[deng]

> As someone much more experienced in other languages like Python and Swift, my biggest surprise when using C++ is that the language standard and the compiler are two different things.

Yes, that's because C++ is a formally standardized language, and Python and Swift are not. C++ is an ISO standard, and it is published in text form. You are free to create your own compiler, and if it works according to the rules written in the official standard, you may call it a standard-conforming compiler. There are of course other languages which are also officially standardized like this (does not have to be ISO), for instance Common Lisp, Scheme and of course Javascript (ECMA). If a language is defined by a reference implementation, then this is an informal way of standardizing your language, and if you want to create your own compiler/interpreter for such a language, you have to carefully evaluate what the reference implementation does.

> I understand it has to do with breaking ABI, but what exactly does this imply?

Very roughly, it means that you cannot link object code with the current ABI with object code that was generated by older compilers with the old ABI (well, it's usually worse: you can link just fine, but your program might or might not crash). This is not unprecedented in C++, we had this when switching from gcc4 to gcc5, it was definitely pretty painful and I'd rather not have this again.