py-grpcio: builds fail for 10.9 and earlier: error: invalid argument '-std=c++14' not allowed with 'C'

[mascguy (Christopher Nielsen)]

This appears to be done by the project's build script(s), but only for 10.9 and earlier:

/opt/local/bin/clang-mp-16 -Wno-unused-result -Wsign-compare -Wunreachable-code -fno-common -dynamic -DNDEBUG -g -fwrapv -O3 -Wall
-pipe -I/opt/local/libexec/openssl11/include -Os -arch x86_64 -isysroot/ -D_WIN32_WINNT=1536 -DGRPC_XDS_USER_AGENT_NAME_SUFFIX=\"Python\"
-DGRPC_XDS_USER_AGENT_VERSION_SUFFIX=\"1.48.0\" -DOPENSSL_NO_ASM=1 -DGPR_BACKWARDS_COMPATIBILITY_MODE=1 -DHAVE_CONFIG_H=1
-DGRPC_ENABLE_FORK_SUPPORT=1 "-DPyMODINIT_FUNC=extern \"C\" __attribute__((visibility (\"default\"))) PyObject*"
-DGRPC_POSIX_FORK_ALLOW_PTHREAD_ATFORK=1 -Isrc/python/grpcio -Iinclude -I. -I/opt/local/include -Ithird_party/address_sorting/include
-I/opt/local/include -I/opt/local/include/re2 -I/opt/local/include/openssl -Ithird_party/upb -Isrc/core/ext/upb-generated
-Isrc/core/ext/upbdefs-generated -Ithird_party/xxhash -I/opt/local/include
-I/opt/local/Library/Frameworks/Python.framework/Versions/3.7/include/python3.7m
-c third_party/address_sorting/address_sorting.c
-o python_build/temp.macosx-10.10-x86_64-cpython-37/third_party/address_sorting/address_sorting.o
-std=c++14 -stdlib=libc++ -fvisibility=hidden -fno-wrapv -fno-exceptions -DHAVE_UNISTD_H -pthread

clang: warning: argument unused during compilation: '-stdlib=libc++' [-Wunused-command-line-argument]
error: invalid argument '-std=c++14' not allowed with 'C'

[ryandesign (Ryan Carsten Schmidt)]

Last I checked, Python doesn't support modules written in C++ so it can't pass flags to C and C++ compilers separately, so any module written in C++ is doomed by design.

[mascguy (Christopher Nielsen)]

Duplicate of issue:62208. (With the caveat that the older ticket mentions Cxx11, while the latest version of the port uses Cxx14. Same fundamental issue though.)