2 // { dg-options "-std=c++1z" }
5 concept bool Class () { return __is_class(T); }
7 // Allow a requires-expression with no parms.
9 concept bool C = requires { typename T::type; };
11 void f1(auto a) requires Class<decltype(a)>() { }
12 void f2(auto a) requires requires (decltype(a) x) { -x; } { }
16 // Allow non-type template parms as constraints.
17 template<bool B> requires B struct S0; // OK
19 template<int N> requires N struct S1 { }; // { dg-error "does not have type" }
20 template<int N> requires N == 0 struct S2 { }; // OK
22 template<typename T, T X> requires X struct S3 { }; // OK
23 S3<int, 0> s3a; // { dg-error "constraint failure|does not have type" }
24 S3<bool, false> s3b; // { dg-error "constraint failure" }