--- c.m4.old	2004-12-01 21:51:25.000000000 +0000
+++ c.m4	2004-12-01 22:18:59.000000000 +0000
@@ -483,7 +483,7 @@
 _AC_LANG_COMPILER_GNU
 GCC=`test $ac_compiler_gnu = yes && echo yes`
 _AC_PROG_CC_G
-_AC_PROG_CC_STDC
+_AC_PROG_CC_C89
 # Some people use a C++ compiler to compile C.  Since we use `exit',
 # in C++ we need to declare it.  In case someone uses the same compiler
 # for both compiling C and C++ we need to have the C++ compiler decide
@@ -785,17 +785,17 @@
 # 4b. C compiler characteristics.  #
 # -------------------------------- #
 
-# _AC_PROG_CC_STDC
-# ----------------
-# If the C compiler in not in ANSI C mode by default, try to add an
-# option to output variable @code{CC} to make it so.  This macro tries
-# various options that select ANSI C on some system or another.  It
-# considers the compiler to be in ANSI C mode if it handles function
-# prototypes correctly.
-AC_DEFUN([_AC_PROG_CC_STDC],
-[AC_MSG_CHECKING([for $CC option to accept ANSI C])
-AC_CACHE_VAL(ac_cv_prog_cc_stdc,
-[ac_cv_prog_cc_stdc=no
+# _AC_PROG_CC_C89 ([ACTION-IF-AVAILABLE], [ACTION-IF-UNAVAILABLE])
+# ----------------------------------------------------------------
+# If the C compiler in not in ANSI C89 (ISO C90) mode by default, try
+# to add an option to output variable @code{CC} to make it so.  This
+# macro tries various options that select ANSI C89 on some system or
+# another.  It considers the compiler to be in ANSI C89 mode if it
+# handles function prototypes correctly.
+AC_DEFUN([_AC_PROG_CC_C89],
+[AC_MSG_CHECKING([for $CC option to accept ANSI C89 C])
+AC_CACHE_VAL(ac_cv_prog_cc_c89,
+[ac_cv_prog_cc_c89=no
 ac_save_CC=$CC
 AC_LANG_CONFTEST([AC_LANG_PROGRAM(
 [[#include <stdarg.h>
@@ -848,26 +848,109 @@
 do
   CC="$ac_save_CC $ac_arg"
   _AC_COMPILE_IFELSE([],
-		     [ac_cv_prog_cc_stdc=$ac_arg
+		     [ac_cv_prog_cc_c89=$ac_arg
 break])
 done
 rm -f conftest.$ac_ext conftest.$ac_objext
 CC=$ac_save_CC
 ])
-case "x$ac_cv_prog_cc_stdc" in
-  x|xno)
-    AC_MSG_RESULT([none needed]) ;;
+case "x$ac_cv_prog_cc_c89" in
+  xno)
+    AC_MSG_RESULT([unsupported])
+    $2 ;;
   *)
-    AC_MSG_RESULT([$ac_cv_prog_cc_stdc])
-    CC="$CC $ac_cv_prog_cc_stdc" ;;
+    if test "x$ac_cv_prog_cc_c89" = x; then
+      AC_MSG_RESULT([none needed])
+    else
+      AC_MSG_RESULT([$ac_cv_prog_cc_c89])
+      CC="$CC $ac_cv_prog_cc_c89"
+    fi
+    $1 ;;
 esac
-])# _AC_PROG_CC_STDC
+])# _AC_PROG_CC_C89
 
 
-# AC_PROG_CC_STDC
-# ---------------
-# Has been merged into AC_PROG_CC.
-AU_DEFUN([AC_PROG_CC_STDC], [])
+# _AC_PROG_CC_C99 ([ACTION-IF-AVAILABLE], [ACTION-IF-UNAVAILABLE])
+# ----------------------------------------------------------------
+# If the C compiler in not in ISO C99 C mode by default, try to add an
+# option to output variable @code{CC} to make it so.  This macro tries
+# various options that select ISO C99 C on some system or another.  It
+# considers the compiler to be in ISO C99 C mode if it handles mixed
+# code and declarations, _Bool, inline and restrict.
+AC_DEFUN([_AC_PROG_CC_C99],
+[AC_MSG_CHECKING([for $CC option to accept ISO C99 C])
+AC_CACHE_VAL(ac_cv_prog_cc_c99,
+[ac_cv_prog_cc_c99=no
+ac_save_CC=$CC
+AC_LANG_CONFTEST([AC_LANG_PROGRAM(
+[[#include <stdbool.h>
+static inline int
+test(const char *restrict text)
+{
+  int i = 0;
+  // Iterate through items via the restricted pointer
+  // and see if C++-style comments work.
+  while (*(text+i) != '\0')
+    ++i;
+  return 0;
+}]],
+[[_Bool success = false;
+  if (test("String literal") != 0)
+    success = true;
+  char *restrict newvar = "Another string";]])])
+# Try
+# GCC		-std=gnu99 -std=c99 -std=iso9899:1999
+# AIX		-qlanglvl=extc99 -qlanglvl=stdc99
+# Intel ICC	-c99
+# IRIX		-c99
+# Solaris	-xc99
+# Tru64		-c99
+for ac_arg in "" -std=gnu99 -std=c99 -std=iso9899:1999 -c99 -xc99 -qlanglvl=extc99 -qlanglvl=stdc99
+do
+  CC="$ac_save_CC $ac_arg"
+  _AC_COMPILE_IFELSE([],
+		     [ac_cv_prog_cc_c99=$ac_arg
+break])
+done
+rm -f conftest.$ac_ext conftest.$ac_objext
+CC=$ac_save_CC
+])
+case "x$ac_cv_prog_cc_c99" in
+  xno)
+    AC_MSG_RESULT([unsupported])
+    $2 ;;
+  *)
+    if test "x$ac_cv_prog_cc_c99" = x; then
+      AC_MSG_RESULT([none needed])
+    else
+      AC_MSG_RESULT([$ac_cv_prog_cc_c99])
+      CC="$CC $ac_cv_prog_cc_c99"
+    fi
+    $1 ;;
+esac
+])# _AC_PROG_CC_C99
+
+
+# AC_PROG_CC_C89 ([ACTION-IF-AVAILABLE], [ACTION-IF-UNAVAILABLE])
+# ---------------------------------------------------------------
+AC_DEFUN([AC_PROG_CC_C89],
+[ AC_REQUIRE([AC_PROG_CC])dnl
+  _AC_PROG_CC_C89([$1], [$2])
+])
+
+
+# AC_PROG_CC_C99 ([ACTION-IF-AVAILABLE], [ACTION-IF-UNAVAILABLE])
+# ---------------------------------------------------------------
+AC_DEFUN([AC_PROG_CC_C99],
+[ AC_REQUIRE([AC_PROG_CC])dnl
+  _AC_PROG_CC_C99([$1], [$2])dnl
+])
+
+
+# AC_PROG_CC_STDC ([ACTION-IF-AVAILABLE], [ACTION-IF-UNAVAILABLE])
+# ----------------------------------------------------------------
+AC_DEFUN([AC_PROG_CC_STDC],
+[AC_PROG_CC_C99([$1], [$2])])
 
 
 # AC_C_BACKSLASH_A
@@ -1207,7 +1290,7 @@
 AC_DEFUN([AC_C_PROTOTYPES],
 [AC_REQUIRE([AC_PROG_CC])dnl
 AC_MSG_CHECKING([for function prototypes])
-if test "$ac_cv_prog_cc_stdc" != no; then
+if test "$ac_cv_prog_cc_c89" != no; then
   AC_MSG_RESULT([yes])
   AC_DEFINE(PROTOTYPES, 1,
 	    [Define to 1 if the C compiler supports function prototypes.])