From patchwork Fri Feb 28 06:33:16 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tom de Vries X-Patchwork-Id: 38345 Received: (qmail 65479 invoked by alias); 28 Feb 2020 06:33:22 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Delivered-To: mailing list gdb-patches@sourceware.org Received: (qmail 65468 invoked by uid 89); 28 Feb 2020 06:33:22 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-25.1 required=5.0 tests=AWL, BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, SPF_PASS autolearn=ham version=3.3.1 spammy=role, language_mode, sk:set_ini X-HELO: mx2.suse.de Received: from mx2.suse.de (HELO mx2.suse.de) (195.135.220.15) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Fri, 28 Feb 2020 06:33:20 +0000 Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 8502DAEDC for ; Fri, 28 Feb 2020 06:33:18 +0000 (UTC) Date: Fri, 28 Feb 2020 07:33:16 +0100 From: Tom de Vries To: gdb-patches@sourceware.org Subject: [PATCH][gdb] Don't set initial language using previous language Message-ID: <20200228063315.GA16995@delia> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.10.1 (2018-07-13) X-IsSubscribed: yes Hi, 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. OK for trunk? Thanks, - Tom [gdb] Don't set initial language using previous language gdb/ChangeLog: 2020-02-28 Tom de Vries * symfile.c (set_initial_language): Use default language for lookup. --- gdb/symfile.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/gdb/symfile.c b/gdb/symfile.c index f1edf2dca5..01c3f5af12 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);