bug#64575: 29.0.92; Help buffers are unnecessarily under Outline mode

bug#64575: 29.0.92; Help buffers are unnecessarily under Outline mode

[Eli Zaretskii]

To reproduce:

  emacs -Q
  C-h f directory-name-p RET

Observe that the *Help* buffer is under Help mode, as expected.

  C-h b

Now the *Help* buffer is under Help mode and Outline minor mode, also
as expected.

  C-h f file-directory-p RET

The *Help* buffer is still under Outline minor mode, although it now
makes no sense, since there are no heading lines in the buffer.

The actual functions you use in "C-h f" don't matter; the point is
that the Outline minor mode, once set by "C-h b", stays turned on in
the *Help* buffers, instead of being reset when not needed.


In GNU Emacs 29.0.92 (build 29, i686-pc-mingw32) of 2023-07-10 built on
 HOME-C4E4A596F7
Repository revision: 419b4d44914701cedf308df58c3e5789715c87e7
Repository branch: emacs-29
Windowing system distributor 'Microsoft Corp.', version 5.1.2600
System Description: Microsoft Windows XP Service Pack 3 (v5.1.0.2600)

Configured using:
 'configure -C --prefix=/d/usr --with-wide-int
 --enable-checking=yes,glyphs 'CFLAGS=-O0 -gdwarf-4 -g3''

Configured features:
ACL GIF GMP GNUTLS HARFBUZZ JPEG JSON LCMS2 LIBXML2 MODULES NOTIFY
W32NOTIFY PDUMPER PNG RSVG SOUND SQLITE3 THREADS TIFF
TOOLKIT_SCROLL_BARS TREE_SITTER WEBP XPM ZLIB

Important settings:
  value of $LANG: ENU
  locale-coding-system: cp1255

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  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
  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 mm-decode mm-bodies mm-encode mail-parse
rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045
ietf-drums mm-util mail-prsvr mail-utils shortdoc text-property-search
thingatpt help-fns radix-tree cl-extra noutline outline icons kmacro
facemenu two-column subr-x help-mode cl-loaddefs cl-lib rmc iso-transl
tooltip cconv eldoc paren electric uniquify ediff-hook vc-hooks
lisp-float-type elisp-mode mwheel dos-w32 ls-lisp disp-table
term/w32-win w32-win w32-vars term/common-win 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
indonesian philippine cham georgian utf-8-lang misc-lang vietnamese
tibetan thai tai-viet lao korean japanese eucjp-ms cp51932 hebrew greek
romanian slovak czech european ethiopic indian cyrillic chinese
composite emoji-zwj charscript charprop case-table epa-hook
jka-cmpr-hook help abbrev obarray oclosure cl-preloaded button loaddefs
theme-loaddefs faces cus-face macroexp files window text-properties
overlay sha1 md5 base64 format env code-pages mule custom widget keymap
hashtable-print-readable backquote threads w32notify w32 lcms2 multi-tty
make-network-process emacs)

Memory information:
((conses 16 60866 13834)
 (symbols 48 6982 0)
 (strings 16 21661 3035)
 (string-bytes 1 493258)
 (vectors 16 10800)
 (vector-slots 8 162298 13373)
 (floats 8 90 170)
 (intervals 40 454 400)
 (buffers 888 13))

bug#64575: 29.0.92; Help buffers are unnecessarily under Outline mode

[Juri Linkov]

> The *Help* buffer is still under Outline minor mode, although it now
> makes no sense, since there are no heading lines in the buffer.

But it has no adverse effect.  OTOH, when some Help command
will insert a heading line, then it will be handled automatically.
For example, 'C-h m' (describe-mode) could take advantage of
outline-minor-mode with heading lines for every displayed minor mode.

> The actual functions you use in "C-h f" don't matter; the point is
> that the Outline minor mode, once set by "C-h b", stays turned on in
> the *Help* buffers, instead of being reset when not needed.

If you still think it should be disabled everywhere outside of 'C-h b',
this could be fixed by such patch:

diff --git a/lisp/help-mode.el b/lisp/help-mode.el
index bf64d032b65..baf924ac8b4 100644
--- a/lisp/help-mode.el
+++ b/lisp/help-mode.el
@@ -498,6 +498,8 @@ help-setup-xref
 because we want to record the \"previous\" position of point so we can
 restore it properly when going back."
   (with-current-buffer (help-buffer)
+    (when (bound-and-true-p outline-minor-mode)
+      (outline-minor-mode -1))
     (when help-xref-stack-item
       (push (cons (point) help-xref-stack-item) help-xref-stack)
       (setq help-xref-forward-stack nil))

bug#64575: 29.0.92; Help buffers are unnecessarily under Outline mode

[Eli Zaretskii]

> From: Juri Linkov <juri@linkov.net>
> Cc: 64575@debbugs.gnu.org
> Date: Wed, 12 Jul 2023 09:35:03 +0300
> 
> > The *Help* buffer is still under Outline minor mode, although it now
> > makes no sense, since there are no heading lines in the buffer.
> 
> But it has no adverse effect.

It isn't a catastrophe, but there are some negative effects.  For
example, it puts the Outline menu on the menu bar, but most of the
items there will either do nothing or signal an error.

It is also confusing to see "Outl" on the mode line of the Help
buffers, but only in some cases and not in others.  It means whatever
features that could be useful to Help are only sometimes available.

> OTOH, when some Help command
> will insert a heading line, then it will be handled automatically.
> For example, 'C-h m' (describe-mode) could take advantage of
> outline-minor-mode with heading lines for every displayed minor mode.

If some Help feature can benefit from outline-minor-mode, it should
turn that mode on by itself, not rely on that being set already by
some other code.

> > The actual functions you use in "C-h f" don't matter; the point is
> > that the Outline minor mode, once set by "C-h b", stays turned on in
> > the *Help* buffers, instead of being reset when not needed.
> 
> If you still think it should be disabled everywhere outside of 'C-h b',
> this could be fixed by such patch:

Thanks, I think this should be installed on master (assuming that it
solves the problem; I didn't have time to try it).

bug#64575: 29.0.92; Help buffers are unnecessarily under Outline mode

[Juri Linkov]

>> OTOH, when some Help command will insert a heading line, then it will
>> be handled automatically.  For example, 'C-h m' (describe-mode) could
>> take advantage of outline-minor-mode with heading lines for every
>> displayed minor mode.
>
> If some Help feature can benefit from outline-minor-mode, it should
> turn that mode on by itself, not rely on that being set already by
> some other code.

I tried to enable outline-minor-mode in the output buffer of 'C-h m',
and it has some problems:

1. outline-regexp of 'C-h b' is not suitable for 'C-h m', because the
output of 'C-h b' is more uniform, but the output of 'C-h m' includes
free-form text that causes false positives for the regexp ".*:$".

2. heading lines of 'C-h m' are beginning with a link, so the link faces
are copied to the outline indicator.

Both these problems could be fixed by adding an asterisk to the beginning
of headings in 'C-h m', for example:

  * Font-Lock minor mode (no indicator):

Does this look nice?  Or should we try to find a regexp for existing output?

>> > The actual functions you use in "C-h f" don't matter; the point is
>> > that the Outline minor mode, once set by "C-h b", stays turned on in
>> > the *Help* buffers, instead of being reset when not needed.
>> 
>> If you still think it should be disabled everywhere outside of 'C-h b',
>> this could be fixed by such patch:
>
> Thanks, I think this should be installed on master (assuming that it
> solves the problem; I didn't have time to try it).

I did more testing, and pushed to master.

bug#64575: 29.0.92; Help buffers are unnecessarily under Outline mode

[Eli Zaretskii]

> From: Juri Linkov <juri@linkov.net>
> Cc: 64575@debbugs.gnu.org
> Date: Thu, 13 Jul 2023 19:39:23 +0300
> 
> I tried to enable outline-minor-mode in the output buffer of 'C-h m',
> and it has some problems:
> 
> 1. outline-regexp of 'C-h b' is not suitable for 'C-h m', because the
> output of 'C-h b' is more uniform, but the output of 'C-h m' includes
> free-form text that causes false positives for the regexp ".*:$".
> 
> 2. heading lines of 'C-h m' are beginning with a link, so the link faces
> are copied to the outline indicator.
> 
> Both these problems could be fixed by adding an asterisk to the beginning
> of headings in 'C-h m', for example:
> 
>   * Font-Lock minor mode (no indicator):
> 
> Does this look nice?  Or should we try to find a regexp for existing output?

I don't know.  We also have ^L that separate sections; can we use that
for Outline, or maybe add some heading after ^L?

> >> > The actual functions you use in "C-h f" don't matter; the point is
> >> > that the Outline minor mode, once set by "C-h b", stays turned on in
> >> > the *Help* buffers, instead of being reset when not needed.
> >> 
> >> If you still think it should be disabled everywhere outside of 'C-h b',
> >> this could be fixed by such patch:
> >
> > Thanks, I think this should be installed on master (assuming that it
> > solves the problem; I didn't have time to try it).
> 
> I did more testing, and pushed to master.

Thanks.  Maybe we should close this bug, and handle the "C-h m" issue
separately.

bug#64575: 29.0.92; Help buffers are unnecessarily under Outline mode

[Juri Linkov]

>> I did more testing, and pushed to master.
>
> Thanks.  Maybe we should close this bug, and handle the "C-h m" issue
> separately.

Created a new bug#64684 for the "C-h m" issue, and closed this one.

bug#64575: 29.0.92; Help buffers are unnecessarily under Outline mode

[Visuwesh]

[புதன் ஜூலை 12, 2023] Juri Linkov wrote:

>> The *Help* buffer is still under Outline minor mode, although it now
>> makes no sense, since there are no heading lines in the buffer.
>
> But it has no adverse effect.  OTOH, when some Help command
> will insert a heading line, then it will be handled automatically.
> For example, 'C-h m' (describe-mode) could take advantage of
> outline-minor-mode with heading lines for every displayed minor mode.

I'm not sure if this issue was fixed in emacs-29 but: after C-h b, say
'C-h f url-retrieve RET' and move the point to the line that says "Each
pair is one of:" and type TAB.  This unintentionally hides text in the
*Help* buffer.

bug#64575: 29.0.92; Help buffers are unnecessarily under Outline mode

[Eli Zaretskii]

> From: Visuwesh <visuweshm@gmail.com>
> Cc: Eli Zaretskii <eliz@gnu.org>,  64575@debbugs.gnu.org
> Date: Sun, 23 Jul 2023 18:46:12 +0530
> 
> [புதன் ஜூலை 12, 2023] Juri Linkov wrote:
> 
> >> The *Help* buffer is still under Outline minor mode, although it now
> >> makes no sense, since there are no heading lines in the buffer.
> >
> > But it has no adverse effect.  OTOH, when some Help command
> > will insert a heading line, then it will be handled automatically.
> > For example, 'C-h m' (describe-mode) could take advantage of
> > outline-minor-mode with heading lines for every displayed minor mode.
> 
> I'm not sure if this issue was fixed in emacs-29

It was fixed on master, so not in Emacs 29.

> after C-h b, say 'C-h f url-retrieve RET' and move the point to the
> line that says "Each pair is one of:" and type TAB.  This
> unintentionally hides text in the *Help* buffer.

This should be fixed on master.