I ran into this with PyOxidizer. CPython's `configure` needs to be made aware of the current macOS SDK version and filter out symbols not present in the target macOS version. I worked around it by `undef`'ing some entries from the generated `pyconfig.h` file.

macOS's clang does emit some warnings when it sees symbols that shouldn't be used with the current target version. CPython's build system should consider adding -Werror=unguarded-availability-new to CFLAGS to turn these warnings into errors so they are caught at compile time and not run time. But there should be proper filtering of affected symbols first, otherwise people won't be able to build CPython when targeting older macOS versions.