1 //===----------------------------------------------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 // <functional> 10 11 // placeholders 12 // The placeholders are constexpr in C++17 and beyond. 13 // libc++ provides constexpr placeholders in C++11 and beyond. 14 15 #include <functional> 16 #include <type_traits> 17 18 #include "test_macros.h" 19 20 template <class T> 21 void test(const T & t)22test(const T& t) 23 { 24 // Test default constructible. 25 T t2; 26 ((void)t2); 27 // Test copy constructible. 28 T t3 = t; 29 ((void)t3); 30 static_assert(std::is_nothrow_copy_constructible<T>::value, ""); 31 static_assert(std::is_nothrow_move_constructible<T>::value, ""); 32 } 33 34 #if TEST_STD_VER >= 11 35 constexpr decltype(std::placeholders::_1) default1{}; 36 constexpr decltype(std::placeholders::_2) default2{}; 37 constexpr decltype(std::placeholders::_3) default3{}; 38 constexpr decltype(std::placeholders::_4) default4{}; 39 constexpr decltype(std::placeholders::_5) default5{}; 40 constexpr decltype(std::placeholders::_6) default6{}; 41 constexpr decltype(std::placeholders::_7) default7{}; 42 constexpr decltype(std::placeholders::_8) default8{}; 43 constexpr decltype(std::placeholders::_9) default9{}; 44 constexpr decltype(std::placeholders::_10) default10{}; 45 46 constexpr decltype(std::placeholders::_1) cp1 = std::placeholders::_1; 47 constexpr decltype(std::placeholders::_2) cp2 = std::placeholders::_2; 48 constexpr decltype(std::placeholders::_3) cp3 = std::placeholders::_3; 49 constexpr decltype(std::placeholders::_4) cp4 = std::placeholders::_4; 50 constexpr decltype(std::placeholders::_5) cp5 = std::placeholders::_5; 51 constexpr decltype(std::placeholders::_6) cp6 = std::placeholders::_6; 52 constexpr decltype(std::placeholders::_7) cp7 = std::placeholders::_7; 53 constexpr decltype(std::placeholders::_8) cp8 = std::placeholders::_8; 54 constexpr decltype(std::placeholders::_9) cp9 = std::placeholders::_9; 55 constexpr decltype(std::placeholders::_10) cp10 = std::placeholders::_10; 56 #endif // TEST_STD_VER >= 11 57 use_placeholders_to_prevent_unused_warning()58void use_placeholders_to_prevent_unused_warning() { 59 #if TEST_STD_VER >= 11 60 ((void)cp1); 61 ((void)cp2); 62 ((void)cp3); 63 ((void)cp4); 64 ((void)cp5); 65 ((void)cp6); 66 ((void)cp7); 67 ((void)cp8); 68 ((void)cp9); 69 ((void)cp10); 70 ((void)default1); 71 ((void)default2); 72 ((void)default3); 73 ((void)default4); 74 ((void)default5); 75 ((void)default6); 76 ((void)default7); 77 ((void)default8); 78 ((void)default9); 79 ((void)default10); 80 #endif 81 } 82 main(int,char **)83int main(int, char**) 84 { 85 use_placeholders_to_prevent_unused_warning(); 86 test(std::placeholders::_1); 87 test(std::placeholders::_2); 88 test(std::placeholders::_3); 89 test(std::placeholders::_4); 90 test(std::placeholders::_5); 91 test(std::placeholders::_6); 92 test(std::placeholders::_7); 93 test(std::placeholders::_8); 94 test(std::placeholders::_9); 95 test(std::placeholders::_10); 96 97 return 0; 98 } 99