Re: [PATCH 1/3] AC_CONFIG_MACRO_DIRS: new macro, mostly for aclocal

[Stefano Lattarini]

On 11/09/2012 07:54 PM, Eric Blake wrote:
> On 11/09/2012 11:47 AM, Stefano Lattarini wrote:
>>> I'm adding my own sign-off and squashing this in; basically, I'm
>>> relaxing the documentation to plan for my subsequent patches where
>>> AC_CONFIG_MACRO_DIR will not be treated as obsolescent, but leaving your
>>> initial implementation separate from my improvements to make it clear
>>> what my improvements accomplish.
>>>
>> How does this interact with the fact that aclocal 1.13 will handle
>> *only* AC_CONFIG_MACRO_DIRS, while continuing (like it did before)
>> to ignore AC_CONFIG_MACRO_DIR?  For a rationale about this, see:
>>
>>   <http://debbugs.gnu.org/cgi/bugreport.cgi?bug=12845>
>>
>> I still believe we should make it clear that AC_CONFIG_MACRO_DIR is
>> obsolescent and should no longer be used; albeit, to avoid gratuitous
>> backward-incompatibility, we'll refrain to have it elicit any warning,
>> at least for the time being ...
> 
> Automake should trace exactly one macro name: AC_CONFIG_MACRO_DIR_TRACE.
>
Ah, OK.  And I guess the same would be true for other third-party tools
wanting to make use of the AC_CONFIG_MACRO_DIRS macro, right?  In which
case, I think this should be explicitly documented in the Autoconf manual.

>  This trace macro will hit once per directory, no matter whether the
> user called AC_CONFIG_MACRO_DIR or AC_CONFIG_MACRO_DIRS.  Furthermore,
> since the trace will hit once per directory, automake doesn't have to go
> to any great lengths to do whitespace normalization - that will have
> already been done by AC_CONFIG_MACRO_DIRS.
> 
> AC_CONFIG_MACRO_DIR can be traced (such as by older libtool), but will
> hit exactly once (whether or not the user used AC_CONFIG_MACRO_DIR
> directly or used AC_CONFIG_MACRO_DIRS).
> 
> Users should then decide what they are targetting:
> - newer tools only (such as automake 1.13) - no need for
> ACLOCAL_AMFLAGS, and use AC_CONFIG_MACRO_DIRS only
> - hybrid support for older AND newer tools - use ACLOCAL_AMFLAGS, and
> call AC_CONFIG_MACRO_DIR exactly once and first.  Newer automake will
> warn about ACLOCAL_AMFLAGS,
>
(and that only from Automake 1.14 BTW).

> but will do the right thing by tracing
> exactly AC_CONFIG_MACRO_DIR_TRACE (and nothing else).
>
OK.

> I'm trying to document this in the patches that I'm writing (right now,
> I'm working on the testsuite to make sure things are tested and
> therefore will not regress).
> 
Thanks for taking the time to explain.  I think the approach you are
proposing is the best one so far.

Best regards,
  Stefano