From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 16279 invoked by alias); 5 Jun 2016 22:28:18 -0000 Mailing-List: contact cygwin-help@cygwin.com; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner@cygwin.com Mail-Followup-To: cygwin@cygwin.com Received: (qmail 16265 invoked by uid 89); 5 Jun 2016 22:28:18 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.8 required=5.0 tests=AWL,BAYES_00,RP_MATCHES_RCVD,SPF_HELO_PASS,SPF_PASS autolearn=ham version=3.3.2 spammy= X-HELO: limerock02.mail.cornell.edu Received: from limerock02.mail.cornell.edu (HELO limerock02.mail.cornell.edu) (128.84.13.242) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Sun, 05 Jun 2016 22:28:07 +0000 X-CornellRouted: This message has been Routed already. Received: from authusersmtp.mail.cornell.edu (granite3.serverfarm.cornell.edu [10.16.197.8]) by limerock02.mail.cornell.edu (8.14.4/8.14.4_cu) with ESMTP id u55MS5pe006535 for ; Sun, 5 Jun 2016 18:28:05 -0400 Received: from [192.168.1.3] (mta-68-175-148-36.twcny.rr.com [68.175.148.36] (may be forged)) (authenticated bits=0) by authusersmtp.mail.cornell.edu (8.14.4/8.12.10) with ESMTP id u55MS4YF008476 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NOT) for ; Sun, 5 Jun 2016 18:28:05 -0400 Subject: Re: bug: configuration problem in perl with gcc libs To: cygwin@cygwin.com References: <20160603161419.GA5300@karasik2> From: Ken Brown Message-ID: <785ef8ef-4335-2d25-284e-6ece02fbd427@cornell.edu> Date: Sun, 05 Jun 2016 22:28:00 -0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.1.1 MIME-Version: 1.0 In-Reply-To: <20160603161419.GA5300@karasik2> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-PMX-Cornell-Gauge: Gauge=XXXXX X-IsSubscribed: yes X-SW-Source: 2016-06/txt/msg00048.txt.bz2 On 6/3/2016 12:14 PM, Dmitry Karasik wrote: > Hello, > > I'd like to report a configuration bug in perl. The problem arises when a 3-rd > party module tries to build an extension using perl configuration with a > gcc-specific library. > > Generally perl extensions don't have a way to specify library to link with > directly, they do that through ExtUtils::MakeMaker, the standard tool for that. > Which in turn tries to resolve '-llibname' using its own > compile-time-configured internal list of lib paths. Everything works so far > libraries are found in perl's libpth (see by running 'perl -V:libpth') which is > /usr/lib on my machine. The problem arises when I need to link together with > libgomp, which is not found there, being a gcc-version-specific library. > > For example, the following minimal Makefile.PL configure script > > use ExtUtils::MakeMaker; > WriteMakefile(NAME => 'foo', LIBS => '-lgomp'); > > will emit a warning > > Warning (mostly harmless): No library found for -lgomp > > and removes -lgomp from the linker command, resulting in perl extension not > being able to compile. > > The problem is confirmed, when, if I edit perl configuration file > /usr/lib/perl5/5.22/i686-cygwin-threads-64int/Config.pm, everything works: > > ldlibpthname => 'PATH', > - libpth => '/usr/lib', > + libpth => '/usr/lib /usr/lib/gcc/i686-pc-cygwin/5.3.0', > osname => 'cygwin', > > I believe perl needs to be built with the properly set/found libpth in advance. I'm no perl expert, but this doesn't strike me as a good solution. It means that a specific gcc version is hard-coded into perl. It seems to me that the bug is in perl's algorithm (in /usr/lib/perl5/5.22/ExtUtils/Liblist/Kid.pm) for finding libraries of the form -lfoo. There's a special case for Cygwin at line 171 that looks for foo.dll (if it hasn't found libfoo.dll.a), which is wrong for two reasons. First, it should look for cygfoo*.dll instead (or in addition). Second, it should look in the path, or at least in /usr/bin, rather than in libpth. In the present case of -lgomp, it would have found /usr/bin/cyggomp-1.dll. Ken -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple