weak_result.pass.cpp (3179B)
1 //===----------------------------------------------------------------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is dual licensed under the MIT and the University of Illinois Open 6 // Source Licenses. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 10 // <functional> 11 12 // reference_wrapper 13 14 // has weak result type 15 16 #include <functional> 17 #include <type_traits> 18 19 template <class Arg, class Result> 20 struct my_unary_function 21 { // std::unary_function was removed in C++17 22 typedef Arg argument_type; 23 typedef Result result_type; 24 }; 25 26 template <class Arg1, class Arg2, class Result> 27 struct my_binary_function 28 { // std::binary_function was removed in C++17 29 typedef Arg1 first_argument_type; 30 typedef Arg2 second_argument_type; 31 typedef Result result_type; 32 }; 33 34 class functor1 35 : public my_unary_function<int, char> 36 { 37 }; 38 39 class functor2 40 : public my_binary_function<char, int, double> 41 { 42 }; 43 44 class functor3 45 : public my_unary_function<char, int>, 46 public my_binary_function<char, int, double> 47 { 48 public: 49 typedef float result_type; 50 }; 51 52 class functor4 53 : public my_unary_function<char, int>, 54 public my_binary_function<char, int, double> 55 { 56 public: 57 }; 58 59 class C {}; 60 61 template <class T> 62 struct has_result_type 63 { 64 private: 65 struct two {char _; char __;}; 66 template <class U> static two test(...); 67 template <class U> static char test(typename U::result_type* = 0); 68 public: 69 static const bool value = sizeof(test<T>(0)) == 1; 70 }; 71 72 int main() 73 { 74 static_assert((std::is_same<std::reference_wrapper<functor1>::result_type, 75 char>::value), ""); 76 static_assert((std::is_same<std::reference_wrapper<functor2>::result_type, 77 double>::value), ""); 78 static_assert((std::is_same<std::reference_wrapper<functor3>::result_type, 79 float>::value), ""); 80 static_assert((std::is_same<std::reference_wrapper<void()>::result_type, 81 void>::value), ""); 82 static_assert((std::is_same<std::reference_wrapper<int*(double*)>::result_type, 83 int*>::value), ""); 84 static_assert((std::is_same<std::reference_wrapper<void(*)()>::result_type, 85 void>::value), ""); 86 static_assert((std::is_same<std::reference_wrapper<int*(*)(double*)>::result_type, 87 int*>::value), ""); 88 static_assert((std::is_same<std::reference_wrapper<int*(C::*)(double*)>::result_type, 89 int*>::value), ""); 90 static_assert((std::is_same<std::reference_wrapper<int (C::*)(double*) const volatile>::result_type, 91 int>::value), ""); 92 static_assert((std::is_same<std::reference_wrapper<C()>::result_type, 93 C>::value), ""); 94 static_assert(has_result_type<std::reference_wrapper<functor3> >::value, ""); 95 static_assert(!has_result_type<std::reference_wrapper<functor4> >::value, ""); 96 static_assert(!has_result_type<std::reference_wrapper<C> >::value, ""); 97 }