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 #include <limits> 24 25 #include "test_macros.h" 26 27 // Ignore warning about std::numeric_limits comparisons being tautological. 28 TEST_GCC_DIAGNOSTIC_IGNORED("-Wtype-limits") 29 30 struct short_container { 31 uint16_t size() const { return 60000; } // not noexcept 32 }; 33 34 template<typename C> 35 void test_container(C& c) 36 { 37 // Can't say noexcept here because the container might not be 38 static_assert( std::is_signed_v<decltype(std::ssize(c))>, ""); 39 assert ( std::ssize(c) == static_cast<decltype(std::ssize(c))>(c.size())); 40 } 41 42 template<typename C> 43 void test_const_container(const C& c) 44 { 45 // Can't say noexcept here because the container might not be 46 static_assert( std::is_signed_v<decltype(std::ssize(c))>, ""); 47 assert ( std::ssize(c) == static_cast<decltype(std::ssize(c))>(c.size())); 48 } 49 50 template<typename T> 51 void test_const_container(const std::initializer_list<T>& c) 52 { 53 LIBCPP_ASSERT_NOEXCEPT(std::ssize(c)); // our std::ssize is conditionally noexcept 54 static_assert( std::is_signed_v<decltype(std::ssize(c))>, ""); 55 assert ( std::ssize(c) == static_cast<decltype(std::ssize(c))>(c.size())); 56 } 57 58 template<typename T> 59 void test_container(std::initializer_list<T>& c) 60 { 61 LIBCPP_ASSERT_NOEXCEPT(std::ssize(c)); // our std::ssize is conditionally noexcept 62 static_assert( std::is_signed_v<decltype(std::ssize(c))>, ""); 63 assert ( std::ssize(c) == static_cast<decltype(std::ssize(c))>(c.size())); 64 } 65 66 template<typename T, size_t Sz> 67 void test_const_array(const T (&array)[Sz]) 68 { 69 ASSERT_NOEXCEPT(std::ssize(array)); 70 static_assert( std::is_signed_v<decltype(std::ssize(array))>, ""); 71 assert ( std::ssize(array) == Sz ); 72 } 73 74 int main(int, char**) 75 { 76 std::vector<int> v; v.push_back(1); 77 std::list<int> l; l.push_back(2); 78 std::array<int, 1> a; a[0] = 3; 79 std::initializer_list<int> il = { 4 }; 80 using SSize = std::common_type_t<std::ptrdiff_t, std::make_signed_t<std::size_t>>; 81 test_container ( v ); 82 ASSERT_SAME_TYPE(SSize, decltype(std::ssize(v))); 83 test_container ( l ); 84 ASSERT_SAME_TYPE(SSize, decltype(std::ssize(l))); 85 test_container ( a ); 86 ASSERT_SAME_TYPE(SSize, decltype(std::ssize(a))); 87 test_container ( il ); 88 ASSERT_SAME_TYPE(SSize, 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(SSize, 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