bug#31138: Native json slower than json.el

[Dmitry Gutov]

On 24.04.2019 9:20, Eli Zaretskii wrote:

> We are talking about a function that expects UTF-8 strings, so
> "non-UTF-8" and "invalid UTF-8" are 2 different ways of saying the
> same thing.

Right, except for the emphasis. But since we're talking about 
documentation, there's a difference between saying "parsing of non-UTF-8 
got slower" and "parsing of invalid UTF-8 got slower".

> However, note that various 7-bit encodings will be taken by such an
> interface as valid UTF-8, since all the bytes are 7-bit ASCII.
> There's nothing we can do about that, just something to keep in mind
> (it isn't supposed to happen in correct usage).

IIUC, in the case the "proper" UTF-8 decoder would do exactly the same 
thing in this case as the "fast path" upon discussion.

BTW, this is a case one could call both "non-UTF-8" and "valid UTF-8".