Re: What lookup-key returns for an undefined key

[Luc Teirlinck]

Eli Zaretskii wrote:

   In Emacs 21.3, lookup-key returns `undefined' for an undefined key; in
   the current CVS it returns nil.

In what concrete way has the behavior of `lookup-key' changed since
21.3?  I could not find any indications of such a change in the
changelogs, nor in actual behavior.  The following produced identical
*ielm* runs in 21.3 and this morning's CVS:

ELISP> (setq kmp (make-sparse-keymap))
(keymap)

ELISP> (define-key kmp "\C-a" 'undefined)
undefined
ELISP> (lookup-key kmp "\C-a")
undefined
ELISP> (lookup-key kmp "\C-b")
nil
ELISP> (lookup-key kmp "\C-a" t)
undefined
ELISP> (lookup-key kmp "\C-b" t)
nil
ELISP>