+192: "Python treats free type declarations as promises."
+ b. What seemed like the same fundamental problem as bug 192a, but
+ was not fixed by the same (APD "more strict type checking
+ sbcl-devel 2002-08-97) patch:
+ (DOTIMES (I ...) (DOTIMES (J ...) (DECLARE ...) ...)):
+ (declaim (optimize (speed 1) (safety 3)))
+ (defun trust-assertion (i)
+ (dotimes (j i)
+ (declare (type (mod 4) i)) ; when commented out, behavior changes!
+ (unless (< i 5)
+ (print j))))
+ (trust-assertion 6) ; prints nothing unless DECLARE is commented out
+
+193: "unhelpful CLOS error reporting when the primary method is missing"
+ In sbcl-0.7.7, when
+ (defmethod foo :before ((x t)) (print x))
+ is the only method defined on FOO, the error reporting when e.g.
+ (foo 12)
+ is relatively unhelpful:
+ There is no primary method for the generic function
+ #<STANDARD-GENERIC-FUNCTION FOO (1)>.
+ with the offending argument nowhere visible in the backtrace. This
+ continues even if there *are* primary methods, just not for the
+ specified arg type, e.g.
+ (defmethod foo ((x character)) (print x))
+ (defmethod foo ((x string)) (print x))
+ (defmethod foo ((x pathname)) ...)
+ In that case it could be very helpful to know what argument value is
+ falling through the cracks of the defined primary methods, but the
+ error message stays the same (even BACKTRACE doesn't tell you what the
+ bad argument value is).
+
+194: "no error from (THE REAL '(1 2 3)) in some cases"
+ fixed parts:
+ a. In sbcl-0.7.7.9,
+ (multiple-value-prog1 (progn (the real '(1 2 3))))
+ returns (1 2 3) instead of signalling an error. This was fixed by
+ APD's "more strict type checking patch", but although the fixed
+ code (in sbcl-0.7.7.19) works (signals TYPE-ERROR) interactively,
+ it's difficult to write a regression test for it, because
+ (IGNORE-ERRORS (MULTIPLE-VALUE-PROG1 (PROGN (THE REAL '(1 2 3)))))
+ still returns (1 2 3).
+ still-broken parts:
+ b. (IGNORE-ERRORS (MULTIPLE-VALUE-PROG1 (PROGN (THE REAL '(1 2 3)))))
+ returns (1 2 3). (As above, this shows up when writing regression
+ tests for fixed-ness of part a.)
+ c. Also in sbcl-0.7.7.9, (IGNORE-ERRORS (THE REAL '(1 2 3))) => (1 2 3).
+ d. At the REPL,
+ (null (ignore-errors
+ (let ((arg1 1)
+ (arg2 (identity (the real #(1 2 3)))))
+ (if (< arg1 arg2) arg1 arg2))))
+ => T
+ but putting the same expression inside (DEFUN FOO () ...),
+ (FOO) => NIL.
+ notes:
+ * Actually this entry is probably multiple bugs, as
+ Alexey Dejneka commented on sbcl-devel 2002-09-03:)
+ I don't think that placing these two bugs in one entry is
+ a good idea: they have different explanations. The second
+ (min 1 nil) is caused by flushing of unused code--IDENTITY
+ can do nothing with it. So it is really bug 122. The first
+ (min nil) is due to M-V-PROG1: substituting a continuation
+ for the result, it forgets about type assertion. The purpose
+ of IDENTITY is to save the restricted continuation from
+ inaccurate transformations.
+ * Alexey Dejneka pointed out that
+ (IGNORE-ERRORS (IDENTITY (THE REAL '(1 2 3))))
+ works as it should. Also
+ (IGNORE-ERRORS (VALUES (THE REAL '(1 2 3))))
+ works as it should. Perhaps this is another case of VALUES type
+ intersections behaving in non-useful ways?
+
+199: "hairy FUNCTION types confuse the compiler"
+ (reported by APD sbcl-devel 2002-09-15)
+ (DEFUN MUR (F)
+ (EQ NIL (FUNCALL F)))
+
+ (DEFUN FOO (F X)
+ (DECLARE (TYPE (AND FUNCTION (SATISFIES MUR)) F))
+ (FUNCALL F X))
+
+ fails to compile, printing
+ failed AVER:
+ "(AND (EQ (IR2-CONTINUATION-PRIMITIVE-TYPE 2CONT) FUNCTION-PTYPE) (EQ CHECK T))"
+
+ APD further reports that this bug is not present in CMUCL.
+
+201: "Incautious type inference from compound CONS types"
+ (reported by APD sbcl-devel 2002-09-17)
+ (DEFUN FOO (X)
+ (LET ((Y (CAR (THE (CONS INTEGER *) X))))
+ (SETF (CAR X) NIL)
+ (FORMAT NIL "~S IS ~S, Y = ~S"
+ (CAR X)
+ (TYPECASE (CAR X)
+ (INTEGER 'INTEGER)
+ (T '(NOT INTEGER)))
+ Y)))
+
+ (FOO ' (1 . 2)) => "NIL IS INTEGER, Y = 1"
+
+203:
+ Compiler does not check THEs on unused values, e.g. in
+
+ (progn (the real (list 1)) t)
+
+ This situation may appear during optimizing away degenerate cases of
+ certain functions: see bugs 54, 192b.
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