user upgrade path for renamed macros

[Filippo Giunchedi]

Hi,
I took some time to test possible upgrade scenarios WRT the macro renaming, I've
come up with the following idea:

Since aclocal prefers files with serial we can set a serial 0 on old files with
renamed macros thus aclocal --diff|--install will pick them. Note that these
files are bound to be removed anyway from the archive so having them serialized
should do no harm beside making the user aware of replacements. (as a side note
we should discuss again the serial usage, but IMO it is not urgent at all right
now)

In addition to the serial provide also a AU_ALIAS([old_name],[new_name]) for
autoupdate to pick up (not strictly necessary but read on)

The last step would be to point users (perhaps in the comments) to running
aclocal [appropriate -I options] --diff
and optionally to autoupdate, or an UPGRADING document or the like.

this last observation is low-priority:
Note that in the above autoconf -Wobsolete won't complain (rightfully) but
passing a third argument to AC_DEFUN autoconf -Wobsolete will signal the macro
as obsolete _but_ autoupdate won't replace the function implementation (it is
not AU_DEFUNed). I couldn't find any documentation about this behaviour so I'm
not sure it is public and/or should be used. In which case it would be nice to
have a third argument to AC_DEFUN (the content is not actually displayed by
autoconf so it is irrelevant)

filippo
-- 
Filippo Giunchedi - http://esaurito.net - 0x6B79D401

UNIX was not designed to stop its users from doing stupid things, as that
would also stop them from doing clever things.
-- Doug Gwyn