Function-quote completion property of declare form

For discussion, see the following thread:
https://lists.gnu.org/r/emacs-devel/2021-02/msg01666.html

* lisp/emacs-lisp/byte-run.el (byte-run--set-completion): Quote with
'function' for syntactical consistency with other declare form
properties.  This allows writing (declare (completion foo)) instead
of (declare (completion 'foo)).
* lisp/emacs-lisp/easymenu.el (easy-menu-do-define):
* lisp/gnus/gnus-sum.el (gnus-summary-make-menu-bar): Prefer
function-put over put for function symbols.
* lisp/subr.el (ignore, undefined): Remove #'-quoting from declare
form; it is no longer needed.

lisp/emacs-lisp/byte-run.el

@@ -149,7 +149,7 @@ The return value of this function is not used."
 (defalias 'byte-run--set-completion
   #'(lambda (f _args val)
       (list 'function-put (list 'quote f)
-            ''completion-predicate val)))
+            ''completion-predicate (list 'function val))))
 
 (defalias 'byte-run--set-modes
   #'(lambda (f _args &rest val)

lisp/emacs-lisp/easymenu.el

@@ -184,12 +184,12 @@ This is expected to be bound to a mouse event."
 				  (funcall
 				   (or (plist-get (get symbol 'menu-prop)
 						  :filter)
-				       'identity)
+                                       #'identity)
 				   (symbol-function symbol)))
 			     symbol))))
       ;; These symbols are commands, but not interesting for users
       ;; to `M-x TAB'.
-      (put symbol 'completion-predicate 'ignore))
+      (function-put symbol 'completion-predicate #'ignore))
     (dolist (map (if (keymapp maps) (list maps) maps))
       (define-key map
         (vector 'menu-bar (easy-menu-intern (car menu)))

lisp/gnus/gnus-sum.el

@@ -2517,7 +2517,7 @@ gnus-summary-show-article-from-menu-as-charset-%s" cs))))
 			       (let ((gnus-summary-show-article-charset-alist
 				      `((1 . ,cs))))
 				 (gnus-summary-show-article 1))))
-		       (put command 'completion-predicate 'ignore)
+                       (function-put command 'completion-predicate #'ignore)
 		       `[,(symbol-name cs) ,command t]))
 		   (sort (coding-system-list) #'string<)))))
 	     ("Washing"

lisp/subr.el

@@ -375,7 +375,7 @@ PREFIX is a string, and defaults to \"g\"."
   "Do nothing and return nil.
 This function accepts any number of ARGUMENTS, but ignores them.
 Also see `always'."
-  (declare (completion #'ignore))
+  (declare (completion ignore))
   (interactive)
   nil)
 
@@ -923,7 +923,7 @@ For an approximate inverse of this, see `key-description'."
 
 (defun undefined ()
   "Beep to tell the user this binding is undefined."
-  (declare (completion #'ignore))
+  (declare (completion ignore))
   (interactive)
   (ding)
   (if defining-kbd-macro