FYI: AC_PREREQ 63

[Akim Demaille]

We'd like to have a smarter missing, which requires a bit more
information from the exit status.  Actually, we should problably now
move onto std exit status values.

Index: ChangeLog
from  Akim Demaille  <address@hidden>

        * lib/m4sugar/m4sugar.m4 (m4_version_prereq): Failure causes an
        exit 63, so that we (or Automake's "missing") can tell the
        difference with a plain failure.
        * doc/autoconf.texi (Notices): Adjust.

Index: doc/autoconf.texi
===================================================================
RCS file: /cvsroot/autoconf/autoconf/doc/autoconf.texi,v
retrieving revision 1.738
diff -u -u -r1.738 autoconf.texi
--- doc/autoconf.texi 23 May 2003 07:14:51 -0000 1.738
+++ doc/autoconf.texi 23 May 2003 13:12:49 -0000
@@ -1639,9 +1639,9 @@
 @acindex{PREREQ}
 @cindex Version
 Ensure that a recent enough version of Autoconf is being used.  If the
-version of Autoconf being used to create @command{configure} is earlier
-than @var{version}, print an error message to the standard error output
-and do not create @command{configure}.  For example:
+version of Autoconf being used to create @command{configure} is
+earlier than @var{version}, print an error message to the standard
+error output and exit with failure (exit status is 63).  For example:
 
 @example
 AC_PREREQ(@value{VERSION})
Index: lib/m4sugar/m4sugar.m4
===================================================================
RCS file: /cvsroot/autoconf/autoconf/lib/m4sugar/m4sugar.m4,v
retrieving revision 2.71
diff -u -u -r2.71 m4sugar.m4
--- lib/m4sugar/m4sugar.m4 22 May 2003 13:24:08 -0000 2.71
+++ lib/m4sugar/m4sugar.m4 23 May 2003 13:12:50 -0000
@@ -1762,7 +1762,8 @@
 m4_define([m4_version_prereq],
 [m4_if(m4_version_compare(m4_defn([m4_PACKAGE_VERSION]), [$1]), -1,
        [m4_default([$3],
-                  [m4_fatal([Autoconf version $1 or higher is required])])],
+                  [m4_fatal([Autoconf version $1 or higher is required],
+                            63)])],
        [$2])[]dnl
 ])