Date: Fri, 19 Aug 2016 10:28:14 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: Tijl Coosemans <tijl@FreeBSD.org> Cc: Dimitry Andric <dim@FreeBSD.org>, freebsd-toolchain@freebsd.org, freebsd-ports@freebsd.org, Steve Kargl <sgk@troutmask.apl.washington.edu>, kargl@uw.edu Subject: Re: Problems with out libgcc_s.so in base Message-ID: <20160819072813.GB83214@kib.kiev.ua> In-Reply-To: <20160819011432.6f2eadbd@kalimero.tijl.coosemans.org> References: <20160814230351.GA10587@troutmask.apl.washington.edu> <20160814233430.GA35872@night.db.net> <20160817211710.GA59205@troutmask.apl.washington.edu> <20160818111521.7f79b9f8@kalimero.tijl.coosemans.org> <AB844E50-01A9-4559-8F7A-FE1F7B768F3A@FreeBSD.org> <20160819011432.6f2eadbd@kalimero.tijl.coosemans.org>
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On Fri, Aug 19, 2016 at 01:14:32AM +0200, Tijl Coosemans wrote: > On Thu, 18 Aug 2016 14:48:28 +0200 Dimitry Andric <dim@FreeBSD.org> wrote: > > On 18 Aug 2016, at 11:15, Tijl Coosemans <tijl@FreeBSD.org> wrote: > >> On Wed, 17 Aug 2016 14:17:10 -0700 Steve Kargl <sgk@troutmask.apl.washington.edu> wrote: > >>> % gfortran6 -o z foo.f90 && ./z > >>> /lib/libgcc_s.so.1: version GCC_4.6.0 required by \ > >>> /usr/local/lib/gcc6/libgfortran.so.3 not found > >>> % ldconfig -r | grep libgcc > >>> 6:-lgcc_s.1 => /lib/libgcc_s.so.1 > >>> 735:-lgcc_s.1 => /usr/local/lib/gcc6/libgcc_s.so.1 > >>> > >>> Clearly, ldd is looking for 735 but finds 6. If the lang/gcc6 could > >>> be convinced to build, install, and use libgcc_s6.so.1, then the > >>> problem is solved without a wrapper. > >> > >> In this case the real cause of the problem is that compilers and linkers > >> search /lib and /usr/lib last and ldconfig searches them first. Renaming > >> the library is just a hack around that. > > > > Well, even if you would adjust the compilers and linkers to look in > > /usr/local/lib first, > > No, I wanted to change /etc/rc.d/ldconfig to put /lib and /usr/lib last. > That would match base ld(1) so anything that links successfully at > compile-time will also link successfully at run-time (if there are no > other search order mismatches leading to conflicts). > > But, this means that in case of a name conflict between base and ports, > the ports provided library is assumed to be the right one. I'm not 100% > sure this is smart. Usually the ports version of a library is more > recent and if the name is the same it should be backward compatible, but > if that's not the case (older or not compatible) base utilities may fail > to run (like ./z in the example above) and that's maybe worse than ports > or locally built programs failing. > > > how would you solve the problem of having > > multiple, possibly incompatible versions of the same library in > > different directories? > > > > For example, on one of my systems, I now have these: > > > > /usr/local/lib/gcc47/libgcc_s.so.1 > > /usr/local/lib/gcc48/libgcc_s.so.1 > > /usr/local/lib/gcc49/libgcc_s.so.1 > > /usr/local/lib/gcc5/libgcc_s.so.1 > > /usr/local/lib/gcc6/libgcc_s.so.1 > > /usr/local/lib/gcc7/libgcc_s.so.1 > > > > So which one are you going to put at the front of the path? The gcc7 > > version? If you are lucky that one is backwards compatible with all the > > previous ones, but still I would like it much better if a program > > compiled by, say, gcc5 was linked *explicitly* against the gcc5 version > > of libgcc_s.so. > > > > Steve's proposed scheme solves that quite nicely, in my opinion. The > > problem is only in the details, as usual. There will be many configure > > scripts and libtool-like utilities out there, that assume libgcc must be > > linked using -lgcc_s, not -lgcc_s$VERSION. > > This is a separate problem that has been discussed many times before. > The ports tree adds -Wl,-rpath to *FLAGS in several places to choose > a library. I now noticed there is a FAQ about this at > https://gcc.gnu.org/faq.html#rpath. It gives some suggestions including > creating wrapper scripts, but they wouldn't work when code is compiled > with gfortran but linked with Clang cc/c++. The only thing that works > in this case is -Wl,-rpath. Another option would be to create a port > that installs a recent version of libgcc in /usr/local/lib and let the > gcc ports use that instead of their own copy. The option which would fix all this mess is: 1. add rpath for gcc lib/ directory into spec file and 2. make ports collection use its own compiler instead of fighting with the base.
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