Adding MPI back to Boost

[Sean Farley]

Mark Moll writes:

>> On Dec 14, 2014, at 2:28 AM, Sean Farley <sean at macports.org> wrote:
>> 
>> So, I've added support into the compilers portgroup for working with
>> the compiler.blacklist variable but that doesn't fix the issue that Ryan
>> tried to fix with r125939:
>> 
>> https://trac.macports.org/changeset/125939
>> 
>> It seems instead that the fix is just to remove the gcc variants:
>> 
>> mpi.setup -gcc
>> 
>> Is there anything wrong with this proposed fix? If no one objects, I'll
>> push my changesets which 1) add blacklist support to the compilers
>> portgroup and 2) add mpi portgroup to boost (but remove gcc variants).
>
> This seems like a good idea. Unless (a) you can use gcc for all of boost’s dependents and (b) there are actual use cases where this would be useful, I’d say that removing gcc variants is a good idea. Mixing libc++ and libstdc++ in boost dependents is bound to lead to problems.

(a) That would require depending on a variant which I don't want to put
    the work into. I wrote a script to do this manually for myself but
    it is still a headache.

(b) Depends on how useful you think testing different compiler speed /
    output is: I would have used it to test dolfin (FEniCS) builds with
    gcc vs clang.