https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100347
--- Comment #13 from Erik Schnetter <schnetter at gmail dot com> --- The failing GCC 11.1.0 is built by Apple Clang 12.0.5 via Spack. Looking at debug output, I see that Spack inserts a "-march=skylake" command line option. (I was not aware of this before.) It does so by creating a compiler wrapper (called "clang++" as well), which calls the actual compiler and adds this (and some other) flags. I seem to recall having read somewhere that GCC's CPU detection code must be built without any "-march=..." flag.