bug#47711: bug#48841: bug#47711: [PATCH VERSION 2] Add new `completion-filter-completions` API and deferred highlighting

[Dmitry Gutov]

On 14.08.2021 14:29, Eli Zaretskii wrote:
> Text properties are stored separately from the string, so I don't
> think adding properties can in general be referred to as "change".

Are you thinking of C strings?

Lisp strings carry text properties in addition to the array of 
characters. It doesn't really matter where in the memory the properties 
and the characters reside.

> Whether in some particular situation that could count as a "change"
> depends on that situation and on the particular property, of course.

I was talking in the general sense: modifying a value.

One can talk about whether a certain modification matters in certain 
situations, but that's not the way to discount a general principle.

> I'm not sure in the context of completion there's any reason to count
> as "change" adding properties that don't affect display.

For the context in question, whether the properties affect display is 
not particularly important. Properties affecting display just make it 
easier to notice that something's wrong. Bug involving other properties 
should be more difficult to investigate.