Re: problems with LD_LIBRARY_PATH and libtool wrapper

[Dan McMahill]

Ralf Wildenhues wrote:
> My analysis was at least partly wrong:
>
> * Ralf Wildenhues wrote on Thu, Aug 21, 2008 at 08:37:37AM CEST:
> > * Dan McMahill wrote on Wed, Aug 20, 2008 at 03:55:19AM CEST:
> > > /bin/ksh ../libtool --tag=CC   --mode=link gcc  -g -O2 -Wall  
> > > -Wl,-R/usr/pkg/lib
> > > -Wl,--rpath -Wl,/usr/pkg/lib -Wl,-R/usr/X11R6/lib -L/usr/pkg/lib  
> > Here's your problem: something adds
> >   -Wl,-R/usr/pkg/lib -Wl,--rpath -Wl,/usr/pkg/lib
> >
> > to the link line of your program.  Find out what that is, probably
> > either some flag in your Makefile.am or a configure macro.
> [...]
>
> > I'm still wondering whether this is a bug in libtool though.
> > Namely:
> >
> > If the user passes run paths with -R to libtool, should these run paths
> > be reordered to always appear _after_ those run paths added by libtool
> > which point to uninstalled locations?
>
> If the user passes run paths with -R to libtool, then they _are_ already
> put after all uninstalled run paths.  So this bug does not exist.
>
> The issue then is one of users passing in run paths via other methods,
> e.g., '-Wl,-R' or '-Wl,--rpath'.  Actually, there are two issues here:
> First, the one Dan reported.  Second, the fact that it is not portable
> to do so.  Even if the instance that added those paths would take care
> to substitute the right system-specific linker flag, then there are
> systems which allow only one such flag on the command line (with run
> paths separated by colon or so).  So libtool _has_ to mangle them any
> way.
>
> We could just decree that passing -Wl,-rpath and the like to libtool is
> not allowed, and one should always pass with -R.  Then the fix would be
> a documentation clarification one only.
>
> So, for you, Dan, that would mean tracking down whatever macro sets
> those flags, and getting it to pass -R to libtool instead.  Or better
> even not passing that: at least if the aim is to link against some
> installed libraries, if those are libtool libraries, they should just
> be listed as /foo/bar/libfoo.la.

ok.  It looks like it is coming from

  pkg-config --libs gtk+-2.0

which is called by way of PKG_CHECK_MODULES.  There is a
/usr/pkg/lib/libgtk.la but thats not what pkg-config puts out.  I'm
thinking thats because the .la is only useful if you're using libtool
for linking.


I guess what I don't see is why the libtool wrapper script doesn't do this:

LD_LIBRARY_PATH="/path/to/libmine/.libs:${LD_LIBRARY_PATH}:/usr/pkg/lib"

instead of

LD_LIBRARY_PATH="/usr/pkg/lib:/path/to/libmine/.libs:${LD_LIBRARY_PATH}"

In other words it seems like we always want our local .libs directory to 
come before other stuff and we might want to make our LD_LIBRARY_PATH 
setting from the environment come before a system path.

-Dan