Fix alien =

TODO.FACTOR.txt

@@ -1,4 +1,3 @@
-- xref leaks gensyms
 - return type stack effects show "void"
 - httpd fep
 

library/alien/aliens.factor

@@ -23,7 +23,15 @@ sequences ;
 UNION: c-ptr byte-array alien ;
 
 M: alien = ( obj obj -- ? )
-    over alien? [ [ alien-address ] 2apply = ] [ 2drop f ] if ;
+    over alien? [
+        2dup [ expired? ] 2apply 2dup or [
+            2swap 2drop
+        ] [
+            2drop [ alien-address ] 2apply
+        ] if =
+    ] [
+        2drop f
+    ] if ;
 
 global [ "libraries" nest drop ] bind
 

library/test/words.factor

@@ -90,3 +90,7 @@ FORGET: foe
 word word-name "last-word-test" set
 
 [ "test-last" ] [ "last-word-test" get ] unit-test
+
+! xref should not retain references to gensyms
+gensym dup [ * ] define-compound
+[ t ] [ \ * usage [ interned? not ] subset empty? ] unit-test