Straighten out the libunwind confusion -- PR 27319

[Ken Cunningham]

> > As of 10.7, libunwind was rolled into libSystem.
> 
> No, Apple started providing it in 10.6 - see the headers and libSystem.
> 

Maybe, I will check -- but I do know the libunwind from the libunwind port is needed for some current ports to build on 10.6 and not on 10.7+

exact details as to why, etc, etc, were mentioned by Jeremy at some point, buried in one of the 60,000 tickets.

> It should be in a different directory that can be accessed by opt-in.

It is already now available in said directory in the newer clang ports, eg clang-19 has it here (from the PR commit):

For interest:
a current libunwind is currently installed as part of the clang builds, eg.:
% port contents clang-19 | grep libunwind
/opt/local/libexec/llvm-19/include/__libunwind_config.h
/opt/local/libexec/llvm-19/include/libunwind.h
/opt/local/libexec/llvm-19/include/libunwind.modulemap
/opt/local/libexec/llvm-19/lib/libunwind/libunwind.1.0.dylib
/opt/local/libexec/llvm-19/lib/libunwind/libunwind.1.dylib
/opt/local/libexec/llvm-19/lib/libunwind/libunwind.a
/opt/local/libexec/llvm-19/lib/libunwind/libunwind.dylib
if testing a newer libunwind is desired on new systems, one can be found there.


However -- my take is forget about it, don't encourage it's use at all, and adapt ports to use libSystem on MacOS as they should.