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a0f50d7316
Implement support for C++2a requires-expressions. Re-commit after compilation failure on some platforms due to alignment issues with PointerIntPair. Differential Revision: https://reviews.llvm.org/D50360
46 lines
2.1 KiB
C++
46 lines
2.1 KiB
C++
// RUN: %clang_cc1 -std=c++2a -fconcepts-ts -x c++ %s -verify
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static_assert(requires { requires true; });
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template<typename T> requires requires { requires false; } // expected-note{{because 'false' evaluated to false}}
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struct r1 {};
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using r1i = r1<int>; // expected-error{{constraints not satisfied for class template 'r1' [with T = int]}}
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template<typename T> requires requires { requires sizeof(T) == 0; } // expected-note{{because 'sizeof(int) == 0' (4 == 0) evaluated to false}}
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struct r2 {};
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using r2i = r2<int>; // expected-error{{constraints not satisfied for class template 'r2' [with T = int]}}
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template<typename T> requires requires (T t) { requires sizeof(t) == 0; } // expected-note{{because 'sizeof (t) == 0' (4 == 0) evaluated to false}}
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struct r3 {};
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using r3i = r3<int>; // expected-error{{constraints not satisfied for class template 'r3' [with T = int]}}
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template<typename T>
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struct X {
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template<typename U> requires requires (U u) { requires sizeof(u) == sizeof(T); } // expected-note{{because 'sizeof (u) == sizeof(T)' would be invalid: invalid application of 'sizeof' to an incomplete type 'void'}}
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struct r4 {};
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};
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using r4i = X<void>::r4<int>; // expected-error{{constraints not satisfied for class template 'r4' [with U = int]}}
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// C++ [expr.prim.req.nested] Examples
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namespace std_example {
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template<typename U> concept C1 = sizeof(U) == 1; // expected-note{{because 'sizeof(int) == 1' (4 == 1) evaluated to false}}
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template<typename T> concept D =
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requires (T t) {
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requires C1<decltype (+t)>; // expected-note{{because 'decltype(+t)' (aka 'int') does not satisfy 'C1'}}
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};
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struct T1 { char operator+() { return 'a'; } };
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static_assert(D<T1>);
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template<D T> struct D_check {}; // expected-note{{because 'short' does not satisfy 'D'}}
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using dc1 = D_check<short>; // expected-error{{constraints not satisfied for class template 'D_check' [with T = short]}}
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template<typename T>
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concept C2 = requires (T a) { // expected-note{{'a' declared here}}
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requires sizeof(a) == 4; // OK
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requires a == 0; // expected-error{{constraint variable 'a' cannot be used in an evaluated context}}
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};
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} |