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* [binutils-gdb] [gdb] Don't set initial language using previous language
@ 2020-02-28 15:15 Tom de Vries
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From: Tom de Vries @ 2020-02-28 15:15 UTC (permalink / raw)
To: gdb-cvs
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=658dadf0b02b618fe81e7b09ad930479941f2236
commit 658dadf0b02b618fe81e7b09ad930479941f2236
Author: Tom de Vries <tdevries@suse.de>
Date: Fri Feb 28 16:14:53 2020 +0100
[gdb] Don't set initial language using previous language
When language is set to auto, part of loading an executable is to update the
language accordingly. This is implemented by set_initial_language.
In case of a c++ executable without DW_AT_main_subprogram,
set_initial_language finds "main" in the minimal symbols, and does a lookup of
"main" in the symbol tables to determine the language of the symbol, and uses
that as initial language.
The symbol lookup is done using lookup_symbol which is a wrapper around
lookup_symbol_in_language, using the current language.
So, consider two c++ executables a.out and b.out, which we'll load one after
another. If we track the resulting lookup_symbol_in_language calls:
...
$ gdb -batch \
-ex "b lookup_symbol_in_language" \
-ex r -ex c -ex c \
--args gdb
...
we find that indeed lookup_symbol_in_language is called once using language_c, and
once using language_c_plus:
...
(gdb) file a.out
Reading symbols from a.out...
Breakpoint 1, lookup_symbol_in_language (name=0x5555568c2050 "main", \
block=0x0, domain=VAR_DOMAIN, lang=language_c, is_a_field_of_this=0x0) \
at ../../gdb/symtab.c:1905
1905 {
(gdb) file b.out
Load new symbol table from "b.out"? (y or n) y
Reading symbols from b.out...
Breakpoint 1, lookup_symbol_in_language (name=0x5555568c2030 "main", \
block=0x0, domain=VAR_DOMAIN, lang=language_cplus, is_a_field_of_this=0x0) \
at ../../gdb/symtab.c:1905
1905 {
(gdb)
...
It seems like a bad idea to have the previous language play a role
in determining the executable language.
Fix this by using lookup_symbol_in_language in set_initial_language with the
default language c as argument.
Tested on x86_64-linux.
gdb/ChangeLog:
2020-02-28 Tom de Vries <tdevries@suse.de>
* symfile.c (set_initial_language): Use default language for lookup.
Diff:
---
gdb/ChangeLog | 4 ++++
gdb/symfile.c | 9 ++++++---
2 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index fce2a03..5f49542 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,7 @@
+2020-02-28 Tom de Vries <tdevries@suse.de>
+
+ * symfile.c (set_initial_language): Use default language for lookup.
+
2020-02-28 Simon Marchi <simon.marchi@efficios.com>
* dwarf2/read.c (cutu_reader::init_tu_and_read_dwo_dies): Remove
diff --git a/gdb/symfile.c b/gdb/symfile.c
index f1edf2d..01c3f5a 100644
--- a/gdb/symfile.c
+++ b/gdb/symfile.c
@@ -1684,11 +1684,15 @@ set_initial_language (void)
if (language_mode == language_mode_manual)
return;
enum language lang = main_language ();
+ /* Make C the default language. */
+ enum language default_lang = language_c;
if (lang == language_unknown)
{
const char *name = main_name ();
- struct symbol *sym = lookup_symbol (name, NULL, VAR_DOMAIN, NULL).symbol;
+ struct symbol *sym
+ = lookup_symbol_in_language (name, NULL, VAR_DOMAIN, default_lang,
+ NULL).symbol;
if (sym != NULL)
lang = sym->language ();
@@ -1696,8 +1700,7 @@ set_initial_language (void)
if (lang == language_unknown)
{
- /* Make C the default language */
- lang = language_c;
+ lang = default_lang;
}
set_language (lang);
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