Variable: completion-auto-help
completion-auto-help is a customizable variable defined in
minibuffer.el.gz.
Value
t
Documentation
Non-nil means automatically provide help for invalid completion input.
If the value is t the *Completions* buffer is displayed whenever completion
is requested but cannot be done.
If the value is lazy, the *Completions* buffer is only displayed after
the second failed attempt to complete.
Probably introduced at or before Emacs version 23.1.
Source Code
;; Defined in /usr/src/emacs/lisp/minibuffer.el.gz
(defcustom completion-auto-help t
"Non-nil means automatically provide help for invalid completion input.
If the value is t the *Completions* buffer is displayed whenever completion
is requested but cannot be done.
If the value is `lazy', the *Completions* buffer is only displayed after
the second failed attempt to complete."
:type '(choice (const nil) (const t) (const lazy)))