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 // UNSUPPORTED: c++98, c++03, c++11, c++14 11 // <optional> 12 13 // struct nullopt_t{see below}; 14 // inline constexpr nullopt_t nullopt(unspecified); 15 16 // [optional.nullopt]/2: 17 // Type nullopt_t shall not have a default constructor or an initializer-list 18 // constructor, and shall not be an aggregate. 19 20 #include <optional> 21 #include <type_traits> 22 23 using std::nullopt_t; 24 using std::nullopt; 25 26 constexpr bool test() 27 { 28 nullopt_t foo{nullopt}; 29 (void)foo; 30 return true; 31 } 32 33 int main() 34 { 35 static_assert(std::is_empty_v<nullopt_t>); 36 static_assert(!std::is_default_constructible_v<nullopt_t>); 37 38 static_assert(std::is_same_v<const nullopt_t, decltype(nullopt)>); 39 static_assert(test()); 40 } 41
