gcc version mismatches

[Kyle Husmann]

> Ok. What solution are you advocating?

Sorry, I don't have any solutions at the moment. Frankly this is out
of my expertise. I like your idea to mix and match the fsf fortran
compiler with the osx toolchain though.

Still, it would be nice to give the user the option to maintain an
entire macports ecosystem all compiled with the fsf gcc, instead of
having to manually add the configure.compiler line to all the
installs. I realize this probably creates a bunch of issues of its own
though.

> It sounds like you're saying we should never mix Apple gcc compilers with fsf gcc compilers. Some very small number of ports require a newer gcc than Apple provides, hence the fsf gcc is the only option. What should we do in that case: force the user to rebuild all ports?

>From my understanding, yes, this would be the only way to go.

> Is it only Apple gcc that's a problem? If so, does that mean the problem is already resolved when using Xcode 4 on Lion and Snow Leopard, where the default compiler is not gcc, but Apple llvm-gcc or Apple clang (depending on Xcode version)?

I'm not familiar with llvm-gcc here so I can't answer this.

> Is Apple clang vs. plain clang also a problem?

No idea, but since C is much simpler of a language, I would probably
guess it was OK.