Make includes (was Re: Time to update documenatiopn regarding supported make implementations?)

[Nathanael Nerode <neroden at twcny dot rr dot com>]

>>> GNU make required due to explicit use of GNU make "include file" 
>feature.
>
>> Yeah, I don't like this either.
>
>Calling it a GNU make feature is a bit questionable, though, unless
>something more than just "include file" is happening.  The latter is
>supported by, e.g., Solaris make.  We've been requiring "include file" 
>for
>INN builds for eons, and I know it works with plenty of makes other 
>than
>the GNU make.
>
>It *doesn't* work with some BSD make programs that expect .include 
>instead
>of include, though.

POSIX doesn't require *any* include feature.

But it seems that nearly any Make actually in use *does* have an include 
feature.

Is it reasonable to design an autoconf test for Make 'include' features 
(so that we can support .include, include, and whatever other syntaxes 
are available); demand that users use a Make with some such feature; 
and then use @INCLUDE@ to do Make includes in a semi-portable manner?

'include' is never actually per se necessary, but it would certainly 
ease the design of non-recursive Makefiles, which are always a good 
idea.

I'm agnostic on this point, just throwing out a thought.

--Nathanael