bug#58216: 28.2; New help-for-help hides user key bindings

[Allen Li]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> Stefan Kangas <stefankangas@gmail.com> writes:
>
>>> It's a regression that `C-h M' isn't shown any more,
>>
>> Was `C-h M' displayed before though?
>
> Ah, no, I guess it wasn't.

Before the recent binding of C-h C-h to help-for-help, C-h C-h was
unbound and thus used the default behavior of printing help for all keys
bound to the prefix map.  As an example see the behavior for C-x C-h.
If the user bound a key with C-h prefix, that binding previously would
show up in C-h C-h help.

Example:

User binds C-h M

Before help-for-help was introduced:

C-h C-h would display the user-bound C-h M mapping

After help-for-help was introduced:

C-h C-h does not display any user mappings with C-h prefix

See https://www.gnu.org/software/emacs/manual/html_node/emacs/Keys.html

    Typing the help character (C-h or F1) after a prefix key displays a list
    of the commands starting with that prefix. The sole exception to this
    rule is ESC: ESC C-h is equivalent to C-M-h, which does something else
    entirely. You can, however, use F1 to display a list of commands
    starting with ESC.