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