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 // UNSUPPORTED: c++03, c++11, c++14 10 11 // <optional> 12 13 // template<class T> 14 // optional(T) -> optional<T>; 15 16 #include <optional> 17 #include <cassert> 18 19 struct A {}; 20 21 int main(int, char**) 22 { 23 // Test the explicit deduction guides 24 25 // Test the implicit deduction guides 26 { 27 // optional() 28 std::optional opt; // expected-error {{no viable constructor or deduction guide for deduction of template arguments of 'optional'}} 29 } 30 31 { 32 // optional(nullopt_t) 33 std::optional opt(std::nullopt); // expected-error-re@optional:* {{static_assert failed{{.*}} "instantiation of optional with nullopt_t is ill-formed"}} 34 } 35 36 return 0; 37 } 38