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The C and C++ Include Header Files
/usr/include/c++/13/typeinfo
$ cat -n /usr/include/c++/13/typeinfo 1 // RTTI support for -*- C++ -*- 2 // Copyright (C) 1994-2023 Free Software Foundation, Inc. 3 // 4 // This file is part of GCC. 5 // 6 // GCC is free software; you can redistribute it and/or modify 7 // it under the terms of the GNU General Public License as published by 8 // the Free Software Foundation; either version 3, or (at your option) 9 // any later version. 10 // 11 // GCC is distributed in the hope that it will be useful, 12 // but WITHOUT ANY WARRANTY; without even the implied warranty of 13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 // GNU General Public License for more details. 15 // 16 // Under Section 7 of GPL version 3, you are granted additional 17 // permissions described in the GCC Runtime Library Exception, version 18 // 3.1, as published by the Free Software Foundation. 19 20 // You should have received a copy of the GNU General Public License and 21 // a copy of the GCC Runtime Library Exception along with this program; 22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 // <http://www.gnu.org/licenses/>. 24 25 /** @file typeinfo 26 * This is a Standard C++ Library header. 27 */ 28 29 #ifndef _TYPEINFO 30 #define _TYPEINFO 31 32 #pragma GCC system_header 33 34 #include <bits/exception.h> 35 #if __cplusplus >= 201103L 36 #include <bits/hash_bytes.h> 37 #endif 38 39 #pragma GCC visibility push(default) 40 41 #if __cplusplus >= 202100L 42 # define __cpp_lib_constexpr_typeinfo 202106L 43 #endif 44 45 extern "C++" { 46 47 namespace __cxxabiv1 48 { 49 class __class_type_info; 50 } // namespace __cxxabiv1 51 52 // Determine whether typeinfo names for the same type are merged (in which 53 // case comparison can just compare pointers) or not (in which case strings 54 // must be compared), and whether comparison is to be implemented inline or 55 // not. We used to do inline pointer comparison by default if weak symbols 56 // are available, but even with weak symbols sometimes names are not merged 57 // when objects are loaded with RTLD_LOCAL, so now we always use strcmp by 58 // default. For ABI compatibility, we do the strcmp inline if weak symbols 59 // are available, and out-of-line if not. Out-of-line pointer comparison 60 // is used where the object files are to be portable to multiple systems, 61 // some of which may not be able to use pointer comparison, but the 62 // particular system for which libstdc++ is being built can use pointer 63 // comparison; in particular for most ARM EABI systems, where the ABI 64 // specifies out-of-line comparison. The compiler's target configuration 65 // can override the defaults by defining __GXX_TYPEINFO_EQUALITY_INLINE to 66 // 1 or 0 to indicate whether or not comparison is inline, and 67 // __GXX_MERGED_TYPEINFO_NAMES to 1 or 0 to indicate whether or not pointer 68 // comparison can be used. 69 70 #ifndef __GXX_MERGED_TYPEINFO_NAMES 71 // By default, typeinfo names are not merged. 72 #define __GXX_MERGED_TYPEINFO_NAMES 0 73 #endif 74 75 // By default follow the old inline rules to avoid ABI changes. 76 #ifndef __GXX_TYPEINFO_EQUALITY_INLINE 77 # if !__GXX_WEAK__ 78 # define __GXX_TYPEINFO_EQUALITY_INLINE 0 79 # else 80 # define __GXX_TYPEINFO_EQUALITY_INLINE 1 81 # endif 82 #endif 83 84 namespace std 85 { 86 /** 87 * @brief Part of RTTI. 88 * 89 * The @c type_info class describes type information generated by 90 * an implementation. 91 */ 92 class type_info 93 { 94 public: 95 /** Destructor first. Being the first non-inline virtual function, this 96 * controls in which translation unit the vtable is emitted. The 97 * compiler makes use of that information to know where to emit 98 * the runtime-mandated type_info structures in the new-abi. */ 99 virtual ~type_info(); 100 101 /** Returns an @e implementation-defined byte string; this is not 102 * portable between compilers! */ 103 const char* name() const _GLIBCXX_NOEXCEPT 104 { return __name[0] == '*' ? __name + 1 : __name; } 105 106 /** Returns true if `*this` precedes `__arg` in the implementation's 107 * collation order. */ 108 bool before(const type_info& __arg) const _GLIBCXX_NOEXCEPT; 109 110 _GLIBCXX23_CONSTEXPR 111 bool operator==(const type_info& __arg) const _GLIBCXX_NOEXCEPT; 112 113 #if __cpp_impl_three_way_comparison < 201907L 114 bool operator!=(const type_info& __arg) const _GLIBCXX_NOEXCEPT 115 { return !operator==(__arg); } 116 #endif 117 118 #if __cplusplus >= 201103L 119 size_t hash_code() const noexcept 120 { 121 # if !__GXX_MERGED_TYPEINFO_NAMES 122 return _Hash_bytes(name(), __builtin_strlen(name()), 123 static_cast<size_t>(0xc70f6907UL)); 124 # else 125 return reinterpret_cast<size_t>(__name); 126 # endif 127 } 128 #endif // C++11 129 130 // Return true if this is a pointer type of some kind 131 virtual bool __is_pointer_p() const; 132 133 // Return true if this is a function type 134 virtual bool __is_function_p() const; 135 136 // Try and catch a thrown type. Store an adjusted pointer to the 137 // caught type in THR_OBJ. If THR_TYPE is not a pointer type, then 138 // THR_OBJ points to the thrown object. If THR_TYPE is a pointer 139 // type, then THR_OBJ is the pointer itself. OUTER indicates the 140 // number of outer pointers, and whether they were const 141 // qualified. 142 virtual bool __do_catch(const type_info *__thr_type, void **__thr_obj, 143 unsigned __outer) const; 144 145 // Internally used during catch matching 146 virtual bool __do_upcast(const __cxxabiv1::__class_type_info *__target, 147 void **__obj_ptr) const; 148 149 protected: 150 const char *__name; 151 152 explicit type_info(const char *__n): __name(__n) { } 153 154 private: 155 // type_info objects cannot be copied. 156 #if __cplusplus >= 201103L 157 type_info& operator=(const type_info&) = delete; 158 type_info(const type_info&) = delete; 159 #else 160 type_info& operator=(const type_info&); 161 type_info(const type_info&); 162 #endif 163 164 #if ! __GXX_TYPEINFO_EQUALITY_INLINE 165 bool __equal(const type_info&) const _GLIBCXX_NOEXCEPT; 166 #endif 167 }; 168 169 #if __GXX_TYPEINFO_EQUALITY_INLINE 170 inline bool 171 type_info::before(const type_info& __arg) const _GLIBCXX_NOEXCEPT 172 { 173 #if !__GXX_MERGED_TYPEINFO_NAMES 174 // Even with the new abi, on systems that support dlopen 175 // we can run into cases where type_info names aren't merged, 176 // so we still need to do string comparison. 177 if (__name[0] != '*' || __arg.__name[0] != '*') 178 return __builtin_strcmp (__name, __arg.__name) < 0; 179 #else 180 // On some targets we can rely on type_info's NTBS being unique, 181 // and therefore address comparisons are sufficient. 182 #endif 183 184 // In old abi, or when weak symbols are not supported, there can 185 // be multiple instances of a type_info object for one 186 // type. Uniqueness must use the __name value, not object address. 187 return __name < __arg.__name; 188 } 189 #endif 190 191 #if __GXX_TYPEINFO_EQUALITY_INLINE || __cplusplus > 202002L 192 _GLIBCXX23_CONSTEXPR inline bool 193 type_info::operator==(const type_info& __arg) const _GLIBCXX_NOEXCEPT 194 { 195 if (std::__is_constant_evaluated()) 196 return this == &__arg; 197 198 if (__name == __arg.__name) 199 return true; 200 201 #if !__GXX_TYPEINFO_EQUALITY_INLINE 202 // ABI requires comparisons to be non-inline. 203 return __equal(__arg); 204 #elif !__GXX_MERGED_TYPEINFO_NAMES 205 // Need to do string comparison. 206 return __name[0] != '*' && __builtin_strcmp (__name, __arg.name()) == 0; 207 #else 208 return false; 209 #endif 210 } 211 # endif 212 213 214 /** 215 * @brief Thrown during incorrect typecasting. 216 * @ingroup exceptions 217 * 218 * If you attempt an invalid @c dynamic_cast expression, an instance of 219 * this class (or something derived from this class) is thrown. */ 220 class bad_cast : public exception 221 { 222 public: 223 bad_cast() _GLIBCXX_USE_NOEXCEPT { } 224 225 // This declaration is not useless: 226 // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118 227 virtual ~bad_cast() _GLIBCXX_USE_NOEXCEPT; 228 229 // See comment in eh_exception.cc. 230 virtual const char* what() const _GLIBCXX_USE_NOEXCEPT; 231 }; 232 233 /** 234 * @brief Thrown when a NULL pointer in a @c typeid expression is used. 235 * @ingroup exceptions 236 */ 237 class bad_typeid : public exception 238 { 239 public: 240 bad_typeid () _GLIBCXX_USE_NOEXCEPT { } 241 242 // This declaration is not useless: 243 // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118 244 virtual ~bad_typeid() _GLIBCXX_USE_NOEXCEPT; 245 246 // See comment in eh_exception.cc. 247 virtual const char* what() const _GLIBCXX_USE_NOEXCEPT; 248 }; 249 } // namespace std 250 251 } // extern "C++" 252 253 #pragma GCC visibility pop 254 255 #endif
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