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3ccda63a3a
The genksyms parser has ambiguities in its grammar, which are currently
suppressed by a workaround in scripts/genksyms/Makefile.
Building genksyms with W=1 generates the following warnings:
YACC scripts/genksyms/parse.tab.[ch]
scripts/genksyms/parse.y: warning: 9 shift/reduce conflicts [-Wconflicts-sr]
scripts/genksyms/parse.y: warning: 5 reduce/reduce conflicts [-Wconflicts-rr]
scripts/genksyms/parse.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
The comment in the parser describes the current problem:
/* This wasn't really a typedef name but an identifier that
shadows one. */
Consider the following simple C code:
typedef int foo;
void my_func(foo foo) {}
In the function parameter list (foo foo), the first 'foo' is a type
specifier (typedef'ed as 'int'), while the second 'foo' is an identifier.
However, the lexer cannot distinguish between the two. Since 'foo' is
already typedef'ed, the lexer returns TYPE for both instances, instead
of returning IDENT for the second one.
To support shadowed identifiers, TYPE can be reduced to either a
simple_type_specifier or a direct_abstract_declarator, which creates
a grammatical ambiguity.
Without analyzing the grammar context, it is very difficult to resolve
this correctly.
This commit introduces a flag, dont_want_type_specifier, which allows
the parser to inform the lexer whether an identifier is expected. When
dont_want_type_specifier is true, the type lookup is suppressed, and
the lexer returns IDENT regardless of any preceding typedef.
After this commit, only 3 shift/reduce conflicts will remain.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Nicolas Schier <n.schier@avm.de>
89 lines
2.1 KiB
C
89 lines
2.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/* Generate kernel symbol version hashes.
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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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*/
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#ifndef MODUTILS_GENKSYMS_H
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#define MODUTILS_GENKSYMS_H 1
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#include <stdbool.h>
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#include <stdio.h>
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#include <list_types.h>
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enum symbol_type {
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SYM_NORMAL, SYM_TYPEDEF, SYM_ENUM, SYM_STRUCT, SYM_UNION,
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SYM_ENUM_CONST
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};
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enum symbol_status {
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STATUS_UNCHANGED, STATUS_DEFINED, STATUS_MODIFIED
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};
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struct string_list {
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struct string_list *next;
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enum symbol_type tag;
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int in_source_file;
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char *string;
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};
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struct symbol {
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struct hlist_node hnode;
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char *name;
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enum symbol_type type;
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struct string_list *defn;
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struct symbol *expansion_trail;
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struct symbol *visited;
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int is_extern;
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int is_declared;
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enum symbol_status status;
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int is_override;
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};
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typedef struct string_list **yystype;
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#define YYSTYPE yystype
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extern int cur_line;
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extern char *cur_filename;
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extern int in_source_file;
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struct symbol *find_symbol(const char *name, enum symbol_type ns, int exact);
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struct symbol *add_symbol(const char *name, enum symbol_type type,
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struct string_list *defn, int is_extern);
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void export_symbol(const char *);
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void free_node(struct string_list *list);
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void free_list(struct string_list *s, struct string_list *e);
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struct string_list *copy_node(struct string_list *);
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struct string_list *copy_list_range(struct string_list *start,
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struct string_list *end);
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int yylex(void);
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int yyparse(void);
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extern bool dont_want_type_specifier;
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void error_with_pos(const char *, ...) __attribute__ ((format(printf, 1, 2)));
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/*----------------------------------------------------------------------*/
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#define xmalloc(size) ({ void *__ptr = malloc(size); \
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if(!__ptr && size != 0) { \
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fprintf(stderr, "out of memory\n"); \
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exit(1); \
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} \
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__ptr; })
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#define xstrdup(str) ({ char *__str = strdup(str); \
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if (!__str) { \
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fprintf(stderr, "out of memory\n"); \
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exit(1); \
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} \
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__str; })
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#endif /* genksyms.h */
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