Subject: Re: bug#78815: 31.0.50; completions truncated

From: Visuwesh <[email-masked]>
Date: Wed, 18 Jun 2025 10:37:44 +0530

[செவ்வாய் ஜூன் 17, 2025] Colin Baxter wrote:

> 1. emacs -Q <RET>
> 2. C-h f <RET> (for example)
> 3. completion <TAB> (for example)
> 4. Completion buffer opens with 131 possible completions
> 5. In foot of buffer is button that reads:
> [Completions truncated, click here to insert the rest.]
> 6. If button is clicked then further completions are shown.
>
> I didn't think was a bug but others suggest it should be reported.
>
> Best Wishes,
>
> Colin Baxter

This is not a bug, it is a consequence of speeding up the creation of
the *Completions* buffer; from etc/NEWS:

    *** "*Completions*" is now displayed faster when there are many candidates.
    As before, if there are more completion candidates than can be displayed
    in the current frame, only a subset of the candidates is displayed.
    This process is now faster: only that subset of the candidates is
    actually inserted into "*Completions*" until you run a command which
    interacts with the text of the "*Completions*" buffer.  This
    optimization only applies when 'completions-format' is 'horizontal' or
    'one-column'.

Unfortunately, the news entry does not call out the new truncated
thingy.
[ I also remember that there was a way to opt-out of truncation in the
  discussion of this patch, but I don't see it anymore?  ]