https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59673
Cameron <dacamara.cameron at gmail dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |dacamara.cameron at gmail dot com --- Comment #1 from Cameron <dacamara.cameron at gmail dot com> --- I also observe the breakage with gcc10: struct A { class B { }; template <typename> class C { }; }; template <typename T> struct U { template <typename> static constexpr bool tvalue = false; }; template <> template <typename V> constexpr bool U<A::B>::tvalue<A::C<V>> = true; static_assert(U<A::B>::tvalue<A::C<int>>); // fails on gcc10. clang10 compiles successfully.