http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54482
--- Comment #3 from Ollie Wild <aaw at gcc dot gnu.org> 2012-09-12 04:58:29 UTC --- Note, however, that simply changing pic_flag to pic_flag="-D_GLIBCXX_SHARED -fPIC -DPIC" is insufficient. It suffers from the same issue as the original problem, namely that, when configured with --with-pic, pic_flag is passed even when compiling objects for libstdc++.a. Since your solution passes -DPIC and -D_GLIBCXX_SHARED in tandem, keying off the new macro suffers from the same limitations as the old one. See my previous comment. In particular, the link there points to a more detailed analysis, as well as a patch which outlines the basics of what I think needs to change. As you correctly suggest, we need a mechanism to pass flags based on whether we're compiling for a static or shared library independently of whether or not -fPIC is used. The aforementioned patch does that in our branch, but that will need to be cleaned up and submitted to upstream libtool before incorporating it in GCC trunk.
