From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED.blaine.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: [Emacs-diffs] master d826037 3/3: Remove the need for temacs.in Date: Thu, 11 Apr 2019 15:35:53 -0400 Message-ID: References: <20190409224339.20116.87667@vcs0.savannah.gnu.org> <20190409224342.0DA1F20E54@vcs0.savannah.gnu.org> <86697de6baf024290a9d0b10743ba2b7.squirrel@dancol.org> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: blaine.gmane.org; posting-host="blaine.gmane.org:195.159.176.226"; logging-data="223452"; mail-complaints-to="usenet@blaine.gmane.org" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) To: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Thu Apr 11 21:37:39 2019 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([209.51.188.17]) by blaine.gmane.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:256) (Exim 4.89) (envelope-from ) id 1hEfVy-000w21-8N for ged-emacs-devel@m.gmane.org; Thu, 11 Apr 2019 21:37:38 +0200 Original-Received: from localhost ([127.0.0.1]:53920 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hEfVx-0002uu-7G for ged-emacs-devel@m.gmane.org; Thu, 11 Apr 2019 15:37:37 -0400 Original-Received: from eggs.gnu.org ([209.51.188.92]:55621) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hEfUT-0002IU-8I for emacs-devel@gnu.org; Thu, 11 Apr 2019 15:36:06 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hEfUR-00047q-Kc for emacs-devel@gnu.org; Thu, 11 Apr 2019 15:36:04 -0400 Original-Received: from [195.159.176.226] (port=43800 helo=blaine.gmane.org) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hEfUR-00044O-Am for emacs-devel@gnu.org; Thu, 11 Apr 2019 15:36:03 -0400 Original-Received: from list by blaine.gmane.org with local (Exim 4.89) (envelope-from ) id 1hEfUN-000twq-4H for emacs-devel@gnu.org; Thu, 11 Apr 2019 21:35:59 +0200 X-Injected-Via-Gmane: http://gmane.org/ Cancel-Lock: sha1:kvVgZMXs5PItF8ZG2gL/lZIdbRY= X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 195.159.176.226 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.org gmane.emacs.devel:235305 Archived-At: > Please don't do this. Computing a fingerprint over temacs.in factors link > layout information into the fingerprint hash. Your approach doesn't. It's > possible to link Emacs in different ways from the same object files and > produce different binaries. I don't think a little build speedup is worth > the safety loss. BTW, regarding this fingerprint: following this discussion, I see that we actually don't know for sure what is preserved between two different runs of `ld` and more to the point, there is no guarantee. So, how'bout we don't compute a fingerprint at all. Instead we generate a UUID: this way we can have our cake (no need for a separate temacs.in) and eat it too (even very subtle changes `ld` does between two different runs will lead to different "fingerprints"). Stefan