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 It, class T>
12 // concept output_iterator;
13 
14 #include <iterator>
15 
16 #include <cstddef>
17 #include "test_iterators.h"
18 
19 struct T { };
20 struct DerivedFromT : T { };
21 
22 static_assert( std::output_iterator<cpp17_output_iterator<int*>, int>);
23 static_assert( std::output_iterator<cpp17_output_iterator<int*>, short>);
24 static_assert( std::output_iterator<cpp17_output_iterator<int*>, long>);
25 static_assert( std::output_iterator<cpp17_output_iterator<T*>, T>);
26 static_assert(!std::output_iterator<cpp17_output_iterator<T const*>, T>);
27 static_assert( std::output_iterator<cpp17_output_iterator<T*>, T const>);
28 static_assert( std::output_iterator<cpp17_output_iterator<T*>, DerivedFromT>);
29 static_assert(!std::output_iterator<cpp17_output_iterator<DerivedFromT*>, T>);
30 
31 static_assert( std::output_iterator<cpp20_output_iterator<int*>, int>);
32 static_assert( std::output_iterator<cpp20_output_iterator<int*>, short>);
33 static_assert( std::output_iterator<cpp20_output_iterator<int*>, long>);
34 static_assert( std::output_iterator<cpp20_output_iterator<T*>, T>);
35 static_assert(!std::output_iterator<cpp20_output_iterator<T const*>, T>);
36 static_assert( std::output_iterator<cpp20_output_iterator<T*>, T const>);
37 static_assert( std::output_iterator<cpp20_output_iterator<T*>, DerivedFromT>);
38 static_assert(!std::output_iterator<cpp20_output_iterator<DerivedFromT*>, T>);
39 
40 // Not satisfied when the iterator is not an input_or_output_iterator
41 static_assert(!std::output_iterator<void, int>);
42 static_assert(!std::output_iterator<void (*)(), int>);
43 static_assert(!std::output_iterator<int&, int>);
44 static_assert(!std::output_iterator<T, int>);
45 
46 // Not satisfied when we can't assign a T to the result of *it++
47 struct WrongPostIncrement {
48     using difference_type = std::ptrdiff_t;
49     T const* operator++(int);
50     WrongPostIncrement& operator++();
51     T& operator*();
52 };
53 static_assert( std::input_or_output_iterator<WrongPostIncrement>);
54 static_assert( std::indirectly_writable<WrongPostIncrement, T>);
55 static_assert(!std::output_iterator<WrongPostIncrement, T>);
56 
57 // Not satisfied when we can't assign a T to the result of *it (i.e. not indirectly_writable)
58 struct NotIndirectlyWritable {
59     using difference_type = std::ptrdiff_t;
60     T* operator++(int);
61     NotIndirectlyWritable& operator++();
62     T const& operator*(); // const so we can't write to it
63 };
64 static_assert( std::input_or_output_iterator<NotIndirectlyWritable>);
65 static_assert(!std::indirectly_writable<NotIndirectlyWritable, T>);
66 static_assert(!std::output_iterator<NotIndirectlyWritable, T>);
67