mxcl/homebrew — pull request #13255 by Sharpie (2012-07-06 23:35:09+00:00)
Title: Add Requirement for MPI compilers

All versions of OS X prior to Lion shipped with some version of Open-MPI, but
without working compiler wrappers for Fortran. Homebrew currently has two
formulae that can supply this software: open-mpi and mpich2.

This commit adds a `MPIDependency` Requirement that can be passed one of four
values when constructed:

:cc, :cxx, :f90, :f77

This will ensure the `mpi` compiler is available and working. For
example, if `depends_on MPIDependency.new(:cc, :f90)` is used, the Requirement
will search for working `mpicc` and `mpif90` wrappers.

If the required wrappers cannot be found, an error message will be displayed
that prompts the user to install one of the Homebrew formulae that provides
MPI.