problem compiling libzzip (PPC, Sorbet Leopard)

[Hangglider]

Hello,

somewhere in the dependencies for some package I have to compile
libzzip. That's less easy than it sounds:

The libzzip package seems to enforce gcc-4.2 (there's /usr/bin/gcc-4.0
and /opt/local/bin/ppc-apple-darwin9-gcc-7.5.0 == /opt/local/bin/gcc
too) and tries to use it with -Warray-bounds. gcc-4.2 doesn't have that,
but gcc7 does. Adding -DCMAKE_C_COMPILER=/opt/local/bin/gcc to the
portfile didn't do the job. so some questions arise:

Is there a well known way to enforce a given compiler?

Would/should I have to replace or remove one of the system's (Xcode's)
compiler(s) to clean things up a bit?

Should I upgrade Xcode, and to which version (PPC32, Sorbet Leopard)?

Thanks in advance for helpful responses.

HG