From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.bugs Subject: bug#31688: 26.1.50; Byte compiler confuses two string variables Date: Mon, 04 Jun 2018 18:58:19 +0300 Message-ID: <83zi0abl2c.fsf@gnu.org> References: <87a7sdkrft.fsf@runbox.com> <87po199id0.fsf@gmail.com> <5c6b2383ccd9c7d9b4058d249274b8c4@webmail.orcon.net.nz> <87d0x8agn3.fsf@gmail.com> <389bb1de5df69b513db3097aa3e000cb@webmail.orcon.net.nz> <87y3fw9g18.fsf@igel.home> <2a9f684c2867ae9a7deccb51d04f9de6@webmail.orcon.net.nz> Reply-To: Eli Zaretskii NNTP-Posting-Host: blaine.gmane.org X-Trace: blaine.gmane.org 1528127835 9582 195.159.176.226 (4 Jun 2018 15:57:15 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Mon, 4 Jun 2018 15:57:15 +0000 (UTC) Cc: gazally@runbox.com, bug-gnu-emacs-bounces+psainty=orcon.net.nz@gnu.org, schwab@linux-m68k.org, npostavs@gmail.com, 31688@debbugs.gnu.org To: Phil Sainty Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Mon Jun 04 17:57:10 2018 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1fPrr4-0002MU-8A for geb-bug-gnu-emacs@m.gmane.org; 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Mon, 04 Jun 2018 11:59:02 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Eli Zaretskii Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Mon, 04 Jun 2018 15:59:02 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 31688 X-GNU-PR-Package: emacs X-GNU-PR-Keywords: Original-Received: via spool by 31688-submit@debbugs.gnu.org id=B31688.152812790218911 (code B ref 31688); Mon, 04 Jun 2018 15:59:02 +0000 Original-Received: (at 31688) by debbugs.gnu.org; 4 Jun 2018 15:58:22 +0000 Original-Received: from localhost ([127.0.0.1]:33496 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1fPrsE-0004uv-Ev for submit@debbugs.gnu.org; Mon, 04 Jun 2018 11:58:22 -0400 Original-Received: from eggs.gnu.org ([208.118.235.92]:59958) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1fPrsC-0004uV-Kh for 31688@debbugs.gnu.org; Mon, 04 Jun 2018 11:58:20 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fPrs3-0001DZ-Bb for 31688@debbugs.gnu.org; Mon, 04 Jun 2018 11:58:15 -0400 Original-Received: from fencepost.gnu.org ([2001:4830:134:3::e]:51094) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fPrs3-0001DO-7Y; Mon, 04 Jun 2018 11:58:11 -0400 Original-Received: from [176.228.60.248] (port=2224 helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:RSA_AES_256_CBC_SHA1:256) (Exim 4.82) (envelope-from ) id 1fPrs2-0000TS-ME; Mon, 04 Jun 2018 11:58:11 -0400 In-reply-to: <2a9f684c2867ae9a7deccb51d04f9de6@webmail.orcon.net.nz> (message from Phil Sainty on Mon, 04 Jun 2018 22:02:27 +1200) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 208.118.235.43 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" Xref: news.gmane.org gmane.emacs.bugs:146954 Archived-At: > Date: Mon, 04 Jun 2018 22:02:27 +1200 > From: Phil Sainty > Cc: Gemini Lasswell , Noam Postavsky , > bug-gnu-emacs , > 31688@debbugs.gnu.org > > Again, it bothers me to think that someone could observe a bug when > running byte-compiled code, and try to debug it but, through the > process of instrumenting functions for debugging, unwittingly change > the behaviour of the code such that the bug no longer occurs. Byte compilation includes optimizations, and the fact that optimized code can behave differently from unoptimized one is well known in every programming language. When you get differences, you have code that relies on undefined behavior, which I believe is the point Andreas was making.