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, c++17
10 
11 // template<class T>
12 //     concept default_initializable = constructible_from<T> &&
13 //     requires { T{}; } &&
14 //     is-default-initializable<T>;
15 
16 #include <concepts>
17 #include <cassert>
18 
19 #include "test_macros.h"
20 
21 template<class T>
22 concept brace_initializable = requires { T{}; };
23 
test()24 void test() {
25     // LWG3149
26     // Changed the concept from constructible_from<T>
27     // to constructible_from<T> &&
28     //    requires { T{}; } && is-default-initializable <T>
29     struct S0 { explicit S0() = default; };
30     S0 x0;
31     S0 y0{};
32     static_assert(std::constructible_from<S0>);
33     static_assert(brace_initializable<S0>);
34     LIBCPP_STATIC_ASSERT(std::__default_initializable<S0>);
35     static_assert(std::default_initializable<S0>);
36 
37     struct S1 { S0 x; }; // Note: aggregate
38     S1 x1;
39     S1 y1{}; // expected-error {{chosen constructor is explicit in copy-initialization}}
40     static_assert(std::constructible_from<S1>);
41     static_assert(!brace_initializable<S1>);
42     LIBCPP_STATIC_ASSERT(std::__default_initializable<S1>);
43     static_assert(!std::default_initializable<S1>);
44 
45     const int x2; // expected-error {{default initialization of an object of const type 'const int'}}
46     const int y2{};
47 
48     static_assert(std::constructible_from<const int>);
49     static_assert(brace_initializable<const int>);
50     LIBCPP_STATIC_ASSERT(!std::__default_initializable<const int>);
51     static_assert(!std::default_initializable<const int>);
52 
53     const int x3[1]; // expected-error-re {{default initialization of an object of const type 'const int{{[ ]*}}[1]'}}
54     const int y3[1]{};
55     static_assert(std::constructible_from<const int[1]>);
56     static_assert(brace_initializable<const int[1]>);
57     LIBCPP_STATIC_ASSERT(!std::__default_initializable<const int[1]>);
58     static_assert(!std::default_initializable<const int[1]>);
59 
60     // Zero-length array extension
61     const int x4[]; // expected-error {{definition of variable with array type needs an explicit size or an initializer}}
62     const int y4[]{};
63     static_assert(!std::constructible_from<const int[]>);
64     static_assert(brace_initializable<const int[]>);
65     LIBCPP_STATIC_ASSERT(!std::__default_initializable<const int[]>);
66     static_assert(!std::default_initializable<const int[]>);
67 }
68