bug#9320: Documentation addition: AC_SUBSTed variables do not work with LIBADD for dependency generation.

[Stefano Lattarini]

Hi Krzesimir, thanks for the report and sorry for the awful delay.

On Thursday 18 August 2011, Krzesimir Nowak wrote:
> Package: automake
> Version: 1.11.1
> 
> It would be useful to add a note to "8.4 Program and Library Variables"
> part of Automake documentation that Automake's dependency generator does
> not generate proper dependencies when maude_LIBADD have variables that
> are AC_SUBSTed. In such case maude_DEPENDENCIES should be used
> explicitly.
>
But that would also override the dependencies automatically computed by
automake ... (which might not be a problem in your case, but it might be
in the general case).

And that's why, in the developement varsion of automake, we have (well,
Ralf has, actually) introduced support for `EXTRA_maude_DEPENDENCIES',
that allows one to *extend* the automake-computed dependencies, instead
of simply override them.  This new variable would be perfect for your
use case. The relevant commit is `v1.11-377-g6edafbb':
  <http://git.savannah.gnu.org/cgit/automake.git/commit/?id=6edafbb>

> If this is a bug then please see an example in attached tarball.
> It contains code for two simple libraries - hello and greeter. Greeter
> depends on hello. There is a file greeter/greeter.am in which I have
> written _LIBADD and _DEPENDENCIES in several ways - the first two tries
> ends with linking error stating about nonexistent libhello.la. Please
> also note that I used a nonrecursive Automake and Makefile.am includes
> greeter.am first and then hello.am (so in a sort of reverse order). If
> hello.am would be included first and then greeter.am - compilation then
> usually passes when compiling it in single thread.
>
I can reproduce the failure with your example; and using the developement
version of automake (master branch) I can fix it using the following in
`greeter/greeter.am':

  greeter_libgreeter_la_LIBADD = $(HELLO_LIBS)
  EXTRA_greeter_libgreeter_la_DEPENDENCIES = $(HELLO_LIBS)

> If this is not a bug I am willing to provide a patch dor documentation.
> 
It's a limitation rather than a bug; and the workaround with
EXTRA_foo_DEPENDENCIES that I've explained above is the documented,
"kosher" way around it.

Still, I can see that the documentation in is not as clear as it could
be in this matter; so feel free to submit a documentation patch (against
master), and we will surely consider it.

Thanks,
  Stefano