Re: make: dependfile preference list

["Simon J. Gerraty" <sjg%crufty.net@localhost>]

On Thu, 19 Apr 2012 07:55:30 +0100, David Laight writes:
>On Wed, Apr 18, 2012 at 11:29:10PM -0700, Simon J. Gerraty wrote:
>> The patch below, adds:
>> 
>>      .MAKE.DEPENDFILE_PREFERENCE
>>                      The ordered list of makefile names (default
>>                      `${.MAKE.DEPENDFILE:T}') that make will look for to
>>                      read
>>                      dependencies from.  Only the first found will be
>>                      read.
>
>I'm not sure this is necessary, the code that auto-reads .depend
>(which is I presume the actual default) 

Yes it defaults to just .depend - to maintain status quo.

>is not really needed
>as the relevant rukes can be added to the makefile itself.

They could be - but then everyone in the world needs to edit 1000's of
makefiles to retain status quo?

Even when ditching .depend in the objdir for an autoupdated
Makefile.depend* in the src tree (so that it can be used to drive the
build itself), the auto-reading is actually very handy.

Right now I set .MAKE.DEPENDFILE = Makefile.depend.${MACHINE}
which is fine when you always build for a dozen architectures in
parallel, but not everyone does that - or not for their entire tree.

>Unfortunately the reading of .depend, like the checks for the obj
>subdirectory, can't be removed without breaking things.

Retaining status quo by default, while  allowing more clever
things easily is the goal.

dirdeps.mk is already complex enough