binutils-gdb/gdb/c-lang.h
Tom Tromey 55fc1623f9 Add name canonicalization for C
PR symtab/29105 shows a number of situations where symbol lookup can
result in the expansion of too many CUs.

What happens is that lookup_signed_typename will try to look up a type
like "signed int".  In cooked_index_functions::expand_symtabs_matching,
when looping over languages, the C++ case will canonicalize this type
name to be "int" instead.  Then this method will proceed to expand
every CU that has an entry for "int" -- i.e., nearly all of them.  A
crucial component of this is that the caller, objfile::lookup_symbol,
does not do this canonicalization, so when it tries to find the symbol
for "signed int", it fails -- causing the loop to continue.

This patch fixes the problem by introducing name canonicalization for
C.  The idea here is that, by making C and C++ agree on the canonical
name when a symbol name can have multiple spellings, we avoid the bad
behavior in objfile::lookup_symbol (and any other such code -- I don't
know if there is any).

Unlike C++, C only has a few situations where canonicalization is
needed.  And, in particular, due to the lack of overloading (thus
avoiding any issues in linespec) and due to the way c-exp.y works, I
think that no canonicalization is needed during symbol lookup -- only
during symtab construction.  This explains why lookup_name_info is not
touched.

The stabs reader is modified on a "best effort" basis.

The DWARF reader needed one small tweak in dwarf2_name to avoid a
regression in dw2-unusual-field-names.exp.  I think this is adequately
explained by the comment, but basically this is a scenario that should
not occur in real code, only the gdb test suite.

lookup_signed_typename is simplified.  It used to search for two
different type names, but now gdb can search just for the canonical
form.

gdb.dwarf2/enum-type.exp needed a small tweak, because the
canonicalizer turns "unsigned integer" into "unsigned int integer".
It seems better here to use the correct C type name.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29105
Tested-by: Simon Marchi <simark@simark.ca>
Reviewed-by: Andrew Burgess <aburgess@redhat.com>
2022-12-01 11:16:41 -07:00

176 lines
5.4 KiB
C++

/* C language support definitions for GDB, the GNU debugger.
Copyright (C) 1992-2022 Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#if !defined (C_LANG_H)
#define C_LANG_H 1
struct ui_file;
struct language_arch_info;
struct type_print_options;
struct parser_state;
#include "value.h"
#include "macroexp.h"
#include "gdbsupport/enum-flags.h"
/* The various kinds of C string and character. Note that these
values are chosen so that they may be or'd together in certain
ways. */
enum c_string_type_values : unsigned
{
/* An ordinary string: "value". */
C_STRING = 0,
/* A wide string: L"value". */
C_WIDE_STRING = 1,
/* A 16-bit Unicode string: u"value". */
C_STRING_16 = 2,
/* A 32-bit Unicode string: U"value". */
C_STRING_32 = 3,
/* An ordinary char: 'v'. This can also be or'd with one of the
above to form the corresponding CHAR value from a STRING
value. */
C_CHAR = 4,
/* A wide char: L'v'. */
C_WIDE_CHAR = 5,
/* A 16-bit Unicode char: u'v'. */
C_CHAR_16 = 6,
/* A 32-bit Unicode char: U'v'. */
C_CHAR_32 = 7
};
DEF_ENUM_FLAGS_TYPE (enum c_string_type_values, c_string_type);
/* Defined in c-exp.y. */
extern int c_parse (struct parser_state *);
extern int c_parse_escape (const char **, struct obstack *);
/* Defined in c-typeprint.c */
/* Print TYPE to STREAM using syntax appropriate for LANGUAGE, a
C-like language. The other parameters are like
type_language_defn::print_type's. */
extern void c_print_type (struct type *type,
const char *varstring,
struct ui_file *stream,
int show, int level,
enum language language,
const struct type_print_options *flags);
extern void c_print_typedef (struct type *,
struct symbol *,
struct ui_file *);
/* Implement la_value_print_inner for the C family of languages. */
extern void c_value_print_inner (struct value *, struct ui_file *, int,
const struct value_print_options *);
extern void c_value_print (struct value *, struct ui_file *,
const struct value_print_options *);
/* These are in c-lang.c: */
extern void c_printchar (int, struct type *, struct ui_file *);
extern void c_language_arch_info (struct gdbarch *gdbarch,
struct language_arch_info *lai);
/* These are in c-typeprint.c: */
extern void c_type_print_base (struct type *, struct ui_file *,
int, int, const struct type_print_options *);
/* These are in cp-valprint.c */
extern void cp_print_class_member (const gdb_byte *, struct type *,
struct ui_file *, const char *);
extern void cp_print_value_fields (struct value *,
struct ui_file *, int,
const struct value_print_options *,
struct type **, int);
/* gcc-2.6 or later (when using -fvtable-thunks)
emits a unique named type for a vtable entry.
Some gdb code depends on that specific name. */
extern const char vtbl_ptr_name[];
extern int cp_is_vtbl_ptr_type (struct type *);
extern int cp_is_vtbl_member (struct type *);
/* Return true if TYPE is a string type. Unlike DEFAULT_IS_STRING_TYPE_P
this will detect arrays of characters not just TYPE_CODE_STRING. */
extern bool c_is_string_type_p (struct type *type);
/* These are in c-valprint.c. */
extern int c_textual_element_type (struct type *, char);
/* Create a new instance of the C compiler and return it. This
function never returns NULL, but rather throws an exception on
failure. This is suitable for use as the
language_defn::get_compile_instance method. */
extern std::unique_ptr<compile_instance> c_get_compile_context ();
/* Create a new instance of the C++ compiler and return it. This
function never returns NULL, but rather throws an exception on
failure. This is suitable for use as the
language_defn::get_compile_instance method. */
extern std::unique_ptr<compile_instance> cplus_get_compile_context ();
/* This takes the user-supplied text and returns a new bit of code to
compile.
This is used as the compute_program language method; see that
for a description of the arguments. */
extern std::string c_compute_program (compile_instance *inst,
const char *input,
struct gdbarch *gdbarch,
const struct block *expr_block,
CORE_ADDR expr_pc);
/* This takes the user-supplied text and returns a new bit of code to compile.
This is used as the compute_program language method; see that
for a description of the arguments. */
extern std::string cplus_compute_program (compile_instance *inst,
const char *input,
struct gdbarch *gdbarch,
const struct block *expr_block,
CORE_ADDR expr_pc);
/* Return the canonical form of the C symbol NAME. If NAME is already
canonical, return nullptr. */
extern gdb::unique_xmalloc_ptr<char> c_canonicalize_name (const char *name);
#endif /* !defined (C_LANG_H) */