Re: Fix LT_WITH_LTDL: AU_ALIAS bug

[Ralf Wildenhues]

Hi Stepan,

* Stepan Kasal wrote on Tue, Oct 25, 2005 at 01:16:06PM CEST:
> On Sat, Sep 10, 2005 at 04:17:52PM +0100, Gary V. Vaughan wrote:
> > :-(  Can you document in HACKING that because of our use of AU_ALIAS to
> > maintain backwards compatibility with earlier libtool interfaces we must
> > not use $# in m4.
> 
> actually, I'd prefer if you could put it this way:
*snip*

Can the Autoconf manual also please _explicitly_ *warn* against using
`$#' at all in macros?

> [ put in public domain, in case you want to paste it somewhere ;-) ]

FYI, public domain is not the same thing as copyright assignment;
disclaimer is ok, though.

Also FYI: I have applied the patch below to Libtool CVS HEAD.

Cheers,
Ralf

2005-10-27  Stepan Kasal  <address@hidden>

        * HACKING: Update note about use of `$#' in m4 macros.

Index: HACKING
===================================================================
RCS file: /cvsroot/libtool/libtool/HACKING,v
retrieving revision 1.21
diff -u -r1.21 HACKING
--- HACKING     26 Sep 2005 12:21:53 -0000      1.21
+++ HACKING     27 Oct 2005 13:23:13 -0000
@@ -241,8 +241,11 @@
    $ECHO ".."          for strings without leading hyphen,
    $ECHO "X.." | $Xsed otherwise.
 
-* Do not use the number of macro arguments `$#' in public macros;
-  AU_ALIAS may change it.
+* The Autoconf manual says that giving an empty parameter is equivalent
+  to not giving it at all.  (In particular, the Autoconf manual doesn't
+  explain that "FOO()" is calling macro FOO with one empty parameter.)
+  To prevent misunderstanding, we should use m4_ifval to check whether
+  a parameter is empty, and not $# to check for the number of parameters.
 
 
 9. Abstraction layers in libltdl