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 // All of these became constexpr in C++17
12 //
13 // template <InputIterator Iter, class Distance>
14 // constexpr void advance(Iter& i, Distance n);
15 //
16 // template <BidirectionalIterator Iter, class Distance>
17 // constexpr void advance(Iter& i, Distance n);
18 //
19 // template <RandomAccessIterator Iter, class Distance>
20 // constexpr void advance(Iter& i, Distance n);
21
22
23 // TODO: test_iterators.h includes <ranges>, and <ranges> includes <chrono> and <atomic>.
24 // Lots of implementation headers under <__chrono/> and <atomic> has signed to unsigned conversion,
25 // which will trigger the -Wsign-conversion warning.
26 // Once those headers are fixed, enable the -Wsign-conversion for this test by removing
27 // <TODO:Remove brackets> below
28
29 // Make sure we catch forced conversions to the difference_type if they happen.
30 // ADDITIONAL_COMPILE_FLAGS<TODO:Remove brackets>(gcc-style-warnings): -Wsign-conversion
31
32 #include <iterator>
33 #include <cassert>
34 #include <cstddef>
35 #include <type_traits>
36
37 #include "test_macros.h"
38 #include "test_iterators.h"
39
40 template <class Distance, class It>
41 TEST_CONSTEXPR_CXX17
check_advance(It it,Distance n,It result)42 void check_advance(It it, Distance n, It result)
43 {
44 static_assert(std::is_same<decltype(std::advance(it, n)), void>::value, "");
45 std::advance(it, n);
46 assert(it == result);
47 }
48
tests()49 TEST_CONSTEXPR_CXX17 bool tests()
50 {
51 const char* s = "1234567890";
52
53 // Check with iterator_traits::difference_type
54 {
55 typedef std::iterator_traits<const char*>::difference_type Distance;
56 check_advance<Distance>(cpp17_input_iterator<const char*>(s), 10, cpp17_input_iterator<const char*>(s+10));
57 check_advance<Distance>(forward_iterator<const char*>(s), 10, forward_iterator<const char*>(s+10));
58 check_advance<Distance>(bidirectional_iterator<const char*>(s+5), 5, bidirectional_iterator<const char*>(s+10));
59 check_advance<Distance>(bidirectional_iterator<const char*>(s+5), -5, bidirectional_iterator<const char*>(s));
60 check_advance<Distance>(random_access_iterator<const char*>(s+5), 5, random_access_iterator<const char*>(s+10));
61 check_advance<Distance>(random_access_iterator<const char*>(s+5), -5, random_access_iterator<const char*>(s));
62 check_advance<Distance>(s+5, 5, s+10);
63 check_advance<Distance>(s+5, -5, s);
64 }
65
66 // Also check with other distance types
67 {
68 typedef int Distance;
69 check_advance<Distance>(cpp17_input_iterator<const char*>(s), 10, cpp17_input_iterator<const char*>(s+10));
70 check_advance<Distance>(forward_iterator<const char*>(s), 10, forward_iterator<const char*>(s+10));
71 check_advance<Distance>(bidirectional_iterator<const char*>(s), 10, bidirectional_iterator<const char*>(s+10));
72 check_advance<Distance>(random_access_iterator<const char*>(s), 10, random_access_iterator<const char*>(s+10));
73 }
74
75 // Check with unsigned distance types to catch signedness-change issues
76 {
77 typedef std::size_t Distance;
78 check_advance<Distance>(cpp17_input_iterator<const char*>(s), 10u, cpp17_input_iterator<const char*>(s+10));
79 check_advance<Distance>(forward_iterator<const char*>(s), 10u, forward_iterator<const char*>(s+10));
80 check_advance<Distance>(bidirectional_iterator<const char*>(s), 10u, bidirectional_iterator<const char*>(s+10));
81 check_advance<Distance>(random_access_iterator<const char*>(s), 10u, random_access_iterator<const char*>(s+10));
82 }
83
84 return true;
85 }
86
main(int,char **)87 int main(int, char**)
88 {
89 tests();
90 #if TEST_STD_VER >= 17
91 static_assert(tests(), "");
92 #endif
93 return 0;
94 }
95