https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114049
--- Comment #1 from Iain Sandoe <iains at gcc dot gnu.org> --- /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks/Kernel.framework/Headers should be a symlink to /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks/Kernel.framework/Versions/A/Headers so either that's broken or we're failing to follow a symlink somehow.