> you can use C++ with templates and not only have much cleaner code, but also avoid forcing the compiler to inline every single call to array_push_back

Actually, you really, really, really want to inline every call to push_back for std::vector. Here is a relevant presentation by Chandler Carruth https://www.youtube.com/watch?v=s4wnuiCwTGU . But, hey, you don't want to make the compiler work for you :).