+/* Copyright (C) 2012-2019 Free Software Foundation, Inc.
+
+ This program 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 of the License, or
+ (at your option) any later version.
+
+ This program 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 program. If not, see <http://www.gnu.org/licenses/>. */
+
#include "config.h"
-#if defined(__GNUC__) && !defined(C_ALLOCA)
-# ifndef alloca
-# define alloca __builtin_alloca
-# endif
-#else /* ! defined (__GNUC__) */
-# ifdef _AIX
- #pragma alloca
+/* This is a merge of code recommended in the autoconf-2.61 documentation
+ with that recommended in the autoconf-2.13 documentation, with added
+ tweaks to heed C_ALLOCA. */
+
+#if defined HAVE_ALLOCA_H && !defined C_ALLOCA
+# include <alloca.h>
+#else
+# if defined __GNUC__ && !defined C_ALLOCA
+# if !defined alloca
+# define alloca __builtin_alloca
+# endif
+# else
+# if defined _AIX
+/* Indented so that pre-ansi C compilers will ignore it, rather than
+ choke on it. Some versions of AIX require this to be the first
+ thing seen by the compiler except for comments and preprocessor
+ directives. */
+ #pragma alloca
# else
-# if defined(HAVE_ALLOCA_H) && !defined(C_ALLOCA)
-# include <alloca.h>
-# else /* ! defined (HAVE_ALLOCA_H) */
-# ifdef __STDC__
-extern PTR alloca (size_t);
-# else /* ! defined (__STDC__) */
-extern PTR alloca ();
-# endif /* ! defined (__STDC__) */
-# endif /* ! defined (HAVE_ALLOCA_H) */
-# ifdef _WIN32
-# include <malloc.h>
+# if defined _MSC_VER && !defined C_ALLOCA
+# include <malloc.h>
+# define alloca _alloca
+# else
+# if !defined alloca
+# if defined __STDC__ || defined __hpux
+# if defined HAVE_STDDEF_H
+# include <stddef.h>
+# if defined __cplusplus
+extern "C" void *alloca (size_t);
+# else
+extern void *alloca (size_t);
+# endif
+# else
+extern void *alloca ();
+# endif
+# else
+extern char *alloca ();
+# endif
+# endif
+# endif
# endif
-# endif /* ! defined (_AIX) */
-#endif /* ! defined (__GNUC__) */
+# endif
+#endif