runtime linker on 9.x/i386: clang vs. gcc

[Mikhail T.]

Hello!

I'm seeing a strange problem with clang-compiled binaries on 9.x/i386 
system. Here it is: if a shared library A needs a symbol provided by a 
shared library B, libA will fail to load into a process even if the 
executable is linked with libB. The only fix (work-around?) is to relink 
libA to explicitly depend on libB. A temporary work-around is to use 
LD_PRELOAD to list all of the necessary libBs...

One example of this is reported in ports/180473 
<http://www.freebsd.org/cgi/query-pr.cgi?pr=ports/180473> -- the 
libprldap6.so refuses to load because of the symbols it needs from 
libnspr4.so. For some reason, the fact, that -lnspr4 is linked into the 
executable (seamonkey or thunderbird), is not sufficient... As the 
ticket suggests, using gcc46 (Mozilla rejects gcc-4.2.x nowadays) 
instead of clang solves the problem (though an even better solution is 
in place since this weekend).

Another example is xorg-server, which, for me, can not load some of the 
drivers because they complain of missing symbols:

    (EE) Failed to load /opt/lib/xorg/modules/drivers/vboxvideo_drv.so: /opt/lib/xorg/modules/drivers/vboxvideo_drv.so: Undefined symbol "DRIFinishScreenInit"

The DRIFinishScreenInit is provided by libdri.so, which the server also 
loads... But, somehow, that is not sufficient. Rebuilding 
vboxvideo_drv.so (provided by emulators/virtualbox-ose-additions 
<http://www.freshports.org/emulators/virtualbox-ose-additions>) with the 
stock cc (gcc-4.2.1) resolves the linking problem -- even if Xorg 
executable and the libdri.so remain clang-compiled.

I am not prepared to argue, whether that's a "right" or "wrong" behavior 
-- but it certainly is inconsistent, because it is only manifested on 
i386 and only when the compiler is clang.

Any thoughts?

    -mi