MaskRay wrote: You might want to test two configurations to ensure that -rtlib= -stdlib= -unwindlib= defaults do not make the new test fail. * default * -DCLANG_DEFAULT_RTLIB=compiler-rt -DCLANG_DEFAULT_UNWINDLIB=libunwind -DCLANG_DEFAULT_CXX_STDLIB=libc++ https://github.com/llvm/llvm-project/pull/139271