> If you have established you have gcc, you might as well use #ident, so
> you don't have to "fool" the compiler at all...

An excellent suggestion, with just one flaw (I think):

if I remember correctly, an ANSI compiler is entitled to choke on

#ifdef __GNUC__
#ident fkfdlkkljfds
#else
...
#endif

because the text in the false branch still has to be legal C preprocessor
material, and the Standard doesn't guarantee that #UNRECOGNIZED is harmless.
(Someone please correct me if the Standard says differently.)