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 // UNSUPPORTED: libcpp-has-no-incomplete-ranges
11 
12 // friend constexpr iterator operator+(iterator i, difference_type n)
13 //   requires advanceable<W>;
14 // friend constexpr iterator operator+(difference_type n, iterator i)
15 //   requires advanceable<W>;
16 
17 #include <ranges>
18 #include <cassert>
19 
20 #include "test_macros.h"
21 #include "../types.h"
22 
23 constexpr bool test() {
24   // When "_Start" is signed integer like.
25   {
26     std::ranges::iota_view<int> io(0);
27     auto iter1 = io.begin();
28     auto iter2 = io.begin();
29     assert(iter1 == iter2);
30     assert(iter1 + 5 != iter2);
31     assert(iter1 + 5 == std::ranges::next(iter2, 5));
32 
33     static_assert(std::is_reference_v<decltype(iter2 += 5)>);
34   }
35 
36   // When "_Start" is not integer like.
37   {
38     std::ranges::iota_view io(SomeInt(0));
39     auto iter1 = io.begin();
40     auto iter2 = io.begin();
41     assert(iter1 == iter2);
42     assert(iter1 + 5 != iter2);
43     assert(iter1 + 5 == std::ranges::next(iter2, 5));
44 
45     static_assert(std::is_reference_v<decltype(iter2 += 5)>);
46   }
47 
48   // When "_Start" is unsigned integer like and n is greater than or equal to zero.
49   {
50     std::ranges::iota_view<unsigned> io(0);
51     auto iter1 = io.begin();
52     auto iter2 = io.begin();
53     assert(iter1 == iter2);
54     assert(iter1 + 5 != iter2);
55     assert(iter1 + 5 == std::ranges::next(iter2, 5));
56 
57     static_assert(std::is_reference_v<decltype(iter2 += 5)>);
58   }
59   {
60     std::ranges::iota_view<unsigned> io(0);
61     auto iter1 = io.begin();
62     auto iter2 = io.begin();
63     assert(iter1 == iter2);
64     assert(iter1 + 0 == iter2);
65   }
66 
67   // When "_Start" is unsigned integer like and n is less than zero.
68   {
69     std::ranges::iota_view<unsigned> io(0);
70     auto iter1 = io.begin();
71     auto iter2 = io.begin();
72     assert(iter1 == iter2);
73     assert(iter1 + 5 != iter2);
74     assert(iter1 + 5 == std::ranges::next(iter2, 5));
75 
76     static_assert(std::is_reference_v<decltype(iter2 += 5)>);
77   }
78 
79   return true;
80 }
81 
82 int main(int, char**) {
83   test();
84   static_assert(test());
85 
86   return 0;
87 }
88