Date: Sat, 20 Aug 2016 18:10:44 +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: <20160820151044.GO83214@kib.kiev.ua> In-Reply-To: <20160819215028.3d8e5b42@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> <20160819072813.GB83214@kib.kiev.ua> <20160819215028.3d8e5b42@kalimero.tijl.coosemans.org>
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On Fri, Aug 19, 2016 at 09:50:28PM +0200, Tijl Coosemans wrote:
> On Fri, 19 Aug 2016 10:28:14 +0300 Konstantin Belousov <kostikbel@gmail.com> wrote:
> > 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.
>
> That still doesn't cover all cases, e.g.:
>
> port exec -> base lib -> libgcc_s.so.1
> -> port lib -> recent libgcc_s.so.1
>
> An example is:
>
> % echo 'int main(void){}' > test.c
> % clang37 -o test test.c -lexecinfo -lgfortran -L/usr/local/lib/gcc5 -Wl,-rpath,/usr/local/lib/gcc5
> % ./test
> /lib/libgcc_s.so.1: version GCC_4.6.0 required by /usr/local/lib/gcc5/libgfortran.so.3 not found
>
> The base library (libexecinfo) doesn't have DT_RPATH or DT_RUNPATH so the
> only way rtld can find the right libgcc_s.so is if the executable (test)
> has DT_RPATH and no DT_RUNPATH. Clang runs ld with --enable-new-dtags
> so the executable has DT_RUNPATH. DT_RPATH is deprecated in the Linux
> world so there are probably more ports that use --enable-new-dtags.
> Another example seems to be Rust.
Indeed, and I rechecked the find_library() code against the latest gABI
once more.
So base libraries linked against libgcc_s are
/lib/libcxxrt.so.1
/usr/lib/libc++.so.1
/usr/lib/libexecinfo.so.1
/usr/lib/libprivatedevdctl.so.0
and only libexecinfo would be somewhat problematic. libcxxrt and libc++
come from C++ runtime, which must be provided by the port's compiler,
the private library should not be linked to by behaving applications.
I suppose that libexecinfo pull unwinder from libgcc_s. It might be
possible just dlopen() libgcc_s for _Unwind_Backtrace, it seems.
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