Problems with out libgcc_s.so in base

[Tijl Coosemans]

On Fri, 19 Aug 2016 10:28:14 +0300 Konstantin Belousov <kostikbel at 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.