py312-msgpack fails to build with Xcode gcc: error: ‘for’ loop initial declaration used outside C99 mode

[barracuda156]

* Building wheel...
/opt/local/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/site-packages/ptr/__init__.py:81: SetuptoolsDeprecationWarning: The test command is disabled and references to it are deprecated.
!!

        ********************************************************************************
        Please remove any references to `setuptools.command.test` in all supported versions of the affected package.

        By 2024-Nov-15, you need to update your project and remove deprecated calls
        or your builds will no longer be supported.
        ********************************************************************************

!!
  class PyTest(orig.test):
running bdist_wheel
running build
running build_py
creating build/lib.macosx-10.6-ppc-cpython-312/msgpack
copying msgpack/__init__.py -> build/lib.macosx-10.6-ppc-cpython-312/msgpack
copying msgpack/exceptions.py -> build/lib.macosx-10.6-ppc-cpython-312/msgpack
copying msgpack/ext.py -> build/lib.macosx-10.6-ppc-cpython-312/msgpack
copying msgpack/fallback.py -> build/lib.macosx-10.6-ppc-cpython-312/msgpack
running build_ext
INFO: Disabling color, you really want to install colorlog.
Disabling color, you really want to install colorlog.
building 'msgpack._cmsgpack' extension
creating build/temp.macosx-10.6-ppc-cpython-312/msgpack
/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_python_py-msgpack/py312-msgpack/work/compwrap/cc/usr/bin/gcc-4.2 -fno-strict-overflow -Wsign-compare -fno-common -dynamic -DNDEBUG -g -O3 -Wall -pipe -Os -arch ppc -isysroot/ -I. -I/opt/local/Library/Frameworks/Python.framework/Versions/3.12/include/python3.12 -c msgpack/_cmsgpack.c -o build/temp.macosx-10.6-ppc-cpython-312/msgpack/_cmsgpack.o
In file included from msgpack/_cmsgpack.c:1300:
msgpack/unpack.h: In function ‘unpack_callback_array’:
msgpack/unpack.h:141: warning: comparison between signed and unsigned
msgpack/unpack.h: In function ‘unpack_callback_map’:
msgpack/unpack.h:176: warning: comparison between signed and unsigned
msgpack/unpack.h: In function ‘unpack_callback_raw’:
msgpack/unpack.h:234: warning: comparison between signed and unsigned
msgpack/unpack.h: In function ‘unpack_callback_bin’:
msgpack/unpack.h:254: warning: comparison between signed and unsigned
In file included from msgpack/_cmsgpack.c:1300:
msgpack/unpack.h: In function ‘unpack_callback_ext’:
msgpack/unpack.h:308: warning: comparison between signed and unsigned
In file included from msgpack/_cmsgpack.c:22596:
/opt/local/Library/Frameworks/Python.framework/Versions/3.12/include/python3.12/internal/pycore_frame.h: In function ‘_PyFrame_Initialize’:
/opt/local/Library/Frameworks/Python.framework/Versions/3.12/include/python3.12/internal/pycore_frame.h:134: error: ‘for’ loop initial declaration used outside C99 mode
error: command '/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_python_py-msgpack/py312-msgpack/work/compwrap/cc/usr/bin/gcc-4.2' failed with exit code 1

ERROR Backend subprocess exited when trying to invoke build_wheel
Command failed:  cd "/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_python_py-msgpack/py312-msgpack/work/msgpack-1.1.0" && /opt/local/Library/Frameworks/Python.framework/Versions/3.12/bin/python3.12 -m build --no-isolation --wheel --outdir /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_python_py-msgpack/py312-msgpack/work 
Exit code: 1
Error: Failed to build py312-msgpack: command execution failed

[Sergey Fedorov <barracuda@…>]

In f65a4c21f7d3b9234de09bf261b65c00a9cc1f73/macports-ports (master):

py-msgpack: fix build on legacy systems

Closes: #71250