libstdc++-v3/testsuite/20_util/function/cons/deduction_c++23.cc

   1 // { dg-do compile { target c++23 } }
   2 // { dg-require-effective-target hosted }
   3
   4 #include <functional>
   5
   6 template<typename T, typename U> struct require_same;
   7 template<typename T> struct require_same<T, T> { using type = void; };
   8
   9 template<typename T, typename U>
  10   typename require_same<T, U>::type
  11   check_type(U&) { }
  12
  13 void
  14 test_static_call_operator()
  15 {
  16   struct F1 { static long operator()() { return 0; } };
  17   std::function func1 = F1{};
  18   check_type<std::function<long()>>(func1);
  19
  20   struct F2 { static float operator()(char, void*) noexcept { return 0; } };
  21   std::function func2 = F2{};
  22   check_type<std::function<float(char, void*)>>(func2);
  23 }
  24
  25 void
  26 test_explicit_object_call_operator()
  27 {
  28   // LWG 3617 - function/packaged_task deduction guides and deducing this
  29   struct F {
  30     int operator()(this const F&) { return 42; }
  31   };
  32
  33   std::function g = F{};
  34   check_type<std::function<int()>>(g);
  35
  36   struct F2 {
  37     short operator()(this F2&, float&) { return 0; }
  38   };
  39
  40   std::function g2 = F2{};
  41   check_type<std::function<short(float&)>>(g2);
  42
  43   struct F3 {
  44     void operator()(this const F3, char*, long) { }
  45   };
  46
  47   std::function g3 = F3{};
  48   check_type<std::function<void(char*, long)>>(g3);
  49
  50   struct F4 {
  51     int i;
  52     operator const int&() const { return i; }
  53     const long& operator()(this int, const long& l) { return l; }
  54   };
  55
  56   std::function g4 = F4{};
  57   check_type<std::function<const long&(const long&)>>(g4);
  58 }