Show key bindings on M-x completion (bug#39035)

* lisp/simple.el (read-extended-command--annotation): New function.
(read-extended-command): Use annotation-function to show key-bindings.

diff --git a/etc/NEWS b/etc/NEWS
index 5395f2ccfb2f6ec28495aa89c9685c60cbb4bd14..04ae3a4ac86e3f1117c283605d1d4497788f118c 100644 (file)
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -109,6 +109,9 @@ like cell phones, tablets or cameras.
 \f
 * Incompatible Lisp Changes in Emacs 28.1
 
+** When 'suggest-key-bindings' is non-nil, the completion list of M-x
+shows equivalent key-bindings for all commands that have them.
+
 ** 'equal' no longer examines some contents of window configurations.
 Instead, it considers window configurations to be equal only if they
 are 'eq'.  To compare contents, use 'compare-window-configurations'

diff --git a/lisp/simple.el b/lisp/simple.el
index 2ec3da680f8b509e8fd76474aa9442e1ec80fdca..09447900ded9a2f1f6aa79b8c5a531d16e301a8c 100644 (file)
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -1788,23 +1788,36 @@ to get different commands to edit and resubmit."
             ;; and it serves as a shorthand for "Extended command: ".
             "M-x ")
      (lambda (string pred action)
-       (let ((pred
-              (if (memq action '(nil t))
-                  ;; Exclude obsolete commands from completions.
-                  (lambda (sym)
-                    (and (funcall pred sym)
-                         (or (equal string (symbol-name sym))
-                             (not (get sym 'byte-obsolete-info)))))
-                pred)))
-         (complete-with-action action obarray string pred)))
+       (if (and suggest-key-bindings (eq action 'metadata))
+          '(metadata
+            (annotation-function . read-extended-command--annotation)
+            (category . command))
+         (let ((pred
+                (if (memq action '(nil t))
+                    ;; Exclude obsolete commands from completions.
+                    (lambda (sym)
+                      (and (funcall pred sym)
+                           (or (equal string (symbol-name sym))
+                               (not (get sym 'byte-obsolete-info)))))
+                  pred)))
+           (complete-with-action action obarray string pred))))
      #'commandp t nil 'extended-command-history)))
 
+(defun read-extended-command--annotation (command-name)
+  (let* ((function (and (stringp command-name) (intern-soft command-name)))
+         (binding (where-is-internal function overriding-local-map t)))
+    (when (and binding (not (stringp binding)))
+      (format " (%s)" (key-description binding)))))
+
 (defcustom suggest-key-bindings t
   "Non-nil means show the equivalent key-binding when M-x command has one.
 The value can be a length of time to show the message for.
 If the value is non-nil and not a number, we wait 2 seconds.
 
-Also see `extended-command-suggest-shorter'."
+Also see `extended-command-suggest-shorter'.
+
+Equivalent key-bindings are also shown in the completion list of
+M-x for all commands that have them."
   :group 'keyboard
   :type '(choice (const :tag "off" nil)
                  (integer :tag "time" 2)