_scope(last_scope);
        environment_pop_to(top);
}

static type_t *make_bitfield_type(type_t *base, expression_t *size,
                                  source_position_t *source_position)
{
        type_t *type        = allocate_type_zero(TYPE_BITFIELD, source_position);
        type->bitfield.base = base;
        type->bitfield.size = size;

        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(1) {
                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();

                        if(!is_type_integer(skip_typeref(base_type))) {
                                errorf(HERE, "bitfield base type '%T' is not an integer type",
                                       base_type);
                        }

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

                        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->decl_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();

                                if(!is_type_integer(type)) {
                                        errorf(HERE, "bitfield base type '%T' is not an "
                                               "integer type", orig_type);
                                }

                                type_t *bitfield_type = make_bitfield_type(orig_type, size, &source_position);
                                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    = 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         = 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 && (c_mode & _GNUC)) {
                        /* TODO */
                        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 && (c_mode & _GNUC)) {
                        /* TODO */
                        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->parent_scope           = global_scope;

        scope_t *old_scope = scope;
        set_scope(global_scope);

        environment_push(declaration);
        /* prepends the declaration to the global declarations list */
        declaration->next   = scope->declarations;
        scope->declarations = declaration;

        assert(scope == global_scope);
        set_scope(old_scope);

        return declaration;
}

/**
 * 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;
}

/**
 * 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_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);
        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->type.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 expression->select.compound_entry->type;

                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;
        ref->symbol = token.v.symbol;

        declaration_t *declaration = get_declaration(ref->symbol, NAMESPACE_NORMAL);

        source_position_t source_position = token.source_position;
        next_token();

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

                        declaration = create_implicit_function(ref->symbol,
                                                               &source_position);
                } else {
                        errorf(HERE, "unknown symbol '%Y' found.", ref->symbol);
                        return create_invalid_expression();
                }
        }

        type_t *type         = declaration->type;

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

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

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

        /* check for deprecated functions */
        if(declaration->deprecated != 0) {
                const char *prefix = "";
                if (is_type_function(declaration->type))
                        prefix = "function ";

                if (declaration->deprecated_string != NULL) {
                        warningf(&source_position,
                                "%s'%Y' was declared 'deprecated(\"%s\")'", prefix, declaration->symbol,
                                declaration->deprecated_string);
                } else {
                        warningf(&source_position,
                                "%s'%Y' was declared 'deprecated'", prefix, declaration->symbol);
                }
        }

        return expression;
}

static void check_cast_allowed(expression_t *expression, type_t *dest_type)
{
        (void) expression;
        (void) dest_type;
        /* TODO check if explicit cast is allowed and issue warnings/errors */
}

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)
{
        source_position_t source_position = token.source_position;

        type_t *type  = parse_typename();

        /* matching add_anchor_token() is at call site */
        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);

        check_cast_allowed(value, type);

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

        return cast;
end_error:
        return create_invalid_expression();
}

/**
 * Parse a statement expression.
 */
static expression_t *parse_statement_expression(void)
{
        expression_t *expression = allocate_expression_zero(EXPR_STATEMENT);

        statement_t *statement           = parse_compound_statement();
        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;

        expect(')');

        return expression;
end_error:
        return create_invalid_expression();
}

/**
 * Parse a braced expression.
 */
static expression_t *parse_brace_expression(void)
{
        eat('(');
        add_anchor_token(')');

        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();
                }
        }

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

        return result;
end_error:
        return create_invalid_expression();
}

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, 0);
                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, 0);
                                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 == NULL)
                        return create_invalid_expression();
                if (decl->parent_scope == &current_function->scope &&
                    decl->next == NULL) {
                        expression->va_starte.parameter = decl;
                        expect(')');
                        return expression;
                }
        }
        errorf(&expr->base.source_position,
               "second argument of 'va_start' must be last parameter of the current function");
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();
}

/**
 * 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();
}

/**
 * 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();
}

/**
 * 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:         return parse_builtin_expect();
                case T___builtin_alloca:
                case T___builtin_nan:
                case T___builtin_nand:
                case T___builtin_nanf:
                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 '(':                        return parse_brace_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 = create_invalid_expression();
        }

        rem_anchor_token(']');
        if(token.type != ']') {
                parse_error_expected("Problem while parsing array access", ']', 0);
                return expression;
        }
        next_token();

        return_type           = automatic_type_conversion(return_type);
        expression->base.type = return_type;

        return expression;
}

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

        if(token.type == '(' && is_declaration_specifier(look_ahead(1), true)) {
                next_token();
                add_anchor_token(')');
                tp_expression->typeprop.type = parse_typename();
                rem_anchor_token(')');
                expect(')');
        } else {
                expression_t *expression = parse_sub_expression(precedence);
                expression->base.type    = revert_automatic_type_conversion(expression);

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

        return tp_expression;
end_error:
        return create_invalid_expression();
}

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

static expression_t *parse_alignof(unsigned precedence)
{
        eat(T___alignof__);
        return parse_typeprop(EXPR_SIZEOF, 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, 0);
                return select;
        }
        symbol_t *symbol      = token.v.symbol;
        select->select.symbol = symbol;
        next_token();

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

        type_t *type_left = type;
        if(is_pointer) {
                if (!is_type_pointer(type)) {
                        if (is_type_valid(type)) {
                                errorf(HERE, "left hand side of '->' is not a pointer, but '%T'", orig_type);
                        }
                        return create_invalid_expression();
                }
                type_left = type->pointer.points_to;
        }
        type_left = skip_typeref(type_left);

        if (type_left->kind != TYPE_COMPOUND_STRUCT &&
            type_left->kind != TYPE_COMPOUND_UNION) {
                if (is_type_valid(type_left)) {
                        errorf(HERE, "request for member '%Y' in something not a struct or "
                               "union, but '%T'", symbol, type_left);
                }
                return create_invalid_expression();
        }

        declaration_t *const declaration = type_left->compound.declaration;

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

        declaration_t *iter = find_compound_entry(declaration, symbol);
        if(iter == NULL) {
                errorf(HERE, "'%T' has no member named '%Y'", orig_type, symbol);
                return create_invalid_expression();
        }

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

        select->select.compound_entry = iter;
        select->base.type             = expression_type;

        if(expression_type->kind == TYPE_BITFIELD) {
                expression_t *extract
                        = allocate_expression_zero(EXPR_UNARY_BITFIELD_EXTRACT);
                extract->unary.value = select;
                extract->base.type   = expression_type->bitfield.base;

                return extract;
        }

        return select;
}

/**
 * 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) {
                function_parameter_t *parameter = function_type->parameters;
                call_argument_t      *argument  = call->arguments;
                for( ; parameter != NULL && argument != NULL;
                                parameter = parameter->next, argument = argument->next) {
                        type_t *expected_type = parameter->type;
                        /* TODO report scope in error messages */
                        expression_t *const arg_expr = argument->expression;
                        type_t       *const res_type = semantic_assign(expected_type, arg_expr,
                                                                       "function call",
                                                                       &arg_expr->base.source_position);
                        if (res_type == NULL) {
                                /* TODO improve error message */
                                errorf(&arg_expr->base.source_position,
                                        "Cannot call function with argument '%E' of type '%T' where type '%T' is expected",
                                        arg_expr, arg_expr->base.type, expected_type);
                        } else {
                                argument->expression = create_implicit_cast(argument->expression, expected_type);
                        }
                }
                /* too few parameters */
                if(parameter != NULL) {
                        errorf(HERE, "too few arguments to function '%E'", expression);
                } else if(argument != NULL) {
                        /* too many parameters */
                        if(!function_type->variadic
                                        && !function_type->unspecified_parameters) {
                                errorf(HERE, "too many arguments to function '%E'", expression);
                        } else {
                                /* do default promotion */
                                for( ; argument != NULL; argument = argument->next) {
                                        type_t *type = argument->expression->base.type;

                                        type = skip_typeref(type);
                                        if(is_type_integer(type)) {
                                                type = promote_integer(type);
                                        } else if(type == type_float) {
                                                type = type_double;
                                        }

                                        argument->expression
                                                = create_implicit_cast(argument->expression, type);
                                }

                                check_format(&result->call);
                        }
                } else {
                        check_format(&result->call);
                }
        }

        return result;
end_error:
        return create_invalid_expression();
}

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

        expression_t *result = allocate_expression_zero(EXPR_CONDITIONAL);

        conditional_expression_t *conditional = &result->conditional;
        conditional->condition = expression;

        /* 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 = 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(&expression->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)) {
                        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_type_pointer(other_type)) {
                        if(!pointers_compatible(true_type, false_type)) {
                                warningf(&expression->base.source_position,
                                                "pointer types '%T' and '%T' in conditional expression are incompatible", true_type, false_type);
                        }
                        result_type = true_type;
                } else if(is_null_pointer_constant(other_expression)) {
                        result_type = pointer_type;
                } else if(is_type_integer(other_type)) {
                        warningf(&expression->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",
                                                &expression->base.source_position, true_type,
                                                false_type);
                }
                result_type = type_error_type;
        }

        conditional->true_expression
                = 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__);

        /* TODO enable extensions */
        expression_t *expression = parse_sub_expression(precedence);
        /* TODO disable extensions */
        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 void semantic_incdec(unary_expression_t *expression)
{
        type_t *const orig_type = expression->value->base.type;
        type_t *const type      = skip_typeref(orig_type);
        /* TODO !is_type_real && !is_type_pointer */
        if(!is_type_arithmetic(type) && type->kind != TYPE_POINTER) {
                if (is_type_valid(type)) {
                        /* TODO: improve error message */
                        errorf(HERE, "operation needs an arithmetic or pointer type");
                }
                return;
        }

        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(HERE, "operation needs an arithmetic type");
                }
                return;
        }

        expression->base.type = orig_type;
}

static void semantic_unexpr_scalar(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)) {
                if (is_type_valid(type)) {
                        errorf(HERE, "operand of ! must be of scalar type");
                }
                return;
        }

        expression->base.type = orig_type;
}

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(HERE, "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(HERE, "Unary '*' needs pointer or arrray 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;
}

/**
 * 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;

        if(value->kind == EXPR_REFERENCE) {
                declaration_t *const declaration = value->reference.declaration;
                if(declaration != NULL) {
                        if (declaration->storage_class == STORAGE_CLASS_REGISTER) {
                                errorf(&expression->base.source_position,
                                       "address of register variable '%Y' requested",
                                       declaration->symbol);
                        }
                        declaration->address_taken = 1;
                }
        }

        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)            \
{                                                                              \
        eat(token_type);                                                           \
                                                                                   \
        expression_t *unary_expression                                             \
                = allocate_expression_zero(unexpression_type);                         \
        unary_expression->base.source_position = *HERE;                            \
        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_arithmetic)
CREATE_UNARY_EXPRESSION_PARSER('!', EXPR_UNARY_NOT,
                               semantic_unexpr_scalar)
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;                                                        \
        eat(token_type);                                                          \
                                                                              \
        expression_t *unary_expression                                            \
                = allocate_expression_zero(unexpression_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 */

        /* § 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_right = promote_integer(type_right);
        type_left  = promote_integer(type_left);

        if(type_left == type_right)
                return type_left;

        bool signed_left  = is_type_signed(type_left);
        bool signed_right = is_type_signed(type_right);
        int  rank_left    = get_rank(type_left);
        int  rank_right   = get_rank(type_right);
        if(rank_left < rank_right) {
                if(signed_left == signed_right || !signed_right) {
                        return type_right;
                } else {
                        return type_left;
                }
        } else {
                if(signed_left == signed_right || !signed_left) {
                        return type_left;
                } else {
                        return type_right;
                }
        }
}

/**
 * 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(HERE, "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 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(HERE, "operation needs 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);

        /* § 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)) {
                expression->base.type = type_left;
        } else if(is_type_pointer(type_right) && is_type_integer(type_left)) {
                expression->base.type = type_right;
        } else if (is_type_valid(type_left) && is_type_valid(type_right)) {
                errorf(HERE, "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);

        /* § 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)) {
                expression->base.type = type_left;
        } else if(is_type_pointer(type_left) && is_type_pointer(type_right)) {
                if(!pointers_compatible(type_left, type_right)) {
                        errorf(HERE,
                               "pointers to incompatible objects to binary '-' ('%T', '%T')",
                               orig_type_left, orig_type_right);
                } else {
                        expression->base.type = type_ptrdiff_t;
                }
        } else if (is_type_valid(type_left) && is_type_valid(type_right)) {
                errorf(HERE, "invalid operands to binary '-' ('%T', '%T')",
                       orig_type_left, orig_type_right);
        }
}

/**
 * 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;
        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)) {
                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))) {
                        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;
}

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;

        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(HERE, "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_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_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)) {
                expression->base.type = type_left;
        } else if (is_type_valid(type_left) && is_type_valid(type_right)) {
                errorf(HERE, "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);

        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(HERE, "operation needs scalar types");
                }
                return;
        }

        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;
}

/**
 * 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;

        type_t *type_left = revert_automatic_type_conversion(left);
        type_left         = skip_typeref(orig_type_left);

        /* must be a modifiable lvalue */
        if (is_type_array(type_left)) {
                errorf(HERE, "cannot assign to arrays ('%E')", left);
                return;
        }
        if(type_left->base.qualifiers & TYPE_QUALIFIER_CONST) {
                errorf(HERE, "assignment to readonly location '%E' (type '%T')", left,
                       orig_type_left);
                return;
        }
        if(is_type_incomplete(type_left)) {
                errorf(HERE,
                       "left-hand side of assignment '%E' has incomplete type '%T'",
                       left, orig_type_left);
                return;
        }
        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;
        }

        type_t *const res_type = semantic_assign(orig_type_left, expression->right,
                        "assignment", &left->base.source_position);
        if (res_type == NULL) {
                errorf(&expression->base.source_position,
                        "cannot assign to '%T' from '%T'",
                        orig_type_left, expression->right->base.type);
        } else {
                expression->right = create_implicit_cast(expression->right, res_type);
        }

        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_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_UNARY_BITFIELD_EXTRACT:    return false;

                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)       \
{                                                                         \
        eat(token_type);                                                      \
        source_position_t pos = *HERE;                                        \
                                                                          \
        expression_t *right = parse_sub_expression(precedence + lr);          \
                                                                          \
        expression_t *binexpr = allocate_expression_zero(binexpression_type); \
        binexpr->base.source_position = pos;                                  \
        binexpr->binary.left  = left;                                         \
        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_binexpr_arithmetic, 1)
CREATE_BINEXPR_PARSER('%', EXPR_BINARY_MOD,      semantic_binexpr_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_arithmetic_assign, 0)
CREATE_BINEXPR_PARSER(T_PERCENTEQUAL, EXPR_BINARY_MOD_ASSIGN,
                      semantic_arithmetic_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,          '*',              16);
        register_infix_parser(parse_EXPR_BINARY_DIV,          '/',              16);
        register_infix_parser(parse_EXPR_BINARY_MOD,          '%',              16);
        register_infix_parser(parse_EXPR_BINARY_SHIFTLEFT,    T_LESSLESS,       16);
        register_infix_parser(parse_EXPR_BINARY_SHIFTRIGHT,   T_GREATERGREATER, 16);
        register_infix_parser(parse_EXPR_BINARY_ADD,          '+',              15);
        register_infix_parser(parse_EXPR_BINARY_SUB,          '-',              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 constraints specification.
 */
static asm_constraint_t *parse_asm_constraints(void)
{
        asm_constraint_t *result = NULL;
        asm_constraint_t *last   = NULL;

        while(token.type == T_STRING_LITERAL || token.type == '[') {
                asm_constraint_t *constraint = allocate_ast_zero(sizeof(constraint[0]));
                memset(constraint, 0, sizeof(constraint[0]));

                if(token.type == '[') {
                        eat('[');
                        if(token.type != T_IDENTIFIER) {
                                parse_error_expected("while parsing asm constraint",
                                                     T_IDENTIFIER, 0);
                                return NULL;
                        }
                        constraint->symbol = token.v.symbol;

                        expect(']');
                }

                constraint->constraints = parse_string_literals();
                expect('(');
                constraint->expression = parse_expression();
                expect(')');

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

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

        asm_statement->outputs = parse_asm_constraints();
        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(';');
        return statement;
end_error:
        return create_invalid_statement();
}

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

        statement_t *statement = allocate_statement_zero(STATEMENT_CASE_LABEL);

        statement->base.source_position  = token.source_position;
        statement->case_label.expression = parse_expression();

        if (c_mode & _GNUC) {
                if (token.type == T_DOTDOTDOT) {
                        next_token();
                        statement->case_label.end_range = parse_expression();
                }
        }

        expect(':');

        if (! is_constant_expression(statement->case_label.expression)) {
                errorf(&statement->base.source_position,
                       "case label does not reduce to an integer constant");
        } else {
                /* TODO: check if the case label is already known */
                if (current_switch != NULL) {
                        /* link all cases into the switch statement */
                        if (current_switch->last_case == NULL) {
                                current_switch->first_case =
                                current_switch->last_case  = &statement->case_label;
                        } else {
                                current_switch->last_case->next = &statement->case_label;
                        }
                } else {
                        errorf(&statement->base.source_position,
                               "case label not within a switch statement");
                }
        }
        statement->case_label.statement = parse_statement();

        return statement;
end_error:
        return create_invalid_statement();
}

/**
 * Finds an existing default label of a switch statement.
 */
static case_label_statement_t *
find_default_label(const switch_statement_t *statement)
{
        case_label_statement_t *label = statement->first_case;
        for ( ; label != NULL; label = label->next) {
                if (label->expression == NULL)
                        return label;
        }
        return NULL;
}

/**
 * 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;

        expect(':');
        if (current_switch != NULL) {
                const case_label_statement_t *def_label = find_default_label(current_switch);
                if (def_label != NULL) {
                        errorf(HERE, "multiple default labels in one switch (previous declared %P)",
                               &def_label->base.source_position);
                } else {
                        /* link all cases into the switch statement */
                        if (current_switch->last_case == NULL) {
                                current_switch->first_case =
                                        current_switch->last_case  = &statement->case_label;
                        } else {
                                current_switch->last_case->next = &statement->case_label;
                        }
                }
        } else {
                errorf(&statement->base.source_position,
                        "'default' label not within a switch statement");
        }
        statement->case_label.statement = parse_statement();

        return statement;
end_error:
        return create_invalid_statement();
}

/**
 * Return the declaration for a given label symbol or create a new one.
 */
static declaration_t *get_label(symbol_t *symbol)
{
        declaration_t *candidate = get_declaration(symbol, NAMESPACE_LABEL);
        assert(current_function != NULL);
        /* 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;
}

/**
 * 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);

        /* if source position is already set then the label is defined twice,
         * otherwise it was just mentioned in a goto so far */
        if(label->source_position.input_name != NULL) {
                errorf(HERE, "duplicate label '%Y' (declared %P)",
                       symbol, &label->source_position);
        } else {
                label->source_position = token.source_position;
        }

        statement_t *statement = allocate_statement_zero(STATEMENT_LABEL);

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

        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();
                }
                return statement;
        } else {
                if (token.type == ';') {
                        /* eat an empty statement here, to avoid the warning about an empty
                         * after a label.  label:; is commonly used to have a label before
                         * a }. */
                        statement->label.statement = create_empty_statement();
                        next_token();
                } else {
                        statement->label.statement = parse_statement();
                }
        }

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

        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;

        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();
        }

        return statement;
end_error:
        return create_invalid_statement();
}

/**
 * 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;

        expect('(');
        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,
                       "switch quantity is not an integer, but '%T'", type);
                type = type_error_type;
        }
        statement->switchs.expression = create_implicit_cast(expr, type);
        expect(')');

        switch_statement_t *rem = current_switch;
        current_switch          = &statement->switchs;
        statement->switchs.body = parse_statement();
        current_switch          = rem;

        if(warning.switch_default &&
           find_default_label(&statement->switchs) == NULL) {
                warningf(&statement->base.source_position, "switch has no default case");
        }

        return statement;
end_error:
        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;

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

        statement->whiles.body = parse_loop_body(statement);

        return statement;
end_error:
        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;

        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(';');

        return statement;
end_error:
        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;

        int      top        = environment_top();
        scope_t *last_scope = scope;
        set_scope(&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);
        set_scope(last_scope);
        environment_pop_to(top);

        return statement;

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

        return create_invalid_statement();
}

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

        if(token.type != T_IDENTIFIER) {
                parse_error_expected("while parsing goto", T_IDENTIFIER, 0);
                eat_statement();
                return NULL;
        }
        symbol_t *symbol = token.v.symbol;
        next_token();

        declaration_t *label = get_label(symbol);

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

        statement->gotos.label = label;

        /* 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)
{
        statement_t *statement;
        if (current_loop == NULL) {
                errorf(HERE, "continue statement not within loop");
                statement = create_invalid_statement();
        } else {
                statement = allocate_statement_zero(STATEMENT_CONTINUE);

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

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

        return statement;
end_error:
        return create_invalid_statement();
}

/**
 * Parse a break statement.
 */
static statement_t *parse_break(void)
{
        statement_t *statement;
        if (current_switch == NULL && current_loop == NULL) {
                errorf(HERE, "break statement not within loop or switch");
                statement = create_invalid_statement();
        } else {
                statement = allocate_statement_zero(STATEMENT_BREAK);

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

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

        return statement;
end_error:
        return create_invalid_statement();
}

/**
 * Parse a __leave statement.
 */
static statement_t *parse_leave(void)
{
        statement_t *statement;
        if (current_try == NULL) {
                errorf(HERE, "__leave statement not within __try");
                statement = create_invalid_statement();
        } else {
                statement = allocate_statement_zero(STATEMENT_LEAVE);

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

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

        return statement;
end_error:
        return create_invalid_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();
        }
        expect(';');

        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 {
                        type_t *const res_type = semantic_assign(return_type,
                                return_value, "'return'", &statement->base.source_position);
                        if (res_type == NULL) {
                                errorf(&statement->base.source_position,
                                       "cannot return something of type '%T' in function returning '%T'",
                                       return_value->base.type, return_type);
                        } else {
                                return_value = create_implicit_cast(return_value, res_type);
                        }
                }
                /* check for returning address of a local var */
                if (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;

        return statement;
end_error:
        return create_invalid_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;
        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;

        if (warning.unused_value && !expression_has_effect(expr)) {
                warningf(&expr->base.source_position, "statement has no effect");
        }

        expect(';');

        return statement;
end_error:
        return create_invalid_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);

        ms_try_statement_t *rem = current_try;
        current_try = &statement->ms_try;
        statement->ms_try.try_statement = parse_compound_statement();
        current_try = rem;

        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();
        } else if(token.type == T__finally) {
                eat(T___finally);
                statement->ms_try.final_statement = parse_compound_statement();
        } else {
                parse_error_expected("while parsing __try statement", T___except, T___finally, 0);
                return create_invalid_statement();
        }
        return statement;
end_error:
        return create_invalid_statement();
}

/**
 * Parse a statement.
 */
static statement_t *parse_statement(void)
{
        statement_t   *statement = NULL;

        /* declaration or statement */
        add_anchor_token(';');
        switch(token.type) {
        case T_asm:
                statement = parse_asm_statement();
                break;

        case T_case:
                statement = parse_case_statement();
                break;

        case T_default:
                statement = parse_default_statement();
                break;

        case '{':
                statement = parse_compound_statement();
                break;

        case T_if:
                statement = parse_if();
                break;

        case T_switch:
                statement = parse_switch();
                break;

        case T_while:
                statement = parse_while();
                break;

        case T_do:
                statement = parse_do();
                break;

        case T_for:
                statement = parse_for();
                break;

        case T_goto:
                statement = parse_goto();
                break;

        case T_continue:
                statement = parse_continue();
                break;

        case T_break:
                statement = parse_break();
                break;

        case T___leave:
                statement = parse_leave();
                break;

        case T_return:
                statement = parse_return();
                break;

        case ';':
                if(warning.empty_statement) {
                        warningf(HERE, "statement is empty");
                }
                statement = create_empty_statement();
                next_token();
                break;

        case T_IDENTIFIER:
                if(look_ahead(1)->type == ':') {
                        statement = parse_label_statement();
                        break;
                }

                if(is_typedef_symbol(token.v.symbol)) {
                        statement = parse_declaration_statement();
                        break;
                }

                statement = parse_expression_statement();
                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__);
                statement = parse_statement();
                break;

        DECLARATION_START
                statement = parse_declaration_statement();
                break;

        case T___try:
                statement = parse_ms_try_statment();
                break;

        default:
                statement = parse_expression_statement();
                break;
        }
        rem_anchor_token(';');

        assert(statement != NULL
                        && statement->base.source_position.input_name != NULL);

        return statement;
}

/**
 * Parse a compound statement.
 */
static statement_t *parse_compound_statement(void)
{
        statement_t *statement = allocate_statement_zero(STATEMENT_COMPOUND);

        statement->base.source_position = token.source_position;

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

        int      top        = environment_top();
        scope_t *last_scope = scope;
        set_scope(&statement->compound.scope);

        statement_t *last_statement = NULL;

        while(token.type != '}' && token.type != T_EOF) {
                statement_t *sub_statement = 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(last_statement != NULL) {
                        last_statement->base.next = sub_statement;
                } else {
                        statement->compound.statements = sub_statement;
                }

                while(sub_statement->base.next != NULL)
                        sub_statement = sub_statement->base.next;

                last_statement = sub_statement;
        }

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

end_error:
        rem_anchor_token('}');
        assert(scope == &statement->compound.scope);
        set_scope(last_scope);
        environment_pop_to(top);

        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__",    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);
}

/**
 * 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->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);
        }
}

/**
 * Parse a translation unit.
 */
static translation_unit_t *parse_translation_unit(void)
{
        translation_unit_t *unit = allocate_ast_zero(sizeof(unit[0]));

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

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

        initialize_builtin_types();

        while(token.type != T_EOF) {
                if (token.type == ';') {
                        /* TODO error in strict mode */
                        warningf(HERE, "stray ';' outside of function");
                        next_token();
                } else {
                        parse_external_declaration();
                }
        }

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

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

        return unit;
}

/**
 * Parse the input.
 *
 * @return  the translation unit or NULL if errors occurred.
 */
translation_unit_t *parse(void)
{
        environment_stack = NEW_ARR_F(stack_entry_t, 0);
        label_stack       = NEW_ARR_F(stack_entry_t, 0);
        diagnostic_count  = 0;
        error_count       = 0;
        warning_count     = 0;

        type_set_output(stderr);
        ast_set_output(stderr);

        lookahead_bufpos = 0;
        for(int i = 0; i < MAX_LOOKAHEAD + 2; ++i) {
                next_token();
        }
        translation_unit_t *unit = parse_translation_unit();

        DEL_ARR_F(environment_stack);
        DEL_ARR_F(label_stack);

        return unit;
}

/**
 * Initialize the parser.
 */
void init_parser(void)
{
        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);
}