1  /* Memory allocation on the stack.
       2  
       3     Copyright (C) 1995, 1999, 2001-2004, 2006-2022 Free Software Foundation,
       4     Inc.
       5  
       6     This file is free software: you can redistribute it and/or modify
       7     it under the terms of the GNU Lesser General Public License as
       8     published by the Free Software Foundation; either version 2.1 of the
       9     License, or (at your option) any later version.
      10  
      11     This file 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 Lesser General Public License for more details.
      15  
      16     You should have received a copy of the GNU Lesser General Public License
      17     along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
      18  
      19  /* Avoid using the symbol _ALLOCA_H here, as Bison assumes _ALLOCA_H
      20     means there is a real alloca function.  */
      21  #ifndef _GL_ALLOCA_H
      22  #define _GL_ALLOCA_H
      23  
      24  /* alloca (N) returns a pointer to N bytes of memory
      25     allocated on the stack, which will last until the function returns.
      26     Use of alloca should be avoided:
      27       - inside arguments of function calls - undefined behaviour,
      28       - in inline functions - the allocation may actually last until the
      29         calling function returns,
      30       - for huge N (say, N >= 65536) - you never know how large (or small)
      31         the stack is, and when the stack cannot fulfill the memory allocation
      32         request, the program just crashes.
      33   */
      34  
      35  #ifndef alloca
      36    /* Some version of mingw have an <alloca.h> that causes trouble when
      37       included after 'alloca' gets defined as a macro.  As a workaround,
      38       include this <alloca.h> first and define 'alloca' as a macro afterwards
      39       if needed.  */
      40  # if defined __GNUC__ && (defined _WIN32 && ! defined __CYGWIN__) && @HAVE_ALLOCA_H@
      41  #  include_next <alloca.h>
      42  # endif
      43  #endif
      44  #ifndef alloca
      45  # if defined __GNUC__ || (__clang_major__ >= 4)
      46  #  define alloca __builtin_alloca
      47  # elif defined _AIX
      48  #  define alloca __alloca
      49  # elif defined _MSC_VER
      50  #  include <malloc.h>
      51  #  define alloca _alloca
      52  # elif defined __DECC && defined __VMS
      53  #  define alloca __ALLOCA
      54  # elif defined __TANDEM && defined _TNS_E_TARGET
      55  #  ifdef  __cplusplus
      56  extern "C"
      57  #  endif
      58  void *_alloca (unsigned short);
      59  #  pragma intrinsic (_alloca)
      60  #  define alloca _alloca
      61  # elif defined __MVS__
      62  #  include <stdlib.h>
      63  # else
      64  #  include <stddef.h>
      65  #  ifdef  __cplusplus
      66  extern "C"
      67  #  endif
      68  void *alloca (size_t);
      69  # endif
      70  #endif
      71  
      72  #endif /* _GL_ALLOCA_H */