X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fpcl%2Fboot.lisp;h=b277f876504308868721f987cfc0bdc1a84a6183;hb=0e35b321b97477bcfedaa1a5aed1fa87d635d262;hp=638f6a9004695342adedc0adc27e3d4632800edf;hpb=617079f738359a0d58282badfd49982a263c15dc;p=sbcl.git

diff --git a/src/pcl/boot.lisp b/src/pcl/boot.lisp
index 638f6a9..b277f87 100644
--- a/src/pcl/boot.lisp
+++ b/src/pcl/boot.lisp
@@ -616,12 +616,14 @@ bootstrapping.
 	   (ecase kind
 	     ((:primitive) `(type ,specializer ,parameter))
 	     ((:defined) 
-	      ;; some BUILT-IN-CLASSes (e.g. REAL) are also :DEFINED
-	      ;; types.  Nothing else should be.
 	      (let ((class (find-class specializer nil)))
-		(aver class)
-		(aver (typep class 'built-in-class)))
-	      `(type ,specializer ,parameter))
+                ;; CLASS can be null here if the user has erroneously
+                ;; tried to use a defined type as a specializer; it
+                ;; can be a non-BUILT-IN-CLASS if the user defines a
+                ;; type and calls (SETF FIND-CLASS) in a consistent
+                ;; way.
+                (when (and class (typep class 'built-in-class))
+                  `(type ,specializer ,parameter))))
 	     ((:instance nil)
 	      (let ((class (find-class specializer nil)))
 		(cond