https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80781
--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> --- Firstly, if you have a patch then it should be sent to gcc-patc...@gcc.gnu.org not entered as a feature request in bugzilla. See https://gcc.gnu.org/contribute.html for details on patch submission and other prerequisites. Patch review happens on the mailing list, not in bugzilla. That said, this isn't really ready for review: Obviously this functionality should be enabled via a -stdlib option (as Clang has) rather than using environment variables. And the default should be libstdc++, so you wouldn't need the BUILDING_ITSELF hack to allow bootstrapping. Instead of changing LIBSTDCXX to c++ you should add a different macro for libc++ and libc++abi and leave the existing one alone. LIBSTDCXX is obviously libstdc++. LIBCXX would be for libc++, and LIBCXXABI would be for libc++abi.
