Bugzilla Bug 62561

If you don't have a Fortran 77 compiler present (i.e., $USE did not contain
"f77" when gcc was emerged), emerging lam-mpi will fail upon configure when it
gets to the Fortran part. The line in the ebuild "econf ...
--enable-languages=c,c++,f77" looks like the culprit.

Given that setting USE="f77" _after_ emerging gcc would not make g77 magically
appear, I don't know Portage well enough to know how to fix it myself.

Reproducible: Always
Steps to Reproduce:
1. Ensure that f77 is not part of your USE flags, and that you haven't emerged
ifc or any other Fortran compiler.
2. emerge gcc
3. emerge lam-mpi
Actual Results:  
emerge lam-mpi fails when configure gets to sniffing for a Fortran compiler

Expected Results:  
It should have seen that there was no Fortran compiler and not tried to compile
Fortran support into lam-mpi.

I don't see any attempt to check for this in any of the ebuilds.

Created an attachment (id=45886) [edit]
lam-mpi ebuild with fortran flag

This is an ebuild that extends the existing lam-mpi ebuild, by adding fortran
support if the fortran flag is set (used by gcc as well). 
Builds on my machine like a dream :)

Since I am a complete noob, could somebody please check if this is done
correctly.
Thanks.

Could you please attach it as a patch? It's easier to look at the changes.

Created an attachment (id=45963) [edit]
updated lam-mpi with fortran flag

OK, that's still not a patch, it's the full ebuild. You're on the right track,
although you may also want to `inherit fortran` near the top to pull in the
fortran eclass. That might change your logic with the USE=fortran a bit.

Fixed in 7.1.1