Subject: 30.0.50; describe-keymap shows unreachable parent map bindings

From: Phil Sainty <[email-masked]>
Date: Sun, 29 Oct 2023 02:34:41 +1300

The following code demonstrates this bug involving parent keymaps:

;; The parent keymap binds key sequence "a b"
;; (making "a" a prefix key with a submap).

(defvar my-keymap-parent
   (let ((map (make-sparse-keymap)))
     (define-key map (kbd "a b") 'foo)
     map))

;; The child keymap binds a command directly to "a" meaning
;; that the parent's submap is not accessible from the child.

(defvar my-keymap-child
   (let ((map (make-sparse-keymap)))
     (set-keymap-parent map my-keymap-parent)
     (define-key map (kbd "a") 'bar)
     map))

;; However (describe-keymap 'my-keymap-child) displays the "a b"
;; binding as if it were a useable key sequence:

Key             Binding
------------------------
a               bar

a b             foo

I think that this output should only show the "a" binding.

-Phil

In GNU Emacs 30.0.50 (build 1, x86_64-pc-linux-gnu, X toolkit, cairo
  version 1.16.0, Xaw scroll bars) of 2023-09-21 built on phil-lp
Repository revision: 01b80a6f0e40a4390717a79a73c61899e2ec2968
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 
11.0.12101004
System Description: Ubuntu 22.04.3 LTS

Configured using:
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