>From eea496940c993b84ef5139846d891276ef0f3117 Mon Sep 17 00:00:00 2001
From: Bruno Haible <bruno@clisp.org>
Date: Mon, 21 Dec 2020 11:37:04 +0100
Subject: [PATCH 5/6] Port AC_FUNC_OBSTACK fixes from Gnulib.

* lib/autoconf/functions.m4 (AC_FUNC_OBSTACK): Do not assume system-supplied
obstack is size_t safe.
---
 lib/autoconf/functions.m4 | 41 ++++++++++++++++++++++++-----------------
 1 file changed, 24 insertions(+), 17 deletions(-)

diff --git a/lib/autoconf/functions.m4 b/lib/autoconf/functions.m4
index 001a165..c56a71a 100644
--- a/lib/autoconf/functions.m4
+++ b/lib/autoconf/functions.m4
@@ -1444,23 +1444,30 @@ AU_ALIAS([AC_MMAP], [AC_FUNC_MMAP])
 AN_FUNCTION([obstack_init], [AC_FUNC_OBSTACK])
 AN_IDENTIFIER([obstack],    [AC_FUNC_OBSTACK])
 AC_DEFUN([AC_FUNC_OBSTACK],
-[AC_LIBSOURCES([obstack.h, obstack.c])dnl
-AC_CACHE_CHECK([for obstacks], ac_cv_func_obstack,
-[AC_LINK_IFELSE(
-    [AC_LANG_PROGRAM([AC_INCLUDES_DEFAULT
-		      [@%:@include "obstack.h"]],
-		     [[struct obstack mem;
-		       @%:@define obstack_chunk_alloc malloc
-		       @%:@define obstack_chunk_free free
-		       obstack_init (&mem);
-		       obstack_free (&mem, 0);]])],
-		[ac_cv_func_obstack=yes],
-		[ac_cv_func_obstack=no])])
-if test $ac_cv_func_obstack = yes; then
-  AC_DEFINE(HAVE_OBSTACK, 1, [Define to 1 if libc includes obstacks.])
-else
-  AC_LIBOBJ(obstack)
-fi
+[
+  AC_LIBSOURCES([obstack.h, obstack.c])dnl
+  AC_CACHE_CHECK([for obstacks that work with any size object],
+    [ac_cv_func_obstack],
+    [AC_LINK_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include "obstack.h"
+            void *obstack_chunk_alloc (size_t n) { return 0; }
+            void obstack_chunk_free (void *p) { }
+            /* Check that an internal function returns size_t, not int.  */
+            size_t _obstack_memory_used (struct obstack *);
+           ]],
+          [[struct obstack mem;
+            obstack_init (&mem);
+            obstack_free (&mem, 0);
+          ]])],
+       [ac_cv_func_obstack=yes],
+       [ac_cv_func_obstack=no])])
+  if test "$ac_cv_func_obstack" = yes; then
+    AC_DEFINE([HAVE_OBSTACK], [1],
+      [Define to 1 if the system has obstacks that work with any size object.])
+  else
+    AC_LIBOBJ([obstack])
+  fi
 ])# AC_FUNC_OBSTACK
 
 
-- 
2.7.4