X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcode%2Ftypedefs.lisp;h=6169aceafbb13bed42ab32a14ea34138c927dbd5;hb=8731c1a7c1a585d190151fa881050fb5e14c0616;hp=36c840628d3aa202ec1ac4f5ddd4cf279fb602a1;hpb=4eb1a6d3ad2b7dcc19ac0ec979a1eb1eb049659a;p=sbcl.git

diff --git a/src/code/typedefs.lisp b/src/code/typedefs.lisp
index 36c8406..6169ace 100644
--- a/src/code/typedefs.lisp
+++ b/src/code/typedefs.lisp
@@ -78,7 +78,17 @@
   ;; (since EQ hashing can't be done portably)
   (hash-value (random (1+ most-positive-fixnum))
 	      :type (and fixnum unsigned-byte)
-	      :read-only t))
+	      :read-only t)
+  ;; Can this object contain other types? A global property of our
+  ;; implementation (which unfortunately seems impossible to enforce
+  ;; with assertions or other in-the-code checks and constraints) is
+  ;; that subclasses which don't contain other types correspond to
+  ;; disjoint subsets (except of course for the NAMED-TYPE T, which
+  ;; covers everything). So NUMBER-TYPE is disjoint from CONS-TYPE is
+  ;; is disjoint from MEMBER-TYPE and so forth. But types which can
+  ;; contain other types, like HAIRY-TYPE and INTERSECTION-TYPE, can
+  ;; violate this rule.
+  (might-contain-other-types-p nil :read-only t))
 (def!method print-object ((ctype ctype) stream)
   (print-unreadable-object (ctype stream :type t)
     (prin1 (type-specifier ctype) stream)))