On Fri, Dec 20, 2019 at 06:18:04PM -0500, Jason Merrill wrote: > > BTW, is the testcase valid in C++17 mode? GCC 7/8/9/trunk accept it, > > but clang++ rejects it. > > No, non-template parameters of class types are a C++20 feature.
Trunk accepts it since r276248 aka PR91923 in -std=c++17 mode.
Jakub
