How does Microsoft handle the fact that UTF-16 is a variable length encoding in their C++ standard library implementation

Question

Having a variable length encoding is indirectly forbidden in the standard.

So I have several questions:

How is the following part of the standard handled?

Answer 1

Two things:

1. There is no "Microsoft STL implementation". The C++ Standard Library shipped with Visual C++ is licensed from Dinkumware.
2. The current C++ Standard knows nothing about Unicode and its encoding forms. std::wstring is merely a container for wchar_t units which happen to be 16-bit on Windows. In practice, if you want to store a UTF-16 encoded string into a wstring, just take into account that you are really storing code units and not code points.