bug#61457: 30.0.50; compiler falsely complains missing ‘describe-char-display’

bug#61457: 30.0.50; compiler falsely complains missing ‘describe-char-display’

[Andreas Röhler]

Hi,

when running ‘M-x byte-compile-file RET’ with the following form in it,

---
(describe-char-display (point) (char-after))
---

compiler complains:

---
In end of data:
foo.el:6831:17: Warning: the function ‘describe-char-display’ is not known
     to be defined.
---

Whereas ‘M-x describe-function RET’ tells correctly:

---
describe-char-display is a byte-compiled Lisp function in
‘descr-text.el’.

(describe-char-display POS CHAR)
---


In GNU Emacs 30.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version
  3.24.33, cairo version 1.16.0) of 2023-02-01
Repository revision: 0214e9021b4dbbda1b6040e3b692f29d77a3b8cc
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12101003
System Description: Ubuntu 22.04.1 LTS

Configured using:
  'configure --with-tree-sitter --with-modules'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GSETTINGS HARFBUZZ JPEG
LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 MODULES NOTIFY INOTIFY PDUMPER PNG
RSVG SECCOMP SOUND THREADS TIFF TOOLKIT_SCROLL_BARS TREE_SITTER X11 XDBE
XIM XINPUT2 XPM GTK3 ZLIB

Important settings:
   value of $LANG: de_DE.UTF-8
   value of $XMODIFIERS: @im=ibus
   locale-coding-system: utf-8-unix

Major mode: elisp-compile

Minor modes in effect:
   tooltip-mode: t
   global-eldoc-mode: t
   show-paren-mode: t
   electric-indent-mode: t
   mouse-wheel-mode: t
   tool-bar-mode: t
   menu-bar-mode: t
   file-name-shadow-mode: t
   global-font-lock-mode: t
   font-lock-mode: t
   blink-cursor-mode: t
   buffer-read-only: t
   line-number-mode: t
   indent-tabs-mode: t
   transient-mark-mode: t
   auto-composition-mode: t
   auto-encryption-mode: t
   auto-compression-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message mailcap yank-media puny dired
dired-loaddefs rfc822 mml mml-sec password-cache epa derived epg rfc6068
epg-config gnus-util time-date subr-x mm-decode mm-bodies mm-encode
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rfc2045 ietf-drums mm-util mail-prsvr mail-utils cl-macs gv skeleton
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ansi-color ring bytecomp byte-compile thingatpt help-fns radix-tree
help-mode misearch multi-isearch cl-loaddefs cl-lib vc-filewise vc-rcs
log-view easy-mmode pcvs-util rmc iso-transl tooltip cconv eldoc paren
electric uniquify ediff-hook vc-hooks lisp-float-type elisp-mode mwheel
term/x-win x-win term/common-win x-dnd tool-bar dnd fontset image
regexp-opt fringe tabulated-list replace newcomment text-mode lisp-mode
prog-mode register page tab-bar menu-bar rfn-eshadow isearch easymenu
timer select scroll-bar mouse jit-lock font-lock syntax font-core
term/tty-colors frame minibuffer nadvice seq simple cl-generic
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romanian slovak czech european ethiopic indian cyrillic chinese
composite emoji-zwj charscript charprop case-table epa-hook
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theme-loaddefs faces cus-face macroexp files window text-properties
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hashtable-print-readable backquote threads dbusbind inotify
dynamic-setting system-font-setting font-render-setting cairo
move-toolbar gtk x-toolkit xinput2 x multi-tty make-network-process
emacs)

Memory information:
((conses 16 110592 10249)
  (symbols 48 19695 0)
  (strings 32 42795 2186)
  (string-bytes 1 841929)
  (vectors 16 13559)
  (vector-slots 8 189901 19612)
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bug#61457: 30.0.50; compiler falsely complains missing ‘describe-char-display’

[Eli Zaretskii]

> Date: Sun, 12 Feb 2023 19:55:08 +0100
> From: Andreas Röhler <andreas.roehler@easy-emacs.de>
> 
> when running ‘M-x byte-compile-file RET’ with the following form in it,
> 
> ---
> (describe-char-display (point) (char-after))
> ---
> 
> compiler complains:
> 
> ---
> In end of data:
> foo.el:6831:17: Warning: the function ‘describe-char-display’ is not known
>      to be defined.

Which is correct: you need to (require 'descr-text).

> Whereas ‘M-x describe-function RET’ tells correctly:
> 
> ---
> describe-char-display is a byte-compiled Lisp function in
> ‘descr-text.el’.
> 
> (describe-char-display POS CHAR)

Which is also correct.

So what is it that you are complaining about here?

bug#61457: 30.0.50; compiler falsely complains missing ‘describe-char-display’

[Andreas Röhler]

Don't understand why `symbol-function' of `help-fns--analyze-function' 
knows about it, but compiler and REPL not.

Am 12.02.23 um 20:21 schrieb Eli Zaretskii:
>> Date: Sun, 12 Feb 2023 19:55:08 +0100
>> From: Andreas Röhler <andreas.roehler@easy-emacs.de>
>>
>> when running ‘M-x byte-compile-file RET’ with the following form in it,
>>
>> ---
>> (describe-char-display (point) (char-after))
>> ---
>>
>> compiler complains:
>>
>> ---
>> In end of data:
>> foo.el:6831:17: Warning: the function ‘describe-char-display’ is not known
>>       to be defined.
> Which is correct: you need to (require 'descr-text).
>
>> Whereas ‘M-x describe-function RET’ tells correctly:
>>
>> ---
>> describe-char-display is a byte-compiled Lisp function in
>> ‘descr-text.el’.
>>
>> (describe-char-display POS CHAR)
> Which is also correct.
>
> So what is it that you are complaining about here?

bug#61457: 30.0.50; compiler falsely complains missing ‘describe-char-display’

[Eli Zaretskii]

> Date: Mon, 13 Feb 2023 09:51:45 +0100
> Cc: 61457@debbugs.gnu.org
> From: Andreas Röhler <andreas.roehler@easy-emacs.de>
> 
> Don't understand why `symbol-function' of `help-fns--analyze-function' 
> knows about it, but compiler and REPL not.

The Help command only knows about its signature and doc string.

Stefan, any comments?

bug#61457: 30.0.50; compiler falsely complains missing ‘describe-char-display’

[Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors]

> Don't understand why `symbol-function' of `help-fns--analyze-function' knows
> about it, but compiler and REPL not.

I believe you're confused:

    ELISP> (symbol-function 'describe-char-display)
    nil
    ELISP> (help-fns--analyze-function 'describe-char-display)
    *** Eval error ***  Symbol’s function definition is void: describe-char-display
    ELISP> 

My crystal ball suggests you have tested these in an Emacs where
`descr-text` happened to be loaded already.


        Stefan

bug#61457: 30.0.50; compiler falsely complains missing ‘describe-char-display’

[Eli Zaretskii]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: Eli Zaretskii <eliz@gnu.org>,  61457@debbugs.gnu.org
> Date: Mon, 13 Feb 2023 14:10:29 -0500
> 
> > Don't understand why `symbol-function' of `help-fns--analyze-function' knows
> > about it, but compiler and REPL not.
> 
> I believe you're confused:
> 
>     ELISP> (symbol-function 'describe-char-display)
>     nil
>     ELISP> (help-fns--analyze-function 'describe-char-display)
>     *** Eval error ***  Symbol’s function definition is void: describe-char-display
>     ELISP> 
> 
> My crystal ball suggests you have tested these in an Emacs where
> `descr-text` happened to be loaded already.

No, "C-h f describe-char-display RET" loads descr-text.

bug#61457: 30.0.50; compiler falsely complains missing ‘describe-char-display’

[Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors]

>> > Don't understand why `symbol-function' of `help-fns--analyze-function' knows
>> > about it, but compiler and REPL not.
>> 
>> I believe you're confused:
>> 
>>     ELISP> (symbol-function 'describe-char-display)
>>     nil
>>     ELISP> (help-fns--analyze-function 'describe-char-display)
>>     *** Eval error ***  Symbol’s function definition is void: describe-char-display
>>     ELISP> 
>> 
>> My crystal ball suggests you have tested these in an Emacs where
>> `descr-text` happened to be loaded already.
>
> No, "C-h f describe-char-display RET" loads descr-text.

`C-h f` is not the same as `symbol-function` or
`help-fns--analyze-function`.  You're just seeing
`help-enable-auto-load` in action.


        Stefan

bug#61457: 30.0.50; compiler falsely complains missing ‘describe-char-display’

[Eli Zaretskii]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: andreas.roehler@easy-emacs.de,  61457@debbugs.gnu.org
> Date: Mon, 13 Feb 2023 16:01:10 -0500
> 
> >> > Don't understand why `symbol-function' of `help-fns--analyze-function' knows
> >> > about it, but compiler and REPL not.
> >> 
> >> I believe you're confused:
> >> 
> >>     ELISP> (symbol-function 'describe-char-display)
> >>     nil
> >>     ELISP> (help-fns--analyze-function 'describe-char-display)
> >>     *** Eval error ***  Symbol’s function definition is void: describe-char-display
> >>     ELISP> 
> >> 
> >> My crystal ball suggests you have tested these in an Emacs where
> >> `descr-text` happened to be loaded already.
> >
> > No, "C-h f describe-char-display RET" loads descr-text.
> 
> `C-h f` is not the same as `symbol-function` or
> `help-fns--analyze-function`.  You're just seeing
> `help-enable-auto-load` in action.

If you read the OP, it was "C-h f" that Andreas used, AFAIU.

bug#61457: 30.0.50; compiler falsely complains missing ‘describe-char-display’

[Andreas Röhler]

Am 14.02.23 um 04:33 schrieb Eli Zaretskii:
>> From: Stefan Monnier <monnier@iro.umontreal.ca>
>> Cc: andreas.roehler@easy-emacs.de,  61457@debbugs.gnu.org
>> Date: Mon, 13 Feb 2023 16:01:10 -0500
>>
>>>>> Don't understand why `symbol-function' of `help-fns--analyze-function' knows
>>>>> about it, but compiler and REPL not.
>>>> I believe you're confused:
>>>>
>>>>      ELISP> (symbol-function 'describe-char-display)
>>>>      nil
>>>>      ELISP> (help-fns--analyze-function 'describe-char-display)
>>>>      *** Eval error ***  Symbol’s function definition is void: describe-char-display
>>>>      ELISP>
>>>>
>>>> My crystal ball suggests you have tested these in an Emacs where
>>>> `descr-text` happened to be loaded already.
>>> No, "C-h f describe-char-display RET" loads descr-text.
>> `C-h f` is not the same as `symbol-function` or
>> `help-fns--analyze-function`.  You're just seeing
>> `help-enable-auto-load` in action.
> If you read the OP, it was "C-h f" that Andreas used, AFAIU.


Correct. BTW have to yank `describe-char-display' at the prompt after 
"Describe function".

When calling C-h f a second time, it's filled in: (default 
describe-char-display):

bug#61457: 30.0.50; compiler falsely complains missing ‘describe-char-display’

[Eli Zaretskii]

> Date: Tue, 14 Feb 2023 09:21:16 +0100
> Cc: 61457@debbugs.gnu.org
> From: Andreas Röhler <andreas.roehler@easy-emacs.de>
> 
> BTW have to yank `describe-char-display' at the prompt after 
> "Describe function".
> 
> When calling C-h f a second time, it's filled in: (default 
> describe-char-display):

That's a feature: it guesses by looking at the "thing at point".

bug#61457: 30.0.50; compiler falsely complains missing ‘describe-char-display’

[Andreas Röhler]

Am 14.02.23 um 14:27 schrieb Eli Zaretskii:
>> Date: Tue, 14 Feb 2023 09:21:16 +0100
>> Cc: 61457@debbugs.gnu.org
>> From: Andreas Röhler <andreas.roehler@easy-emacs.de>
>>
>> BTW have to yank `describe-char-display' at the prompt after
>> "Describe function".
>>
>> When calling C-h f a second time, it's filled in: (default
>> describe-char-display):
> That's a feature: it guesses by looking at the "thing at point".


A similar bug happens with another utility of mine, editing stuff in a 
dired-buffer. Below an example-version:

---

(defun foo ()
   (interactive "*")
     (wdired-change-to-wdired-mode)
     ;; Do some edits
     (wdired-finish-edit))

---

M-x byte-compile-file RET complains

---

In end of data:
eil.el:5:6: Warning: the function ‘wdired-finish-edit’ is not known to be
     defined.
---

Which isn't useful, as (wdired-change-to-wdired-mode) already loaded wdired.