libheif - no vailable compiler on Leopard

[rmottola (Riccardo)]

On leopard PPC libheif refuses to build:

--->  Configuring libheif
Error: Failed to configure libheif: Invalid value for configure.compiler:

no compiler is shown

[kencu (Ken)]

we are ready for full testing of the PR to upgrade leopard and tiger to gcc14, if you're game for that.

might also help solve some of these issues.

[rmottola (Riccardo)]

forcing gcc7 yields:

-- Performing Test has_potentially_evaluated_expression
CMake Error in /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_multimedia_libheif/libheif/work/build/CMakeFiles/CMakeScratch/TryCompile-MwG9yJ/CMakeLists.txt:
  Target "cmTC_2501c" requires the language dialect "CXX20" .  But the
  current compiler "GNU" does not support this, or CMake does not know the
  flags to enable it.

so yes, we need a newer c++ compiler. AFAIK, the minimum version would be gcc8, one of the compiler I proposed to have in the list. At the end I don't know if this needs all up to gcc14 to get gcc8, I lost a bit in the discussion @kencu. Latest I have now is 7.

gcc8 is known to fail. Try to install anyway? [y/N]

[kencu (Ken)]

the PR is ready for testing. Please help

the new compiler list will be gcc14, gcc10, then gcc7 etc as now

[Christopher Nielsen <mascguy@…>]

In 12a7fefb64dd7374f95bfd9e1850dd20918c67d0/macports-ports (master):

libheif: add fallback for 10.5 and earlier

Fixes: #71420