Re: $(wildcard ) evaluation

[Philip Guenther]

On Wed, Jul 23, 2008 at 11:36 AM, Garrett Cooper <address@hidden> wrote:
> On Wed, Jul 23, 2008 at 10:34 AM, Garrett Cooper <address@hidden> wrote:
>>
>> You'll need double the $ in defines if you're referencing variables
>> outside the scope of the define.
>>
>> I'd read more about second-expansion, et all in the manual.

Uh, what?  "second-expansion", as used in the GNU make manual, is
restricted to prerequisite lists as described in section 3.10,
"Secondary Expansion".

If you're referring to uses of $(eval), well, that only applies to
$(eval), which wasn't present in the poster's makefile.  ($(call) does
*not* involve double expansion: the contents of the called variable
are expanded just once.)


> Scratch "if you're referencing variables outside the scope of the
> define". If you're happy with the statements being evaluated /
> resolved in the first-pass of the define, $ is fine. Otherwise, use $$
> to defer its expansion until make gets around to the second define
> eval (which is what you want here).

No, he doesn't want $(eval), and it wouldn't solve the problem anyway.
 The principle effect of using eval is that the Makefile instantly
because a bazillion times harder to understand.  If someone is having
problems with their makefile already, adding $(eval) is only going to
make it worse.

The original poster's problem is almost certainly due to the
combination of caching and a Makefile which doesn't tell the full
truth.  In particular: make caches the list of files in each directory
as it happens to read them, and will answer $(wildcard) expansions
from that cache.  As part of that, make assumes that your makefile
tells the truth and that a file won't be created unless it was the
target of a rule that was invoked at some point.

My guess is that the *.out files are created as the side-effect of
some other rule.  Make doesn't know that, so it doesn't know to add
them to the cache, so $(wildcard *.out) gives the wrong result.

Raleigh, does that sound like it could be case?  What creates the *.out files?


Philip Guenther


BTW, if all the uses of 'artifacts' pass $@ as the argument, then you
don't need to use $(call).  Just use $@ in the definition of artifacts
and expand it in the rule's commands as just $(artifacts).  'define'
creates a recursively expanded variable, so its contents won't be
expanded until it used somwhere the expansion is forced, such as when
the commands are executed.  At that point, $@ will have the correct
value.