GCC 4.2 made it to testing. I don't expect compatibility problems for gcc itself, but I do expect gcj and fortran programs to break: libgcj and libfortran bumped soname. This means all fortran apps that link against libfortran will need a rebuild and that all apps that have been compiled to native code with gcc-gcj will need a recompile. These programs will get recompiled soon. For gcc-gcj, I don't expect any program to use native code, the only one I've seen for now is gjdoc, which is already built with it. The new GNU hashing style supported by gcc 4.2.0 isn't included, our binutils and glibc don't support it. I've read something about 2MB bigger libraries because of another extra hashtable added to every lib, so I don't feel much for backporting or switching to a 2.17.xx binutils release now. Happy testing!