m4_version_prereq (was: rename gl_FUNC_MBRTOWC)

[Eric Blake]

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According to Eric Blake on 12/18/2008 6:06 AM:
> According to Bruno Haible on 12/18/2008 3:44 AM:
>>>   m4_version_prereq([2.60],, [
>>>
>>> It works at least back to Autoconf 2.59.
>> Thanks for the hint. But m4_version_prereq is undocumented (as already 
>> mentioned
>> in [1]).
> 
> Not for long.  I'm committing a patch to rectify that today.
> 

As follows:

- --
Don't work too hard, make some time for fun as well!

Eric Blake             address@hidden
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>From 96ab16be4a15f75fad0b28dd40a49ddcb201188f Mon Sep 17 00:00:00 2001
From: Eric Blake <address@hidden>
Date: Thu, 18 Dec 2008 06:44:59 -0700
Subject: [PATCH] Document m4_version_prereq.

* doc/autoconf.texi (Number processing Macros)
<m4_version_prereq>: Add documentation.
* NEWS: Mention it.
Reported by Bruno Haible.

Signed-off-by: Eric Blake <address@hidden>
---
 ChangeLog         |    8 ++++++++
 NEWS              |    2 +-
 doc/autoconf.texi |   12 ++++++++++++
 3 files changed, 21 insertions(+), 1 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 704ec47..86c6c4b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2008-12-18  Eric Blake  <address@hidden>
+
+       Document m4_version_prereq.
+       * doc/autoconf.texi (Number processing Macros)
+       <m4_version_prereq>: Add documentation.
+       * NEWS: Mention it.
+       Reported by Bruno Haible.
+
 2008-12-10  Jim Meyering  <address@hidden>
 
        AC_HEADER_ASSERT: don't say assertions are disabled when they're not
diff --git a/NEWS b/NEWS
index 65e5486..2e7fa1e 100644
--- a/NEWS
+++ b/NEWS
@@ -30,7 +30,7 @@ GNU Autoconf NEWS - User visible changes.
    m4_map_args_pair  m4_set_map
 
 ** The following m4sugar macros are documented now:
-   m4_copy  m4_dumpdefs  m4_rename
+   m4_copy  m4_dumpdefs  m4_rename  m4_version_prereq
 
 ** The m4sugar macro m4_expand has been taught to handle unterminated
    comments and shell case statements.  As a result, it is used
diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index d232e4e..aeeb388 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -11835,6 +11835,18 @@ Number processing Macros
 @end example
 @end defmac
 
address@hidden m4_version_prereq (@var{version}, @ovar{if-new-enough}, @
+  @dvar{if-old, m4_fatal})
address@hidden
+Compares @var{version} against the version of Autoconf currently
+running.  If the running version is at @var{version} or newer, expand
address@hidden, but if @var{version} is larger than the version
+currently executing, expand @var{if-old}, which defaults to printing an
+error message and exiting m4sugar with status 63.  When given only one
+argument, this behaves like @code{AC_PREREQ} (@pxref{Versioning}).
+Remember that the autoconf philosophy favors feature checks over version
+checks.
address@hidden defmac
 
 @node Set manipulation Macros
 @subsection Set manipulation in M4
-- 
1.6.0.4