Assuming all things use the same rtti and exception settings and all are using same C++ standard library (libstdc++ vs libc++) And then there are other flags -

Assuming all things use the same rtti and exception settings and all are using same C++ standard library (libstdc++ vs libc++) And then there are other flags - for instance when gcc/libstdc++ broke std::string in order to switch from a recounted string to a non-refcounted with small string optimisation in order to be C+11 compatible ... Sure, there are system defaults, but things vary and often recompiling everything and statically linking avoids those issues.