1 // { dg-options "-std=c++17 -fconcepts" }
4 concept bool C() { return __is_class(T); }
7 concept bool D() { return C<T>() and __is_empty(T); }
9 template<template<typename Q> requires C<Q>() class X>
12 // An unconstrained template can be used as an argument for any
13 // constrained template template parameter.
14 template<typename A> struct T0 { };
17 // Matching constraints are valid.
18 template<typename A> requires C<A>() struct T1 { };