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// REQUIRES: c++11
10
11// <utility>
12
13// Test that only the default constructor is constexpr in C++11
14
15#include <utility>
16#include <cassert>
17
18struct ExplicitT {
19 constexpr explicit ExplicitT(int x) : value(x) {}
20 constexpr explicit ExplicitT(ExplicitT const& o) : value(o.value) {}
21 int value;
22};
23
24struct ImplicitT {
25 constexpr ImplicitT(int x) : value(x) {}
26 constexpr ImplicitT(ImplicitT const& o) : value(o.value) {}
27 int value;
28};
29
30void f() {
31 {
32 using P = std::pair<int, int>;
33 constexpr int x = 42;
34 constexpr P default_p{};
35 constexpr P copy_p(default_p);
36 constexpr P const_U_V(x, x); // expected-error {{must be initialized by a constant expression}}
37 constexpr P U_V(42, 101); // expected-error {{must be initialized by a constant expression}}
38 }
39 {
40 using P = std::pair<ExplicitT, ExplicitT>;
41 constexpr std::pair<int, int> other;
42 constexpr ExplicitT e(99);
43 constexpr P const_U_V(e, e); // expected-error {{must be initialized by a constant expression}}
44 constexpr P U_V(42, 101); // expected-error {{must be initialized by a constant expression}}
45 constexpr P pair_U_V(other); // expected-error {{must be initialized by a constant expression}}
46 }
47 {
48 using P = std::pair<ImplicitT, ImplicitT>;
49 constexpr std::pair<int, int> other;
50 constexpr ImplicitT i = 99;
51 constexpr P const_U_V = {i, i}; // expected-error {{must be initialized by a constant expression}}
52 constexpr P U_V = {42, 101}; // expected-error {{must be initialized by a constant expression}}
53 constexpr P pair_U_V = other; // expected-error {{must be initialized by a constant expression}}
54 }
55}
56

source code of libcxx/test/std/utilities/utility/pairs/pairs.pair/ctor.not_constexpr_cxx11.verify.cpp