-fwhole-program for a shared library object

[Daniel Drake <ddrake at brontes3d dot com>]

Hi,

I'm interested in the new -fwhole-program -combine functionality offered
in GCC 4.1 but am having trouble applying it to this particular
scenario.

Is -fwhole-program supposed to cover situations like this? Should I be
doing this another way? Is this a bug?


I am building a .so library from several .c files. Several functions and
variables are shared between these files. Currently, these files are
built into individual .o files then linked together at the end into
a .so object. The public interface to this library is only 2 functions
(this is a Python module).

Currently, all of the shared functions/variables in these files are
accessible to the outside world. I want to avoid this - these functions
are internal only. I only want 2 specific functions available to the
outside.

So, after reading about -fwhole-program -combine I added
__attribute__((externally_visible)) to the 2 functions I'm looking to
provide to library users. I also modified the compliation system to
compile all the files in the same command, and ended up with:

gcc -shared -fwhole-program -combine file1.c file2.c file3.c -o mylib.so

Now, when I try and run a program against this library, it fails to load
due to undefined symbols in mylib.so. The symbols it claims about are
internal functions/variables shared between the various .c files but
*not* intended for use by the outside world (hence they shouldn't be in
the external symbol table or however it works).

What am I missing?

Thanks,
Daniel