Subject: Re: bug#13928: [PATCH] plans: enabling subdir-object by default is blocked on bug#13928

From: Johan Kristensen <[email-masked]>
Date: Sat, 5 Jul 2014 19:59:34 +0200

Hi,

What is the current status of this bug? I spent some time tracking down the
reason for this bug, but I am totally new to the automake sources and what
would be required for a patch to be acceptable. The problem is that when
the dummy dependency-files is created by "./config.status" (by code from
"m4/depout.m4"), only the DEPDIR variable is substituted. Any other
variable expansions are ignored.

I have a couple of suggestions for a fix. The first is to somehow delegate
the creation of the dummy dependency-files to make, and executing something
like "make dummy-depfiles" from config.status. This seems like the most
straightforward solution but raises the question of how to handle the
includes that are missing. One solution to this problem would be to have
some conditional include of the dependency-files based on if target
"dummy-depfiles" is built. An other solution would be to generate a
temporary Makefile without these includes.

The other alternative is to resolve all variables in depout.m4. To be
correct this would require a recursive lookup of all variable substitutions
in the Makefile. Perhaps the structure imposed by automake makes this kind
of trivial but I have no idea. Will automake under some circumstances
output something like "+=", "?=" or conditional assigns? This would make a
solution along these lines intractable.

kind regards,
Johan Kristensen