This is not safe in general, even within a single language. For instance, on Windows, it is essentially required that a pointer is freed by code from the dynami

This is not safe in general, even within a single language. For instance, on Windows, it is essentially required that a pointer is freed by code from the dynamic library (even if they're both written in, say, C) that allocated it, because (IIRC) they could be using different versions of the platform allocator.