1// RTTI support for -*- C++ -*- 2// Copyright (C) 1994-2018 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 41extern "C++" { 42 43namespace __cxxabiv1 44{ 45 class __class_type_info; 46} // namespace __cxxabiv1 47 48// Determine whether typeinfo names for the same type are merged (in which 49// case comparison can just compare pointers) or not (in which case strings 50// must be compared), and whether comparison is to be implemented inline or 51// not. We used to do inline pointer comparison by default if weak symbols 52// are available, but even with weak symbols sometimes names are not merged 53// when objects are loaded with RTLD_LOCAL, so now we always use strcmp by 54// default. For ABI compatibility, we do the strcmp inline if weak symbols 55// are available, and out-of-line if not. Out-of-line pointer comparison 56// is used where the object files are to be portable to multiple systems, 57// some of which may not be able to use pointer comparison, but the 58// particular system for which libstdc++ is being built can use pointer 59// comparison; in particular for most ARM EABI systems, where the ABI 60// specifies out-of-line comparison. The compiler's target configuration 61// can override the defaults by defining __GXX_TYPEINFO_EQUALITY_INLINE to 62// 1 or 0 to indicate whether or not comparison is inline, and 63// __GXX_MERGED_TYPEINFO_NAMES to 1 or 0 to indicate whether or not pointer 64// comparison can be used. 65 66#ifndef __GXX_MERGED_TYPEINFO_NAMES 67// By default, typeinfo names are not merged. 68#define __GXX_MERGED_TYPEINFO_NAMES 0 69#endif 70 71// By default follow the old inline rules to avoid ABI changes. 72#ifndef __GXX_TYPEINFO_EQUALITY_INLINE 73 #if !__GXX_WEAK__ 74 #define __GXX_TYPEINFO_EQUALITY_INLINE 0 75 #else 76 #define __GXX_TYPEINFO_EQUALITY_INLINE 1 77 #endif 78#endif 79 80namespace std 81{ 82 /** 83 * @brief Part of RTTI. 84 * 85 * The @c type_info class describes type information generated by 86 * an implementation. 87 */ 88 class type_info 89 { 90 public: 91 /** Destructor first. Being the first non-inline virtual function, this 92 * controls in which translation unit the vtable is emitted. The 93 * compiler makes use of that information to know where to emit 94 * the runtime-mandated type_info structures in the new-abi. */ 95 virtual ~type_info(); 96 97 /** Returns an @e implementation-defined byte string; this is not 98 * portable between compilers! */ 99 const char* name() const _GLIBCXX_NOEXCEPT 100 { return __name[0] == '*' ? __name + 1 : __name; } 101 102#if !__GXX_TYPEINFO_EQUALITY_INLINE 103 // In old abi, or when weak symbols are not supported, there can 104 // be multiple instances of a type_info object for one 105 // type. Uniqueness must use the _name value, not object address. 106 bool before(const type_info& __arg) const _GLIBCXX_NOEXCEPT; 107 bool operator==(const type_info& __arg) const _GLIBCXX_NOEXCEPT; 108#else 109 #if !__GXX_MERGED_TYPEINFO_NAMES 110 /** Returns true if @c *this precedes @c __arg in the implementation's 111 * collation order. */ 112 // Even with the new abi, on systems that support dlopen 113 // we can run into cases where type_info names aren't merged, 114 // so we still need to do string comparison. 115 bool before(const type_info& __arg) const _GLIBCXX_NOEXCEPT 116 { return (__name[0] == '*' && __arg.__name[0] == '*') 117 ? __name < __arg.__name 118 : __builtin_strcmp (__name, __arg.__name) < 0; } 119 120 bool operator==(const type_info& __arg) const _GLIBCXX_NOEXCEPT 121 { 122 return ((__name == __arg.__name) 123 || (__name[0] != '*' && 124 __builtin_strcmp (__name, __arg.__name) == 0)); 125 } 126 #else 127 // On some targets we can rely on type_info's NTBS being unique, 128 // and therefore address comparisons are sufficient. 129 bool before(const type_info& __arg) const _GLIBCXX_NOEXCEPT 130 { return __name < __arg.__name; } 131 132 bool operator==(const type_info& __arg) const _GLIBCXX_NOEXCEPT 133 { return __name == __arg.__name; } 134 #endif 135#endif 136 bool operator!=(const type_info& __arg) const _GLIBCXX_NOEXCEPT 137 { return !operator==(__arg); } 138 139#if __cplusplus >= 201103L 140 size_t hash_code() const noexcept 141 { 142# if !__GXX_MERGED_TYPEINFO_NAMES 143 return _Hash_bytes(name(), __builtin_strlen(name()), 144 static_cast<size_t>(0xc70f6907UL)); 145# else 146 return reinterpret_cast<size_t>(__name); 147# endif 148 } 149#endif // C++11 150 151 // Return true if this is a pointer type of some kind 152 virtual bool __is_pointer_p() const; 153 154 // Return true if this is a function type 155 virtual bool __is_function_p() const; 156 157 // Try and catch a thrown type. Store an adjusted pointer to the 158 // caught type in THR_OBJ. If THR_TYPE is not a pointer type, then 159 // THR_OBJ points to the thrown object. If THR_TYPE is a pointer 160 // type, then THR_OBJ is the pointer itself. OUTER indicates the 161 // number of outer pointers, and whether they were const 162 // qualified. 163 virtual bool __do_catch(const type_info *__thr_type, void **__thr_obj, 164 unsigned __outer) const; 165 166 // Internally used during catch matching 167 virtual bool __do_upcast(const __cxxabiv1::__class_type_info *__target, 168 void **__obj_ptr) const; 169 170 protected: 171 const char *__name; 172 173 explicit type_info(const char *__n): __name(__n) { } 174 175 private: 176 /// Assigning type_info is not supported. 177 type_info& operator=(const type_info&); 178 type_info(const type_info&); 179 }; 180 181 /** 182 * @brief Thrown during incorrect typecasting. 183 * @ingroup exceptions 184 * 185 * If you attempt an invalid @c dynamic_cast expression, an instance of 186 * this class (or something derived from this class) is thrown. */ 187 class bad_cast : public exception 188 { 189 public: 190 bad_cast() _GLIBCXX_USE_NOEXCEPT { } 191 192 // This declaration is not useless: 193 // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118 194 virtual ~bad_cast() _GLIBCXX_USE_NOEXCEPT; 195 196 // See comment in eh_exception.cc. 197 virtual const char* what() const _GLIBCXX_USE_NOEXCEPT; 198 }; 199 200 /** 201 * @brief Thrown when a NULL pointer in a @c typeid expression is used. 202 * @ingroup exceptions 203 */ 204 class bad_typeid : public exception 205 { 206 public: 207 bad_typeid () _GLIBCXX_USE_NOEXCEPT { } 208 209 // This declaration is not useless: 210 // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118 211 virtual ~bad_typeid() _GLIBCXX_USE_NOEXCEPT; 212 213 // See comment in eh_exception.cc. 214 virtual const char* what() const _GLIBCXX_USE_NOEXCEPT; 215 }; 216} // namespace std 217 218} // extern "C++" 219 220#pragma GCC visibility pop 221 222#endif 223