+;;; a type specifier
+;;;
+;;; FIXME: The SB!KERNEL:INSTANCE here really means CL:CLASS.
+;;; However, the CL:CLASS type is only defined once PCL is loaded,
+;;; which is before this is evaluated. Once PCL is moved into cold
+;;; init, this might be fixable.
+(def!type type-specifier () '(or list symbol sb!kernel:instance))
+