Adjust side-effect-free declarations

* lisp/emacs-lisp/byte-opt.el (side-effect-and-error-free-fns):
Add `eql` here.
* lisp/emacs-lisp/cl-macs.el (eql, cl-subst, cl-sublis):
Don't set the `side-effect-free` property here.
`cl-subst` and `cl-sublis` are not side-effect-free.
* lisp/emacs-lisp/cl-extra.el (cl-revappend):
Declare side-effect-free.
* lisp/emacs-lisp/cl-lib.el (cl-copy-list):
Declare side-effect-free and error-free.

lisp/emacs-lisp/byte-opt.el

@@ -1706,7 +1706,7 @@ See Info node `(elisp) Integer Basics'."
 	 charsetp commandp cons consp
 	 current-buffer current-global-map current-indentation
 	 current-local-map current-minor-mode-maps current-time
-	 eobp eolp eq equal
+	 eobp eolp eq equal eql
 	 floatp following-char framep
 	 hash-table-p
 	 identity indirect-function integerp integer-or-marker-p

lisp/emacs-lisp/cl-extra.el

@@ -567,6 +567,7 @@ too large if positive or too small if negative)."
 ;;;###autoload
 (defun cl-revappend (x y)
   "Equivalent to (append (reverse X) Y)."
+  (declare (side-effect-free t))
   (nconc (reverse x) y))
 
 ;;;###autoload

lisp/emacs-lisp/cl-lib.el

@@ -459,6 +459,7 @@ Thus, `(cl-list* A B C D)' is equivalent to `(nconc (list A B C) D)', or to
 (defun cl-copy-list (list)
   "Return a copy of LIST, which may be a dotted list.
 The elements of LIST are not copied, just the list structure itself."
+  (declare (side-effect-free error-free))
   (if (consp list)
       (let ((res nil))
 	(while (consp list) (push (pop list) res))

lisp/emacs-lisp/cl-macs.el

@@ -3690,14 +3690,14 @@ macro that returns its `&whole' argument."
 
 ;;; Things that are side-effect-free.
 (mapc (lambda (x) (function-put x 'side-effect-free t))
-      '(cl-oddp cl-evenp cl-signum last butlast cl-ldiff cl-pairlis cl-gcd
+      '(cl-oddp cl-evenp cl-signum cl-ldiff cl-pairlis cl-gcd
         cl-lcm cl-isqrt cl-floor cl-ceiling cl-truncate cl-round cl-mod cl-rem
         cl-subseq cl-list-length cl-get cl-getf))
 
 ;;; Things that are side-effect-and-error-free.
 (mapc (lambda (x) (function-put x 'side-effect-free 'error-free))
-      '(eql cl-list* cl-subst cl-acons cl-equalp
-        cl-random-state-p copy-tree cl-sublis))
+      '(cl-list* cl-acons cl-equalp
+        cl-random-state-p copy-tree))
 
 ;;; Types and assertions.