How to get rid of the conflict between /usr/local/lib/gcc49/libgcc_s.so.1 and /lib/libgcc_s.so.1

[Ian Lepore]

On Thu, 2017-04-20 at 09:35 -0700, Yuri wrote:
> Currently, FreeBSD can't run software that includes both fortran and 
> clang-built parts that use exceptions.
> 
> The immediate reason is that /usr/local/lib/gcc49/libgfortran.so.3 
> requires a newer version of libgcc,
> /usr/local/lib/gcc49/libgcc_s.so.1, 
> but the older version /lib/libgcc_s.so.1 is used by the rest of the
> system.
> 
> The immediate message is: ImportError: /lib/libgcc_s.so.1: version 
> GCC_4.6.0 required by /usr/local/lib/gcc49/libgfortran.so.3 not found
> 
> libgcc update us impossible due to the licensing change, libgcc is
> now GPL.
> 
> 
> One or only thing that is used in libgcc is the low level Unwind 
> functionality. There are some alternative unwind implementations,
> for 
> example https://github.com/pathscale/libunwind with the MIT license.
> 
> Anybody has an idea how to solve this problem?
> 
> 
> One example of failure is 
> https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=217459, but most 
> science software is affected.
> 
> 

A PR about this with lots more info and some potential fixes (or at
least workarounds) is:

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=208120

-- Ian