I have failures in this test because the grep @b gets confused by the clang version including a repository name like this
!1 = !{!"clang version 10.0.0 (git@build-machine:llvm/llvm-monorepo.git fe958c0e8c89ec663c8e551936778e2cbb460154)"}
I considered something like grep -w but my understanding of the manpages was that that isn't super portable. So I think it is easier to make clang not to output that metadata using -fno-ident.