On Wed, 2008-04-02 at 17:30 -0700, Joe Buck wrote: > On Wed, Apr 02, 2008 at 05:16:23PM -0700, Xiaoxiang Liu wrote: > > I have a question regarding GCC4 version compatibility? In general, > > should two versions with same major version number be compatible? > > Specifically, I want to confirm whether a C++ library built with gcc > > 4.1.X will link correctly using gcc 4.2.2? > > For C++, you need the first two numbers to match. So, 4.1.x with 4.1.y > should work, 4.1.x with 4.2.y probably not.
This is a complex issue, but two versions of G++ produce libraries that are binary compatible if both versions of the compiler follow the same ABI and use compatible versions of libstdc++. By ABI I mean both the Application Binary Interface for the target and the multi-vendor C++ ABI. Changes to both ABIs are documented in GCC release notes, such as http://gcc.gnu.org/gcc-4.2/changes.html . For more information see ABI Policy and Guidelines, The GNU C++ Library Documentation http://gcc.gnu.org/onlinedocs/libstdc++/abi.html Binary Compatibility, GCC Manual http://gcc.gnu.org/onlinedocs/gcc/Compatibility.html Changes within x.y.* are compatible, changes within x.* are compatible if there have been no ABI changes to the compiler or library. At least, that's how things should be; as it says in every GCC source file: GCC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. Janis
