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       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             : 
      41             : extern "C++" {
      42             : 
      43             : namespace __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             : 
      80             : namespace 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        1570 :     const char* name() const _GLIBCXX_NOEXCEPT
     100        1570 :     { 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           0 :     bool operator==(const type_info& __arg) const _GLIBCXX_NOEXCEPT
     121             :     {
     122           0 :       return ((__name == __arg.__name)
     123           0 :               || (__name[0] != '*' &&
     124           0 :                   __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