bug#53590: 28.0.91; icompletion-vertical-mode gets stuck on 'M-x man RET awk'

[Eli Zaretskii <eliz@gnu.org>]

> Date: Thu, 27 Jan 2022 22:36:39 +0000 (UTC)
> From: Van Ly <van.ly@sdf.org>
> 
> When the icompletion-vertical-mode setting is on, looking up a manpage
> feels unresponsive, for example, looking up 'awk' echoes 'a' in the
> minibuffer at the 'Manual entry:' prompt, then finds
> 'awk [No matches]' but shows the manpage on RET.
> 
> When completion-styles is
> 
> > (basic partial-completion emacs22)
> 
> # steps to reproduce behavior
> * start by 'emacs -Q'
> * customize 'icompletion-vertical-mode' to enable for session
> * type 'M-x man RET awk'
> 
> # observed behavior
> # minibuffer at 'Manual entry:' prompt
> * shows 'a' of awk and is unresponsive, then 'awk [No matches]' shows
> * awk RET shows *Man awk* AWK(1) page
> 
> # expected behavior
> # minibuffer at 'Manual entry:' prompt
> * progressively shows 'a' 'aw' 'awk' while typing
> * progressively shows icompletion-vertical-mode suggestions
> * awk RET shows *Man awk* AWK(1) page

I cannot reproduce this: it works for me as expected.  Are you sure
"M-x man" on your system is capable of completion in the default
completion mode in "emacs -Q"?  If not, maybe your man-db database is
missing or outdated?