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 // <optional>
10 // UNSUPPORTED: c++03, c++11, c++14
11 // UNSUPPORTED: clang-5
12 // UNSUPPORTED: libcpp-no-deduction-guides
13 // Clang 5 will generate bad implicit deduction guides
14 // Specifically, for the copy constructor.
15
16
17 // template<class T>
18 // optional(T) -> optional<T>;
19
20
21 #include <optional>
22 #include <cassert>
23
24 struct A {};
25
main(int,char **)26 int main(int, char**)
27 {
28 // Test the explicit deduction guides
29
30 // Test the implicit deduction guides
31 {
32 // optional()
33 std::optional opt; // expected-error-re {{{{declaration of variable 'opt' with deduced type 'std::optional' requires an initializer|no viable constructor or deduction guide for deduction of template arguments of 'optional'}}}}
34 // clang-6 gives a bogus error here:
35 // declaration of variable 'opt' with deduced type 'std::optional' requires an initializer
36 // clang-7 (and later) give a better message:
37 // no viable constructor or deduction guide for deduction of template arguments of 'optional'
38 // So we check for one or the other.
39 }
40
41 {
42 // optional(nullopt_t)
43 std::optional opt(std::nullopt); // expected-error-re@optional:* {{static_assert failed{{.*}} "instantiation of optional with nullopt_t is ill-formed"}}
44 }
45
46 return 0;
47 }
48