How to reliable detect a MacPorts-ported compiler?

[Jeffrey Walton]

>> For Apple, we can detect Apple ported gear with:
>>
>>  $ clang++ -dM -E - < /dev/null | grep -i apple
>>  #define __APPLE_CC__ 6000
>>  #define __APPLE__ 1
>>  #define __VERSION__ "4.2.1 Compatible Apple LLVM 5.1 (clang-503.0.40)"
>>  #define __apple_build_version__ 5030040
>
> Well, that's clang, not gcc.

Right, but the APPLE_CC tells me its an Apple port.

>> What strings or bits is MacPorts providing?
>
> If you want to know if gcc is FSF GCC compiled by MacPOrts, you could inspect the version string:
>
> $ gcc-mp-6 --version
> gcc-mp-6 (MacPorts gcc6 6-20150830_0+universal) 6.0.0 20150830 (experimental)
> Copyright (C) 2015 Free Software Foundation, Inc.
> This is free software; see the source for copying conditions.  There is NO
> warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
>
> Note that this includes the string "MacPorts".

OK, thanks.

Jeff