gcc/libstdc++-v3/libsupc++/exception_defines.h

// -fno-exceptions Support -*- C++ -*-

// Copyright (C) 2001-2017 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 3, 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.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

/** @file bits/exception_defines.h
 *  This is an internal header file, included by other library headers.
 *  Do not attempt to use it directly. @headername{exception}
 */

#ifndef _EXCEPTION_DEFINES_H
#define _EXCEPTION_DEFINES_H 1

#if ! __cpp_exceptions
// Iff -fno-exceptions, transform error handling code to work without it.
# define __try      if (true)
# define __catch(X) if (false)
# define __throw_exception_again
#else
// Else proceed normally.
# define __try      try
# define __catch(X) catch(X)
# define __throw_exception_again throw
#endif

#endif