Minor cus-theme.el simplifications

* lisp/cus-theme.el (custom-new-theme-mode, customize-themes)
(custom-theme-choose-mode): Use setq-local.
(customize-create-theme): Ditto.  Use delete-all-overlays.
(describe-theme-1, custom-theme-summary): Simplify logic.

lisp/cus-theme.el

@@ -47,7 +47,7 @@
 Do not call this mode function yourself.  It is meant for internal use."
   (use-local-map custom-new-theme-mode-map)
   (custom--initialize-widget-variables)
-  (set (make-local-variable 'revert-buffer-function) #'custom-theme-revert))
+  (setq-local revert-buffer-function #'custom-theme-revert))
 (put 'custom-new-theme-mode 'mode-class 'special)
 
 (defvar custom-theme-name nil)
@@ -93,15 +93,14 @@ named *Custom Theme*."
   (switch-to-buffer (get-buffer-create (or buffer "*Custom Theme*")))
   (let ((inhibit-read-only t))
     (erase-buffer)
-    (dolist (ov (overlays-in (point-min) (point-max)))
-      (delete-overlay ov)))
+    (delete-all-overlays))
   (custom-new-theme-mode)
   (make-local-variable 'custom-theme-name)
-  (set (make-local-variable 'custom-theme--save-name) theme)
-  (set (make-local-variable 'custom-theme-faces) nil)
-  (set (make-local-variable 'custom-theme-variables) nil)
-  (set (make-local-variable 'custom-theme-description) "")
-  (set (make-local-variable 'custom-theme--migrate-settings) nil)
+  (setq-local custom-theme--save-name theme)
+  (setq-local custom-theme-faces nil)
+  (setq-local custom-theme-variables nil)
+  (setq-local custom-theme-description "")
+  (setq-local custom-theme--migrate-settings nil)
   (make-local-variable 'custom-theme-insert-face-marker)
   (make-local-variable 'custom-theme-insert-variable-marker)
   (make-local-variable 'custom-theme--listed-faces)
@@ -513,8 +512,7 @@ It includes all faces in list FACES."
 			(condition-case nil
 			    (read (current-buffer))
 			  (end-of-file nil)))))
-	    (and sexp (listp sexp)
-		 (eq (car sexp) 'deftheme)
+            (and (eq (car-safe sexp) 'deftheme)
 		 (setq doc (nth 2 sexp)))))))
     (princ "\n\nDocumentation:\n")
     (princ (if (stringp doc)
@@ -552,10 +550,10 @@ It includes all faces in list FACES."
 Do not call this mode function yourself.  It is meant for internal use."
   (use-local-map custom-theme-choose-mode-map)
   (custom--initialize-widget-variables)
-  (set (make-local-variable 'revert-buffer-function)
-       (lambda (_ignore-auto noconfirm)
-	 (when (or noconfirm (y-or-n-p "Discard current choices? "))
-	   (customize-themes (current-buffer))))))
+  (setq-local revert-buffer-function
+              (lambda (_ignore-auto noconfirm)
+                (when (or noconfirm (y-or-n-p "Discard current choices? "))
+                  (customize-themes (current-buffer))))))
 (put 'custom-theme-choose-mode 'mode-class 'special)
 
 ;;;###autoload
@@ -568,7 +566,7 @@ omitted, a buffer named *Custom Themes* is used."
   (let ((inhibit-read-only t))
     (erase-buffer))
   (custom-theme-choose-mode)
-  (set (make-local-variable 'custom--listed-themes) nil)
+  (setq-local custom--listed-themes nil)
   (make-local-variable 'custom-theme-allow-multiple-selections)
   (and (null custom-theme-allow-multiple-selections)
        (> (length custom-enabled-themes) 1)
@@ -662,8 +660,7 @@ Theme files are named *-theme.el in `"))
 			  (condition-case nil
 			      (read (current-buffer))
 			    (end-of-file nil)))))
-	      (and sexp (listp sexp)
-		   (eq (car sexp) 'deftheme)
+              (and (eq (car-safe sexp) 'deftheme)
 		   (setq doc (nth 2 sexp))))))))
     (cond ((null doc)
 	   "(no documentation available)")