1 // I, Howard Hinnant, hereby place this code in the public domain. 2 3 // Test the reference collapsing rules. Note that there are recent differences 4 // for how cv-qualifications are applied to reference types. 7.1.3, 14.3.1 5 6 // { dg-do compile { target c++11 } } 7 8 template <bool> struct sa; 9 template <> struct sa<true> {}; 10 11 template <class T, T v> 12 struct integral_constant 13 { 14 static const T value = v; 15 typedef T value_type; 16 typedef integral_constant<T, v> type; 17 }; 18 19 typedef integral_constant<bool, true> true_type; 20 typedef integral_constant<bool, false> false_type; 21 22 template <class T> struct is_lvalue_reference : public integral_constant<bool, false> {}; 23 template <class T> struct is_lvalue_reference<T&> : public integral_constant<bool, true> {}; 24 25 template <class T> struct is_rvalue_reference : public integral_constant<bool, false> {}; 26 template <class T> struct is_rvalue_reference<T&&> : public integral_constant<bool, true> {}; 27 28 template <class T> struct remove_reference {typedef T type;}; 29 template <class T> struct remove_reference<T&> {typedef T type;}; 30 template <class T> struct remove_reference<T&&> {typedef T type;}; 31 32 template <class T> struct is_const : public integral_constant<bool, false> {}; 33 template <class T> struct is_const<T const> : public integral_constant<bool, true> {}; 34 35 template <class T> struct is_volatile : public integral_constant<bool, false> {}; 36 template <class T> struct is_volatile<T volatile> : public integral_constant<bool, true> {}; 37 38 struct A {}; 39 40 typedef A& Alref; 41 typedef const A& cAlref; 42 typedef volatile A& vAlref; 43 typedef const volatile A& cvAlref; 44 45 typedef A&& Arref; 46 typedef const A&& cArref; 47 typedef volatile A&& vArref; 48 typedef const volatile A&& cvArref; 49 50 template <class T, bool is_lvalue_ref, bool is_rvalue_ref, bool s_const, bool s_volatile> 51 void test() 52 { 53 sa<is_lvalue_reference<T>::value == is_lvalue_ref> t1; 54 sa<is_rvalue_reference<T>::value == is_rvalue_ref> t2; 55 sa<is_const <typename remove_reference<T>::type>::value == s_const> t3; 56 sa<is_volatile<typename remove_reference<T>::type>::value == s_volatile> t4; 57 sa<is_const <typename remove_reference<const T>::type>::value == s_const > t5; 58 sa<is_volatile<typename remove_reference< volatile T>::type>::value == s_volatile> t6; 59 } 60 61 int main() 62 { 63 // sanity check 64 test< A&, true, false, false, false>(); 65 test<const A&, true, false, true, false>(); 66 test< volatile A&, true, false, false, true>(); 67 test<const volatile A&, true, false, true, true>(); 68 test< A&&, false, true, false, false>(); 69 test<const A&&, false, true, true, false>(); 70 test< volatile A&&, false, true, false, true>(); 71 test<const volatile A&&, false, true, true, true>(); 72 73 // lvalue reference test 74 75 // Alref 76 test< Alref&, true, false, false, false>(); 77 test<const Alref&, true, false, false, false>(); 78 test< volatile Alref&, true, false, false, false>(); 79 test<const volatile Alref&, true, false, false, false>(); 80 81 // cAlref 82 test< cAlref&, true, false, true, false>(); 83 test<const cAlref&, true, false, true, false>(); 84 test< volatile cAlref&, true, false, true, false>(); 85 test<const volatile cAlref&, true, false, true, false>(); 86 87 // vAlref 88 test< vAlref&, true, false, false, true>(); 89 test<const vAlref&, true, false, false, true>(); 90 test< volatile vAlref&, true, false, false, true>(); 91 test<const volatile vAlref&, true, false, false, true>(); 92 93 // cvAlref 94 test< cvAlref&, true, false, true, true>(); 95 test<const cvAlref&, true, false, true, true>(); 96 test< volatile cvAlref&, true, false, true, true>(); 97 test<const volatile cvAlref&, true, false, true, true>(); 98 99 // Arref 100 test< Arref&, true, false, false, false>(); 101 test<const Arref&, true, false, false, false>(); 102 test< volatile Arref&, true, false, false, false>(); 103 test<const volatile Arref&, true, false, false, false>(); 104 105 // cArref 106 test< cArref&, true, false, true, false>(); 107 test<const cArref&, true, false, true, false>(); 108 test< volatile cArref&, true, false, true, false>(); 109 test<const volatile cArref&, true, false, true, false>(); 110 111 // vArref 112 test< vArref&, true, false, false, true>(); 113 test<const vArref&, true, false, false, true>(); 114 test< volatile vArref&, true, false, false, true>(); 115 test<const volatile vArref&, true, false, false, true>(); 116 117 // vArref 118 test< cvArref&, true, false, true, true>(); 119 test<const cvArref&, true, false, true, true>(); 120 test< volatile cvArref&, true, false, true, true>(); 121 test<const volatile cvArref&, true, false, true, true>(); 122 123 // rvalue reference test 124 125 // Alref 126 test< Alref&&, true, false, false, false>(); 127 test<const Alref&&, true, false, false, false>(); 128 test< volatile Alref&&, true, false, false, false>(); 129 test<const volatile Alref&&, true, false, false, false>(); 130 131 // cAlref 132 test< cAlref&&, true, false, true, false>(); 133 test<const cAlref&&, true, false, true, false>(); 134 test< volatile cAlref&&, true, false, true, false>(); 135 test<const volatile cAlref&&, true, false, true, false>(); 136 137 // vAlref 138 test< vAlref&&, true, false, false, true>(); 139 test<const vAlref&&, true, false, false, true>(); 140 test< volatile vAlref&&, true, false, false, true>(); 141 test<const volatile vAlref&&, true, false, false, true>(); 142 143 // cvAlref 144 test< cvAlref&&, true, false, true, true>(); 145 test<const cvAlref&&, true, false, true, true>(); 146 test< volatile cvAlref&&, true, false, true, true>(); 147 test<const volatile cvAlref&&, true, false, true, true>(); 148 149 // Arref 150 test< Arref&&, false, true, false, false>(); 151 test<const Arref&&, false, true, false, false>(); 152 test< volatile Arref&&, false, true, false, false>(); 153 test<const volatile Arref&&, false, true, false, false>(); 154 155 // cArref 156 test< cArref&&, false, true, true, false>(); 157 test<const cArref&&, false, true, true, false>(); 158 test< volatile cArref&&, false, true, true, false>(); 159 test<const volatile cArref&&, false, true, true, false>(); 160 161 // vArref 162 test< vArref&&, false, true, false, true>(); 163 test<const vArref&&, false, true, false, true>(); 164 test< volatile vArref&&, false, true, false, true>(); 165 test<const volatile vArref&&, false, true, false, true>(); 166 167 // cvArref 168 test< cvArref&&, false, true, true, true>(); 169 test<const cvArref&&, false, true, true, true>(); 170 test< volatile cvArref&&, false, true, true, true>(); 171 test<const volatile cvArref&&, false, true, true, true>(); 172 173 return 0; 174 } 175