Re: autoupdate: AU_ALIAS shouldn't affect itself

[Eric Gallager]

On Wed, Jan 27, 2021 at 1:48 AM Eric Gallager <egall@gwmail.gwu.edu> wrote:

> On Tue, Jan 26, 2021 at 4:00 PM Nick Bowler <nbowler@draconx.ca> wrote:
>
>> On 2021-01-26, egall--- via Bug reports for autoconf
>> <bug-autoconf@gnu.org> wrote:
>> > Say I have an M4 macro file with an AU_ALIAS usage in it like this:
>> >
>> > AU_ALIAS([BNV_HAVE_QT], [AX_HAVE_QT])
>> >
>> > If I run autoupdate on this file, that will become:
>> >
>> > AU_ALIAS([AX_HAVE_QT], [AX_HAVE_QT])
>> >
>> > This seems pointless, as now the AU_ALIAS won't do what it was
>> originally
>> > meant to do anymore. Perhaps autoupdate could be updated to stop making
>> > this change.
>>
>> It does seem counterproductive.  Unfortunately autoupdate doesn't actually
>> understand m4 syntax so it often runs into problems similar this one.
>
>
> Yeah, another one like this I noticed was autoupdate expanding macros in
> comments,
> which means I can't do things like this:
>
> dnl Can't use AC_TYPE_SIGNAL here because it is obsolete
> or
> # Stop using AC_HEADER_STDC here because it is deprecated
>
> (without escaping them, that is)
>

Also, another location to have autoupdate ignore would be inside of an
AC_REQUIRE([]).
I have seen autoupdate change:
AC_REQUIRE([AC_HEADER_STDC])dnl
...into:
AC_REQUIRE([m4_warn([obsolete],
[The preprocessor macro `STDC_HEADERS' is obsolete.
  Except in unusual embedded environments, you can safely include all
  ISO C90 headers unconditionally.])dnl
# Autoupdate added the next two lines to ensure that your configure
# script's behavior did not change.  They are probably safe to remove.
AC_CHECK_INCLUDES_DEFAULT
AC_PROG_EGREP
])dnl
...which is wrong.


>
> I'm sure it could be improved to better handle this specific case, though.
>>
>> But for the same reason, you should be able to work around the problem
>> just by quoting differently, for example:
>>
>>   AU_ALIAS([BNV_][HAVE_QT], [AX_HAVE_QT])
>>
>> Cheers,
>>   Nick
>>
>