Re: Issues w/ "relink" and cross-compilation

[Ralf Wildenhues]

Hello Philip,

thanks for the reports.

* Philip Prindeville wrote on Sun, Jul 11, 2010 at 02:38:28AM CEST:
> The problem is that a lot of projects that we use in turn use
> libtool (and not always terribly up-to-date versions of it),

this is something I'm afraid you need to take up with the projects.

> and
> what seems to happen is that the relink stage uses -L/usr/lib by
> default, even when cross-compiling.

This is a bug in libtool.  I could argue about calling it a limitation,
but that doesn't really matter.

> There's probably a really simple trick to getting this not to happen,
> but it's not obvious to me.  Also, it would be nice if libtool figured
> out the need to do this on its own (i.e. figure out that it's
> cross-compiling and that -Lxxx for any host libraries shouldn't be
> included).
> 
> Can someone walk me through the workaround?

I'm not sure there is a general workaround.  For some setups it helps to
(temporarily) remove the .la files of the libraries relinked against.

I don't really have the time to look into this right now (and I expect
it to be at least a little bigger project), but here's what you (and
others) can do to help: post small reproducible examples, ideally as
portable as possible, and ideally as XFAILing testsuite additions
against tests/destdir.at so that it is clear what it is that is to be
fixed.

If you are not at ease with Autotest, a small shell script that creates
the necessary files and invokes libtool in the way that exposes the
bug(s) is fine, too.  It's just that IIRC, there were a lot more than
just one detail to get right here, some quite debatable because they
don't apply in all situations, and I think we should start by collecting
setups that we think ought to work.

One complication when writing tests for this is that tests shouldn't
mess with system directories like /usr/lib or /usr/local/lib but OTOH
libtool treats directories listed in sys_lib_search_path_spec and
sys_lib_dlsearch_path_spec special.  It might be necessary to use a
munged libtool script (similar to tests/install.at and others) that
adds entries to these below the build tree so we can play with them.
(Of course the test then needs to ensure that the link editor and/or
runtime linker really searches these directories.)

These comments of course all hold for the --sysroot stuff as well, which
is in a similar category of issues.

Please note that nontrivial additions need copyright assignment (ping me
and I'll send you the form off-list).

If somebody has done the work of searching for proposed patches for
these issues (IIRC there are a couple floating around at least in some
distros) then posting links would be a good thing.

Thanks,
Ralf