bug#57529: 28.1; `C-c C-x' prefix key and keymap, `C-c C-x C-h'

bug#57529: 28.1; `C-c C-x' prefix key and keymap, `C-c C-x C-h'

[Drew Adams]

Dunno, but this seems like a bug (you decide):

https://emacs.stackexchange.com/q/73390/

`C-c' is a prefix key bound to `mode-specific-map', but it seems to be
set up in C source code.  `C-c C-x' is apparently defined (unlike, say,
`C-c C-x 4') as a prefix key, but it's not clear what its keymap is (and
it's apparently empty by default).

Dunno what changes should be made, to make clear to users what the story
is - why, for example, `C-c C-x' just waits for another key, even though
there's no such key defined in the keymap.

Maybe this is a more general "problem", for empty prefix keys?  Or is it
a result of the prefix being defined in C?

In GNU Emacs 28.1 (build 2, x86_64-w64-mingw32)
 of 2022-04-21 built on AVALON
Windowing system distributor 'Microsoft Corp.', version 10.0.19044
System Description: Microsoft Windows 10 Pro (v10.0.2009.19044.1889)

Configured using:
 'configure --with-modules --without-dbus --with-native-compilation
 --without-compress-install CFLAGS=-O2'

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

(NATIVE_COMP present but libgccjit not available)

Important settings:
  value of $LANG: ENU
  locale-coding-system: cp1252

bug#57529: 28.1; `C-c C-x' prefix key and keymap, `C-c C-x C-h'

[Eli Zaretskii]

> From: Drew Adams <drew.adams@oracle.com>
> Date: Thu, 1 Sep 2022 18:05:46 +0000
> 
> Dunno, but this seems like a bug (you decide):
> 
> https://emacs.stackexchange.com/q/73390/
> 
> `C-c' is a prefix key bound to `mode-specific-map', but it seems to be
> set up in C source code.

Why do you think it is set up in C?  "C-h v" tells me otherwise.

> `C-c C-x' is apparently defined (unlike, say,
> `C-c C-x 4') as a prefix key, but it's not clear what its keymap is (and
> it's apparently empty by default).
> 
> Dunno what changes should be made, to make clear to users what the story
> is - why, for example, `C-c C-x' just waits for another key, even though
> there's no such key defined in the keymap.
> 
> Maybe this is a more general "problem", for empty prefix keys?  Or is it
> a result of the prefix being defined in C?

There's a good answer on stackexchange for this "problem", and I'm not
sure what else would we need to do about this report except close it.

bug#57529: 28.1; `C-c C-x' prefix key and keymap, `C-c C-x C-h'

[Drew Adams]

> There's a good answer on stackexchange for this

There is now, yes.

> and I'm not sure what else would we need to
> do about this report except close it.

There's this, from that good answer:

  The automatic help system from pressing C-h
  (help-char) after a prefix key isn't aware of
  translation maps, which is why it doesn't help here.

Is that unawareness by design?  Inevitable?  Or
is it feasible to imagine an enhancement that
lets you use `C-h' in a given major mode to see
the `C-c C-x' bindings in that mode?

If that's not a ridiculous enhancement request
then consider this report to request it.  If
no such enhancement is feasible or makes sense
then feel free to close this.  Thx.