Broken --enable-suppress-external-warning for Apple Clang 15 on x86_64 #29174
Description
Apple Clang 15 does not support -Xclang -internal-isystem anymore. On both x86_64 and arm64 platforms, the following check:
Lines 742 to 744 in 65c05db
fails with
error: unknown argument: '-internal-isystem/usr/local/include'.
It makes the --enable-suppress-external-warnings option not working for dependency packages installed by Homebrew and linked to /usr/local, which happens for all non-keg packages on x86_64. There is no such an effect on arm64.
For a related discussion refer to #29165 (comment).