X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~mdw/git/sod/blobdiff_plain/8152ead4c5c5980414d1a4f21a98e851cc25c9b1..57b365324f35a6237602ab840c23f4f06c8c317c:/src/module-parse.lisp

diff --git a/src/module-parse.lisp b/src/module-parse.lisp
index c5b28a6..747bdf7 100644
--- a/src/module-parse.lisp
+++ b/src/module-parse.lisp
@@ -260,6 +260,21 @@ (defun parse-class-body (scanner pset name supers)
   (with-parser-context (token-scanner-context :scanner scanner)
     (when name (make-class-type name))
     (let* ((duff (null name))
+	   (superclasses
+	    (let ((superclasses (restart-case
+				    (mapcar #'find-sod-class
+					    (or supers (list "SodObject")))
+				  (continue ()
+				    (setf duff t)
+				    (list (find-sod-class "SodObject"))))))
+	      (find-duplicates (lambda (first second)
+				 (declare (ignore second))
+				 (setf duff t)
+				 (cerror* "Class `~A' has duplicate ~
+					   direct superclass `~A'"
+					  name first))
+			       superclasses)
+	      (delete-duplicates superclasses)))
 	   (synthetic-name (or name
 			       (let ((var (synthetic-name)))
 				 (unless pset
@@ -267,14 +282,7 @@ (defun parse-class-body (scanner pset name supers)
 				 (unless (pset-get pset "nick")
 				   (add-property pset "nick" var :type :id))
 				 var)))
-	   (class (make-sod-class synthetic-name
-				  (restart-case
-				      (mapcar #'find-sod-class
-					      (or supers (list "SodObject")))
-				    (continue ()
-				      (setf duff t)
-				      (list (find-sod-class "SodObject"))))
-				  pset scanner))
+	   (class (make-sod-class synthetic-name superclasses pset scanner))
 	   (nick (sod-class-nickname class)))
 
       (labels ((must-id ()