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 // <iterator>
12 // template <class C> constexpr auto ssize(const C& c)
13 // -> common_type_t<ptrdiff_t, make_signed_t<decltype(c.size())>>; // C++20
14 // template <class T, ptrdiff_t> constexpr ptrdiff_t ssize(const T (&array)[N]) noexcept; // C++20
15
16 #include <iterator>
17 #include <cassert>
18 #include <vector>
19 #include <array>
20 #include <list>
21 #include <initializer_list>
22 #include <string_view>
23
24 #include "test_macros.h"
25
26 // Ignore warning about std::numeric_limits comparisons being tautological.
27 #ifdef __GNUC__
28 #pragma GCC diagnostic ignored "-Wtype-limits"
29 #endif
30
31 struct short_container {
sizeshort_container32 uint16_t size() const { return 60000; } // not noexcept
33 };
34
35 template<typename C>
test_container(C & c)36 void test_container(C& c)
37 {
38 // Can't say noexcept here because the container might not be
39 static_assert( std::is_signed_v<decltype(std::ssize(c))>, "");
40 assert ( std::ssize(c) == static_cast<decltype(std::ssize(c))>(c.size()));
41 }
42
43 template<typename C>
test_const_container(const C & c)44 void test_const_container(const C& c)
45 {
46 // Can't say noexcept here because the container might not be
47 static_assert( std::is_signed_v<decltype(std::ssize(c))>, "");
48 assert ( std::ssize(c) == static_cast<decltype(std::ssize(c))>(c.size()));
49 }
50
51 template<typename T>
test_const_container(const std::initializer_list<T> & c)52 void test_const_container(const std::initializer_list<T>& c)
53 {
54 LIBCPP_ASSERT_NOEXCEPT(std::ssize(c)); // our std::ssize is conditionally noexcept
55 static_assert( std::is_signed_v<decltype(std::ssize(c))>, "");
56 assert ( std::ssize(c) == static_cast<decltype(std::ssize(c))>(c.size()));
57 }
58
59 template<typename T>
test_container(std::initializer_list<T> & c)60 void test_container(std::initializer_list<T>& c)
61 {
62 LIBCPP_ASSERT_NOEXCEPT(std::ssize(c)); // our std::ssize is conditionally noexcept
63 static_assert( std::is_signed_v<decltype(std::ssize(c))>, "");
64 assert ( std::ssize(c) == static_cast<decltype(std::ssize(c))>(c.size()));
65 }
66
67 template<typename T, size_t Sz>
test_const_array(const T (& array)[Sz])68 void test_const_array(const T (&array)[Sz])
69 {
70 ASSERT_NOEXCEPT(std::ssize(array));
71 static_assert( std::is_signed_v<decltype(std::ssize(array))>, "");
72 assert ( std::ssize(array) == Sz );
73 }
74
main(int,char **)75 int main(int, char**)
76 {
77 std::vector<int> v; v.push_back(1);
78 std::list<int> l; l.push_back(2);
79 std::array<int, 1> a; a[0] = 3;
80 std::initializer_list<int> il = { 4 };
81 test_container ( v );
82 ASSERT_SAME_TYPE(ptrdiff_t, decltype(std::ssize(v)));
83 test_container ( l );
84 ASSERT_SAME_TYPE(ptrdiff_t, decltype(std::ssize(l)));
85 test_container ( a );
86 ASSERT_SAME_TYPE(ptrdiff_t, decltype(std::ssize(a)));
87 test_container ( il );
88 ASSERT_SAME_TYPE(ptrdiff_t, decltype(std::ssize(il)));
89
90 test_const_container ( v );
91 test_const_container ( l );
92 test_const_container ( a );
93 test_const_container ( il );
94
95 std::string_view sv{"ABC"};
96 test_container ( sv );
97 ASSERT_SAME_TYPE(ptrdiff_t, decltype(std::ssize(sv)));
98 test_const_container ( sv );
99
100 static constexpr int arrA [] { 1, 2, 3 };
101 ASSERT_SAME_TYPE(ptrdiff_t, decltype(std::ssize(arrA)));
102 static_assert( std::is_signed_v<decltype(std::ssize(arrA))>, "");
103 test_const_array ( arrA );
104
105 // From P1227R2:
106 // Note that the code does not just return the std::make_signed variant of
107 // the container's size() method, because it's conceivable that a container
108 // might choose to represent its size as a uint16_t, supporting up to
109 // 65,535 elements, and it would be a disaster for std::ssize() to turn a
110 // size of 60,000 into a size of -5,536.
111
112 short_container sc;
113 // is the return type signed? Is it big enough to hold 60K?
114 // is the "signed version" of sc.size() too small?
115 static_assert( std::is_signed_v< decltype(std::ssize(sc))>, "");
116 static_assert( std::numeric_limits< decltype(std::ssize(sc))>::max() > 60000, "");
117 static_assert( std::numeric_limits<std::make_signed_t<decltype(std:: size(sc))>>::max() < 60000, "");
118 assert (std::ssize(sc) == 60000);
119 LIBCPP_ASSERT_NOT_NOEXCEPT(std::ssize(sc));
120
121 return 0;
122 }
123