lang/gcc1[34] do not build on Darwin when lang/libunwind is installed

[Brook Milligan <brook%nmsu.edu@localhost>]

The lang/gcc13 and lang/gcc14 (perhaps others) will not build on Darwin (at least with 24 + Xcode 16, but I believe earlier as well) when the lang/libunwind package is installed.  This seems to be because gcc picks the wrong libunwind, which results in undefined references to _Unwind_Ptr.  Does anyone else see this?

Here is one of various discussions about this: https://trac.macports.org/ticket/70326.

It is also a known issue and MacPorts has declared a conflict, at least for gcc14: https://github.com/macports/macports-ports/blob/ee065f7787c786aa421c184690d6e365b6bec58b/lang/gcc14/Portfile#L332

Should pkgsrc also declare that gcc1[34] conflict with libunwind?

One note I came across (but cannot find again) suggested that the order of include file search differs with Apple clang when -sysroot is used versus when it is not, and that might be responsible.  Is there a way to replace -sysroot with some combination of -I and -L (or otherwise) so I can test this hypothesis?  It would be nice to figure out how to build gcc when libunwind is installed (the opposite is fine), but I’m not seeing solutions out there.

Any suggestions are greatly appreciated.

Thanks a lot.

Cheers,
Brook