From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.bugs Subject: bug#18968: 25.0.50; unhelpful "unused" warning from byte compiler Date: Wed, 05 Nov 2014 22:28:50 -0500 Message-ID: References: <87zjc5gi7j.fsf@tromey.com> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1415244568 10439 80.91.229.3 (6 Nov 2014 03:29:28 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 6 Nov 2014 03:29:28 +0000 (UTC) Cc: 18968@debbugs.gnu.org To: Tom Tromey Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Thu Nov 06 04:29:21 2014 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1XmDlA-00011N-H1 for geb-bug-gnu-emacs@m.gmane.org; Thu, 06 Nov 2014 04:29:20 +0100 Original-Received: from localhost ([::1]:49715 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XmDlA-0003dj-2y for geb-bug-gnu-emacs@m.gmane.org; Wed, 05 Nov 2014 22:29:20 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:42112) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XmDkz-0003d9-Ni for bug-gnu-emacs@gnu.org; Wed, 05 Nov 2014 22:29:17 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XmDks-000215-86 for bug-gnu-emacs@gnu.org; Wed, 05 Nov 2014 22:29:09 -0500 Original-Received: from debbugs.gnu.org ([140.186.70.43]:53476) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XmDks-00020v-4T for bug-gnu-emacs@gnu.org; Wed, 05 Nov 2014 22:29:02 -0500 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.80) (envelope-from ) id 1XmDkr-0008KL-O4 for bug-gnu-emacs@gnu.org; Wed, 05 Nov 2014 22:29:01 -0500 X-Loop: help-debbugs@gnu.org Resent-From: Stefan Monnier Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Thu, 06 Nov 2014 03:29:01 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 18968 X-GNU-PR-Package: emacs X-GNU-PR-Keywords: Original-Received: via spool by 18968-submit@debbugs.gnu.org id=B18968.141524453331994 (code B ref 18968); Thu, 06 Nov 2014 03:29:01 +0000 Original-Received: (at 18968) by debbugs.gnu.org; 6 Nov 2014 03:28:53 +0000 Original-Received: from localhost ([127.0.0.1]:50689 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.80) (envelope-from ) id 1XmDkj-0008Jx-Fn for submit@debbugs.gnu.org; Wed, 05 Nov 2014 22:28:53 -0500 Original-Received: from ironport2-out.teksavvy.com ([206.248.154.181]:24388) by debbugs.gnu.org with esmtp (Exim 4.80) (envelope-from ) id 1XmDkg-0008Jo-Sw for 18968@debbugs.gnu.org; Wed, 05 Nov 2014 22:28:51 -0500 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AvAMAOatTlRLd+sd/2dsb2JhbABcgw6DYoZ+yDmDGgQCAoEcFwEBfIQDAQEDAVYjBQsLNBIUGA0kiEsJy3IBAQEBAQEEAQEBAR6RCAeESwWLZKY8gW+EFh+CegEBAQ X-IPAS-Result: AvAMAOatTlRLd+sd/2dsb2JhbABcgw6DYoZ+yDmDGgQCAoEcFwEBfIQDAQEDAVYjBQsLNBIUGA0kiEsJy3IBAQEBAQEEAQEBAR6RCAeESwWLZKY8gW+EFh+CegEBAQ X-IronPort-AV: E=Sophos;i="5.04,797,1406606400"; d="scan'208";a="96075588" Original-Received: from 75-119-235-29.dsl.teksavvy.com (HELO ceviche.home) ([75.119.235.29]) by ironport2-out.teksavvy.com with ESMTP/TLS/DHE-RSA-AES256-SHA; 05 Nov 2014 22:28:50 -0500 Original-Received: by ceviche.home (Postfix, from userid 20848) id 098ED660D4; Wed, 5 Nov 2014 22:28:50 -0500 (EST) In-Reply-To: <87zjc5gi7j.fsf@tromey.com> (Tom Tromey's message of "Wed, 05 Nov 2014 19:45:36 -0700") User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.4.50 (gnu/linux) X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.15 Precedence: list X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x 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:95594 > Byte-compile this program: > (defvar q-x) > (defun z () > (pop (aref q-x 0)) > nil) > I get: > q.el:2:8:Warning: value returned from (aref v 0) is unused > I think this warning is not very useful; I'd tend to agree, tho it turned out it was useful because it pointed out that (aref v 0) was called twice by the macro-expanded code instead of only once. So I installed the patch below which should fix the underlying problem. Stefan === modified file 'lisp/subr.el' --- lisp/subr.el 2014-10-30 05:15:28 +0000 +++ lisp/subr.el 2014-11-06 03:25:36 +0000 @@ -169,7 +169,8 @@ ;; So we can use `pop' in the bootstrap before `gv' can be used. (list 'prog1 place (list 'setq place (list 'cdr place))) (gv-letplace (getter setter) place - `(prog1 ,getter ,(funcall setter `(cdr ,getter))))))) + (macroexp-let2 macroexp-copyable-p x getter + `(prog1 ,x ,(funcall setter `(cdr ,x)))))))) (defmacro when (cond &rest body) "If COND yields non-nil, do BODY, else return nil.