+(defun sb!xc:upgraded-array-element-type (spec &optional environment)
+ #!+sb-doc
+ "Return the element type that will actually be used to implement an array
+ with the specifier :ELEMENT-TYPE Spec."
+ (declare (ignore environment))
+ (if (unknown-type-p (specifier-type spec))
+ (error "undefined type: ~S" spec)
+ (type-specifier (array-type-specialized-element-type
+ (specifier-type `(array ,spec))))))
+