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 // <iterator>
10 
11 // class istream_iterator
12 
13 // istream_iterator(); // constexpr since C++11
14 // C++17 says: If is_trivially_default_constructible_v<T> is true, then this
15 //    constructor is a constexpr constructor.
16 
17 #include <cassert>
18 #include <iterator>
19 #include <string>
20 #include <type_traits>
21 
22 #include "test_macros.h"
23 
24 struct S { S(); }; // not constexpr
25 
26 #if TEST_STD_VER > 14
27 template <typename T, bool isTrivial = std::is_trivially_default_constructible_v<T>>
28 struct test_trivial {
operator ()test_trivial29 void operator ()() const {
30     constexpr std::istream_iterator<T> it;
31     (void)it;
32     }
33 };
34 
35 template <typename T>
36 struct test_trivial<T, false> {
operator ()test_trivial37 void operator ()() const {}
38 };
39 #endif
40 
41 
main(int,char **)42 int main(int, char**) {
43     {
44     typedef std::istream_iterator<int> T;
45     T it;
46     assert(it == T());
47 #if TEST_STD_VER >= 11
48     constexpr T it2;
49     (void)it2;
50 #endif
51     }
52 
53 #if TEST_STD_VER > 14
54     test_trivial<int>()();
55     test_trivial<char>()();
56     test_trivial<double>()();
57     test_trivial<S>()();
58     test_trivial<std::string>()();
59 #endif
60 
61   return 0;
62 }
63