From: Chris Roberts via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
To: 72511@debbugs.gnu.org
Subject: bug#72511: 30.0.50; prefix-completions is always nil in help--symbol-completion-table
Date: Wed, 7 Aug 2024 13:53:05 +0200 [thread overview]
Message-ID: <20240807135305.189c2c3e@cdr> (raw)
On lines 209-214 inside the function `help--symbol-complete-table' in
help-fns.el there is a following block of code:
(when help-enable-completion-autoload
(let ((prefixes (radix-tree-prefixes (help-definition-prefixes) string)))
(help--load-prefixes prefixes)))
(let ((prefix-completions
(and help-enable-completion-autoload
(mapcar #'intern (all-completions string definition-prefixes)))))
By default, `help-enable-completion-autoload' is t, so this code should
normally run. The perceived problem here is that the definition of
`help-definition-prefixes' function is as follows:
(defun help-definition-prefixes ()
"Return the up-to-date radix-tree form of `definition-prefixes'."
(when (> (hash-table-count definition-prefixes) 0)
(maphash (lambda (prefix files)
(let ((old (radix-tree-lookup help-definition-prefixes prefix)))
(setq help-definition-prefixes
(radix-tree-insert help-definition-prefixes
prefix (append old files)))))
definition-prefixes)
(clrhash definition-prefixes))
help-definition-prefixes)
Because of the `clrhash', `definition-prefixes' will always be empty
after the function call to `help-definition-prefixes'. So in practice,
`definition-prefixes' will always have zero elements when we're trying
to calculate `prefix-completions', which makes the calls to
`all-completions' and `mapcar' basically no-ops. The end result is that
`prefix-completions' will always be NIL.
This can be verified by evaluating the following code in emacs -Q:
(require 'radix-tree)
(require 'help-fns)
(let ((string "string-remove-prefix"))
(format "Definition prefixes count before: %d\n%sDefinition prefixes count after: %d\nPrefix completions: %s\n"
(hash-table-count definition-prefixes)
(or
(when help-enable-completion-autoload
(let ((prefixes (radix-tree-prefixes (help-definition-prefixes) string)))
(help--load-prefixes prefixes)))
"")
(hash-table-count definition-prefixes)
(let ((prefix-completions
(and help-enable-completion-autoload
(mapcar #'intern (all-completions string definition-prefixes)))))
prefix-completions)))
This has been first introduced in commit fd8084a (Automatically find
vars and functions via definition-prefixes)
I'm not sure if this was the intended behavior or not, but it seemed
suspicious to me, so I decided it's better to report it.
It might also be useful to note that `prefix-completion' is used in the
following way:
(complete-with-action action obarray string
(if pred (lambda (sym)
(or (funcall pred sym)
(memq sym prefix-completions)))))
I'm not sure what `pred' will be in this context, or what impact
`prefix-completions' being always NIL will have, if any. But I believe
that at the very least the code pertaining to `prefix-completions' could
concievably be removed.
Also, was clearing out the entirety of `definition-prefixes' on completion
really the intended behavior? As it stands, just C-h f s <TAB> is enough
to completely truncate it.
In GNU Emacs 30.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version
3.24.33, cairo version 1.16.0) of 2024-01-09 built on cdr
Repository revision: 774c8ec74c98d69d56b2511a613145f2b69fb2eb
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version
11.0.12101004 System Description: Linux Mint 21.2
Configured features:
CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GSETTINGS HARFBUZZ JPEG
LIBSELINUX LIBXML2 MODULES NOTIFY INOTIFY PDUMPER PNG SECCOMP SOUND
SQLITE3 THREADS TIFF TOOLKIT_SCROLL_BARS X11 XDBE XIM XINPUT2 XPM GTK3
ZLIB
next reply other threads:[~2024-08-07 11:53 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-07 11:53 Chris Roberts via Bug reports for GNU Emacs, the Swiss army knife of text editors [this message]
2024-08-07 14:20 ` bug#72511: 30.0.50; prefix-completions is always nil in help--symbol-completion-table Eli Zaretskii
2024-08-14 15:50 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2024-08-17 9:35 ` Eli Zaretskii
2024-08-20 12:13 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
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