On Sat, 20 Mar 2021, 01:13 Tim Song via Libstdc++, <libstd...@gcc.gnu.org> wrote:
> On Fri, Mar 19, 2021 at 3:13 PM Jonathan Wakely via Libstdc++ > <libstd...@gcc.gnu.org> wrote: > > > > Implement this C++23 feature, as proposed by P1048R1. > > > > This implementation assumes that a C++23 compiler supports concepts > > already. I don't see any point in using preprocessor hacks to detect > > compilers which define __cplusplus to a post-C++20 value but don't > > support concepts yet. > > > > libstdc++-v3/ChangeLog: > > > > * include/std/type_traits (is_scoped_enum): Define. > > * include/std/version (__cpp_lib_is_scoped_enum): Define. > > * testsuite/20_util/is_scoped_enum/value.cc: New test. > > * testsuite/20_util/is_scoped_enum/version.cc: New test. > > > > Tested powerpc64le-linux. Committed to trunk. > > > > Using __underlying_type breaks for incomplete enumeration types. GCC > doesn't have incomplete scoped enums due to > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89025 but unscoped ones > exist: > > enum E { > x = std::is_scoped_enum_v<E> > }; > Thanks, I'll just use int then. Maybe not until Monday though.
