Re: inter-library-dependency, how?

[Bert Wesarg]

Hi,


> Hi Nick,
>
> thanks for the quick response.
>
> Am 09.09.2011 18:01, schrieb Nick Bowler:
>
>     On 2011-09-09 17:56 +0200, Christian Rössel wrote:
>
>         I want to build a program that depends on a libtool library that depends
>         on a non-libtool library that needs rpath information to be found a 
> runtime.
>
>         My Makefile.am looks like this:
>         lib_LTLIBRARIES    = libfoo.la
>         libfoo_la_SOURCES  = libfoo.c  libfoo.h
>         libfoo_la_CPPFLAGS = -I/opt/packages/papi/4.1.2.1/include
>         libfoo_la_LDFLAGS  = -L/opt/packages/papi/4.1.2.1/lib
>         libfoo_la_LIBADD   = -lpapi
>
>         bin_PROGRAMS = foo
>         foo_SOURCES  = foo.c
>         foo_LDADD    = libfoo.la
>
>     [...]
>
>         Building and linking succeeds, but trying to run ./foo leads to
>         ./foo: error while loading shared libraries: libpapi.so: cannot open
>         shared object file: No such file or directory
>
>         The library is in the location specified by libfoo_la_LDFLAGS (.a and
>         .so). But the rpath /opt/packages/papi/4.1.2.1/lib is not available. How
>         do I get it into foo without specifying it as
>         foo_LDFLAGS = -Wl,-rpath /opt/packages/papi/4.1.2.1/lib?
>
>     Looking at 
> https://www.gnu.org/software/libtool/manual/libtool.html#Link-mode,
>
>        -R libdir
>            If output-file is a program, add libdir to its run-time path. If
>            output-file is a library, add -Rlibdir to its dependency_libs, so
>            that, whenever the library is linked into a program, libdir will
>            be added to its run-time path.
>
>     So it seems that adding -R/opt/packages/papi/4.1.2.1/lib to
>     libfoo_la_LDFLAGS would do the trick?
>
> Well, like the documentations says, -R/opt/packages/papi/4.1.2.1/lib is
> added to the dependency_libs:
> dependency_libs=' -R/opt/packages/papi/4.1.2.1/lib
> -L/opt/packages/papi/4.1.2.1/lib -lpapi'
>
> But when I link libfoo.la into foo, nothing is added to foo's runpath:
> libtool: link: gcc -g -O2 -o foo foo.o  ./.libs/libfoo.a
> -L/opt/packages/papi/4.1.2.1/lib -lpapi
>
> So, the problem remains. Any help appreciated.

Christian and I independently solved this with the following fix:

diff --git i/libltdl/config/ltmain.m4sh w/libltdl/config/ltmain.m4sh
index ca67c8a..f79ab5b 100644 libltdl/config/ltmain.m4sh
--- i/libltdl/config/ltmain.m4sh
+++ w/libltdl/config/ltmain.m4sh
@@ -6391,8 +6391,7 @@ func_mode_link ()
            # Pragmatically, this seems to cause very few problems in
            # practice:
            case $deplib in
-           -L*) new_libs="$deplib $new_libs" ;;
-           -R*) ;;
+           -L*|-R*) new_libs="$deplib $new_libs" ;;
            *)
              # And here is the reason: when a library appears more
              # than once as an explicit dependence of a library, or

With this patch, the -R flag inside the dependency_libs list is honored 
and appropriately added to the link command.

Is there anything wrong with this approach. If not we propose this patch 
for inclusion. A proper ChangeLog and Signed-of-by line will follow 
than. I will also try to transform Christians example into an test than.

Thanks.

Bert

> Thanks,