Re: VCSWITNESS = fail ** 2

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sun, 12 Jan 2014 13:45:23 -0500
> From: "Eric S. Raymond" <esr@thyrsus.com>
> Cc: emacs-devel@gnu.org
> 
> So I reverted to the trunk version and instrumented, by inserting an
> echo before the generated make command.  Lo and behold, vcswitness was
> empty.

Is it still empty for you with the current trunk?  (It is not empty
for me.)  If so, do you have a .bzr/checkout/dirstate file under the
top-level directory of your bzr branch?  Also, did you try that in the
bzr branch, or in the directory where you build (assuming that they
are different, i.e. that you don't build in-place)?

> Those three lines are, by demonstration, so prone to be misread that they 
> tripped up Eli and me in two different ways and I still have no theory
> to account for why they were different.
> 
> That says "maintainence nightmare - should be scrapped and replaced"
> to me.

Maybe so, but replaced with what?

The main requirement for this trick is that the value of VCSWITNESS is
computed in the top-level Makefile, but used in a sub-Make.  So the
variables that should be expanded by the sub-Make should be quoted,
while those that need to be expanded by the top-level Make should not
be quoted.  Is there a better way of expressing that than what we have
now?