Implement __builtin_types_compatible_p().
[cparser] / parser.c
index 8d8a013..b993871 100644 (file)
--- a/parser.c
+++ b/parser.c
@@ -42,7 +42,7 @@
 #include "adt/array.h"
 
 //#define PRINT_TOKENS
-#define MAX_LOOKAHEAD 2
+#define MAX_LOOKAHEAD 1
 
 typedef struct {
        entity_t           *old_entity;
@@ -58,14 +58,14 @@ struct argument_list_t {
 
 typedef struct gnu_attribute_t gnu_attribute_t;
 struct gnu_attribute_t {
-       gnu_attribute_kind_t kind;           /**< The kind of the GNU attribute. */
+       gnu_attribute_kind_t kind;          /**< The kind of the GNU attribute. */
        gnu_attribute_t     *next;
-       bool                 invalid;        /**< Set if this attribute had argument errors, */
-       bool                 have_arguments; /**< True, if this attribute has arguments. */
+       bool                 invalid;       /**< Set if this attribute had argument errors, */
+       bool                 has_arguments; /**< True, if this attribute has arguments. */
        union {
                size_t              value;
                string_t            string;
-               atomic_type_kind_t  akind;
+               symbol_t           *symbol;
                long                argument;  /**< Single argument. */
                argument_list_t    *arguments; /**< List of argument expressions. */
        } u;
@@ -113,7 +113,7 @@ static token_t              token;
 /** The lookahead ring-buffer. */
 static token_t              lookahead_buffer[MAX_LOOKAHEAD];
 /** Position of the next token in the lookahead buffer. */
-static int                  lookahead_bufpos;
+static size_t               lookahead_bufpos;
 static stack_entry_t       *environment_stack = NULL;
 static stack_entry_t       *label_stack       = NULL;
 static scope_t             *file_scope        = NULL;
@@ -351,7 +351,7 @@ static size_t get_entity_struct_size(entity_kind_t kind)
                [ENTITY_LOCAL_LABEL]     = sizeof(label_t),
                [ENTITY_NAMESPACE]       = sizeof(namespace_t)
        };
-       assert(kind < sizeof(sizes) / sizeof(sizes[0]));
+       assert(kind < lengthof(sizes));
        assert(sizes[kind] != 0);
        return sizes[kind];
 }
@@ -381,7 +381,6 @@ static size_t get_statement_struct_size(statement_kind_t kind)
                [STATEMENT_COMPOUND]    = sizeof(compound_statement_t),
                [STATEMENT_RETURN]      = sizeof(return_statement_t),
                [STATEMENT_DECLARATION] = sizeof(declaration_statement_t),
-               [STATEMENT_LOCAL_LABEL] = sizeof(local_label_statement_t),
                [STATEMENT_IF]          = sizeof(if_statement_t),
                [STATEMENT_SWITCH]      = sizeof(switch_statement_t),
                [STATEMENT_EXPRESSION]  = sizeof(expression_statement_t),
@@ -397,7 +396,7 @@ static size_t get_statement_struct_size(statement_kind_t kind)
                [STATEMENT_MS_TRY]      = sizeof(ms_try_statement_t),
                [STATEMENT_LEAVE]       = sizeof(leave_statement_t)
        };
-       assert(kind < sizeof(sizes) / sizeof(sizes[0]));
+       assert(kind < lengthof(sizes));
        assert(sizes[kind] != 0);
        return sizes[kind];
 }
@@ -410,33 +409,34 @@ static size_t get_statement_struct_size(statement_kind_t kind)
 static size_t get_expression_struct_size(expression_kind_t kind)
 {
        static const size_t sizes[] = {
-               [EXPR_INVALID]                 = sizeof(expression_base_t),
-               [EXPR_REFERENCE]               = sizeof(reference_expression_t),
-               [EXPR_REFERENCE_ENUM_VALUE]    = sizeof(reference_expression_t),
-               [EXPR_CONST]                   = sizeof(const_expression_t),
-               [EXPR_CHARACTER_CONSTANT]      = sizeof(const_expression_t),
-               [EXPR_WIDE_CHARACTER_CONSTANT] = sizeof(const_expression_t),
-               [EXPR_STRING_LITERAL]          = sizeof(string_literal_expression_t),
-               [EXPR_WIDE_STRING_LITERAL]     = sizeof(wide_string_literal_expression_t),
-               [EXPR_COMPOUND_LITERAL]        = sizeof(compound_literal_expression_t),
-               [EXPR_CALL]                    = sizeof(call_expression_t),
-               [EXPR_UNARY_FIRST]             = sizeof(unary_expression_t),
-               [EXPR_BINARY_FIRST]            = sizeof(binary_expression_t),
-               [EXPR_CONDITIONAL]             = sizeof(conditional_expression_t),
-               [EXPR_SELECT]                  = sizeof(select_expression_t),
-               [EXPR_ARRAY_ACCESS]            = sizeof(array_access_expression_t),
-               [EXPR_SIZEOF]                  = sizeof(typeprop_expression_t),
-               [EXPR_ALIGNOF]                 = sizeof(typeprop_expression_t),
-               [EXPR_CLASSIFY_TYPE]           = sizeof(classify_type_expression_t),
-               [EXPR_FUNCNAME]                = sizeof(funcname_expression_t),
-               [EXPR_BUILTIN_SYMBOL]          = sizeof(builtin_symbol_expression_t),
-               [EXPR_BUILTIN_CONSTANT_P]      = sizeof(builtin_constant_expression_t),
-               [EXPR_BUILTIN_PREFETCH]        = sizeof(builtin_prefetch_expression_t),
-               [EXPR_OFFSETOF]                = sizeof(offsetof_expression_t),
-               [EXPR_VA_START]                = sizeof(va_start_expression_t),
-               [EXPR_VA_ARG]                  = sizeof(va_arg_expression_t),
-               [EXPR_STATEMENT]               = sizeof(statement_expression_t),
-               [EXPR_LABEL_ADDRESS]           = sizeof(label_address_expression_t),
+               [EXPR_INVALID]                    = sizeof(expression_base_t),
+               [EXPR_REFERENCE]                  = sizeof(reference_expression_t),
+               [EXPR_REFERENCE_ENUM_VALUE]       = 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_TYPES_COMPATIBLE_P] = sizeof(builtin_types_compatible_expression_t),
+               [EXPR_BUILTIN_PREFETCH]           = sizeof(builtin_prefetch_expression_t),
+               [EXPR_OFFSETOF]                   = sizeof(offsetof_expression_t),
+               [EXPR_VA_START]                   = sizeof(va_start_expression_t),
+               [EXPR_VA_ARG]                     = sizeof(va_arg_expression_t),
+               [EXPR_STATEMENT]                  = sizeof(statement_expression_t),
+               [EXPR_LABEL_ADDRESS]              = sizeof(label_address_expression_t),
        };
        if (kind >= EXPR_UNARY_FIRST && kind <= EXPR_UNARY_LAST) {
                return sizes[EXPR_UNARY_FIRST];
@@ -444,7 +444,7 @@ static size_t get_expression_struct_size(expression_kind_t kind)
        if (kind >= EXPR_BINARY_FIRST && kind <= EXPR_BINARY_LAST) {
                return sizes[EXPR_BINARY_FIRST];
        }
-       assert(kind < sizeof(sizes) / sizeof(sizes[0]));
+       assert(kind < lengthof(sizes));
        assert(sizes[kind] != 0);
        return sizes[kind];
 }
@@ -527,7 +527,7 @@ static size_t get_type_struct_size(type_kind_t kind)
                [TYPE_TYPEDEF]         = sizeof(typedef_type_t),
                [TYPE_TYPEOF]          = sizeof(typeof_type_t),
        };
-       assert(sizeof(sizes) / sizeof(sizes[0]) == (int) TYPE_TYPEOF + 1);
+       assert(lengthof(sizes) == (int)TYPE_TYPEOF + 1);
        assert(kind <= TYPE_TYPEOF);
        assert(sizes[kind] != 0);
        return sizes[kind];
@@ -563,7 +563,7 @@ static size_t get_initializer_size(initializer_kind_t kind)
                [INITIALIZER_LIST]        = sizeof(initializer_list_t),
                [INITIALIZER_DESIGNATOR]  = sizeof(initializer_designator_t)
        };
-       assert(kind < sizeof(sizes) / sizeof(*sizes));
+       assert(kind < lengthof(sizes));
        assert(sizes[kind] != 0);
        return sizes[kind];
 }
@@ -580,14 +580,6 @@ static initializer_t *allocate_initializer_zero(initializer_kind_t 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.
  */
@@ -613,7 +605,7 @@ static inline void next_token(void)
        lookahead_buffer[lookahead_bufpos] = lexer_token;
        lexer_next_token();
 
-       lookahead_bufpos = (lookahead_bufpos+1) % MAX_LOOKAHEAD;
+       lookahead_bufpos = (lookahead_bufpos + 1) % MAX_LOOKAHEAD;
 
 #ifdef PRINT_TOKENS
        print_token(stderr, &token);
@@ -624,10 +616,10 @@ static inline void next_token(void)
 /**
  * Return the next token with a given lookahead.
  */
-static inline const token_t *look_ahead(int num)
+static inline const token_t *look_ahead(size_t num)
 {
-       assert(num > 0 && num <= MAX_LOOKAHEAD);
-       int pos = (lookahead_bufpos+num-1) % MAX_LOOKAHEAD;
+       assert(0 < num && num <= MAX_LOOKAHEAD);
+       size_t pos = (lookahead_bufpos + num - 1) % MAX_LOOKAHEAD;
        return &lookahead_buffer[pos];
 }
 
@@ -758,7 +750,7 @@ static void eat_block(void)
                next_token();
 }
 
-#define eat(token_type)  do { assert(token.type == (token_type)); next_token(); } while (0)
+#define eat(token_type) (assert(token.type == (token_type)), next_token())
 
 /**
  * Report a parse error because an expected token was not found.
@@ -978,13 +970,8 @@ static int get_akind_rank(atomic_type_kind_t akind)
 static int get_rank(const type_t *type)
 {
        assert(!is_typeref(type));
-       /* The C-standard allows promoting enums to int or unsigned int (see § 7.2.2
-        * and esp. footnote 108). However we can't fold constants (yet), so we
-        * can't decide whether unsigned int is possible, while int always works.
-        * (unsigned int would be preferable when possible... for stuff like
-        *  struct { enum { ... } bla : 4; } ) */
        if (type->kind == TYPE_ENUM)
-               return get_akind_rank(ATOMIC_TYPE_INT);
+               return get_akind_rank(type->enumt.akind);
 
        assert(type->kind == TYPE_ATOMIC);
        return get_akind_rank(type->atomic.akind);
@@ -1032,21 +1019,18 @@ static expression_t *create_cast_expression(expression_t *expression,
 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;
+       if (expression->kind == EXPR_UNARY_CAST ||
+                       expression->kind == EXPR_UNARY_CAST_IMPLICIT) {
+               type_t *const type = skip_typeref(expression->base.type);
+               if (types_compatible(type, type_void_ptr))
+                       expression = expression->unary.value;
        }
 
-       /* 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;
+       return
+               is_type_integer(type)              &&
+               is_constant_expression(expression) &&
+               fold_constant(expression) == 0;
 }
 
 /**
@@ -1328,7 +1312,7 @@ static gnu_attribute_t *allocate_gnu_attribute(gnu_attribute_kind_t kind)
        attribute->kind            = kind;
        attribute->next            = NULL;
        attribute->invalid         = false;
-       attribute->have_arguments  = false;
+       attribute->has_arguments   = false;
 
        return attribute;
 }
@@ -1477,35 +1461,13 @@ static void parse_gnu_attribute_model_arg(gnu_attribute_t *attribute)
  */
 static void parse_gnu_attribute_mode_arg(gnu_attribute_t *attribute)
 {
-       /* TODO: find out what is allowed here... */
-
-       /* at least: byte, word, pointer, list of machine modes
-        * __XXX___ is interpreted as XXX */
        add_anchor_token(')');
 
        if (token.type != T_IDENTIFIER) {
                expect(T_IDENTIFIER, end_error);
        }
 
-       /* This isn't really correct, the backend should provide a list of machine
-        * specific modes (according to gcc philosophy that is...) */
-       const char *symbol_str = token.v.symbol->string;
-       if (strcmp_underscore("QI",   symbol_str) == 0 ||
-           strcmp_underscore("byte", symbol_str) == 0) {
-               attribute->u.akind = ATOMIC_TYPE_CHAR;
-       } else if (strcmp_underscore("HI", symbol_str) == 0) {
-               attribute->u.akind = ATOMIC_TYPE_SHORT;
-       } else if (strcmp_underscore("SI",      symbol_str) == 0
-               || strcmp_underscore("word",    symbol_str) == 0
-               || strcmp_underscore("pointer", symbol_str) == 0) {
-               attribute->u.akind = ATOMIC_TYPE_INT;
-       } else if (strcmp_underscore("DI", symbol_str) == 0) {
-               attribute->u.akind = ATOMIC_TYPE_LONGLONG;
-       } else {
-               if (warning.other)
-                       warningf(HERE, "ignoring unknown mode '%s'", symbol_str);
-               attribute->invalid = true;
-       }
+       attribute->u.symbol = token.v.symbol;
        next_token();
 
        rem_anchor_token(')');
@@ -1591,7 +1553,7 @@ end_error:
  */
 static void check_no_argument(gnu_attribute_t *attribute, const char *name)
 {
-       if (!attribute->have_arguments)
+       if (!attribute->has_arguments)
                return;
 
        /* should have no arguments */
@@ -1741,7 +1703,7 @@ static decl_modifiers_t parse_gnu_attribute(gnu_attribute_t **attributes)
                                                /* empty args are allowed */
                                                next_token();
                                        } else
-                                               attribute->have_arguments = true;
+                                               attribute->has_arguments = true;
                                }
 
                                switch (kind) {
@@ -1800,7 +1762,7 @@ static decl_modifiers_t parse_gnu_attribute(gnu_attribute_t **attributes)
 
                                case GNU_AK_ALIGNED:
                                        /* __align__ may be used without an argument */
-                                       if (attribute->have_arguments) {
+                                       if (attribute->has_arguments) {
                                                parse_gnu_attribute_const_arg(attribute);
                                        }
                                        break;
@@ -1808,7 +1770,7 @@ static decl_modifiers_t parse_gnu_attribute(gnu_attribute_t **attributes)
                                case GNU_AK_FORMAT_ARG:
                                case GNU_AK_REGPARM:
                                case GNU_AK_TRAP_EXIT:
-                                       if (!attribute->have_arguments) {
+                                       if (!attribute->has_arguments) {
                                                /* should have arguments */
                                                errorf(HERE, "wrong number of arguments specified for '%s' attribute", name);
                                                attribute->invalid = true;
@@ -1818,7 +1780,7 @@ static decl_modifiers_t parse_gnu_attribute(gnu_attribute_t **attributes)
                                case GNU_AK_ALIAS:
                                case GNU_AK_SECTION:
                                case GNU_AK_SP_SWITCH:
-                                       if (!attribute->have_arguments) {
+                                       if (!attribute->has_arguments) {
                                                /* should have arguments */
                                                errorf(HERE, "wrong number of arguments specified for '%s' attribute", name);
                                                attribute->invalid = true;
@@ -1826,7 +1788,7 @@ static decl_modifiers_t parse_gnu_attribute(gnu_attribute_t **attributes)
                                                parse_gnu_attribute_string_arg(attribute, &attribute->u.string);
                                        break;
                                case GNU_AK_FORMAT:
-                                       if (!attribute->have_arguments) {
+                                       if (!attribute->has_arguments) {
                                                /* should have arguments */
                                                errorf(HERE, "wrong number of arguments specified for '%s' attribute", name);
                                                attribute->invalid = true;
@@ -1835,29 +1797,29 @@ static decl_modifiers_t parse_gnu_attribute(gnu_attribute_t **attributes)
                                        break;
                                case GNU_AK_WEAKREF:
                                        /* may have one string argument */
-                                       if (attribute->have_arguments)
+                                       if (attribute->has_arguments)
                                                parse_gnu_attribute_string_arg(attribute, &attribute->u.string);
                                        break;
                                case GNU_AK_NONNULL:
-                                       if (attribute->have_arguments)
+                                       if (attribute->has_arguments)
                                                parse_gnu_attribute_const_arg_list(attribute);
                                        break;
                                case GNU_AK_TLS_MODEL:
-                                       if (!attribute->have_arguments) {
+                                       if (!attribute->has_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) {
+                                       if (!attribute->has_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) {
+                                       if (!attribute->has_arguments) {
                                                /* should have arguments */
                                                errorf(HERE, "wrong number of arguments specified for '%s' attribute", name);
                                        } else {
@@ -1865,7 +1827,7 @@ static decl_modifiers_t parse_gnu_attribute(gnu_attribute_t **attributes)
                                        }
                                        break;
                                case GNU_AK_MODE:
-                                       if (!attribute->have_arguments) {
+                                       if (!attribute->has_arguments) {
                                                /* should have arguments */
                                                errorf(HERE, "wrong number of arguments specified for '%s' attribute", name);
                                        } else {
@@ -1874,12 +1836,12 @@ static decl_modifiers_t parse_gnu_attribute(gnu_attribute_t **attributes)
                                        break;
                                case GNU_AK_INTERRUPT:
                                        /* may have one string argument */
-                                       if (attribute->have_arguments)
+                                       if (attribute->has_arguments)
                                                parse_gnu_attribute_interrupt_arg(attribute);
                                        break;
                                case GNU_AK_SENTINEL:
                                        /* may have one string argument */
-                                       if (attribute->have_arguments)
+                                       if (attribute->has_arguments)
                                                parse_gnu_attribute_const_arg(attribute);
                                        break;
                                case GNU_AK_LAST:
@@ -2178,6 +2140,7 @@ unary:
                case EXPR_FUNCNAME:
                case EXPR_BUILTIN_SYMBOL:
                case EXPR_BUILTIN_CONSTANT_P:
+               case EXPR_BUILTIN_TYPES_COMPATIBLE_P:
                case EXPR_BUILTIN_PREFETCH:
                case EXPR_OFFSETOF:
                case EXPR_STATEMENT: // TODO
@@ -2286,6 +2249,7 @@ static initializer_t *initializer_from_expression(type_t *orig_type,
                                                return initializer_from_string(array_type,
                                                        &expression->string.value);
                                        }
+                                       break;
 
                                case EXPR_WIDE_STRING_LITERAL: {
                                        type_t *bare_wchar_type = skip_typeref(type_wchar_t);
@@ -2293,6 +2257,7 @@ static initializer_t *initializer_from_expression(type_t *orig_type,
                                                return initializer_from_wide_string(array_type,
                                                        &expression->wide_string.value);
                                        }
+                                       break;
                                }
 
                                default:
@@ -2946,7 +2911,7 @@ static initializer_t *parse_initializer(parse_initializer_env_t *env)
                result = parse_scalar_initializer(type, env->must_be_constant);
        }
 
-       /* § 6.7.8 (22) array initializers for arrays with unknown size determine
+       /* § 6.7.8:22 array initializers for arrays with unknown size determine
         * the array type size */
        if (is_type_array(type) && type->array.size_expression == NULL
                        && result != NULL) {
@@ -3033,8 +2998,8 @@ static compound_t *parse_compound_type_specifier(bool is_struct)
                        compound = &entity->compound;
                        if (compound->base.parent_scope != current_scope &&
                            (token.type == '{' || token.type == ';')) {
-                               /* we're in an inner scope and have a definition. Override
-                                  existing definition in outer scope */
+                               /* we're in an inner scope and have a definition. Shadow
+                                * existing definition in outer scope */
                                compound = NULL;
                        } else if (compound->complete && token.type == '{') {
                                assert(symbol != NULL);
@@ -3148,7 +3113,18 @@ static type_t *parse_enum_specifier(void)
                next_token();
 
                entity = get_entity(symbol, NAMESPACE_ENUM);
-               assert(entity == NULL || entity->kind == ENTITY_ENUM);
+               if (entity != NULL) {
+                       assert(entity->kind == ENTITY_ENUM);
+                       if (entity->base.parent_scope != current_scope &&
+                                       (token.type == '{' || token.type == ';')) {
+                               /* we're in an inner scope and have a definition. Shadow
+                                * existing definition in outer scope */
+                               entity = NULL;
+                       } else if (entity->enume.complete && token.type == '{') {
+                               errorf(HERE, "multiple definitions of 'enum %Y' (previous definition %P)",
+                                               symbol, &entity->base.source_position);
+                       }
+               }
        } else if (token.type != '{') {
                parse_error_expected("while parsing enum type specifier",
                                     T_IDENTIFIER, '{', NULL);
@@ -3168,12 +3144,9 @@ static type_t *parse_enum_specifier(void)
 
        type_t *const type = allocate_type_zero(TYPE_ENUM);
        type->enumt.enume  = &entity->enume;
+       type->enumt.akind  = ATOMIC_TYPE_INT;
 
        if (token.type == '{') {
-               if (entity->enume.complete) {
-                       errorf(HERE, "multiple definitions of 'enum %Y' (previous definition %P)",
-                              symbol, &entity->base.source_position);
-               }
                if (symbol != NULL) {
                        environment_push(entity);
                }
@@ -3286,13 +3259,7 @@ static type_t *create_builtin_type(symbol_t *const symbol,
        type_t *type            = allocate_type_zero(TYPE_BUILTIN);
        type->builtin.symbol    = symbol;
        type->builtin.real_type = real_type;
-
-       type_t *result = typehash_insert(type);
-       if (type != result) {
-               free_type(type);
-       }
-
-       return result;
+       return identify_new_type(type);
 }
 
 static type_t *get_typedef_type(symbol_t *symbol)
@@ -3621,6 +3588,78 @@ static void finish_union_type(compound_type_t *type)
        type->base.alignment = alignment;
 }
 
+static type_t *handle_attribute_mode(const gnu_attribute_t *attribute,
+                                     type_t *orig_type)
+{
+       type_t *type = skip_typeref(orig_type);
+
+       /* at least: byte, word, pointer, list of machine modes
+        * __XXX___ is interpreted as XXX */
+
+       /* This isn't really correct, the backend should provide a list of machine
+        * specific modes (according to gcc philosophy that is...) */
+       const char         *symbol_str = attribute->u.symbol->string;
+       bool                sign       = is_type_signed(type);
+       atomic_type_kind_t  akind;
+       if (strcmp_underscore("QI",   symbol_str) == 0 ||
+           strcmp_underscore("byte", symbol_str) == 0) {
+               akind = sign ? ATOMIC_TYPE_CHAR : ATOMIC_TYPE_UCHAR;
+       } else if (strcmp_underscore("HI", symbol_str) == 0) {
+               akind = sign ? ATOMIC_TYPE_SHORT : ATOMIC_TYPE_USHORT;
+       } else if (strcmp_underscore("SI",      symbol_str) == 0
+               || strcmp_underscore("word",    symbol_str) == 0
+               || strcmp_underscore("pointer", symbol_str) == 0) {
+               akind = sign ? ATOMIC_TYPE_INT : ATOMIC_TYPE_UINT;
+       } else if (strcmp_underscore("DI", symbol_str) == 0) {
+               akind = sign ? ATOMIC_TYPE_LONGLONG : ATOMIC_TYPE_ULONGLONG;
+       } else {
+               if (warning.other)
+                       warningf(HERE, "ignoring unknown mode '%s'", symbol_str);
+               return orig_type;
+       }
+
+       if (type->kind == TYPE_ATOMIC) {
+               type_t *copy       = duplicate_type(type);
+               copy->atomic.akind = akind;
+               return identify_new_type(copy);
+       } else if (type->kind == TYPE_ENUM) {
+               type_t *copy      = duplicate_type(type);
+               copy->enumt.akind = akind;
+               return identify_new_type(copy);
+       } else if (is_type_pointer(type)) {
+               warningf(HERE, "__attribute__((mode)) on pointers not implemented yet (ignored)");
+               return type;
+       }
+
+       errorf(HERE, "__attribute__((mode)) only allowed on integer, enum or pointer type");
+       return orig_type;
+}
+
+static type_t *handle_type_attributes(const gnu_attribute_t *attributes,
+                                      type_t *type)
+{
+       const gnu_attribute_t *attribute = attributes;
+       for ( ; attribute != NULL; attribute = attribute->next) {
+               if (attribute->invalid)
+                       continue;
+
+               if (attribute->kind == GNU_AK_MODE) {
+                       type = handle_attribute_mode(attribute, type);
+               } else if (attribute->kind == GNU_AK_ALIGNED) {
+                       int alignment = 32; /* TODO: fill in maximum useful alignment for
+                                              target machine */
+                       if (attribute->has_arguments)
+                               alignment = attribute->u.argument;
+
+                       type_t *copy         = duplicate_type(type);
+                       copy->base.alignment = attribute->u.argument;
+                       type                 = identify_new_type(copy);
+               }
+       }
+
+       return type;
+}
+
 static void parse_declaration_specifiers(declaration_specifiers_t *specifiers)
 {
        type_t            *type              = NULL;
@@ -3636,8 +3675,6 @@ static void parse_declaration_specifiers(declaration_specifiers_t *specifiers)
        while (true) {
                specifiers->modifiers
                        |= parse_attributes(&specifiers->gnu_attributes);
-               if (specifiers->modifiers & DM_TRANSPARENT_UNION)
-                       modifiers |= TYPE_MODIFIER_TRANSPARENT_UNION;
 
                switch (token.type) {
                /* storage class */
@@ -3858,6 +3895,9 @@ wrong_thread_stoarge_class:
        }
 
 finish_specifiers:
+       specifiers->modifiers
+               |= parse_attributes(&specifiers->gnu_attributes);
+
        in_gcc_extension = old_gcc_extension;
 
        if (type == NULL || (saw_error && type_specifiers != 0)) {
@@ -4032,9 +4072,13 @@ warn_about_long_long:
                        type                  = allocate_type_zero(TYPE_IMAGINARY);
                        type->imaginary.akind = atomic_type;
                } else {
-                       type               = allocate_type_zero(TYPE_ATOMIC);
-                       type->atomic.akind = atomic_type;
+                       type                 = allocate_type_zero(TYPE_ATOMIC);
+                       type->atomic.akind   = atomic_type;
                }
+               type->base.alignment = get_atomic_type_alignment(atomic_type);
+               unsigned const size  = get_atomic_type_size(atomic_type);
+               type->base.size      =
+                       type_specifiers & SPECIFIER_COMPLEX ? size * 2 : size;
                newtype = true;
        } else if (type_specifiers != 0) {
                errorf(HERE, "multiple datatypes in declaration");
@@ -4042,15 +4086,19 @@ warn_about_long_long:
 
        /* FIXME: check type qualifiers here */
 
+       if (specifiers->modifiers & DM_TRANSPARENT_UNION)
+               modifiers |= TYPE_MODIFIER_TRANSPARENT_UNION;
        type->base.qualifiers = qualifiers;
        type->base.modifiers  = modifiers;
 
-       type_t *result = typehash_insert(type);
-       if (newtype && result != type) {
-               free_type(type);
+       if (newtype) {
+               type = identify_new_type(type);
+       } else {
+               type = typehash_insert(type);
        }
 
-       specifiers->type = result;
+       type = handle_type_attributes(specifiers->gnu_attributes, type);
+       specifiers->type = type;
        return;
 
 end_error:
@@ -4550,34 +4598,28 @@ static void parse_declaration_attributes(entity_t *entity)
        if (type == NULL)
                return;
 
-       /* handle these strange/stupid mode attributes */
        gnu_attribute_t *attribute = attributes;
        for ( ; attribute != NULL; attribute = attribute->next) {
-               if (attribute->kind != GNU_AK_MODE || attribute->invalid)
+               if (attribute->invalid)
                        continue;
 
-               atomic_type_kind_t  akind = attribute->u.akind;
-               if (!is_type_signed(type)) {
-                       switch (akind) {
-                       case ATOMIC_TYPE_CHAR: akind = ATOMIC_TYPE_UCHAR; break;
-                       case ATOMIC_TYPE_SHORT: akind = ATOMIC_TYPE_USHORT; break;
-                       case ATOMIC_TYPE_INT: akind = ATOMIC_TYPE_UINT; break;
-                       case ATOMIC_TYPE_LONGLONG: akind = ATOMIC_TYPE_ULONGLONG; break;
-                       default:
-                               panic("invalid akind in mode attribute");
-                       }
-               } else {
-                       switch (akind) {
-                       case ATOMIC_TYPE_CHAR: akind = ATOMIC_TYPE_SCHAR; break;
-                       case ATOMIC_TYPE_SHORT: akind = ATOMIC_TYPE_SHORT; break;
-                       case ATOMIC_TYPE_INT: akind = ATOMIC_TYPE_INT; break;
-                       case ATOMIC_TYPE_LONGLONG: akind = ATOMIC_TYPE_LONGLONG; break;
-                       default:
-                               panic("invalid akind in mode attribute");
+               if (attribute->kind == GNU_AK_MODE) {
+                       type = handle_attribute_mode(attribute, type);
+               } else if (attribute->kind == GNU_AK_ALIGNED) {
+                       int alignment = 32; /* TODO: fill in maximum usefull alignment for target machine */
+                       if (attribute->has_arguments)
+                               alignment = attribute->u.argument;
+
+                       if (entity->kind == ENTITY_TYPEDEF) {
+                               type_t *copy         = duplicate_type(type);
+                               copy->base.alignment = attribute->u.argument;
+                               type                 = identify_new_type(copy);
+                       } else if(entity->kind == ENTITY_VARIABLE) {
+                               entity->variable.alignment = alignment;
+                       } else if(entity->kind == ENTITY_COMPOUND_MEMBER) {
+                               entity->compound_member.alignment = alignment;
                        }
                }
-
-               type = make_atomic_type(akind, type->base.qualifiers);
        }
 
        type_modifiers_t type_modifiers = type->base.modifiers;
@@ -4585,13 +4627,9 @@ static void parse_declaration_attributes(entity_t *entity)
                type_modifiers |= TYPE_MODIFIER_TRANSPARENT_UNION;
 
        if (type->base.modifiers != type_modifiers) {
-               type_t *copy = duplicate_type(type);
+               type_t *copy         = duplicate_type(type);
                copy->base.modifiers = type_modifiers;
-
-               type = typehash_insert(copy);
-               if (type != copy) {
-                       obstack_free(type_obst, copy);
-               }
+               type                 = identify_new_type(copy);
        }
 
        if (entity->kind == ENTITY_TYPEDEF) {
@@ -4619,7 +4657,7 @@ static type_t *construct_declarator_type(construct_type_t *construct_list, type_
                        function_type->function.return_type = type;
 
                        type_t *skipped_return_type = skip_typeref(type);
-                       /* §6.7.5.3(1) */
+                       /* §6.7.5.3:1 */
                        if (is_type_function(skipped_return_type)) {
                                errorf(HERE, "function returning function is not allowed");
                        } else if (is_type_array(skipped_return_type)) {
@@ -4681,7 +4719,7 @@ static type_t *construct_declarator_type(construct_type_t *construct_list, type_
                        }
 
                        type_t *skipped_type = skip_typeref(type);
-                       /* §6.7.5.2(1) */
+                       /* §6.7.5.2:1 */
                        if (is_type_incomplete(skipped_type)) {
                                errorf(HERE, "array of incomplete type '%T' is not allowed", type);
                        } else if (is_type_function(skipped_type)) {
@@ -4692,14 +4730,12 @@ static type_t *construct_declarator_type(construct_type_t *construct_list, type_
                }
                }
 
-               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;
+               /* The function type was constructed earlier.  Freeing it here will
+                * destroy other types. */
+               if (iter->kind == CONSTRUCT_FUNCTION) {
+                       type = typehash_insert(type);
+               } else {
+                       type = identify_new_type(type);
                }
        }
 
@@ -4784,16 +4820,18 @@ static entity_t *parse_declarator(const declaration_specifiers_t *specifiers,
                if (flags & DECL_CREATE_COMPOUND_MEMBER) {
                        entity = allocate_entity_zero(ENTITY_COMPOUND_MEMBER);
 
-                       if (specifiers->is_inline && is_type_valid(type)) {
-                               errorf(&env.source_position,
-                                               "compound member '%Y' declared 'inline'", env.symbol);
-                       }
+                       if (env.symbol != NULL) {
+                               if (specifiers->is_inline && is_type_valid(type)) {
+                                       errorf(&env.source_position,
+                                                       "compound member '%Y' declared 'inline'", env.symbol);
+                               }
 
-                       if (specifiers->thread_local ||
-                               specifiers->storage_class != STORAGE_CLASS_NONE) {
-                               errorf(&env.source_position,
-                                          "compound member '%Y' must have no storage class",
-                                          env.symbol);
+                               if (specifiers->thread_local ||
+                                               specifiers->storage_class != STORAGE_CLASS_NONE) {
+                                       errorf(&env.source_position,
+                                                       "compound member '%Y' must have no storage class",
+                                                       env.symbol);
+                               }
                        }
                } else if (flags & DECL_IS_PARAMETER) {
                        orig_type = semantic_parameter(&env.source_position, orig_type,
@@ -4806,52 +4844,56 @@ static entity_t *parse_declarator(const declaration_specifiers_t *specifiers,
                        entity->function.is_inline  = specifiers->is_inline;
                        entity->function.parameters = env.parameters;
 
-                       if (specifiers->thread_local || (
-                                       specifiers->storage_class != STORAGE_CLASS_EXTERN &&
-                                       specifiers->storage_class != STORAGE_CLASS_NONE   &&
-                                       specifiers->storage_class != STORAGE_CLASS_STATIC)
-                          ) {
-                               errorf(&env.source_position,
-                                          "invalid storage class for function '%Y'", env.symbol);
+                       if (env.symbol != NULL) {
+                               if (specifiers->thread_local || (
+                                                       specifiers->storage_class != STORAGE_CLASS_EXTERN &&
+                                                       specifiers->storage_class != STORAGE_CLASS_NONE   &&
+                                                       specifiers->storage_class != STORAGE_CLASS_STATIC
+                                               )) {
+                                       errorf(&env.source_position,
+                                                       "invalid storage class for function '%Y'", env.symbol);
+                               }
                        }
                } else {
                        entity = allocate_entity_zero(ENTITY_VARIABLE);
 
                        entity->variable.get_property_sym = specifiers->get_property_sym;
                        entity->variable.put_property_sym = specifiers->put_property_sym;
-                       if (specifiers->alignment != 0) {
-                               /* TODO: add checks here */
-                               entity->variable.alignment = specifiers->alignment;
-                       }
-
-                       if (specifiers->is_inline && is_type_valid(type)) {
-                               errorf(&env.source_position,
-                                          "variable '%Y' declared 'inline'", env.symbol);
-                       }
 
                        entity->variable.thread_local = specifiers->thread_local;
 
-                       bool invalid_storage_class = false;
-                       if (current_scope == file_scope) {
-                               if (specifiers->storage_class != STORAGE_CLASS_EXTERN &&
-                                               specifiers->storage_class != STORAGE_CLASS_NONE   &&
-                                               specifiers->storage_class != STORAGE_CLASS_STATIC) {
-                                       invalid_storage_class = true;
+                       if (env.symbol != NULL) {
+                               if (specifiers->is_inline && is_type_valid(type)) {
+                                       errorf(&env.source_position,
+                                                       "variable '%Y' declared 'inline'", env.symbol);
                                }
-                       } else {
-                               if (specifiers->thread_local &&
-                                               specifiers->storage_class == STORAGE_CLASS_NONE) {
-                                       invalid_storage_class = true;
+
+                               bool invalid_storage_class = false;
+                               if (current_scope == file_scope) {
+                                       if (specifiers->storage_class != STORAGE_CLASS_EXTERN &&
+                                                       specifiers->storage_class != STORAGE_CLASS_NONE   &&
+                                                       specifiers->storage_class != STORAGE_CLASS_STATIC) {
+                                               invalid_storage_class = true;
+                                       }
+                               } else {
+                                       if (specifiers->thread_local &&
+                                                       specifiers->storage_class == STORAGE_CLASS_NONE) {
+                                               invalid_storage_class = true;
+                                       }
+                               }
+                               if (invalid_storage_class) {
+                                       errorf(&env.source_position,
+                                                       "invalid storage class for variable '%Y'", env.symbol);
                                }
-                       }
-                       if (invalid_storage_class) {
-                               errorf(&env.source_position,
-                                               "invalid storage class for variable '%Y'", env.symbol);
                        }
                }
 
-               entity->base.source_position          = env.source_position;
-               entity->base.symbol                   = env.symbol;
+               if (env.symbol != NULL) {
+                       entity->base.symbol          = env.symbol;
+                       entity->base.source_position = env.source_position;
+               } else {
+                       entity->base.source_position = specifiers->source_position;
+               }
                entity->base.namespc                  = NAMESPACE_NORMAL;
                entity->declaration.type              = orig_type;
                entity->declaration.modifiers         = env.modifiers;
@@ -4959,6 +5001,16 @@ static void error_redefined_as_different_kind(const source_position_t *pos,
               get_entity_kind_name(new_kind), &old->base.source_position);
 }
 
+static bool is_error_entity(entity_t *const ent)
+{
+       if (is_declaration(ent)) {
+               return is_type_valid(skip_typeref(ent->declaration.type));
+       } else if (ent->kind == ENTITY_TYPEDEF) {
+               return is_type_valid(skip_typeref(ent->typedefe.type));
+       }
+       return false;
+}
+
 /**
  * record entities for the NAMESPACE_NORMAL, and produce error messages/warnings
  * for various problems that occur for multiple definitions
@@ -5018,8 +5070,10 @@ static entity_t *record_entity(entity_t *entity, const bool is_definition)
        if (previous_entity != NULL &&
                        previous_entity->base.parent_scope == current_scope) {
                if (previous_entity->kind != entity->kind) {
-                       error_redefined_as_different_kind(pos, previous_entity,
-                                                         entity->kind);
+                       if (!is_error_entity(previous_entity) && !is_error_entity(entity)) {
+                               error_redefined_as_different_kind(pos, previous_entity,
+                                               entity->kind);
+                       }
                        goto finish;
                }
                if (previous_entity->kind == ENTITY_ENUM_VALUE) {
@@ -5055,7 +5109,7 @@ static entity_t *record_entity(entity_t *entity, const bool is_definition)
                type_t *const orig_type = decl->type;
                assert(orig_type != NULL);
                type_t *const type      = skip_typeref(orig_type);
-               type_t *      prev_type = skip_typeref(prev_decl->type);
+               type_t *const prev_type = skip_typeref(prev_decl->type);
 
                if (!types_compatible(type, prev_type)) {
                        errorf(pos,
@@ -5074,20 +5128,16 @@ static entity_t *record_entity(entity_t *entity, const bool is_definition)
                                         prev_decl->type, symbol);
                        }
 
-                       unsigned new_storage_class = decl->storage_class;
-                       if (is_type_incomplete(prev_type)) {
-                               prev_decl->type = type;
-                               prev_type       = type;
-                       }
+                       storage_class_t new_storage_class = decl->storage_class;
 
                        /* pretend no storage class means extern for function
                         * declarations (except if the previous declaration is neither
                         * none nor extern) */
                        if (entity->kind == ENTITY_FUNCTION) {
-                               if (prev_type->function.unspecified_parameters) {
+                               /* the previous declaration could have unspecified parameters or
+                                * be a typedef, so use the new type */
+                               if (prev_type->function.unspecified_parameters || is_definition)
                                        prev_decl->type = type;
-                                       prev_type       = type;
-                               }
 
                                switch (old_storage_class) {
                                case STORAGE_CLASS_NONE:
@@ -5110,6 +5160,8 @@ static entity_t *record_entity(entity_t *entity, const bool is_definition)
                                default:
                                        break;
                                }
+                       } else if (is_type_incomplete(prev_type)) {
+                               prev_decl->type = type;
                        }
 
                        if (old_storage_class == STORAGE_CLASS_EXTERN &&
@@ -5256,7 +5308,7 @@ static void parse_init_declarator_rest(entity_t *entity)
        current_init_decl = NULL;
 
        if (entity->kind == ENTITY_VARIABLE) {
-               /* § 6.7.5 (22)  array initializers for arrays with unknown size
+               /* § 6.7.5:22  array initializers for arrays with unknown size
                 * determine the array type size */
                declaration->type            = env.type;
                entity->variable.initializer = initializer;
@@ -5314,11 +5366,9 @@ static void check_variable_type_complete(entity_t *ent)
        if (!is_type_incomplete(type))
                return;
 
-       /* GCC allows global arrays without size and assigns them a length of one,
-        * if no different declaration follows */
-       if (is_type_array(type) &&
-                       c_mode & _GNUC      &&
-                       ent->base.parent_scope == file_scope) {
+       /* §6.9.2:2 and §6.9.2:5: At the end of the translation incomplete arrays
+        * are given length one. */
+       if (is_type_array(type) && ent->base.parent_scope == file_scope) {
                ARR_APP1(declaration_t*, incomplete_arrays, decl);
                return;
        }
@@ -5482,6 +5532,9 @@ decl_list_end:
 
        parameter = entity->function.parameters.entities;
        for (; parameter != NULL; parameter = parameter->base.next) {
+               if (parameter->kind != ENTITY_PARAMETER)
+                       continue;
+
                type_t *parameter_type = parameter->declaration.type;
                if (parameter_type == NULL) {
                        if (strict_mode) {
@@ -5523,12 +5576,9 @@ decl_list_end:
        new_type->function.parameters             = parameters;
        new_type->function.unspecified_parameters = true;
 
-       type = typehash_insert(new_type);
-       if (type != new_type) {
-               obstack_free(type_obst, new_type);
-       }
+       new_type = identify_new_type(new_type);
 
-       entity->declaration.type = type;
+       entity->declaration.type = new_type;
 
        rem_anchor_token('{');
 }
@@ -5701,6 +5751,7 @@ static bool expression_returns(expression_t const *const expr)
                case EXPR_FUNCNAME:
                case EXPR_BUILTIN_SYMBOL:
                case EXPR_BUILTIN_CONSTANT_P:
+               case EXPR_BUILTIN_TYPES_COMPATIBLE_P:
                case EXPR_BUILTIN_PREFETCH:
                case EXPR_OFFSETOF:
                case EXPR_INVALID:
@@ -5799,7 +5850,6 @@ static void check_reachable(statement_t *const stmt)
        switch (stmt->kind) {
                case STATEMENT_INVALID:
                case STATEMENT_EMPTY:
-               case STATEMENT_LOCAL_LABEL:
                case STATEMENT_ASM:
                        next = stmt->base.next;
                        break;
@@ -6061,7 +6111,7 @@ found_break_parent:
                if (next == NULL) {
                        noreturn_candidate = false;
 
-                       type_t *const type = current_function->base.type;
+                       type_t *const type = skip_typeref(current_function->base.type);
                        assert(is_type_function(type));
                        type_t *const ret  = skip_typeref(type->function.return_type);
                        if (warning.return_type                    &&
@@ -6078,7 +6128,6 @@ found_break_parent:
                        case STATEMENT_INVALID:
                        case STATEMENT_EMPTY:
                        case STATEMENT_DECLARATION:
-                       case STATEMENT_LOCAL_LABEL:
                        case STATEMENT_EXPRESSION:
                        case STATEMENT_ASM:
                        case STATEMENT_RETURN:
@@ -6315,7 +6364,8 @@ static void parse_external_declaration(void)
        }
 
        assert(is_declaration(ndeclaration));
-       type_t *type = skip_typeref(ndeclaration->declaration.type);
+       type_t *const orig_type = ndeclaration->declaration.type;
+       type_t *      type      = skip_typeref(orig_type);
 
        if (!is_type_function(type)) {
                if (is_type_valid(type)) {
@@ -6324,6 +6374,11 @@ static void parse_external_declaration(void)
                }
                eat_block();
                return;
+       } else if (is_typeref(orig_type)) {
+               /* §6.9.1:2 */
+               errorf(&ndeclaration->base.source_position,
+                               "type of function definition '%#T' is a typedef",
+                               orig_type, ndeclaration->base.symbol);
        }
 
        if (warning.aggregate_return &&
@@ -6340,18 +6395,15 @@ static void parse_external_declaration(void)
                        ndeclaration->base.symbol);
        }
 
-       /* § 6.7.5.3 (14) a function definition with () means no
+       /* § 6.7.5.3:14 a function definition with () means no
         * parameters (and not unspecified parameters) */
-       if (type->function.unspecified_parameters
-                       && type->function.parameters == NULL
-                       && !type->function.kr_style_parameters) {
-               type_t *duplicate = duplicate_type(type);
-               duplicate->function.unspecified_parameters = false;
+       if (type->function.unspecified_parameters &&
+                       type->function.parameters == NULL     &&
+                       !type->function.kr_style_parameters) {
+               type_t *copy                          = duplicate_type(type);
+               copy->function.unspecified_parameters = false;
+               type                                  = identify_new_type(copy);
 
-               type = typehash_insert(duplicate);
-               if (type != duplicate) {
-                       obstack_free(type_obst, duplicate);
-               }
                ndeclaration->declaration.type = type;
        }
 
@@ -6792,11 +6844,7 @@ static entity_t *create_implicit_function(symbol_t *symbol,
        ntype->function.return_type            = type_int;
        ntype->function.unspecified_parameters = true;
        ntype->function.linkage                = LINKAGE_C;
-
-       type_t *type = typehash_insert(ntype);
-       if (type != ntype) {
-               free_type(ntype);
-       }
+       type_t *type                           = identify_new_type(ntype);
 
        entity_t *entity = allocate_entity_zero(ENTITY_FUNCTION);
        entity->declaration.storage_class          = STORAGE_CLASS_EXTERN;
@@ -6836,12 +6884,7 @@ static type_t *make_function_2_type(type_t *return_type, type_t *argument_type1,
        type->function.return_type = return_type;
        type->function.parameters  = parameter1;
 
-       type_t *result = typehash_insert(type);
-       if (result != type) {
-               free_type(type);
-       }
-
-       return result;
+       return identify_new_type(type);
 }
 
 /**
@@ -6862,12 +6905,7 @@ static type_t *make_function_1_type(type_t *return_type, type_t *argument_type)
        type->function.return_type = return_type;
        type->function.parameters  = parameter;
 
-       type_t *result = typehash_insert(type);
-       if (result != type) {
-               free_type(type);
-       }
-
-       return result;
+       return identify_new_type(type);
 }
 
 static type_t *make_function_0_type(type_t *return_type)
@@ -6876,12 +6914,7 @@ static type_t *make_function_0_type(type_t *return_type)
        type->function.return_type = return_type;
        type->function.parameters  = NULL;
 
-       type_t *result = typehash_insert(type);
-       if (result != type) {
-               free_type(type);
-       }
-
-       return result;
+       return identify_new_type(type);
 }
 
 /**
@@ -6912,6 +6945,9 @@ static type_t *get_builtin_symbol_type(symbol_t *symbol)
                return make_function_1_type(type_void, type_valist);
        case T___builtin_expect:
                return make_function_2_type(type_long, type_long, type_long);
+       case T___builtin_return_address:
+       case T___builtin_frame_address:
+               return make_function_1_type(type_void_ptr, type_unsigned_int);
        default:
                internal_errorf(HERE, "not implemented builtin identifier found");
        }
@@ -6963,7 +6999,7 @@ type_t *revert_automatic_type_conversion(const expression_t *expression)
                        assert(is_declaration(entity));
                        type_t   *type   = entity->declaration.type;
                        return get_qualified_type(type,
-                                                 expression->base.type->base.qualifiers);
+                                       expression->base.type->base.qualifiers);
                }
 
                case EXPR_UNARY_DEREFERENCE: {
@@ -6998,10 +7034,9 @@ type_t *revert_automatic_type_conversion(const expression_t *expression)
                case EXPR_COMPOUND_LITERAL:
                        return expression->compound_literal.type;
 
-               default: break;
+               default:
+                       return expression->base.type;
        }
-
-       return expression->base.type;
 }
 
 static expression_t *parse_reference(void)
@@ -7494,7 +7529,7 @@ static expression_t *parse_builtin_symbol(void)
 }
 
 /**
- * Parses a __builtin_constant() expression.
+ * Parses a __builtin_constant_p() expression.
  */
 static expression_t *parse_builtin_constant(void)
 {
@@ -7514,6 +7549,31 @@ end_error:
        return create_invalid_expression();
 }
 
+/**
+ * Parses a __builtin_types_compatible_p() expression.
+ */
+static expression_t *parse_builtin_types_compatible(void)
+{
+       expression_t *expression = allocate_expression_zero(EXPR_BUILTIN_TYPES_COMPATIBLE_P);
+
+       eat(T___builtin_types_compatible_p);
+
+       expect('(', end_error);
+       add_anchor_token(')');
+       add_anchor_token(',');
+       expression->builtin_types_compatible.left = parse_typename();
+       rem_anchor_token(',');
+       expect(',', end_error);
+       expression->builtin_types_compatible.right = parse_typename();
+       rem_anchor_token(')');
+       expect(')', end_error);
+       expression->base.type = type_int;
+
+       return expression;
+end_error:
+       return create_invalid_expression();
+}
+
 /**
  * Parses a __builtin_prefetch() expression.
  */
@@ -7755,23 +7815,23 @@ end_error:
 static expression_t *parse_primary_expression(void)
 {
        switch (token.type) {
-               case T_false:                    return parse_bool_const(false);
-               case T_true:                     return parse_bool_const(true);
-               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_false:                        return parse_bool_const(false);
+               case T_true:                         return parse_bool_const(true);
+               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_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___func__:                     return parse_function_keyword();
+               case T___PRETTY_FUNCTION__:          return parse_pretty_function_keyword();
+               case T___FUNCSIG__:                  return parse_funcsig_keyword();
+               case T___FUNCDNAME__:                return parse_funcdname_keyword();
+               case T___builtin_offsetof:           return parse_offsetof();
+               case T___builtin_va_start:           return parse_va_start();
+               case T___builtin_va_arg:             return parse_va_arg();
                case T___builtin_expect:
                case T___builtin_alloca:
                case T___builtin_inf:
@@ -7781,23 +7841,26 @@ static expression_t *parse_primary_expression(void)
                case T___builtin_nanf:
                case T___builtin_nanl:
                case T___builtin_huge_val:
-               case T___builtin_va_end:         return parse_builtin_symbol();
+               case T___builtin_va_end:
+               case T___builtin_return_address:
+               case T___builtin_frame_address:      return parse_builtin_symbol();
                case T___builtin_isgreater:
                case T___builtin_isgreaterequal:
                case T___builtin_isless:
                case T___builtin_islessequal:
                case T___builtin_islessgreater:
-               case T___builtin_isunordered:    return parse_compare_builtin();
-               case T___builtin_constant_p:     return parse_builtin_constant();
-               case T___builtin_prefetch:       return parse_builtin_prefetch();
-               case T__assume:                  return parse_assume();
+               case T___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___builtin_types_compatible_p: return parse_builtin_types_compatible();
+               case T__assume:                      return parse_assume();
                case T_ANDAND:
                        if (GNU_MODE)
                                return parse_label_address();
                        break;
 
-               case '(':                        return parse_parenthesized_expression();
-               case T___noop:                   return parse_noop_expression();
+               case '(':                            return parse_parenthesized_expression();
+               case T___noop:                       return parse_noop_expression();
        }
 
        errorf(HERE, "unexpected token %K, expected an expression", &token);
@@ -8073,6 +8136,28 @@ static void check_call_argument(const function_parameter_t *parameter,
        }
 }
 
+/**
+ * Handle the semantic restrictions of builtin calls
+ */
+static void handle_builtin_argument_restrictions(call_expression_t *call) {
+       switch (call->function->builtin_symbol.symbol->ID) {
+               case T___builtin_return_address:
+               case T___builtin_frame_address: {
+                       /* argument must be constant */
+                       call_argument_t *argument = call->arguments;
+
+                       if (! is_constant_expression(argument->expression)) {
+                               errorf(&call->base.source_position,
+                                      "argument of '%Y' must be a constant expression",
+                                      call->function->builtin_symbol.symbol);
+                       }
+                       break;
+               }
+               default:
+                       break;
+       }
+}
+
 /**
  * Parse a call expression, ie. expression '( ... )'.
  *
@@ -8165,6 +8250,10 @@ static expression_t *parse_call_expression(expression_t *expression)
                         "function call has aggregate value");
        }
 
+       if (call->function->kind == EXPR_BUILTIN_SYMBOL) {
+               handle_builtin_argument_restrictions(&result->call);
+       }
+
 end_error:
        return result;
 }
@@ -8530,7 +8619,7 @@ static bool check_pointer_arithmetic(const source_position_t *source_position,
 
 static bool is_lvalue(const expression_t *expression)
 {
-       /* TODO: doesn't seem to be consistent with §6.3.2.1 (1) */
+       /* TODO: doesn't seem to be consistent with §6.3.2.1:1 */
        switch (expression->kind) {
        case EXPR_ARRAY_ACCESS:
        case EXPR_COMPOUND_LITERAL:
@@ -8856,7 +8945,8 @@ static void warn_div_by_zero(binary_expression_t const *const expression)
 /**
  * Check the semantic restrictions for a div/mod expression.
  */
-static void semantic_divmod_arithmetic(binary_expression_t *expression) {
+static void semantic_divmod_arithmetic(binary_expression_t *expression)
+{
        semantic_binexpr_arithmetic(expression);
        warn_div_by_zero(expression);
 }
@@ -9292,17 +9382,17 @@ static void semantic_binexpr_assign(binary_expression_t *expression)
 static bool expression_has_effect(const expression_t *const expr)
 {
        switch (expr->kind) {
-               case EXPR_UNKNOWN:                   break;
-               case EXPR_INVALID:                   return true; /* do NOT warn */
-               case EXPR_REFERENCE:                 return false;
-               case EXPR_REFERENCE_ENUM_VALUE:      return false;
+               case EXPR_UNKNOWN:                    break;
+               case EXPR_INVALID:                    return true; /* do NOT warn */
+               case EXPR_REFERENCE:                  return false;
+               case EXPR_REFERENCE_ENUM_VALUE:       return false;
                /* suppress the warning for microsoft __noop operations */
-               case EXPR_CONST:                     return expr->conste.is_ms_noop;
-               case EXPR_CHARACTER_CONSTANT:        return false;
-               case EXPR_WIDE_CHARACTER_CONSTANT:   return false;
-               case EXPR_STRING_LITERAL:            return false;
-               case EXPR_WIDE_STRING_LITERAL:       return false;
-               case EXPR_LABEL_ADDRESS:             return false;
+               case EXPR_CONST:                      return expr->conste.is_ms_noop;
+               case EXPR_CHARACTER_CONSTANT:         return false;
+               case EXPR_WIDE_CHARACTER_CONSTANT:    return false;
+               case EXPR_STRING_LITERAL:             return false;
+               case EXPR_WIDE_STRING_LITERAL:        return false;
+               case EXPR_LABEL_ADDRESS:              return false;
 
                case EXPR_CALL: {
                        const call_expression_t *const call = &expr->call;
@@ -9318,38 +9408,40 @@ static bool expression_has_effect(const expression_t *const expr)
                /* 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;
+                       conditional_expression_t const *const cond = &expr->conditional;
+                       expression_t             const *const t    = cond->true_expression;
                        return
-                               expression_has_effect(cond->true_expression) &&
+                               (t == NULL || expression_has_effect(t)) &&
                                expression_has_effect(cond->false_expression);
                }
 
-               case EXPR_SELECT:                    return false;
-               case EXPR_ARRAY_ACCESS:              return false;
-               case EXPR_SIZEOF:                    return false;
-               case EXPR_CLASSIFY_TYPE:             return false;
-               case EXPR_ALIGNOF:                   return false;
-
-               case EXPR_FUNCNAME:                  return false;
-               case EXPR_BUILTIN_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;
+               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_TYPES_COMPATIBLE_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 */
@@ -9358,39 +9450,39 @@ static bool expression_has_effect(const expression_t *const expr)
                        return is_type_atomic(type, ATOMIC_TYPE_VOID);
                }
 
-               case EXPR_UNARY_CAST_IMPLICIT:       return true;
-               case EXPR_UNARY_ASSUME:              return true;
-               case EXPR_UNARY_DELETE:              return true;
-               case EXPR_UNARY_DELETE_ARRAY:        return true;
-               case EXPR_UNARY_THROW:               return true;
-
-               case EXPR_BINARY_ADD:                return false;
-               case EXPR_BINARY_SUB:                return false;
-               case EXPR_BINARY_MUL:                return false;
-               case EXPR_BINARY_DIV:                return false;
-               case EXPR_BINARY_MOD:                return false;
-               case EXPR_BINARY_EQUAL:              return false;
-               case EXPR_BINARY_NOTEQUAL:           return false;
-               case EXPR_BINARY_LESS:               return false;
-               case EXPR_BINARY_LESSEQUAL:          return false;
-               case EXPR_BINARY_GREATER:            return false;
-               case EXPR_BINARY_GREATEREQUAL:       return false;
-               case EXPR_BINARY_BITWISE_AND:        return false;
-               case EXPR_BINARY_BITWISE_OR:         return false;
-               case EXPR_BINARY_BITWISE_XOR:        return false;
-               case EXPR_BINARY_SHIFTLEFT:          return false;
-               case EXPR_BINARY_SHIFTRIGHT:         return false;
-               case EXPR_BINARY_ASSIGN:             return true;
-               case EXPR_BINARY_MUL_ASSIGN:         return true;
-               case EXPR_BINARY_DIV_ASSIGN:         return true;
-               case EXPR_BINARY_MOD_ASSIGN:         return true;
-               case EXPR_BINARY_ADD_ASSIGN:         return true;
-               case EXPR_BINARY_SUB_ASSIGN:         return true;
-               case EXPR_BINARY_SHIFTLEFT_ASSIGN:   return true;
-               case EXPR_BINARY_SHIFTRIGHT_ASSIGN:  return true;
-               case EXPR_BINARY_BITWISE_AND_ASSIGN: return true;
-               case EXPR_BINARY_BITWISE_XOR_ASSIGN: return true;
-               case EXPR_BINARY_BITWISE_OR_ASSIGN:  return true;
+               case EXPR_UNARY_CAST_IMPLICIT:        return true;
+               case EXPR_UNARY_ASSUME:               return true;
+               case EXPR_UNARY_DELETE:               return true;
+               case EXPR_UNARY_DELETE_ARRAY:         return true;
+               case EXPR_UNARY_THROW:                return true;
+
+               case EXPR_BINARY_ADD:                 return false;
+               case EXPR_BINARY_SUB:                 return false;
+               case EXPR_BINARY_MUL:                 return false;
+               case EXPR_BINARY_DIV:                 return false;
+               case EXPR_BINARY_MOD:                 return false;
+               case EXPR_BINARY_EQUAL:               return false;
+               case EXPR_BINARY_NOTEQUAL:            return false;
+               case EXPR_BINARY_LESS:                return false;
+               case EXPR_BINARY_LESSEQUAL:           return false;
+               case EXPR_BINARY_GREATER:             return false;
+               case EXPR_BINARY_GREATEREQUAL:        return false;
+               case EXPR_BINARY_BITWISE_AND:         return false;
+               case EXPR_BINARY_BITWISE_OR:          return false;
+               case EXPR_BINARY_BITWISE_XOR:         return false;
+               case EXPR_BINARY_SHIFTLEFT:           return false;
+               case EXPR_BINARY_SHIFTRIGHT:          return false;
+               case EXPR_BINARY_ASSIGN:              return true;
+               case EXPR_BINARY_MUL_ASSIGN:          return true;
+               case EXPR_BINARY_DIV_ASSIGN:          return true;
+               case EXPR_BINARY_MOD_ASSIGN:          return true;
+               case EXPR_BINARY_ADD_ASSIGN:          return true;
+               case EXPR_BINARY_SUB_ASSIGN:          return true;
+               case EXPR_BINARY_SHIFTLEFT_ASSIGN:    return true;
+               case EXPR_BINARY_SHIFTRIGHT_ASSIGN:   return true;
+               case EXPR_BINARY_BITWISE_AND_ASSIGN:  return true;
+               case EXPR_BINARY_BITWISE_XOR_ASSIGN:  return true;
+               case EXPR_BINARY_BITWISE_OR_ASSIGN:   return true;
 
                /* Only examine the right hand side of && and ||, because the left hand
                 * side already has the effect of controlling the execution of the right
@@ -9402,12 +9494,12 @@ static bool expression_has_effect(const expression_t *const expr)
                case EXPR_BINARY_COMMA:
                        return expression_has_effect(expr->binary.right);
 
-               case EXPR_BINARY_ISGREATER:          return false;
-               case EXPR_BINARY_ISGREATEREQUAL:     return false;
-               case EXPR_BINARY_ISLESS:             return false;
-               case EXPR_BINARY_ISLESSEQUAL:        return false;
-               case EXPR_BINARY_ISLESSGREATER:      return false;
-               case EXPR_BINARY_ISUNORDERED:        return false;
+               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");
@@ -10061,7 +10153,8 @@ end_error:
  *
  * @param statement  the switch statement to check
  */
-static void check_enum_cases(const switch_statement_t *statement) {
+static void check_enum_cases(const switch_statement_t *statement)
+{
        const type_t *type = skip_typeref(statement->expression->base.type);
        if (! is_type_enum(type))
                return;
@@ -10554,12 +10647,11 @@ static statement_t *parse_declaration_statement(void)
                parse_declaration(record_entity, DECL_FLAGS_NONE);
        }
 
-       if (before == NULL) {
-               statement->declaration.declarations_begin = current_scope->entities;
-       } else {
-               statement->declaration.declarations_begin = before->base.next;
-       }
-       statement->declaration.declarations_end = current_scope->last_entity;
+       declaration_statement_t *const decl  = &statement->declaration;
+       entity_t                *const begin =
+               before != NULL ? before->base.next : current_scope->entities;
+       decl->declarations_begin = begin;
+       decl->declarations_end   = begin != NULL ? current_scope->last_entity : NULL;
 
        return statement;
 }
@@ -10699,10 +10791,13 @@ static void parse_namespace_definition(void)
                next_token();
 
                entity = get_entity(symbol, NAMESPACE_NORMAL);
-               if (entity != NULL && entity->kind != ENTITY_NAMESPACE
-                               && entity->base.parent_scope == current_scope) {
-                       error_redefined_as_different_kind(&token.source_position,
-                                                         entity, ENTITY_NAMESPACE);
+               if (entity       != NULL             &&
+                               entity->kind != ENTITY_NAMESPACE &&
+                               entity->base.parent_scope == current_scope) {
+                       if (!is_error_entity(entity)) {
+                               error_redefined_as_different_kind(&token.source_position,
+                                               entity, ENTITY_NAMESPACE);
+                       }
                        entity = NULL;
                }
        }
@@ -11342,8 +11437,8 @@ translation_unit_t *finish_parsing(void)
        return result;
 }
 
-/* GCC allows global arrays without size and assigns them a length of one,
- * if no different declaration follows */
+/* §6.9.2:2 and §6.9.2:5: At the end of the translation incomplete arrays
+ * are given length one. */
 static void complete_incomplete_arrays(void)
 {
        size_t n = ARR_LEN(incomplete_arrays);
@@ -11366,9 +11461,7 @@ static void complete_incomplete_arrays(void)
                new_type->array.has_implicit_size = true;
                new_type->array.size              = 1;
 
-               type_t *const result = typehash_insert(new_type);
-               if (type != result)
-                       free_type(type);
+               type_t *const result = identify_new_type(new_type);
 
                decl->type = result;
        }