[Bug bootstrap/52623] 4.7.0-RC-20120314: bootstrap failure on AIX due to multilib and using C++ in post-stage1

["michael.haubenwallner at salomon dot at" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52623

--- Comment #3 from Michael Haubenwallner <michael.haubenwallner at salomon dot at> 2012-03-21 09:38:00 UTC ---
(In reply to comment #2)
> We should disable libquadmath on AIX.  It is not needed or useful there.
> 
> Have you tried adding --disable-libquadmath when configuring GCC?

For --enable-languages=c,c++ only, I can bootstrap using --disable-libquadmath.
Haven't tried other languages needing their own target libraries.

But the problem isn't with libquadmath itself, but with config-ml.in setting
LD_LIBRARY_PATH to find the multilib-wise libstdc++.a, and (interesting enough)
the AIX 7.1 loader listening to LD_LIBRARY_PATH now.

Consider these simple commands to trigger the configure-error in
ppc64/libquadmath:

$ ./gcc/xgcc
xgcc: fatal error: no input files
compilation terminated.

$ LD_LIBRARY_PATH=`pwd`/powerpc-ibm-aix7.1.0.0/ppc64/libstdc++-v3/src/.libs
./gcc/xgcc
exec(): 0509-036 Cannot load program ./gcc/xgcc because of the following
errors:
        0509-150   Dependent module
/big1/local/src/test/gcc/gcc-4.7.0-RC-20120314/build/powerpc-ibm-aix7.1.0.0/ppc64/libstdc++-v3/src/.libs/libstdc++.a(libstdc++.so.6)
could not be loaded.
        0509-103   The module has an invalid magic number.

Unfortunately, the AIX loader stops searching at the first matching archive
filename found,
even if it doesn't contain a matching shared object.


However, ldd shipped with AIX 7.1 still ignores LD_LIBRARY_PATH:

$ ldd ./gcc/xgcc
./gcc/xgcc needs:
         /usr/lib/libc.a(shr.o)
         /usr/lib/libiconv.a(shr4.o)
        
/big1/local/src/test/gcc/gcc-4.7.0-RC-20120314/build/prev-powerpc-ibm-aix7.1.0.0/libstdc++-v3/src/.libs/libstdc++.a(libstdc++.so.6)
         /unix
         /usr/lib/libcrypt.a(shr.o)
        
/big1/local/src/test/gcc/gcc-4.7.0-RC-20120314/build/./prev-gcc/libgcc_s.a(shr.o)

$ LD_LIBRARY_PATH=`pwd`/powerpc-ibm-aix7.1.0.0/ppc64/libstdc++-v3/src/.libs ldd
./gcc/xgcc
./gcc/xgcc needs:
         /usr/lib/libc.a(shr.o)
         /usr/lib/libiconv.a(shr4.o)
        
/big1/local/src/test/gcc/gcc-4.7.0-RC-20120314/build/prev-powerpc-ibm-aix7.1.0.0/libstdc++-v3/src/.libs/libstdc++.a(libstdc++.so.6)
         /unix
         /usr/lib/libcrypt.a(shr.o)
        
/big1/local/src/test/gcc/gcc-4.7.0-RC-20120314/build/./prev-gcc/libgcc_s.a(shr.o)