From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Paul Eggert Newsgroups: gmane.emacs.bugs Subject: bug#8496: some file locking code in insert-file-contents cannot be right Date: Wed, 13 Apr 2011 17:40:49 -0700 Organization: UCLA Computer Science Department Message-ID: <4DA64291.5060207@cs.ucla.edu> NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Trace: dough.gmane.org 1302743267 21754 80.91.229.12 (14 Apr 2011 01:07:47 GMT) X-Complaints-To: usenet@dough.gmane.org NNTP-Posting-Date: Thu, 14 Apr 2011 01:07:47 +0000 (UTC) To: 8496@debbugs.gnu.org Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Thu Apr 14 03:07:39 2011 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([140.186.70.17]) by lo.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1QAB1z-0005a4-N4 for geb-bug-gnu-emacs@m.gmane.org; Thu, 14 Apr 2011 03:07:35 +0200 Original-Received: from localhost ([::1]:53108 helo=lists2.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QAB1z-0007bT-5v for geb-bug-gnu-emacs@m.gmane.org; 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U; Linux x86_64; en-US; rv:1.9.2.15) Gecko/20110307 Fedora/3.1.9-0.39.b3pre.fc14 Thunderbird/3.1.9 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6 (newer, 3) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6 (newer, 3) X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.11 Precedence: list Resent-Date: Wed, 13 Apr 2011 20:42:02 -0400 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6 (newer, 3) X-Received-From: 140.186.70.43 X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Original-Sender: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.bugs:45801 Archived-At: As a result of the "mark unexported symbols 'static'" patch that I'm working on, in the Emacs trunk I found some file-locking code inside insert-file-contents that cannot be right: if (NILP (visit) && inserted > 0) { #ifdef CLASH_DETECTION if (!NILP (BVAR (current_buffer, file_truename)) /* Make binding buffer-file-name to nil effective. */ && !NILP (BVAR (current_buffer, filename)) && SAVE_MODIFF >= MODIFF) we_locked_file = 1; #endif /* CLASH_DETECTION */ prepare_to_modify_buffer (GPT, GPT, NULL); } The above code is equivalent to a no-op, since 'inserted' must be zero here. There's later code: #ifdef CLASH_DETECTION if (we_locked_file) unlock_file (BVAR (current_buffer, file_truename)); #endif that is also a no-op, because 'we_locked_file' must be zero. GCC merrily optimizes all this code away, but I don't think that was intended. What *is* intended here?