https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85282
--- Comment #5 from Rustam Abdullaev <rustamabd at gmail dot com> --- (In reply to Jonathan Wakely from comment #3) > https://wg21.link/cwg727 > > N.B. this is a C++17 feature that does not seem to have been approved as a > DR, but Clang supports it in all language modes. > CWG 727 says "Adopted at the February/March, 2017 meeting", and [temp.class.spec]/5 in ISO/IEC 14882:2017(E) is reflecting the new wording. So this is in C++17. The defect is on GCC side.
