From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 16713 invoked by alias); 24 Oct 2007 17:15:51 -0000 Received: (qmail 16702 invoked by uid 22791); 24 Oct 2007 17:15:51 -0000 X-Spam-Check-By: sourceware.org Received: from mail.codesourcery.com (HELO mail.codesourcery.com) (65.74.133.4) by sourceware.org (qpsmtpd/0.31) with ESMTP; Wed, 24 Oct 2007 17:15:49 +0000 Received: (qmail 26239 invoked from network); 24 Oct 2007 17:15:46 -0000 Received: from unknown (HELO localhost) (carlos@127.0.0.2) by mail.codesourcery.com with ESMTPA; 24 Oct 2007 17:15:46 -0000 Date: Wed, 24 Oct 2007 17:24:00 -0000 From: Carlos O'Donell To: Jim Blandy Cc: gdb-patches@sourceware.org, Daniel Jacobowitz Subject: Re: [PATCH] Fix uninitialized use of variables. Message-ID: <20071024171544.GO21241@lios> References: <20071020172137.GC28823@lios> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.16 (2007-06-11) Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org X-SW-Source: 2007-10/txt/msg00591.txt.bz2 On Tue, Oct 23, 2007 at 04:17:29PM -0700, Jim Blandy wrote: > > Carlos O'Donell writes: > > In symtab.c (find_line_common) the variable *exact_match is not set if > > no match is found. Callers of find_line_common expect *exact_match to be > > set. The solution is to initialize *exact_match to zero, assuming an > > inexact match. In the case that we don't find a match in > > find_line_common, the statement `(best_index < 0 || !exact)' in > > symtab.c:2267 is true, instead of undefined. The comment is adjusted to > > indicate that one must look at another symtab if we failed to find a > > match `best_index < 0' or we found an inexact match `!exact.' > > As far as the symtab.c change is concerned: the specification of > find_line_common is that *EXACT_MATCH is set only if the function > returns a match (a non-negative value). As far as I can see, > find_line_symtab doesn't actually use the value of 'exact' unless the > corresponding call to find_line_common returned a match. So the > warning looks spurious to me. > > (I don't mind initializing 'exact' in find_line_symtab to placate the > compiler.) Sorry, yes, the boolean short circuit avoids the evaluation of !exact. The compiler probably can't see that though and warns that it *may* be an uninitialized use of the variable. I'll whip up a patch that initializes exact in find_line_symtab. Thanks for the review. Cheers, Carlos. -- Carlos O'Donell CodeSourcery carlos@codesourcery.com (650) 331-3385 x716