[Bug libgcc/123976] GCC 15.2.0 (libgcc) does not build on PPC Mac OS X 10.5.8, Leopard, because of missing "md-unwind-def.h"

[vital.had at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123976

--- Comment #131 from Sergey Fedorov <vital.had at gmail dot com> ---
(In reply to Peter Dyballa from comment #129)
> (In reply to Sergey Fedorov from comment #124)
> > (In reply to Peter Dyballa from comment #120)
> > > (In reply to Iain Sandoe from comment #119)
> > 
> > P. S. BTW, if you build outside of *Ports, make sure to set the PATH so that
> > /opt/local/bin is NOT in it. (Alternatively, all ports are deactivated.)
> > Otherwise we are back to the same problem: arbitrary binaries can be picked.
> 
> Sergey, I *have* practically switched off MacPorts, as documented. Only a
> few ports are active, those that are needed to build GCC-16.1. I do not use
> PPC Leopard productively, that would be too dangerous (mostly port is
> fetching software from the internet, other files are files are provided by
> my recent MacBook), so I can spend a few weeks or months in this state. 'ls
> -l /opt/local/bin | wc -l' reports "309", 'ls -l /opt/local/sbin | wc -l'
> gives zero (0). I even activated a set of ports to temporarily have xz to
> outpack the GCC sources and deactivated that set afterwards. Right now these
> ports are active:
> 
> bzip2                          @1.0.8_0 
> cctools                        @949.0.1_3 
> db48                           @4.8.30_5 
> expat                          @2.8.1_0 
> gcc15                          @15.2.0_0 
> gcc_select                     @0.1_10 
> gettext-runtime                @1.0_0 
> gmp                            @6.3.0_0 
> isl                            @0.24_1 
> ld64                           @3_6+ld64_97 
> ld64-97                        @97.17_9+llvm34 
> libedit                        @20251016-3.1_0 
> libffi                         @3.4.8_0 
> libgcc                         @15_0 
> libgcc15                       @15.2.0_0 
> libiconv                       @1.18_0 
> libmacho-headers               @949.0.1_0 
> libmpc                         @1.4.1_0 
> libunwind-headers              @5.0.1_0 
> llvm-3.4                       @3.4.2_17 
> llvm_select                    @2_1 
> llvm_select-3.4                @2_1 
> lz4                            @1.10.0_0 
> mpfr                           @4.2.2_0 
> ncurses                        @6.6_0 
> openssl11                      @1.1.1w_1 
> python2_select                 @0.1_0 
> python27                       @2.7.18_10 
> python_select                  @0.3_10 
> sqlite3                        @3.53.2_0 
> xz                             @5.8.3_0 
> zlib                           @1.3.2_0 
> zstd                           @1.5.7_0 
> 
> Suggest which to forcibly deactivate!

None of these gcc15 ports should be active when you are building gcc15 or
gcc16. Also libunwind-headers must not be there (it is probably used to build
cctools on 10.5, but not needed at runtime, and is actually harmful). I think
libmacho-headers is not needed for anything at runtime and also should be
deactivated. Other ones are probably harmless.

For the record, I stopped using upstream MacPorts on powerpc systems quite a
while ago, since it is both suboptimal and on many instances just broken, so I
cannot guarantee anything with regard to it. But as a general rule, when you
build the primary compiler (or anything really important), it makes sense to
start from `sudo port deactivate active`, and then `sudo port -v -N install
libgcc15`, for example, will only activate/build what is really needed.