Hi, I'm confused about ABI compatibility for libstdc++ and hope that that someone on this list can enlighten me :-). According to https://gcc.gnu.org/onlinedocs/libstdc++/manual/abi.html ABI forward compatibility is guaranteed from GCC 4.2.2 up to GCC 11. Although, under 'Outstanding Issues' it is not recommended. So is it now okay, or not and does it apply to template code ? But up to our concrete problem. We use Ubuntu 20.04 (GCC 9.3) and got a vendor driver .so build under Ubuntu 16.04 (GCC V5.4) (and can't get a newer build version). This library uses stl types in its interface classes, so it defines some Weck symbols for example for std::vector<SomeClass>. If I now build my own application against the driver I can manage to generate a wild mix of symbols for std::vector<SomeClass> coming from a way newer and the older versions. E.g. push_back from the GCC 5.4 build and constructor destructor initializer_list stuff from GCC 9.3. Is this mixing of template generated code allowed, or are we in for trouble ? Greetings Janosch