1 // { dg-do run } 2 // { dg-options "-std=c++17 -fconcepts" } 3 4 #include <cassert> 5 6 template<typename T> C()7 concept bool C() { return __is_class(T); } 8 9 template<typename T> D()10 concept bool D() { return C<T>() && __is_empty(T); } 11 12 struct X { } x; 13 struct Y { int n; } y; 14 15 int called = 0; 16 17 template<typename T> 18 struct S { fS19 void f() { called = 0; } // #1 fS20 void f() requires C<T>() { called = 0; } // #2 21 gS22 void g() requires C<T>() { } // #1 gS23 void g() requires D<T>() { } // #2 24 }; 25 f()26template<> void S<int>::f() { called = 1; } // Spec of #1 f()27template<> void S<X>::f() { called = 2; } // Spec of #2 28 g()29template<> void S<X>::g() { called = 3; } // Spec of #2 g()30template<> void S<Y>::g() { called = 4; } // Spec of #1 31 main()32int main() { 33 S<double> sd; 34 S<int> si; 35 S<X> sx; 36 S<Y> sy; 37 38 sd.f(); 39 assert(called == 0); 40 si.f(); 41 assert(called == 1); 42 sx.f(); 43 assert(called == 2); 44 sy.f(); 45 assert(called == 0); 46 47 sx.g(); 48 assert(called == 3); 49 sy.g(); 50 assert(called == 4); 51 } 52