bug#50804: Command substitutions for keys without keymaps

[Stefan Kangas]

Lars Ingebrigtsen <larsi@gnus.org> writes:

>> I'm not sure about the notation.  Perhaps "\\[[...]]" is okay, or
>> perhaps we want some other delimiter.
>
> What about...  \\`C-h'
>
> Hm.  Possibly too confusing.

Using some other delimiters than "\\[]" would probably be nice though,
because:

    (substitute-command-keys "\\[[C-h]]")
    => "M-x [C-h]"

    (substitute-command-keys "\\`C-h`")
    => "\\‘C-h‘"

The second one will be printed as "\‘C-h‘" on old versions, which isn't
perfect but not too bad.  Even if the extra "\" is distracting, it is at
least not actively misleading...