.. _manage_gcc_abi: How to manage the GCC >= 5 ABI ============================== In the GCC 5.1 release libstdc++ introduced a `new library ABI `_ that includes new implementations of ``std::string`` and ``std::list``. These changes were necessary to conform to the 2011 C++ standard which forbids Copy-On-Write strings and requires lists to keep track of their size. You can choose which ABI to use in your Conan packages by adjusting the ``compiler.libcxx``: - **libstdc++**: Old ABI. - **libstdc++11**: New ABI. When Conan create the default profile the first time it runs, adjust the ``compiler.libcxx`` setting to ``libstdc++`` for backwards compatibility. If you are using GCC >= 5, your compiler is likely using the new CXX11 ABI by default (libstdc++11). If you want Conan to use the new ABI, edit the default profile at ``~/.conan/profiles/default`` adjusting ``compiler.libcxx=libstdc++11`` or override this setting in the profile you are using. If you are using the :ref:`CMake build helper ` or the :ref:`AutotoolsBuildEnvironment build helper ` Conan will adjust automatically the ``_GLIBCXX_USE_CXX11_ABI`` flag to manage the ABI.