| // { dg-do compile { target c++20 } } | |
| template<typename T> | |
| concept Class = __is_class(T); | |
| template<typename T> | |
| requires Class<T> | |
| using X = T*; | |
| template<typename T> | |
| using Y = X<T>; // { dg-error "constraint" } | |
| template<Class T> using Z = T*; | |
| struct S { }; | |
| X<S> x1; // OK | |
| X<int> x2; // { dg-error "template constraint failure" } | |
| Y<int> y1; // { dg-message "" } | |
| Z<S> z1; // ok |