libstdc++-v3/libsupc++/new

   1 // The -*- C++ -*- dynamic memory management header.
   2
   3 // Copyright (C) 1994-2019 Free Software Foundation, Inc.
   4
   5 // This file is part of GCC.
   6 //
   7 // GCC is free software; you can redistribute it and/or modify
   8 // it under the terms of the GNU General Public License as published by
   9 // the Free Software Foundation; either version 3, or (at your option)
  10 // any later version.
  11 //
  12 // GCC is distributed in the hope that it will be useful,
  13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 // GNU General Public License for more details.
  16 //
  17 // Under Section 7 of GPL version 3, you are granted additional
  18 // permissions described in the GCC Runtime Library Exception, version
  19 // 3.1, as published by the Free Software Foundation.
  20
  21 // You should have received a copy of the GNU General Public License and
  22 // a copy of the GCC Runtime Library Exception along with this program;
  23 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  24 // <http://www.gnu.org/licenses/>.
  25
  26 /** @file new
  27  *  This is a Standard C++ Library header.
  28  *
  29  *  The header @c new defines several functions to manage dynamic memory and
  30  *  handling memory allocation errors; see
  31  *  http://gcc.gnu.org/onlinedocs/libstdc++/18_support/howto.html#4 for more.
  32  */
  33
  34 #ifndef _NEW
  35 #define _NEW
  36
  37 #pragma GCC system_header
  38
  39 #include <bits/c++config.h>
  40 #include <exception>
  41
  42 #pragma GCC visibility push(default)
  43
  44 extern "C++" {
  45
  46 namespace std
  47 {
  48   /**
  49    *  @brief  Exception possibly thrown by @c new.
  50    *  @ingroup exceptions
  51    *
  52    *  @c bad_alloc (or classes derived from it) is used to report allocation
  53    *  errors from the throwing forms of @c new.  */
  54   class bad_alloc : public exception
  55   {
  56   public:
  57     bad_alloc() throw() { }
  58
  59 #if __cplusplus >= 201103L
  60     bad_alloc(const bad_alloc&) = default;
  61     bad_alloc& operator=(const bad_alloc&) = default;
  62 #endif
  63
  64     // This declaration is not useless:
  65     // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118
  66     virtual ~bad_alloc() throw();
  67
  68     // See comment in eh_exception.cc.
  69     virtual const char* what() const throw();
  70   };
  71
  72 #if __cplusplus >= 201103L
  73   class bad_array_new_length : public bad_alloc
  74   {
  75   public:
  76     bad_array_new_length() throw() { }
  77
  78     // This declaration is not useless:
  79     // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118
  80     virtual ~bad_array_new_length() throw();
  81
  82     // See comment in eh_exception.cc.
  83     virtual const char* what() const throw();
  84   };
  85 #endif
  86
  87 #if __cpp_aligned_new
  88   enum class align_val_t: size_t {};
  89 #endif
  90
  91   struct nothrow_t
  92   {
  93 #if __cplusplus >= 201103L
  94     explicit nothrow_t() = default;
  95 #endif
  96   };
  97
  98   extern const nothrow_t nothrow;
  99
 100   /** If you write your own error handler to be called by @c new, it must
 101    *  be of this type.  */
 102   typedef void (*new_handler)();
 103
 104   /// Takes a replacement handler as the argument, returns the
 105   /// previous handler.
 106   new_handler set_new_handler(new_handler) throw();
 107
 108 #if __cplusplus >= 201103L
 109   /// Return the current new handler.
 110   new_handler get_new_handler() noexcept;
 111 #endif
 112 } // namespace std
 113
 114 //@{
 115 /** These are replaceable signatures:
 116  *  - normal single new and delete (no arguments, throw @c bad_alloc on error)
 117  *  - normal array new and delete (same)
 118  *  - @c nothrow single new and delete (take a @c nothrow argument, return
 119  *    @c NULL on error)
 120  *  - @c nothrow array new and delete (same)
 121  *
 122  *  Placement new and delete signatures (take a memory address argument,
 123  *  does nothing) may not be replaced by a user's program.
 124 */
 125 _GLIBCXX_NODISCARD void* operator new(std::size_t) _GLIBCXX_THROW (std::bad_alloc)
 126   __attribute__((__externally_visible__));
 127 _GLIBCXX_NODISCARD void* operator new[](std::size_t) _GLIBCXX_THROW (std::bad_alloc)
 128   __attribute__((__externally_visible__));
 129 void operator delete(void*) _GLIBCXX_USE_NOEXCEPT
 130   __attribute__((__externally_visible__));
 131 void operator delete[](void*) _GLIBCXX_USE_NOEXCEPT
 132   __attribute__((__externally_visible__));
 133 #if __cpp_sized_deallocation
 134 void operator delete(void*, std::size_t) _GLIBCXX_USE_NOEXCEPT
 135   __attribute__((__externally_visible__));
 136 void operator delete[](void*, std::size_t) _GLIBCXX_USE_NOEXCEPT
 137   __attribute__((__externally_visible__));
 138 #endif
 139 _GLIBCXX_NODISCARD void* operator new(std::size_t, const std::nothrow_t&) _GLIBCXX_USE_NOEXCEPT
 140   __attribute__((__externally_visible__, __malloc__));
 141 _GLIBCXX_NODISCARD void* operator new[](std::size_t, const std::nothrow_t&) _GLIBCXX_USE_NOEXCEPT
 142   __attribute__((__externally_visible__, __malloc__));
 143 void operator delete(void*, const std::nothrow_t&) _GLIBCXX_USE_NOEXCEPT
 144   __attribute__((__externally_visible__));
 145 void operator delete[](void*, const std::nothrow_t&) _GLIBCXX_USE_NOEXCEPT
 146   __attribute__((__externally_visible__));
 147 #if __cpp_aligned_new
 148 _GLIBCXX_NODISCARD void* operator new(std::size_t, std::align_val_t)
 149   __attribute__((__externally_visible__));
 150 _GLIBCXX_NODISCARD void* operator new(std::size_t, std::align_val_t, const std::nothrow_t&)
 151   _GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__, __malloc__));
 152 void operator delete(void*, std::align_val_t)
 153   _GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__));
 154 void operator delete(void*, std::align_val_t, const std::nothrow_t&)
 155   _GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__));
 156 _GLIBCXX_NODISCARD void* operator new[](std::size_t, std::align_val_t)
 157   __attribute__((__externally_visible__));
 158 _GLIBCXX_NODISCARD void* operator new[](std::size_t, std::align_val_t, const std::nothrow_t&)
 159   _GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__, __malloc__));
 160 void operator delete[](void*, std::align_val_t)
 161   _GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__));
 162 void operator delete[](void*, std::align_val_t, const std::nothrow_t&)
 163   _GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__));
 164 #if __cpp_sized_deallocation
 165 void operator delete(void*, std::size_t, std::align_val_t)
 166   _GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__));
 167 void operator delete[](void*, std::size_t, std::align_val_t)
 168   _GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__));
 169 #endif // __cpp_sized_deallocation
 170 #endif // __cpp_aligned_new
 171
 172 // Default placement versions of operator new.
 173 _GLIBCXX_NODISCARD inline void* operator new(std::size_t, void* __p) _GLIBCXX_USE_NOEXCEPT
 174 { return __p; }
 175 _GLIBCXX_NODISCARD inline void* operator new[](std::size_t, void* __p) _GLIBCXX_USE_NOEXCEPT
 176 { return __p; }
 177
 178 // Default placement versions of operator delete.
 179 inline void operator delete  (void*, void*) _GLIBCXX_USE_NOEXCEPT { }
 180 inline void operator delete[](void*, void*) _GLIBCXX_USE_NOEXCEPT { }
 181 //@}
 182 } // extern "C++"
 183
 184 #if __cplusplus >= 201703L
 185 #ifdef _GLIBCXX_HAVE_BUILTIN_LAUNDER
 186 namespace std
 187 {
 188 #define __cpp_lib_launder 201606
 189   /// Pointer optimization barrier [ptr.launder]
 190   template<typename _Tp>
 191     [[nodiscard]] constexpr _Tp*
 192     launder(_Tp* __p) noexcept
 193     { return __builtin_launder(__p); }
 194
 195   // The program is ill-formed if T is a function type or
 196   // (possibly cv-qualified) void.
 197
 198   template<typename _Ret, typename... _Args _GLIBCXX_NOEXCEPT_PARM>
 199     void launder(_Ret (*)(_Args...) _GLIBCXX_NOEXCEPT_QUAL) = delete;
 200   template<typename _Ret, typename... _Args _GLIBCXX_NOEXCEPT_PARM>
 201     void launder(_Ret (*)(_Args......) _GLIBCXX_NOEXCEPT_QUAL) = delete;
 202
 203   void launder(void*) = delete;
 204   void launder(const void*) = delete;
 205   void launder(volatile void*) = delete;
 206   void launder(const volatile void*) = delete;
 207 }
 208 #endif // _GLIBCXX_HAVE_BUILTIN_LAUNDER
 209 #endif // C++17
 210
 211 #if __cpp_impl_destroying_delete
 212 #define __cpp_lib_destroying_delete 201806L
 213 namespace std
 214 {
 215   struct destroying_delete_t
 216   {
 217     explicit destroying_delete_t() = default;
 218   };
 219   inline constexpr destroying_delete_t destroying_delete{};
 220 }
 221 #endif // destroying delete
 222
 223 #pragma GCC visibility pop
 224
 225 #endif