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// RUN: %clang_cc1 -std=c++2a -x c++ %s -verify
// Examples from standard
template<typename T, typename U>
concept convertible_to = requires(T t) { U(t); };
template<typename T>
concept R = requires (T i) {
typename T::type;
{*i} -> convertible_to<const typename T::type&>;
};
template<typename T> requires R<T> struct S {};
struct T {
using type = int;
type i;
const type &operator*() { return i; }
};
using si = S<T>;
template<typename T>
requires requires (T x) { x + x; } // expected-note{{because 'x + x' would be invalid: invalid operands to binary expression ('T' and 'T')}}
T add(T a, T b) { return a + b; } // expected-note{{candidate template ignored: constraints not satisfied [with T = T]}}
int x = add(1, 2);
int y = add(T{}, T{}); // expected-error{{no matching function for call to 'add'}}
template<typename T>
concept C = requires (T x) { x + x; }; // expected-note{{because 'x + x' would be invalid: invalid operands to binary expression ('T' and 'T')}}
template<typename T> requires C<T> // expected-note{{because 'T' does not satisfy 'C'}}
T add2(T a, T b) { return a + b; } // expected-note{{candidate template ignored: constraints not satisfied [with T = T]}}
int z = add2(1, 2);
int w = add2(T{}, T{}); // expected-error{{no matching function for call to 'add2'}}
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