bug#64656: 29.0.91; Doc of minibuffer histories and completing-read - automatic addition of completions to DEFAULT list

[Juri Linkov]

>> The problem is that it's too late to identify the
>> existing callers and to add an explicit list of defaults to them.
>
> Or perhaps you mean existing `completing-read'
> calls in the vanilla Emacs code, not user code?
>
> If so, I'd say don't worry about it.

We can't help but worry because we can't break
existing `completing-read' calls.

> Don't second-guess what the `M-n' queue should be for
> existing `completing-read' calls.  Or if you
> really want to, go ahead, investigate them one
> by one.

That's the problem: it's a too big task
to check all existing `completing-read' calls
to add explicit DEFAULTS.