Add copyright notice.

(AC_FUNC_STRERROR_R): Always do char* test, so that it gets cached.
Merge changes from latest Autoconf CVS.
Rename ac_cv_func_strerror_r_works to ac_cv_func_strerror_r_char_p,
and rename HAVE_WORKING_STRERROR_R to STRERROR_R_CHAR_P, since
POSIX decided to standardize on the int flavor of strerror_r.

m4/error.m4

@@ -1,4 +1,4 @@
-#serial 3
+#serial 4
 
 dnl FIXME: put these prerequisite-only *.m4 files in a separate
 dnl directory -- otherwise, they'll conflict with existing files.
@@ -6,7 +6,8 @@ dnl directory -- otherwise, they'll conflict with existing files.
 dnl These are the prerequisite macros for GNU's error.c file.
 AC_DEFUN([jm_PREREQ_ERROR],
 [
-  AC_CHECK_FUNCS(strerror strerror_r vprintf doprnt)
+  AC_CHECK_FUNCS(strerror vprintf doprnt)
+  AC_CHECK_DECLS([strerror])
   AC_FUNC_STRERROR_R
   AC_HEADER_STDC
 ])

m4/strerror_r.m4

@@ -1,9 +1,23 @@
-#serial 1002
+#serial 1003
 # Experimental replacement for the function in the latest CVS autoconf.
-# If the compile-test says strerror_r doesn't work, then resort to a
-# `run'-test that works on BeOS and segfaults on DEC Unix.
 # Use with the error.c file in ../lib.
 
+# Copyright 2001 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 2, 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, write to the Free Software Foundation,
+# Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
+
 undefine([AC_FUNC_STRERROR_R])
 
 # AC_FUNC_STRERROR_R
@@ -11,56 +25,35 @@ undefine([AC_FUNC_STRERROR_R])
 AC_DEFUN([AC_FUNC_STRERROR_R],
 [AC_CHECK_DECLS([strerror_r])
 AC_CHECK_FUNCS([strerror_r])
-if test $ac_cv_func_strerror_r = yes; then
-  AC_CHECK_HEADERS(string.h)
-  AC_CACHE_CHECK([for working strerror_r],
-                 ac_cv_func_strerror_r_works,
+AC_CACHE_CHECK([whether strerror_r returns char *],
+               ac_cv_func_strerror_r_char_p,
    [
-    AC_TRY_COMPILE(
-     [
-#       include <stdio.h>
-#       if HAVE_STRING_H
-#        include <string.h>
-#       endif
-     ],
-     [
-       char buf[100];
-       char x = *strerror_r (0, buf, sizeof buf);
-     ],
-     ac_cv_func_strerror_r_works=yes,
-     ac_cv_func_strerror_r_works=no
-    )
-    if test $ac_cv_func_strerror_r_works = no; then
-      # strerror_r seems not to work, but now we have to choose between
+    ac_cv_func_strerror_r_char_p=no
+    if test $ac_cv_have_decl_strerror_r = yes; then
+      AC_COMPILE_IFELSE([AC_LANG_PROGRAM([AC_INCLUDES_DEFAULT],
+	[[
+	  char buf[100];
+	  char x = *strerror_r (0, buf, sizeof buf);
+	  char *p = strerror_r (0, buf, sizeof buf);
+	]])],
+			ac_cv_func_strerror_r_char_p=yes)
+    else
+      # strerror_r is not declared.  Choose between
       # systems that have relatively inaccessible declarations for the
       # function.  BeOS and DEC UNIX 4.0 fall in this category, but the
       # former has a strerror_r that returns char*, while the latter
       # has a strerror_r that returns `int'.
       # This test should segfault on the DEC system.
-      AC_TRY_RUN(
-       [
-#       include <stdio.h>
-#       include <string.h>
-#       include <ctype.h>
-
-	extern char *strerror_r ();
-
-	int
-	main ()
-	{
-	  char buf[100];
+      AC_RUN_IFELSE([AC_LANG_PROGRAM([AC_INCLUDES_DEFAULT
+	extern char *strerror_r ();],
+	[[char buf[100];
 	  char x = *strerror_r (0, buf, sizeof buf);
-	  exit (!isalpha (x));
-	}
-       ],
-       ac_cv_func_strerror_r_works=yes,
-       ac_cv_func_strerror_r_works=no,
-       ac_cv_func_strerror_r_works=no)
+	  exit (!isalpha (x));]])],
+                    ac_cv_func_strerror_r_char_p=yes, , :)
     fi
   ])
-  if test $ac_cv_func_strerror_r_works = yes; then
-    AC_DEFINE(HAVE_WORKING_STRERROR_R, 1,
-      [Define to 1 if `strerror_r' returns a string.])
-  fi
+if test $ac_cv_func_strerror_r_char_p = yes; then
+  AC_DEFINE([STRERROR_R_CHAR_P], 1,
+	    [Define to 1 if strerror_r returns char *.])
 fi
 ])# AC_FUNC_STRERROR_R