1*67c608a9SSaar Raz // RUN: %clang_cc1 -std=c++2a -x c++ %s -verify 2a0f50d73SSaar Raz 3a0f50d73SSaar Raz // Examples from standard 4a0f50d73SSaar Raz 5a0f50d73SSaar Raz template<typename T, typename U> 6a0f50d73SSaar Raz concept convertible_to = requires(T t) { U(t); }; 7a0f50d73SSaar Raz 8a0f50d73SSaar Raz template<typename T> 9a0f50d73SSaar Raz concept R = requires (T i) { 10a0f50d73SSaar Raz typename T::type; 11a0f50d73SSaar Raz {*i} -> convertible_to<const typename T::type&>; 12a0f50d73SSaar Raz }; 13a0f50d73SSaar Raz 14a0f50d73SSaar Raz template<typename T> requires R<T> struct S {}; 15a0f50d73SSaar Raz 16a0f50d73SSaar Raz struct T { 17a0f50d73SSaar Raz using type = int; 18a0f50d73SSaar Raz type i; operator *T19a0f50d73SSaar Raz const type &operator*() { return i; } 20a0f50d73SSaar Raz }; 21a0f50d73SSaar Raz 22a0f50d73SSaar Raz using si = S<T>; 23a0f50d73SSaar Raz 24a0f50d73SSaar Raz template<typename T> 25a0f50d73SSaar Raz requires requires (T x) { x + x; } // expected-note{{because 'x + x' would be invalid: invalid operands to binary expression ('T' and 'T')}} add(T a,T b)26a0f50d73SSaar RazT add(T a, T b) { return a + b; } // expected-note{{candidate template ignored: constraints not satisfied [with T = T]}} 27a0f50d73SSaar Raz 28a0f50d73SSaar Raz int x = add(1, 2); 29a0f50d73SSaar Raz int y = add(T{}, T{}); // expected-error{{no matching function for call to 'add'}} 30a0f50d73SSaar Raz 31a0f50d73SSaar Raz template<typename T> 32a0f50d73SSaar Raz concept C = requires (T x) { x + x; }; // expected-note{{because 'x + x' would be invalid: invalid operands to binary expression ('T' and 'T')}} 33a0f50d73SSaar Raz template<typename T> requires C<T> // expected-note{{because 'T' does not satisfy 'C'}} add2(T a,T b)34a0f50d73SSaar RazT add2(T a, T b) { return a + b; } // expected-note{{candidate template ignored: constraints not satisfied [with T = T]}} 35a0f50d73SSaar Raz 36a0f50d73SSaar Raz int z = add2(1, 2); 37a0f50d73SSaar Raz int w = add2(T{}, T{}); // expected-error{{no matching function for call to 'add2'}}