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 I2, class S2>
12 // requires convertible_to<const I2&, I> && convertible_to<const S2&, S>
13 // constexpr common_iterator(const common_iterator<I2, S2>& x);
14
15 #include <cassert>
16 #include <iterator>
17 #include <type_traits>
18
test()19 constexpr bool test()
20 {
21 struct Base {};
22 struct Derived : Base {};
23
24 using BaseIt = std::common_iterator<Base*, const Base*>;
25 using DerivedIt = std::common_iterator<Derived*, const Derived*>;
26 static_assert(std::is_convertible_v<DerivedIt, BaseIt>); // Derived* to Base*
27 static_assert(!std::is_constructible_v<DerivedIt, BaseIt>); // Base* to Derived*
28
29 Derived a[10] = {};
30 DerivedIt it = DerivedIt(a); // the iterator type
31 BaseIt jt = BaseIt(it);
32 assert(jt == BaseIt(a));
33
34 it = DerivedIt((const Derived*)a); // the sentinel type
35 jt = BaseIt(it);
36 assert(jt == BaseIt(a));
37
38 return true;
39 }
40
main(int,char **)41 int main(int, char**) {
42 test();
43 static_assert(test());
44
45 return 0;
46 }
47