clang/test/SemaTemplate/pr52909.cpp

   1 // RUN: %clang_cc1 -std=c++20 -verify %s
   2 // RUN: %clang_cc1 -std=c++2b -verify %s
   3
   4 namespace PR52905 {
   5 template <class> concept C = true;
   6
   7 struct A {
   8   int begin();
   9   int begin() const;
  10 };
  11
  12 template <class T>
  13 concept Beginable = requires (T t) {
  14   { t.begin } -> C;
  15   // expected-note@-1 {{because 't.begin' would be invalid: reference to non-static member function must be called}}
  16 };
  17
  18 static_assert(Beginable<A>); // expected-error {{static assertion failed}}
  19                              // expected-note@-1 {{does not satisfy 'Beginable'}}
  20 } // namespace PR52905
  21
  22 namespace PR52909a {
  23
  24 template<class> constexpr bool B = true;
  25 template<class T> concept True = B<T>;
  26
  27 template <class T>
  28 int foo(T t) requires requires { // expected-note {{candidate template ignored: constraints not satisfied}}
  29     {t.begin} -> True; // expected-note {{because 't.begin' would be invalid: reference to non-static member function must be called}}
  30 }
  31 {}
  32
  33 struct A { int begin(); };
  34 auto x = foo(A()); // expected-error {{no matching function for call to 'foo'}}
  35
  36 } // namespace PR52909a
  37
  38 namespace PR52909b {
  39
  40 template<class> concept True = true;
  41
  42 template<class T> concept C = requires {
  43     { T::begin } -> True; // expected-note {{because 'T::begin' would be invalid: reference to overloaded function could not be resolved}}
  44 };
  45
  46 struct A {
  47     static void begin(int);
  48     static void begin(double);
  49 };
  50
  51 static_assert(C<A>); // expected-error {{static assertion failed}}
  52   // expected-note@-1 {{because 'A' does not satisfy 'C'}}
  53
  54 } // namespace PR52909b
  55
  56 namespace PR53075 {
  57 template<class> concept True = true;
  58
  59 template<class T> concept C = requires {
  60     { &T::f } -> True; // expected-note {{because '&T::f' would be invalid: reference to overloaded function could not be resolved}}
  61 };
  62
  63 struct S {
  64     int *f();
  65     int *f() const;
  66 };
  67
  68 static_assert(C<S>); // expected-error {{static assertion failed}}
  69   // expected-note@-1 {{because 'S' does not satisfy 'C'}}
  70
  71 } // namespace PR53075