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![Richard Yao](/assets/img/avatar_default.png)
I noticed that genksyms will segfault when it sees duplicate function pointer type declaration when I placed the same function pointer definition in two separate headers in a local branch as an intermediate step of some refactoring. This can be reproduced by piping the following minimal test case into `genksyms -r /dev/null` or alternatively, putting it into a C file attempting a build: typedef int (*f)(); typedef int (*f)(); Attaching gdb to genksyms to understand this failure is useless without changing CFLAGS to emit debuginfo. Once you have debuginfo, you will find that the failure is that `char *s` was NULL and the program executed `while(*s)`. At which point, further debugging requires familiarity with compiler front end / parser development. What happens is that flex identifies the first instance of the token "f" as IDENT and the yacc parser adds it to the symbol table. On the second instance, flex will identify "f" as TYPE, which triggers an error case in the yacc parser. Given that TYPE would have been IDENT had it not been in the symbol table, the the segmentaion fault could be avoided by treating TYPE as IDENT in the affected rule. Some might consider placing identical function pointer type declarations in different headers to be poor style might consider a failure to be beneficial. However, failing through a segmentation fault makes the cause non-obvious and can waste the time of anyone who encounters it. Signed-off-by: Richard Yao <richard.yao@clusterhq.com> Acked-by: Madhuri Yechuri <madhuriyechuri@clusterhq.com> Signed-off-by: Michal Marek <mmarek@suse.com>
513 lines
11 KiB
Text
513 lines
11 KiB
Text
/* C global declaration parser for genksyms.
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Copyright 1996, 1997 Linux International.
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New implementation contributed by Richard Henderson <rth@tamu.edu>
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Based on original work by Bjorn Ekwall <bj0rn@blox.se>
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This file is part of the Linux modutils.
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This program is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by the
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Free Software Foundation; either version 2 of the License, or (at your
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option) any later version.
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This program is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software Foundation,
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Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
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%{
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#include <assert.h>
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#include <stdlib.h>
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#include <string.h>
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#include "genksyms.h"
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static int is_typedef;
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static int is_extern;
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static char *current_name;
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static struct string_list *decl_spec;
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static void yyerror(const char *);
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static inline void
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remove_node(struct string_list **p)
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{
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struct string_list *node = *p;
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*p = node->next;
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free_node(node);
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}
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static inline void
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remove_list(struct string_list **pb, struct string_list **pe)
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{
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struct string_list *b = *pb, *e = *pe;
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*pb = e;
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free_list(b, e);
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}
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/* Record definition of a struct/union/enum */
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static void record_compound(struct string_list **keyw,
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struct string_list **ident,
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struct string_list **body,
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enum symbol_type type)
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{
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struct string_list *b = *body, *i = *ident, *r;
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if (i->in_source_file) {
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remove_node(keyw);
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(*ident)->tag = type;
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remove_list(body, ident);
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return;
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}
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r = copy_node(i); r->tag = type;
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r->next = (*keyw)->next; *body = r; (*keyw)->next = NULL;
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add_symbol(i->string, type, b, is_extern);
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}
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%}
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%token ASM_KEYW
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%token ATTRIBUTE_KEYW
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%token AUTO_KEYW
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%token BOOL_KEYW
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%token CHAR_KEYW
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%token CONST_KEYW
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%token DOUBLE_KEYW
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%token ENUM_KEYW
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%token EXTERN_KEYW
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%token EXTENSION_KEYW
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%token FLOAT_KEYW
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%token INLINE_KEYW
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%token INT_KEYW
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%token LONG_KEYW
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%token REGISTER_KEYW
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%token RESTRICT_KEYW
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%token SHORT_KEYW
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%token SIGNED_KEYW
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%token STATIC_KEYW
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%token STRUCT_KEYW
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%token TYPEDEF_KEYW
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%token UNION_KEYW
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%token UNSIGNED_KEYW
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%token VOID_KEYW
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%token VOLATILE_KEYW
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%token TYPEOF_KEYW
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%token EXPORT_SYMBOL_KEYW
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%token ASM_PHRASE
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%token ATTRIBUTE_PHRASE
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%token TYPEOF_PHRASE
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%token BRACE_PHRASE
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%token BRACKET_PHRASE
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%token EXPRESSION_PHRASE
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%token CHAR
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%token DOTS
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%token IDENT
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%token INT
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%token REAL
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%token STRING
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%token TYPE
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%token OTHER
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%token FILENAME
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%%
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declaration_seq:
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declaration
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| declaration_seq declaration
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;
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declaration:
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{ is_typedef = 0; is_extern = 0; current_name = NULL; decl_spec = NULL; }
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declaration1
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{ free_list(*$2, NULL); *$2 = NULL; }
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;
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declaration1:
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EXTENSION_KEYW TYPEDEF_KEYW { is_typedef = 1; } simple_declaration
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{ $$ = $4; }
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| TYPEDEF_KEYW { is_typedef = 1; } simple_declaration
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{ $$ = $3; }
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| simple_declaration
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| function_definition
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| asm_definition
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| export_definition
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| error ';' { $$ = $2; }
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| error '}' { $$ = $2; }
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;
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simple_declaration:
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decl_specifier_seq_opt init_declarator_list_opt ';'
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{ if (current_name) {
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struct string_list *decl = (*$3)->next;
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(*$3)->next = NULL;
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add_symbol(current_name,
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is_typedef ? SYM_TYPEDEF : SYM_NORMAL,
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decl, is_extern);
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current_name = NULL;
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}
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$$ = $3;
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}
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;
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init_declarator_list_opt:
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/* empty */ { $$ = NULL; }
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| init_declarator_list
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;
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init_declarator_list:
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init_declarator
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{ struct string_list *decl = *$1;
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*$1 = NULL;
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add_symbol(current_name,
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is_typedef ? SYM_TYPEDEF : SYM_NORMAL, decl, is_extern);
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current_name = NULL;
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$$ = $1;
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}
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| init_declarator_list ',' init_declarator
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{ struct string_list *decl = *$3;
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*$3 = NULL;
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free_list(*$2, NULL);
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*$2 = decl_spec;
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add_symbol(current_name,
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is_typedef ? SYM_TYPEDEF : SYM_NORMAL, decl, is_extern);
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current_name = NULL;
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$$ = $3;
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}
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;
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init_declarator:
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declarator asm_phrase_opt attribute_opt initializer_opt
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{ $$ = $4 ? $4 : $3 ? $3 : $2 ? $2 : $1; }
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;
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/* Hang on to the specifiers so that we can reuse them. */
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decl_specifier_seq_opt:
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/* empty */ { decl_spec = NULL; }
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| decl_specifier_seq
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;
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decl_specifier_seq:
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decl_specifier { decl_spec = *$1; }
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| decl_specifier_seq decl_specifier { decl_spec = *$2; }
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;
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decl_specifier:
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storage_class_specifier
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{ /* Version 2 checksumming ignores storage class, as that
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is really irrelevant to the linkage. */
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remove_node($1);
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$$ = $1;
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}
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| type_specifier
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;
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storage_class_specifier:
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AUTO_KEYW
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| REGISTER_KEYW
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| STATIC_KEYW
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| EXTERN_KEYW { is_extern = 1; $$ = $1; }
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| INLINE_KEYW { is_extern = 0; $$ = $1; }
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;
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type_specifier:
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simple_type_specifier
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| cvar_qualifier
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| TYPEOF_KEYW '(' parameter_declaration ')'
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| TYPEOF_PHRASE
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/* References to s/u/e's defined elsewhere. Rearrange things
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so that it is easier to expand the definition fully later. */
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| STRUCT_KEYW IDENT
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{ remove_node($1); (*$2)->tag = SYM_STRUCT; $$ = $2; }
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| UNION_KEYW IDENT
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{ remove_node($1); (*$2)->tag = SYM_UNION; $$ = $2; }
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| ENUM_KEYW IDENT
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{ remove_node($1); (*$2)->tag = SYM_ENUM; $$ = $2; }
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/* Full definitions of an s/u/e. Record it. */
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| STRUCT_KEYW IDENT class_body
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{ record_compound($1, $2, $3, SYM_STRUCT); $$ = $3; }
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| UNION_KEYW IDENT class_body
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{ record_compound($1, $2, $3, SYM_UNION); $$ = $3; }
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| ENUM_KEYW IDENT enum_body
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{ record_compound($1, $2, $3, SYM_ENUM); $$ = $3; }
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/*
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* Anonymous enum definition. Tell add_symbol() to restart its counter.
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*/
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| ENUM_KEYW enum_body
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{ add_symbol(NULL, SYM_ENUM, NULL, 0); $$ = $2; }
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/* Anonymous s/u definitions. Nothing needs doing. */
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| STRUCT_KEYW class_body { $$ = $2; }
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| UNION_KEYW class_body { $$ = $2; }
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;
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simple_type_specifier:
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CHAR_KEYW
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| SHORT_KEYW
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| INT_KEYW
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| LONG_KEYW
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| SIGNED_KEYW
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| UNSIGNED_KEYW
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| FLOAT_KEYW
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| DOUBLE_KEYW
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| VOID_KEYW
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| BOOL_KEYW
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| TYPE { (*$1)->tag = SYM_TYPEDEF; $$ = $1; }
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;
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ptr_operator:
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'*' cvar_qualifier_seq_opt
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{ $$ = $2 ? $2 : $1; }
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;
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cvar_qualifier_seq_opt:
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/* empty */ { $$ = NULL; }
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| cvar_qualifier_seq
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;
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cvar_qualifier_seq:
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cvar_qualifier
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| cvar_qualifier_seq cvar_qualifier { $$ = $2; }
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;
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cvar_qualifier:
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CONST_KEYW | VOLATILE_KEYW | ATTRIBUTE_PHRASE
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| RESTRICT_KEYW
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{ /* restrict has no effect in prototypes so ignore it */
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remove_node($1);
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$$ = $1;
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}
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;
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declarator:
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ptr_operator declarator { $$ = $2; }
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| direct_declarator
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;
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direct_declarator:
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IDENT
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{ if (current_name != NULL) {
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error_with_pos("unexpected second declaration name");
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YYERROR;
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} else {
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current_name = (*$1)->string;
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$$ = $1;
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}
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}
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| TYPE
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{ if (current_name != NULL) {
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error_with_pos("unexpected second declaration name");
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YYERROR;
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} else {
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current_name = (*$1)->string;
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$$ = $1;
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}
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}
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| direct_declarator '(' parameter_declaration_clause ')'
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{ $$ = $4; }
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| direct_declarator '(' error ')'
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{ $$ = $4; }
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| direct_declarator BRACKET_PHRASE
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{ $$ = $2; }
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| '(' declarator ')'
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{ $$ = $3; }
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| '(' error ')'
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{ $$ = $3; }
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;
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/* Nested declarators differ from regular declarators in that they do
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not record the symbols they find in the global symbol table. */
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nested_declarator:
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ptr_operator nested_declarator { $$ = $2; }
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| direct_nested_declarator
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;
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direct_nested_declarator:
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IDENT
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| TYPE
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| direct_nested_declarator '(' parameter_declaration_clause ')'
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{ $$ = $4; }
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| direct_nested_declarator '(' error ')'
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{ $$ = $4; }
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| direct_nested_declarator BRACKET_PHRASE
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{ $$ = $2; }
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| '(' nested_declarator ')'
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{ $$ = $3; }
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| '(' error ')'
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{ $$ = $3; }
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;
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parameter_declaration_clause:
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parameter_declaration_list_opt DOTS { $$ = $2; }
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| parameter_declaration_list_opt
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| parameter_declaration_list ',' DOTS { $$ = $3; }
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;
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parameter_declaration_list_opt:
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/* empty */ { $$ = NULL; }
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| parameter_declaration_list
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;
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parameter_declaration_list:
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parameter_declaration
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| parameter_declaration_list ',' parameter_declaration
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{ $$ = $3; }
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;
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parameter_declaration:
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decl_specifier_seq m_abstract_declarator
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{ $$ = $2 ? $2 : $1; }
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;
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m_abstract_declarator:
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ptr_operator m_abstract_declarator
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{ $$ = $2 ? $2 : $1; }
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| direct_m_abstract_declarator
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;
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direct_m_abstract_declarator:
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/* empty */ { $$ = NULL; }
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| IDENT
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{ /* For version 2 checksums, we don't want to remember
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private parameter names. */
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remove_node($1);
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$$ = $1;
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}
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/* This wasn't really a typedef name but an identifier that
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shadows one. */
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| TYPE
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{ remove_node($1);
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$$ = $1;
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}
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| direct_m_abstract_declarator '(' parameter_declaration_clause ')'
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{ $$ = $4; }
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| direct_m_abstract_declarator '(' error ')'
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{ $$ = $4; }
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| direct_m_abstract_declarator BRACKET_PHRASE
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{ $$ = $2; }
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| '(' m_abstract_declarator ')'
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{ $$ = $3; }
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| '(' error ')'
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{ $$ = $3; }
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;
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function_definition:
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decl_specifier_seq_opt declarator BRACE_PHRASE
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{ struct string_list *decl = *$2;
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*$2 = NULL;
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add_symbol(current_name, SYM_NORMAL, decl, is_extern);
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$$ = $3;
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}
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;
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initializer_opt:
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/* empty */ { $$ = NULL; }
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| initializer
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;
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/* We never care about the contents of an initializer. */
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initializer:
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'=' EXPRESSION_PHRASE
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{ remove_list($2, &(*$1)->next); $$ = $2; }
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;
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class_body:
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'{' member_specification_opt '}' { $$ = $3; }
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| '{' error '}' { $$ = $3; }
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;
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member_specification_opt:
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/* empty */ { $$ = NULL; }
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| member_specification
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;
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member_specification:
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member_declaration
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| member_specification member_declaration { $$ = $2; }
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;
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member_declaration:
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decl_specifier_seq_opt member_declarator_list_opt ';'
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{ $$ = $3; }
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| error ';'
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{ $$ = $2; }
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;
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member_declarator_list_opt:
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/* empty */ { $$ = NULL; }
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| member_declarator_list
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;
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member_declarator_list:
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member_declarator
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| member_declarator_list ',' member_declarator { $$ = $3; }
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;
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member_declarator:
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nested_declarator attribute_opt { $$ = $2 ? $2 : $1; }
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| IDENT member_bitfield_declarator { $$ = $2; }
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| member_bitfield_declarator
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;
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member_bitfield_declarator:
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':' EXPRESSION_PHRASE { $$ = $2; }
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;
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attribute_opt:
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/* empty */ { $$ = NULL; }
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| attribute_opt ATTRIBUTE_PHRASE
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;
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enum_body:
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'{' enumerator_list '}' { $$ = $3; }
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| '{' enumerator_list ',' '}' { $$ = $4; }
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;
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enumerator_list:
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enumerator
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| enumerator_list ',' enumerator
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enumerator:
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IDENT
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{
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const char *name = strdup((*$1)->string);
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add_symbol(name, SYM_ENUM_CONST, NULL, 0);
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}
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| IDENT '=' EXPRESSION_PHRASE
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{
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const char *name = strdup((*$1)->string);
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struct string_list *expr = copy_list_range(*$3, *$2);
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add_symbol(name, SYM_ENUM_CONST, expr, 0);
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}
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asm_definition:
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ASM_PHRASE ';' { $$ = $2; }
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;
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asm_phrase_opt:
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/* empty */ { $$ = NULL; }
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| ASM_PHRASE
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;
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export_definition:
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EXPORT_SYMBOL_KEYW '(' IDENT ')' ';'
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{ export_symbol((*$3)->string); $$ = $5; }
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;
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%%
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static void
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yyerror(const char *e)
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{
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error_with_pos("%s", e);
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}
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