1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
|
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++03, c++11, c++14, c++17
// constexpr iterator& operator--() requires decrementable<W>;
// constexpr iterator operator--(int) requires decrementable<W>;
#include <cassert>
#include <ranges>
#include <type_traits>
#include "test_macros.h"
#include "../types.h"
template<class T>
concept Decrementable =
requires(T i) {
--i;
} ||
requires(T i) {
i--;
};
constexpr bool test() {
{
std::ranges::iota_view<int> io(0);
auto iter1 = std::next(io.begin());
auto iter2 = std::next(io.begin());
assert(iter1 == iter2);
assert(--iter1 != iter2--);
assert(iter1 == iter2);
static_assert(!std::is_reference_v<decltype(iter2--)>);
static_assert( std::is_reference_v<decltype(--iter2)>);
static_assert(std::same_as<std::remove_reference_t<decltype(--iter2)>, decltype(iter2--)>);
}
{
std::ranges::iota_view io(SomeInt(0));
auto iter1 = std::next(io.begin());
auto iter2 = std::next(io.begin());
assert(iter1 == iter2);
assert(--iter1 != iter2--);
assert(iter1 == iter2);
static_assert(!std::is_reference_v<decltype(iter2--)>);
static_assert( std::is_reference_v<decltype(--iter2)>);
static_assert(std::same_as<std::remove_reference_t<decltype(--iter2)>, decltype(iter2--)>);
}
static_assert(!Decrementable<std::ranges::iota_view<NotDecrementable>>);
return true;
}
int main(int, char**) {
test();
static_assert(test());
return 0;
}
|
