(file-coding-system-alist): Fix previous commit.

lisp/cus-start.el

@@ -116,26 +116,18 @@ Leaving \"Default\" unchecked is equivalent with specifying a default of
 	      mule
 	      (alist
 	       :key-type (regexp :tag "File regexp")
-	       :value-type
-	       (choice
-		:value (undecided . undecided)
-		(cons :tag "Encoding/decoding pair"
-		      :value (undecided . undecided)
-		      (coding-system :tag "Decoding")
-		      (coding-system :tag "Encoding"))
-		(coding-system
-		 :tag "Single coding system"
-		 :value undecided
-		 :validate
-		 (lambda (widget)
-		   (unless (or (coding-system-p (widget-value widget))
-			       (functionp (widget-value widget)))
-		     (widget-put
-		      widget
-		      :error (format "Invalid coding system: %S"
-				     (widget-value widget)))
-		     widget)))
-		(function :value ignore))))
+	       :value-type (choice
+			    :value (undecided . undecided)
+			    (cons :tag "Encoding/decoding pair"
+				  :value (undecided . undecided)
+				  (coding-system :tag "Decoding")
+				  (coding-system :tag "Encoding"))
+			    (coding-system
+			     :tag "Single coding system"
+			     :value undecided
+			     :match (lambda (widget value)
+				      (and value (not (functionp value)))))
+			    (function :value ignore))))
 	     (selection-coding-system mule coding-system)
 	     ;; dired.c
 	     (completion-ignored-extensions dired