gcc/libstdc++-v3/include/c_std/bits/std_cstddef.h

// -*- C++ -*- header wrapper.

// Copyright (C) 1997-1999, 2000 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 2, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING.  If not, write to the Free
// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
// USA.

// As a special exception, you may use this file as part of a free software
// library without restriction.  Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License.  This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.

//
// ISO C++ 14882: 18.1  Types
//

#ifndef _CPP_CSTDDEF
#define _CPP_CSTDDEF 1

# ifdef _IN_C_LEGACY_  /* sub-included by a C header */
      // get out of the "legacy"
    } // close extern "C"
  }   // close namespace _C_legacy::
#  undef _IN_C_LEGACY_
#  define _STDDEF_NEED_C_LEGACY_
# endif

namespace _C_legacy {
  extern "C" {
#   define _IN_C_LEGACY_
#   pragma GCC system_header

//#   define __need_ptrdiff_t
//#   define __need_size_t
#   include_next <stddef.h>
  }
} // namespace _C_legacy

#  undef ptrdiff_t  
#  undef size_t  
#  undef wchar_t

namespace std {
  using _C_legacy::ptrdiff_t;
  using _C_legacy::size_t;
} // namespace std
  
# undef _IN_C_LEGACY_

  // Expose global C names, including non-standard ones, but shadow
  // some names and types with the std:: C++ version.
  using std::ptrdiff_t;
  using std::size_t;

  // 3.9.1 Fundamental Types
  // p 5
  // wchar_t is a fundamental type
  // using std::wchar_t;

# ifdef _STDDEF_NEED_C_LEGACY_
  // dive back into the "swamp"
  namespace _C_legacy {
    extern "C" {
#  define _IN_C_LEGACY_
#  undef _STDDEF_NEED_C_LEGACY_
# endif /* _STDDEF_NEED_C_LEGACY_ */

#endif  /*_CPP_CSTDDEF*/