From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 49831 invoked by alias); 16 Nov 2016 17:32:41 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 49811 invoked by uid 89); 16 Nov 2016 17:32:41 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-4.8 required=5.0 tests=BAYES_00,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=lc X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Wed, 16 Nov 2016 17:32:30 +0000 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id C9DC377349; Wed, 16 Nov 2016 17:32:29 +0000 (UTC) Received: from [127.0.0.1] (ovpn03.gateway.prod.ext.phx2.redhat.com [10.5.9.3]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id uAGHWSFC019180; Wed, 16 Nov 2016 12:32:29 -0500 Subject: Re: [PATCH 3/4] Makefile: Replace old suffix rules with pattern rules To: Eli Zaretskii References: <20161116160808.12830-1-simon.marchi@ericsson.com> <20161116160808.12830-4-simon.marchi@ericsson.com> <83lgwjfknq.fsf@gnu.org> <0fa3954e-1f8a-f7f8-aad7-d31d45aa981e@redhat.com> <83k2c3fitl.fsf@gnu.org> Cc: simon.marchi@ericsson.com, gdb-patches@sourceware.org From: Pedro Alves Message-ID: Date: Wed, 16 Nov 2016 17:32:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <83k2c3fitl.fsf@gnu.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-SW-Source: 2016-11/txt/msg00435.txt.bz2 On 11/16/2016 05:14 PM, Eli Zaretskii wrote: >> Cc: gdb-patches@sourceware.org >> From: Pedro Alves >> Date: Wed, 16 Nov 2016 16:56:02 +0000 >> >> Given the shared ancestry, and the fact that GCC nowadays requires >> GNU make, I think it may be worth it to take a look at what >> does GCC's Makefile.in do. >> >> In this case, it has: >> >> ~~~ >> # Suppress smart makes who think they know how to automake yacc and flex file >> .y.c: >> .l.c: >> >> # The only suffixes we want for implicit rules are .c and .o, so clear >> # the list and add them. This speeds up GNU Make, and allows -r to work. >> # For i18n support, we also need .gmo, .po, .pox. >> # This must come before the language makefile fragments to allow them to >> # add suffixes and rules of their own. >> .SUFFIXES: >> .SUFFIXES: .c .cc .o .po .pox .gmo >> ~~~ >> >> I don't know why they still add some suffixes instead of relying >> on the pattern rules. Might just be legacy. > > No, it's because of the built-in rules. They are by default > considered no matter which pattern rules you have in the Makefile, > because theoretically each .c file can be built from some other file > in any number of ways. I still don't understand. The question is why they add back some suffixes _after_ having deleted all the implicit rules. I.e., why do: .SUFFIXES: .SUFFIXES: .c instead of: .SUFFIXES: %.o: %.c They use pattern rules for other, more specific cases, AFAICS. Thanks, Pedro Alves