help build mpich with gcc6

[Anton Shterenlikht]

>From mexas Tue Feb 21 15:00:10 2017
>To: freebsd-ports at freebsd.org
>Subject: help build mpich with gcc6
>Reply-To: mexas at bris.ac.uk
>
>I added
>
>USE_GCC=        6+
>
>to net/mpich/Makefile
>
>but it seems this affected only the C and C++ parts:
>
>$ mpichversion
>*skip*
>
>MPICH CC:       gcc6  -O2 -pipe  -fstack-protector -Wl,-rpath=/usr/local/lib/gcc6 -fno-strict-aliasing 
>MPICH CXX:      g++6  -O2 -pipe -fstack-protector -Wl,-rpath=/usr/local/lib/gcc6 -fno-strict-aliasing  -Wl,-rpath=/usr/local/lib/gcc6
>MPICH F77:      gfortran49  -O -Wl,-rpath=/usr/local/lib/gcc49
>MPICH FC:       gfortran49  -Wl,-rpath=/usr/local/lib/gcc49
>
>The Fortran parts remained at lang/gcc level.
>
>What settings shall I use to make Fortran components
>built with gfortran6 instead?
>
>Thanks
>
>Anton

I moved one step further.
With

DEFAULT_VERSIONS=gcc=6

in /etc/make.conf

I get:

MPICH CC:       cc  -O2 -pipe  -fstack-protector -fno-strict-aliasing 
MPICH CXX:      c++  -O2 -pipe -fstack-protector -fno-strict-aliasing 
MPICH F77:      gfortran6  -O -Wl,-rpath=/usr/local/lib/gcc6
MPICH FC:       gfortran6  -Wl,-rpath=/usr/local/lib/gcc6

which seems to be fine for my purposes.
But is DEFAULT_VERSIONS the best solution?

Thanks

Anton