Re: multilib support

[Bob Friesenhahn]

On Fri, 31 Mar 2006, Simon Stelling wrote:

> Ralf Wildenhues wrote:
> > That is only half of the problem.  If it were the only problem, then we
> > could just prepend all the lib64 paths on GNU/Linux, and the sparcv9
> > ones on Solaris.  The other half is that libtool does not skip libraries
> > it finds there: deplibs_check_method is set to pass_all.
> >
> > So the task is: find a good replacement for that which is both cheap and
> > accurate.  And feasible.
>
> Uhm, why is that a problem? If libtool did a check which ABI it's actually
> compiling/linking for, it could always prepend the appropriate path, no?

That sounds like a good plan.  Unfortunately, libtool does not appear 
to check ABIs while linking.  Instead it uses the first library that 
it finds.

> This would of course only fix the -l case. It wouldn't work if *.{l,}a files are
> specified directly. But IMHO, whatever is specifying the files directly has to
> make sure it takes the right ones itself.
>
> Only way I could think of to fix .la files would be to compare the output of
> `file -L lib${name}.so` with they output of file on a little program we just
> compile ourself. However, that would break if the .so file is not the library
> itself but e.g. a ld script.

A longer term approach would be to encode the ABI into the .la files 
so that .la files with the wrong ABI can be quickly skipped without 
inspecting the associated library.

Bob
======================================
Bob Friesenhahn
address@hidden, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/