From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.bugs Subject: bug#42147: 28.0.50; pure vs side-effect-free, missing optimizations? Date: Mon, 10 Aug 2020 18:10:39 -0400 Message-ID: References: <3A9CC2A3-8307-47B2-8D80-795C0AF020E1@acm.org> <0433A879-C98D-4B1A-B85C-A15DA9289099@acm.org> <1621669100.2102667.1593639091621@mail.yahoo.com> <33C2E2C8-16A6-47A9-B3A4-8A5F43648E04@acm.org> <51FE77F3-CA05-459A-9601-9E1EEBC1E2FE@acm.org> <1213DD41-01F9-4605-8D32-D750B6CE2B35@acm.org> <81F989D1-3CC4-450B-89D6-E9C16F766277@acm.org> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="24832"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) Cc: Mattias =?UTF-8?Q?Engdeg=C3=A5rd?= , Paul Eggert , Andrea Corallo , 42147@debbugs.gnu.org To: Philipp Stephani Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Tue Aug 11 00:11:10 2020 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1k5G0c-0006NP-KF for geb-bug-gnu-emacs@m.gmane-mx.org; Tue, 11 Aug 2020 00:11:10 +0200 Original-Received: from localhost ([::1]:55008 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1k5G0a-0003dP-W6 for geb-bug-gnu-emacs@m.gmane-mx.org; Mon, 10 Aug 2020 18:11:09 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:48792) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1k5G0U-0003dH-CD for bug-gnu-emacs@gnu.org; Mon, 10 Aug 2020 18:11:02 -0400 Original-Received: from debbugs.gnu.org ([209.51.188.43]:54456) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1k5G0U-000493-2F for bug-gnu-emacs@gnu.org; Mon, 10 Aug 2020 18:11:02 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1k5G0T-0000Sc-Rf for bug-gnu-emacs@gnu.org; Mon, 10 Aug 2020 18:11:01 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Stefan Monnier Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Mon, 10 Aug 2020 22:11:01 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 42147 X-GNU-PR-Package: emacs Original-Received: via spool by 42147-submit@debbugs.gnu.org id=B42147.15970974491751 (code B ref 42147); Mon, 10 Aug 2020 22:11:01 +0000 Original-Received: (at 42147) by debbugs.gnu.org; 10 Aug 2020 22:10:49 +0000 Original-Received: from localhost ([127.0.0.1]:37769 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1k5G0H-0000SA-Eh for submit@debbugs.gnu.org; Mon, 10 Aug 2020 18:10:49 -0400 Original-Received: from mailscanner.iro.umontreal.ca ([132.204.25.50]:13778) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1k5G0F-0000Rx-JZ for 42147@debbugs.gnu.org; Mon, 10 Aug 2020 18:10:48 -0400 Original-Received: from pmg3.iro.umontreal.ca (localhost [127.0.0.1]) by pmg3.iro.umontreal.ca (Proxmox) with ESMTP id 518D04410B8; Mon, 10 Aug 2020 18:10:42 -0400 (EDT) Original-Received: from mail01.iro.umontreal.ca (unknown [172.31.2.1]) by pmg3.iro.umontreal.ca (Proxmox) with ESMTP id ED9A0441020; Mon, 10 Aug 2020 18:10:40 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=iro.umontreal.ca; s=mail; t=1597097440; bh=jzDgh1RbD5cOCdD8RGeXwMTGC1z27uakeBg/6be/2Zw=; h=From:To:Cc:Subject:References:Date:In-Reply-To:From; b=QrDQ2ZeQtoWofEGMHccPNZ3yBEhG3tpDr85YfLmoXwB/jRXzbfexXqR/F5NckgXU6 FC+nBsBD/gJBtuOWhMOqR9C+UHnxpOf5xt8YlleUIkd9VJtymUXzr0P0UmkuGB6Qoz PB2Ry/PYIpYSnsKRi79DZQqITfW6fVqhqz1VBtFXD4BvmjLDNPn3YY4lLZlpTT2lF/ yMk0omz20/cREnQkudS/KVAO85VM+t6qMASZZ1ob4l8jtIzC9IS5TSYPIjWxpHU3sV 9Xuk44phIfnx1vBAkMPTKmgS2Yk6k+xPRW+OAIM8DFa3o97kxFG2qE1ruG/wMr3O9G 9mvgr5P+o3cWA== Original-Received: from milanesa (unknown [45.72.246.108]) by mail01.iro.umontreal.ca (Postfix) with ESMTPSA id 83CE312078C; Mon, 10 Aug 2020 18:10:40 -0400 (EDT) In-Reply-To: (Philipp Stephani's message of "Mon, 10 Aug 2020 15:42:48 +0200") X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list 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-mx.org@gnu.org Original-Sender: "bug-gnu-emacs" Xref: news.gmane.io gmane.emacs.bugs:184604 Archived-At: > Arguments relating to probabilities ("most users", "vast majority", > "rare") don't really apply here, as the discussion is about > correctness. A pure function must be pure 100% of the time, no > exceptions allowed. `package-get-version' can't possibly be pure: it > doesn't take any argument, so if it were pure, it would have to return > a constant in the mathematical sense. It's a borderline case: it's designed such that if the compiler pre-evaluates it, the result will indeed be the same as if it were evaluated later at run-time. So it's correct w.r.t "allow constant-folding", even tho it's not "pure". Stefan