xref: /llvm-project/libcxx/test/std/iterators/iterator.primitives/iterator.traits/empty.pass.cpp (revision 9f01ac3b3257ab925a2b1229dba19e3eb86a706b)
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 // template<class NotAnIterator>
12 // struct iterator_traits
13 // {
14 // };
15 
16 #include <iterator>
17 
18 #include "test_macros.h"
19 
20 struct not_an_iterator
21 {
22 };
23 
24 template <class T>
25 struct has_value_type
26 {
27 private:
28     struct two {char lx; char lxx;};
29     template <class U> static two test(...);
30     template <class U> static char test(typename U::value_type* = 0);
31 public:
32     static const bool value = sizeof(test<T>(0)) == 1;
33 };
34 
main(int,char **)35 int main(int, char**)
36 {
37     typedef std::iterator_traits<not_an_iterator> It;
38     static_assert(!(has_value_type<It>::value), "");
39 
40     return 0;
41 }
42