Make: target not updated until run again

[Brian Mearns-2]

I'm trying to create an "archive" (copy of the project) as follows:
The top level Makefile creates the directory and copies some stuff
into it. Then it recurses into subdirectories, and tells them to add
their own files to the directory it created. If the subdirectory
Makefiles decide to actually add anything to the directory, they touch
it to make it up to date.

Then I've got another rule to "package" the archive into a tar file,
which has the archive directory as a dependent, so it should only run
if the directory is more up to date than the tar.

The problem is, if the recursive Makefiles update the archive, but the
top level doesn't, the tar rule doesn't run, until I run the target a
second time.

I hope the Makefile below illustrates my situation. Basically, the
"archive" phony target is used to create the archive: it calls the
"my_archive" target which is like the top-level archive rule (it only
runs if the file "source" is more up to date than the my_archive dir),
and then it calls the update_my_archive, which is meant to simulate
the recursive makefiles: it updates the my_archive dir. "after-
archive" is meant to take the place of the tar file: it should run
whenever my_archive changes.

the default target is "top", which calls the "archive" target to
update the archive, and then calls after-archive. The "archive" target
always (in this case) leads to my_archive being updated, so I would
expect after-archive to have to run as well. But as I said, it only
runs if I run make twice. Below is the makefile, and following that is
a terminal transcript showing the output when I run make consecutive
times.

If anyone can explain why after-archive is considered up to date
compared to my_archive, when a previous dependency updates my_archive,
I would really appreciate it. Especially if you can also help me
figure out how to fix it.

Running GNU Make 3.81, on Fedora 9: Linux 2.6.26.5-45.fc9.i686

Thanks,
-Brian

### Makefile: ######

.PHONY:top
top: archive after-archive
        @echo Ran "top"

.PHONY:archive
archive: my_archive update_my_archive
        @echo Ran "archive"

my_archive: source
        @echo Updating my_archive because source changed
        touch my_archive

.PHONY:update_my_archive
update_my_archive:
        @echo Further modifying my_archive...
        touch my_archive

after-archive: my_archive
        @echo my_archive changed:
        touch after-archive

### End Makefile #########
##### Terminal: ##########
$ make top
Further modifying my_archive...
touch my_archive
Ran archive
my_archive changed:
touch after-archive
Ran top

$ make top
Further modifying my_archive...
touch my_archive
Ran archive
Ran top

$ make top
Further modifying my_archive...
touch my_archive
Ran archive
my_archive changed:
touch after-archive
Ran top

$ make top
Further modifying my_archive...
touch my_archive
Ran archive
Ran top

[Brian Mearns-2]

Sorry for the duplicate post.

[Ralf Wildenhues]

Hello Brian,

* mearns.b@... wrote on Fri, Oct 03, 2008 at 12:04:04AM CEST:
> I'm trying to create an "archive" (copy of the project) as follows:
> The top level Makefile creates the directory and copies some stuff
> into it. Then it recurses into subdirectories, and tells them to add
> their own files to the directory it created.

Sounds like you're more or less doing manually what Automake provides
with its 'distdir' rule.

> If the subdirectory
> Makefiles decide to actually add anything to the directory, they touch
> it to make it up to date.

That's the problem, AFAICS: you cannot have several rules updating the
same file, that will confuse make.

Whenever you can't express the dependencies between files as a directed
tree, you have to either use stamp files, and/or reinvoke make within a
rule to let it recompute the set of needed rules based on updated
timestamps.

For example, post-update actions can typically be realized like this:

target: deps...
        update_target
        $(MAKE) post-action-for-target

Hope that helps to get you going (otherwise please report back).

Cheers,
Ralf

[Brian Mearns-2]

Thanks, so much, Ralf. I guess I didn't have a good understanding of
how Make handles dependencies, but your response has made it more
clear. I'll take another (more thorough) look over the Make manual,
and then try it again with your suggestion.

FYI, I'm not using automake because I'm trying to keep my project
easily cross-platform: I'm not sure if there's an easy to use set of
auto tools for windows. If you know of such a set, that'd be great.

Thanks for the help,
-Brian

On Oct 5, 6:18 am, Ralf Wildenhues <Ralf.Wildenh...@...> wrote:

> Hello Brian,
>
> * mearn...@... wrote on Fri, Oct 03, 2008 at 12:04:04AM CEST:
>
> > I'm trying to create an "archive" (copy of the project) as follows:
> > The top level Makefile creates the directory and copies some stuff
> > into it. Then it recurses into subdirectories, and tells them to add
> > their own files to the directory it created.
>
> Sounds like you're more or less doing manually what Automake provides
> with its 'distdir' rule.
>
> > If the subdirectory
> > Makefiles decide to actually add anything to the directory, they touch
> > it to make it up to date.
>
> That's the problem, AFAICS: you cannot have several rules updating the
> same file, that will confuse make.
>
> Whenever you can't express the dependencies between files as a directed
> tree, you have to either use stamp files, and/or reinvoke make within a
> rule to let it recompute the set of needed rules based on updated
> timestamps.
>
> For example, post-update actions can typically be realized like this:
>
> target: deps...
>         update_target
>         $(MAKE) post-action-for-target
>
> Hope that helps to get you going (otherwise please report back).
>
> Cheers,
> Ralf

[Ralf Wildenhues]

* mearns.b@... wrote on Sun, Oct 05, 2008 at 11:48:24PM CEST:
> FYI, I'm not using automake because I'm trying to keep my project
> easily cross-platform: I'm not sure if there's an easy to use set of
> auto tools for windows. If you know of such a set, that'd be great.

autotools work fine on w32, for example using Cygwin or using MinGW.

Cheers,
Ralf

[Brian Mearns-2]

Brilliant, Ralf! I got so caught up in why it wasn't working the way I
wanted it to, I couldn't come up with an alternate solution.
"Recursively" calling Make with the post-update target worked just
fine.

I'm also pleased to hear autotools work so well on win32. I've seen
that there are ports, but for some reason, I didn't have luck with
them before. Probably because I assumed it was too much hassle. But it
sounds like now would be a good time to learn how to use them.

Thanks, so much.

-Brian

On Mon, Oct 6, 2008 at 2:09 AM, Ralf Wildenhues <Ralf.Wildenhues@...> wrote:

> * mearns.b@... wrote on Sun, Oct 05, 2008 at 11:48:24PM CEST:
>> FYI, I'm not using automake because I'm trying to keep my project
>> easily cross-platform: I'm not sure if there's an easy to use set of
>> auto tools for windows. If you know of such a set, that'd be great.
>
> autotools work fine on w32, for example using Cygwin or using MinGW.
>
> Cheers,
> Ralf
>