> __CYGWIN__ is defined for gcc; gcc -v should report 'cygwin special'.
> I do not recommend changing the environment to __CYGMING__ to match
> in a further attempt at humour.
>
> If you want people to use the information you provide rationally, do
> not colour that information with irrational attempts at humour to
> provide misinformation that causes doubt.
>
> We need to trust the output of gcc -v.
No, this is completely wrong and absolutely not what you want to do. The
output of "gcc -v" is a human-readable summary of various internal information
which can be obtained by more reliable means for programmatic use. Your
attempt to indirectly deduce the same info from a freeform text string
presupposes many assumptions that simply do not hold, and therefore is doomed
to incorrectness.