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#47391: 27.2; static list return from function and nconc Date: Thu, 25 Mar 2021 11:43:20 -0400 Message-ID: References: <87r1k32sir.fsf@hm.sivalik.com> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="35460"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) Cc: Rajeev Narang , 47391@debbugs.gnu.org, Emacs developers To: Philipp Stephani Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Thu Mar 25 16:49:45 2021 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 1lPSEy-00095L-8l for geb-bug-gnu-emacs@m.gmane-mx.org; Thu, 25 Mar 2021 16:49:44 +0100 Original-Received: from localhost ([::1]:51668 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lPSEx-0007k6-A9 for geb-bug-gnu-emacs@m.gmane-mx.org; Thu, 25 Mar 2021 11:49:43 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:45232) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lPS9S-0001rx-Nt for bug-gnu-emacs@gnu.org; Thu, 25 Mar 2021 11:44:02 -0400 Original-Received: from debbugs.gnu.org ([209.51.188.43]:55991) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1lPS9S-0002fZ-El for bug-gnu-emacs@gnu.org; Thu, 25 Mar 2021 11:44:02 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1lPS9S-00036O-C6 for bug-gnu-emacs@gnu.org; Thu, 25 Mar 2021 11:44:02 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Stefan Monnier Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Thu, 25 Mar 2021 15:44:02 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 47391 X-GNU-PR-Package: emacs Original-Received: via spool by 47391-submit@debbugs.gnu.org id=B47391.161668701011875 (code B ref 47391); Thu, 25 Mar 2021 15:44:02 +0000 Original-Received: (at 47391) by debbugs.gnu.org; 25 Mar 2021 15:43:30 +0000 Original-Received: from localhost ([127.0.0.1]:39304 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1lPS8w-00035T-AE for submit@debbugs.gnu.org; Thu, 25 Mar 2021 11:43:30 -0400 Original-Received: from mailscanner.iro.umontreal.ca ([132.204.25.50]:64204) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1lPS8u-00035G-Sh for 47391@debbugs.gnu.org; Thu, 25 Mar 2021 11:43:29 -0400 Original-Received: from pmg2.iro.umontreal.ca (localhost.localdomain [127.0.0.1]) by pmg2.iro.umontreal.ca (Proxmox) with ESMTP id 88367809E7; Thu, 25 Mar 2021 11:43:23 -0400 (EDT) Original-Received: from mail01.iro.umontreal.ca (unknown [172.31.2.1]) by pmg2.iro.umontreal.ca (Proxmox) with ESMTP id 35FD380675; Thu, 25 Mar 2021 11:43:22 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=iro.umontreal.ca; s=mail; t=1616687002; bh=yjukXNXFZuAbfp8EHWGt8jMMPpNGLNmo074RC9wuREY=; h=From:To:Cc:Subject:References:Date:In-Reply-To:From; b=gLlKN09kzQDSmxTUv5Mz3dgR0YWnDCZ4pdDWMqGjyj3D2FcYtXRlTkMfcjYow4WKB Xc1kh9ZcVxw5CB+k8uqr4gHFAVk29FA0ALsx+nr8mnTT0KOtgKBbQGsoJk+DudJGQA nf0g3qys9fs/2lq0A9qcEVS90QKUODlVdTuvZHSLv0myQ9SKIp4GuOMCQbqRtYaZcE Mm4FJZAHl8PY4TFe3fQsrlge5CtqhQjyFxsGln/qPAdb1M/qIIv/ypvu60pcoZZDqb vDoKcHbSgqVgPHCPZs5WrBMdPQkx5+ELGkUf4vmASc6GD2tD+4fnk9acHTAz8UFOFR NSnFQBX+0lKPA== Original-Received: from alfajor (unknown [216.154.43.249]) by mail01.iro.umontreal.ca (Postfix) with ESMTPSA id E671F12014C; Thu, 25 Mar 2021 11:43:21 -0400 (EDT) In-Reply-To: (Philipp Stephani's message of "Thu, 25 Mar 2021 16:28:26 +0100") 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:203008 Archived-At: >> (defun fn () '(1 2)) >> >> (nconc (fn) '(3)) >> -> (1 2 3) > > This is undefined behavior/unsupported. The value that (fn) evaluates > to is immutable, but nconc mutates it. > >> >> (nconc (fn) '(3)) >> -> (1 2 3 3) ? should be (1 2 3) >> >> If this is not a bug, then hfy-invisible, hfy-face-to-style-i may need to be fixed. > > If they use this pattern, then they should indeed be fixed. Note that in the code above, we usually consider that the bug is not in `fn` but in the use of `nconc` on a list which the code doesn't know can safely be mutated (it should hence use `append` instead). Stefan