https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91277
Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Target Milestone|--- |10.0 Resolution|--- |FIXED Keywords| |ice-on-invalid-code Status|NEW |RESOLVED --- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Fixed in GCC 10+ <source>:6:30: error: placeholder type not allowed in this context 6 | concept Ohh = requires(T t, Test<typename T::type> sth){ | ^~~~~~~~~~~~~~~~~~~~~~ <source>: In function 'int main(int, char**)': <source>:25:5: error: 'cout' was not declared in this scope 25 | cout << B<A<int>>::value; | ^~~~