bug#48356: 28.0.50; choose-completion discards the suffix after the completion boundary

[Stefan Monnier via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

> ...which translates to "/" because of the double slash -- the filesystem
>  root directory (*). But that's the same data which would be used by any
>  other proposed solution, too.

More or less, tho the "ideal" solution is to do that in the
completion-style code, which has a bit more knowledge about it.

>  So maybe it should be either be fixed in the
>  completion table (avoid adding trailing slash when the last boundary is
>  already followed by slash?), or the insertion code should do some
>  additional post-processing of the completion string.

I think you can fix it in the same ad-hoc way we use elsewhere: compare
the first char after the boundary with the last char of the completion
and drop one of the two if they're the same.

> +             (base-suffix (let ((suffix (buffer-substring (point) end)))
> +                            (substring
> +                             suffix
> +                             (cdr (completion-boundaries string
> +                                                         minibuffer-completion-table
> +                                                         minibuffer-completion-predicate
> +                                                         suffix)))))

I think you want to be careful to pass (buffer-substring start (point))
rather than `string` to `completion-boundaries`.

In theory this approach can "do the wrong thing" with some completion
styles, but AFAIK they haven't been written yet.  🙂


        Stefan