+ It causes insertion of wrong type assertions into generated
+ code. E.g.
+
+ (defun foo (x s)
+ (let ((f (etypecase x
+ (character #'write-char)
+ (integer #'write-byte))))
+ (funcall f x s)
+ (etypecase x
+ (character (write-char x s))
+ (integer (write-byte x s)))))
+
+ Then (FOO #\1 *STANDARD-OUTPUT*) signals type error.
+
+ (In 0.7.9.1 the result type is (FUNCTION * *), so Python does not
+ produce invalid code, but type checking is not accurate. Similar
+ problems exist with VALUES-TYPE-INTERSECTION.)
+
+218: "VALUES type specifier semantics"
+ (THE (VALUES ...) ...) in safe code discards extra values.
+
+ (defun test (x y) (the (values integer) (truncate x y)))
+ (test 10 4) => 2
+
+219: "DEFINE-COMPILER-MACRO in non-toplevel contexts evaluated at compile-time"
+ In sbcl-0.7.9:
+
+ * (defun foo (x)
+ (when x
+ (define-compiler-macro bar (&whole whole)
+ (declare (ignore whole))
+ (print "expanding compiler macro")
+ 1)))
+ FOO
+ * (defun baz (x) (bar))
+ [ ... ]
+ "expanding compiler macro"
+ BAZ
+ * (baz t)
+ 1
+
+220:
+ Sbcl 0.7.9 fails to compile
+
+ (multiple-value-call #'list
+ (the integer (helper))
+ nil)
+
+ Type check for INTEGER is inserted, the result of which serves as
+ the first argument of M-V-C, is inserted after evaluation of NIL. So
+ arguments of M-V-C are pushed in the wrong order. As a temporary
+ workaround type checking was disabled for M-V-Cs in 0.7.9.13. A
+ better solution would be to put a check between evaluation of
+ arguments, but it could be tricky to check result types of PROG1, IF
+ etc.
+
+222: "environment problems in PCL"
+ Evaluating
+
+ (symbol-macrolet ((x 1))
+ (defmethod foo (z)
+ (macrolet ((ml (form) `(progn ,form ,x)))
+ (ml (print x)))))
+
+ causes
+
+ debugger invoked on condition of type UNBOUND-VARIABLE:
+ The variable X is unbound.
+