+
+352: forward-referenced-class trouble
+ reported by Bruno Haible on sbcl-devel
+ (defclass c (a) ())
+ (setf (class-name (find-class 'a)) 'b)
+ (defclass a () (x))
+ (defclass b () (y))
+ (make-instance 'c)
+ Expected: an instance of c, with a slot named x
+ Got: debugger invoked on a SIMPLE-ERROR in thread 78906:
+ While computing the class precedence list of the class named C.
+ The class named B is a forward referenced class.
+ The class named B is a direct superclass of the class named C.
+
+ [ Is this actually a bug? DEFCLASS only replaces an existing class
+ when the class name is the proper name of that class, and in the
+ above code the class found by (FIND-CLASS 'A) does not have a
+ proper name. CSR, 2006-08-07 ]
+
+353: debugger suboptimalities on x86
+ On x86 backtraces for undefined functions start with a bogus stack
+ frame, and backtraces for throws to unknown catch tags with a "no
+ debug information" frame. These are both due to CODE-COMPONENT-FROM-BITS
+ (used on non-x86 platforms) being a more complete solution then what
+ is done on x86.
+
+ On x86/linux large portions of tests/debug.impure.lisp have been commented
+ out as failures. The probable culprit for these problems is in x86-call-context
+ (things work fine on x86/freebsd).
+
+ More generally, the debugger internals suffer from excessive x86/non-x86
+ conditionalization and OAOOMization: refactoring the common parts would
+ be good.
+
+354: XEPs in backtraces
+ Under default compilation policy
+ (defun test ()
+ (throw :unknown t))
+ (test)
+ Has the XEP for TEST in the backtrace, not the TEST frame itself.
+ (sparc and x86 at least)
+
+ Since SBCL 0.8.20.1 this is hidden unless *SHOW-ENTRY-POINT-DETAILS*
+ is true (instead there appear two TEST frames at least on ppc). The
+ underlying cause seems to be that SB-C::TAIL-ANNOTATE will not merge
+ the tail-call for the XEP, since Python has by that time proved that
+ the function can never return; same happens if the function holds an
+ unconditional call to ERROR.
+
+356: PCL corruption
+ (reported by Bruno Haible)
+ After the "layout depth conflict" error, the CLOS is left in a state where
+ it's not possible to define new standard-class subclasses any more.
+ Test case:
+ (defclass prioritized-dispatcher ()
+ ((dependents :type list :initform nil)))
+ (defmethod sb-pcl:validate-superclass ((c1 sb-pcl:funcallable-standard-class)
+ (c2 (eql (find-class 'prioritized-dispatcher))))
+ t)
+ (defclass prioritized-generic-function (prioritized-dispatcher standard-generic-function)
+ ()
+ (:metaclass sb-pcl:funcallable-standard-class))
+ ;; ERROR, Quit the debugger with ABORT
+ (defclass typechecking-reader-class (standard-class)
+ ())
+ Expected: #<STANDARD-CLASS TYPECHECKING-READER-CLASS>
+ Got: ERROR "The assertion SB-PCL::WRAPPERS failed."
+
+ [ This test case does not cause the error any more. However,
+ similar problems can be observed with
+
+ (defclass foo (standard-class) ()
+ (:metaclass sb-mop:funcallable-standard-class))
+ (sb-mop:finalize-inheritance (find-class 'foo))
+ ;; ERROR, ABORT
+ (defclass bar (standard-class) ())
+ (make-instance 'bar)
+ ]
+
+357: defstruct inheritance of initforms
+ (reported by Bruno Haible)
+ When defstruct and defclass (with :metaclass structure-class) are mixed,
+ 1. some slot initforms are ignored by the DEFSTRUCT generated constructor
+ function, and
+ 2. all slot initforms are ignored by MAKE-INSTANCE. (This can be arguably
+ OK for initforms that were given in a DEFSTRUCT form, but for those
+ given in a DEFCLASS form, I think it qualifies as a bug.)
+ Test case:
+ (defstruct structure02a
+ slot1
+ (slot2 t)
+ (slot3 (floor pi)))
+ (defclass structure02b (structure02a)
+ ((slot4 :initform -44)
+ (slot5)
+ (slot6 :initform t)
+ (slot7 :initform (floor (* pi pi)))
+ (slot8 :initform 88))
+ (:metaclass structure-class))
+ (defstruct (structure02c (:include structure02b (slot8 -88)))
+ slot9
+ (slot10 t)
+ (slot11 (floor (exp 3))))
+ ;; 1. Form:
+ (let ((a (make-structure02c)))
+ (list (structure02c-slot4 a)
+ (structure02c-slot5 a)
+ (structure02c-slot6 a)
+ (structure02c-slot7 a)))
+ Expected: (-44 nil t 9)
+ Got: (SB-PCL::..SLOT-UNBOUND.. SB-PCL::..SLOT-UNBOUND..
+ SB-PCL::..SLOT-UNBOUND.. SB-PCL::..SLOT-UNBOUND..)
+ ;; 2. Form:
+ (let ((b (make-instance 'structure02c)))
+ (list (structure02c-slot2 b)
+ (structure02c-slot3 b)
+ (structure02c-slot4 b)
+ (structure02c-slot6 b)
+ (structure02c-slot7 b)
+ (structure02c-slot8 b)
+ (structure02c-slot10 b)
+ (structure02c-slot11 b)))
+ Expected: (t 3 -44 t 9 -88 t 20)
+ Got: (0 0 0 0 0 0 0 0)
+
+359: wrong default value for ensure-generic-function's :generic-function-class argument
+ (reported by Bruno Haible)
+ ANSI CL is silent on this, but the MOP's specification of ENSURE-GENERIC-FUNCTION says:
+ "The remaining arguments are the complete set of keyword arguments
+ received by ENSURE-GENERIC-FUNCTION."
+ and the spec of ENSURE-GENERIC-FUNCTION-USING-CLASS:
+ ":GENERIC-FUNCTION-CLASS - a class metaobject or a class name. If it is not
+ supplied, it defaults to the class named STANDARD-GENERIC-FUNCTION."
+ This is not the case in SBCL. Test case:
+ (defclass my-generic-function (standard-generic-function)
+ ()
+ (:metaclass sb-pcl:funcallable-standard-class))
+ (setf (fdefinition 'foo1)
+ (make-instance 'my-generic-function :name 'foo1))
+ (ensure-generic-function 'foo1
+ :generic-function-class (find-class 'standard-generic-function))
+ (class-of #'foo1)
+ ; => #<SB-MOP:FUNCALLABLE-STANDARD-CLASS STANDARD-GENERIC-FUNCTION>
+ (setf (fdefinition 'foo2)
+ (make-instance 'my-generic-function :name 'foo2))
+ (ensure-generic-function 'foo2)
+ (class-of #'foo2)
+ Expected: #<SB-MOP:FUNCALLABLE-STANDARD-CLASS STANDARD-GENERIC-FUNCTION>
+ Got: #<SB-MOP:FUNCALLABLE-STANDARD-CLASS MY-GENERIC-FUNCTION>
+
+362: missing error when a slot-definition is created without a name
+ (reported by Bruno Haible)
+ The MOP says about slot-definition initialization:
+ "The :NAME argument is a slot name. An ERROR is SIGNALled if this argument
+ is not a symbol which can be used as a variable name. An ERROR is SIGNALled
+ if this argument is not supplied."
+ Test case:
+ (make-instance (find-class 'sb-pcl:standard-direct-slot-definition))
+ Expected: ERROR
+ Got: #<SB-MOP:STANDARD-DIRECT-SLOT-DEFINITION NIL>
+
+363: missing error when a slot-definition is created with a wrong documentation object
+ (reported by Bruno Haible)
+ The MOP says about slot-definition initialization:
+ "The :DOCUMENTATION argument is a STRING or NIL. An ERROR is SIGNALled
+ if it is not. This argument default to NIL during initialization."
+ Test case:
+ (make-instance (find-class 'sb-pcl:standard-direct-slot-definition)
+ :name 'foo
+ :documentation 'not-a-string)
+ Expected: ERROR
+ Got: #<SB-MOP:STANDARD-DIRECT-SLOT-DEFINITION FOO>
+
+369: unlike-an-intersection behavior of VALUES-TYPE-INTERSECTION
+ In sbcl-0.8.18.2, the identity $(x \cap y \cap y)=(x \cap y)$
+ does not hold for VALUES-TYPE-INTERSECTION, even for types which
+ can be intersected exactly, so that ASSERTs fail in this test case:
+ (in-package :cl-user)
+ (let ((types (mapcar #'sb-c::values-specifier-type
+ '((values (vector package) &optional)
+ (values (vector package) &rest t)
+ (values (vector hash-table) &rest t)
+ (values (vector hash-table) &optional)
+ (values t &optional)
+ (values t &rest t)
+ (values nil &optional)
+ (values nil &rest t)
+ (values sequence &optional)
+ (values sequence &rest t)
+ (values list &optional)
+ (values list &rest t)))))
+ (dolist (x types)
+ (dolist (y types)
+ (let ((i (sb-c::values-type-intersection x y)))
+ (assert (sb-c::type= i (sb-c::values-type-intersection i x)))
+ (assert (sb-c::type= i (sb-c::values-type-intersection i y)))))))
+
+370: reader misbehaviour on large-exponent floats
+ (read-from-string "1.0s1000000000000000000000000000000000000000")
+ causes the reader to attempt to create a very large bignum (which it
+ will then attempt to coerce to a rational). While this isn't
+ completely wrong, it is probably not ideal -- checking the floating
+ point control word state and then returning the relevant float
+ (most-positive-short-float or short-float-infinity) or signalling an
+ error immediately would seem to make more sense.
+
+372: floating-point overflow not signalled on ppc/darwin
+ The following assertions in float.pure.lisp fail on ppc/darwin
+ (Mac OS X version 10.3.7):
+ (assert (raises-error? (scale-float 1.0 most-positive-fixnum)
+ floating-point-overflow))
+ (assert (raises-error? (scale-float 1.0d0 (1+ most-positive-fixnum))
+ floating-point-overflow)))
+ as the SCALE-FLOAT just returns
+ #.SB-EXT:SINGLE/DOUBLE-FLOAT-POSITIVE-INFINITY. These tests have been
+ disabled on Darwin for now.
+
+377: Memory fault error reporting
+ On those architectures where :C-STACK-IS-CONTROL-STACK is in
+ *FEATURES*, we handle SIG_MEMORY_FAULT (SEGV or BUS) on an altstack,
+ so we cannot handle the signal directly (as in interrupt_handle_now())
+ in the case when the signal comes from some external agent (the user
+ using kill(1), or a fault in some foreign code, for instance). As
+ of sbcl-0.8.20.20, this is fixed by calling
+ arrange_return_to_lisp_function() to a new error-signalling
+ function, but as a result the error reporting is poor: we cannot
+ even tell the user at which address the fault occurred. We should
+ arrange such that arguments can be passed to the function called from
+ arrange_return_to_lisp_function(), but this looked hard to do in
+ general without suffering from memory leaks.
+
+379: TRACE :ENCAPSULATE NIL broken on ppc/darwin
+ See commented-out test-case in debug.impure.lisp.
+
+380: Accessor redefinition fails because of old accessor name
+ When redefining an accessor, SB-PCL::FIX-SLOT-ACCESSORS may try to
+ find the generic function named by the old accessor name using
+ ENSURE-GENERIC-FUNCTION and then remove the old accessor's method in
+ the GF. If the old name does not name a function, or if the old name
+ does not name a generic function, no attempt to find the GF or remove
+ any methods is made.
+
+ However, if an unrelated GF with an incompatible lambda list exists,
+ the class redefinition will fail when SB-PCL::REMOVE-READER-METHOD
+ tries to find and remove a method with an incompatible lambda list
+ from the unrelated generic function.
+
+381: incautious calls to EQUAL in fasl dumping
+ Compiling
+ (frob #(#1=(a #1#)))
+ (frob #(#1=(b #1#)))
+ (frob #(#1=(a #1#)))
+ in sbcl-0.9.0 causes CONTROL-STACK-EXHAUSTED. My (WHN) impression
+ is that this follows from the use of (MAKE-HASH-TABLE :TEST 'EQUAL)
+ to detect sharing, in which case fixing it might require either
+ getting less ambitious about detecting shared list structure, or
+ implementing the moral equivalent of EQUAL hash tables in a
+ cycle-tolerant way.
+
+382: externalization unexpectedly changes array simplicity
+ COMPILE-FILE and LOAD
+ (defun foo ()
+ (let ((x #.(make-array 4 :fill-pointer 0)))
+ (values (eval `(typep ',x 'simple-array))
+ (typep x 'simple-array))))
+ then (FOO) => T, NIL.
+
+ Similar problems exist with SIMPLE-ARRAY-P, ARRAY-HEADER accessors
+ and all array dimension functions.
+
+383: ASH'ing non-constant zeros
+ Compiling
+ (lambda (b)
+ (declare (type (integer -2 14) b))
+ (declare (ignorable b))
+ (ash (imagpart b) 57))
+ on PPC (and other platforms, presumably) gives an error during the
+ emission of FASH-ASH-LEFT/FIXNUM=>FIXNUM as the assembler attempts to
+ stuff a too-large constant into the immediate field of a PPC
+ instruction. Either the VOP should be fixed or the compiler should be
+ taught how to transform this case away, paying particular attention
+ to side-effects that might occur in the arguments to ASH.
+
+384: Compiler runaway on very large character types
+
+ (compile nil '(lambda (x)
+ (declare (type (member #\a 1) x))
+ (the (member 1 nil) x)))
+
+ The types apparently normalize into a very large type, and the compiler
+ gets lost in REMOVE-DUPLICATES. Perhaps the latter should use
+ a better algorithm (one based on hash tables, say) on very long lists
+ when :TEST has its default value?
+
+ A simpler example:
+
+ (compile nil '(lambda (x) (the (not (eql #\a)) x)))
+
+ (partially fixed in 0.9.3.1, but a better representation for these
+ types is needed.)
+
+385:
+ (format nil "~4,1F" 0.001) => "0.00" (should be " 0.0");
+ (format nil "~4,1@F" 0.001) => "+.00" (should be "+0.0").
+
+386: SunOS/x86 stack exhaustion handling broken
+ According to <http://alfa.s145.xrea.com/sbcl/solaris-x86.html>, the
+ stack exhaustion checking (implemented with a write-protected guard
+ page) does not work on SunOS/x86.
+
+388:
+ (found by Dmitry Bogomolov)
+
+ (defclass foo () ((x :type (unsigned-byte 8))))
+ (defclass bar () ((x :type symbol)))
+ (defclass baz (foo bar) ())
+
+ causes error
+
+ SB-PCL::SPECIALIZER-APPLICABLE-USING-TYPE-P cannot handle the second argument
+ (UNSIGNED-BYTE 8).
+
+ [ Can't trigger this any more, as of 2006-08-07 ]
+
+389:
+ (reported several times on sbcl-devel, by Rick Taube, Brian Rowe and
+ others)
+
+ ROUND-NUMERIC-BOUND assumes that float types always have a FORMAT
+ specifying whether they're SINGLE or DOUBLE. This is true for types
+ computed by the type system itself, but the compiler type derivation
+ short-circuits this and constructs non-canonical types. A temporary
+ fix was made to ROUND-NUMERIC-BOUND for the sbcl-0.9.6 release, but
+ the right fix is to remove the abstraction violation in the
+ compiler's type deriver.
+
+393: Wrong error from methodless generic function
+ (DEFGENERIC FOO (X))
+ (FOO 1 2)
+ gives NO-APPLICABLE-METHOD rather than an argument count error.
+
+395: Unicode and streams
+ One of the remaining problems in SBCL's Unicode support is the lack
+ of generality in certain streams.
+ a. FILL-POINTER-STREAMs: SBCL refuses to write (e.g. using FORMAT)
+ to streams made from strings that aren't character strings with
+ fill-pointers:
+ (let ((v (make-array 5 :fill-pointer 0 :element-type 'standard-char)))
+ (format v "foo")
+ v)
+ should return a non-simple base string containing "foo" but
+ instead errors.
+
+ (reported on sbcl-help by "tichy")
+
+396: block-compilation bug
+ (let ((x 1))
+ (dotimes (y 10)
+ (let ((y y))
+ (when (funcall (eval #'(lambda (x) (eql x 2))) y)
+ (defun foo (z)
+ (incf x (incf y z))))))
+ (defun bar (z)
+ (foo z)
+ (values x)))
+ (bar 1) => 11, should be 4.
+
+397: SLEEP accuracy
+ The more interrupts arrive the less accurate SLEEP's timing gets.
+ (time (sb-thread:terminate-thread
+ (prog1 (sb-thread:make-thread (lambda ()
+ (loop
+ (princ #\!)
+ (force-output)
+ (sb-ext:gc))))
+ (sleep 1))))
+
+398: GC-unsafe SB-ALIEN string deporting
+ Translating a Lisp string to an alien string by taking a SAP to it
+ as done by the :DEPORT-GEN methods for C-STRING and UTF8-STRING
+ is not safe, since the Lisp string can move. For example the
+ following code will fail quickly on both cheneygc and pre-0.9.8.19
+ GENCGC:
+
+ (setf (bytes-consed-between-gcs) 4096)
+ (define-alien-routine "strcmp" int (s1 c-string) (s2 c-string))
+
+ (loop
+ (let ((string "hello, world"))
+ (assert (zerop (strcmp string string)))))
+
+ (This will appear to work on post-0.9.8.19 GENCGC, since
+ the GC no longer zeroes memory immediately after releasing
+ it after a minor GC. Either enabling the READ_PROTECT_FREE_PAGES
+ #define in gencgc.c or modifying the example so that a major
+ GC will occasionally be triggered would unmask the bug.)
+
+ On cheneygc the only solution would seem to be allocating some alien
+ memory, copying the data over, and arranging that it's freed once we
+ return. For GENCGC we could instead try to arrange that the string
+ from which the SAP is taken is always pinned.
+
+ For some more details see comments for (define-alien-type-method
+ (c-string :deport-gen) ...) in host-c-call.lisp.
+
+402: "DECLAIM DECLARATION does not inform the PCL code-walker"
+ reported by Vincent Arkesteijn:
+
+ (declaim (declaration foo))
+ (defgeneric bar (x))
+ (defmethod bar (x)
+ (declare (foo x))
+ x)
+
+ ==> WARNING: The declaration FOO is not understood by
+ SB-PCL::SPLIT-DECLARATIONS.
+ Please put FOO on one of the lists SB-PCL::*NON-VAR-DECLARATIONS*,
+ SB-PCL::*VAR-DECLARATIONS-WITH-ARG*, or
+ SB-PCL::*VAR-DECLARATIONS-WITHOUT-ARG*.
+ (Assuming it is a variable declaration without argument).
+
+403: FORMAT/PPRINT-LOGICAL-BLOCK of CONDITIONs ignoring *PRINT-CIRCLE*
+ In sbcl-0.9.13.34,
+ (defparameter *c*
+ (make-condition 'simple-error
+ :format-control "ow... ~S"
+ :format-arguments '(#1=(#1#))))
+ (setf *print-circle* t *print-level* 4)
+ (format nil "~@<~A~:@>" *c*)
+ gives
+ "ow... (((#)))"
+ where I (WHN) believe the correct result is "ow... #1=(#1#)",
+ like the result from (PRINC-TO-STRING *C*). The question of
+ what the correct result is is complicated by the hairy text in
+ the Hyperspec "22.3.5.2 Tilde Less-Than-Sign: Logical Block",
+ Other than the difference in its argument, ~@<...~:> is
+ exactly the same as ~<...~:> except that circularity detection
+ is not applied if ~@<...~:> is encountered at top level in a
+ format string.
+ But because the odd behavior happens even without the at-sign,
+ (format nil "~<~A~:@>" (list *c*)) ; => "ow... (((#)))"
+ and because something seemingly similar can happen even in
+ PPRINT-LOGICAL-BLOCK invoked directly without FORMAT,
+ (pprint-logical-block (*standard-output* '(some nonempty list))
+ (format *standard-output* "~A" '#1=(#1#)))
+ (which prints "(((#)))" to *STANDARD-OUTPUT*), I don't think
+ that the 22.3.5.2 trickiness is fundamental to the problem.
+
+ My guess is that the problem is related to the logic around the MODE
+ argument to CHECK-FOR-CIRCULARITY, but I haven't reverse-engineered
+ enough of the intended meaning of the different MODE values to be
+ confident of this.
+
+404: nonstandard DWIMness in LOOP with unportably-ordered clauses
+ In sbcl-0.9.13, the code
+ (loop with stack = (make-array 2 :fill-pointer 2 :initial-element t)
+ for length = (length stack)
+ while (plusp length)
+ for element = (vector-pop stack)
+ collect element)
+ compiles without error or warning and returns (T T). Unfortunately,
+ it is inconsistent with the ANSI definition of the LOOP macro,
+ because it mixes up VARIABLE-CLAUSEs with MAIN-CLAUSEs. Furthermore,
+ SBCL's interpretation of the intended meaning is only one possible,
+ unportable interpretation of the noncompliant code; in CLISP 2.33.2,
+ the code compiles with a warning
+ LOOP: FOR clauses should occur before the loop's main body
+ and then fails at runtime with
+ VECTOR-POP: #() has length zero
+ perhaps because CLISP has shuffled the clauses into an
+ ANSI-compliant order before proceeding.
+
+405: a TYPE-ERROR in MERGE-LETS exercised at DEBUG 3
+ In sbcl-0.9.16.21 on linux/86, compiling
+ (declaim (optimize (debug 3)))
+ (defstruct foo bar)
+ (let ()
+ (flet ((i (x) (frob x (foo-bar foo))))
+ (i :five)))
+ causes a TYPE-ERROR
+ The value NIL is not of type SB-C::PHYSENV.
+ in MERGE-LETS.
+
+406: functional has external references -- failed aver
+ Given the following food in a single file
+ (eval-when (:compile-toplevel :load-toplevel :execute)
+ (defstruct foo3))
+ (defstruct bar
+ (foo #.(make-foo3)))
+ as of 0.9.18.11 the file compiler breaks on it:
+ failed AVER: "(NOT (FUNCTIONAL-HAS-EXTERNAL-REFERENCES-P CLAMBDA))"
+ Defining the missing MAKE-LOAD-FORM method makes the error go away.
+
+407: misoptimization of loop, COERCE 'FLOAT, and HANDLER-CASE for bignums
+ (reported by Ariel Badichi on sbcl-devel 2007-01-09)
+ 407a: In sbcl-1.0.1 on Linux x86,
+ (defun foo ()
+ (loop for n from (expt 2 1024) do
+ (handler-case
+ (coerce n 'single-float)
+ (simple-type-error ()
+ (format t "Got here.~%")
+ (return-from foo)))))
+ (foo)
+ causes an infinite loop, where handling the error would be expected.
+ 407b: In sbcl-1.0.1 on Linux x86,
+ (defun bar ()
+ (loop for n from (expt 2 1024) do
+ (handler-case
+ (format t "~E~%" (coerce n 'single-float))
+ (simple-type-error ()
+ (format t "Got here.~%")
+ (return-from bar)))))
+ fails to compile, with
+ Too large to be represented as a SINGLE-FLOAT: ...
+ from
+ 0: ((LABELS SB-BIGNUM::CHECK-EXPONENT) ...)
+ 1: ((LABELS SB-BIGNUM::FLOAT-FROM-BITS) ...)
+ 2: (SB-KERNEL:%SINGLE-FLOAT ...)
+ 3: (SB-C::BOUND-FUNC ...)
+ 4: (SB-C::%SINGLE-FLOAT-DERIVE-TYPE-AUX ...)
+
+408: SUBTYPEP confusion re. OR of SATISFIES of not-yet-defined predicate
+ As reported by Levente M\'{e}sz\'{a}ros sbcl-devel 2006-02-20,
+ (aver (equal (multiple-value-list
+ (subtypep '(or (satisfies x) string)
+ '(or (satisfies x) integer)))
+ '(nil nil)))
+ fails. Also, beneath that failure lurks another failure,
+ (aver (equal (multiple-value-list
+ (subtypep 'string
+ '(or (satisfies x) integer)))
+ '(nil nil)))
+ Having looked at this for an hour or so in sbcl-1.0.2, and
+ specifically having looked at the output from
+ laptop$ sbcl
+ * (let ((x 'string)
+ (y '(or (satisfies x) integer)))
+ (trace sb-kernel::union-complex-subtypep-arg2
+ sb-kernel::invoke-complex-subtypep-arg1-method
+ sb-kernel::type-union
+ sb-kernel::type-intersection
+ sb-kernel::type=)
+ (subtypep x y))
+ my (WHN) impression is that the problem is that the semantics of TYPE=
+ are wrong for what the UNION-COMPLEX-SUBTYPEP-ARG2 code is trying
+ to use it for. The comments on the definition of TYPE= probably
+ date back to CMU CL and seem to define it as a confusing thing:
+ its primary value is something like "certainly equal," and its
+ secondary value is something like "certain about that certainty."
+ I'm left uncertain how to fix UNION-COMPLEX-SUBTYPEP-ARG2 without
+ reducing its generality by removing the TYPE= cleverness. Possibly
+ the tempting TYPE/= relative defined next to it might be a
+ suitable replacement for the purpose. Probably, though, it would
+ be best to start by reverse engineering exactly what TYPE= and
+ TYPE/= do, and writing an explanation which is so clear that one
+ can see immediately what it's supposed to mean in odd cases like
+ (TYPE= '(SATISFIES X) 'INTEGER) when X isn't defined yet.
+
+409: MORE TYPE SYSTEM PROBLEMS
+ Found while investigating an optimization failure for extended
+ sequences. The extended sequence type implementation was altered to
+ work around the problem, but the fundamental problem remains, to wit:
+ (sb-kernel:type= (sb-kernel:specifier-type '(or float ratio))
+ (sb-kernel:specifier-type 'single-float))
+ returns NIL, NIL on sbcl-1.0.3.
+ (probably related to bug #408)
+
+410: read circularities and type declarations
+ Consider the definition
+ (defstruct foo (a 0 :type (not symbol)))
+ followed by
+ (setf *print-circle* t) ; just in case
+ (read-from-string "#1=#s(foo :a #1#)")
+ This gives a type error (#:G1 is not a (NOT SYMBOL)) because of the
+ implementation of read circularity, using a symbol as a marker for
+ the previously-referenced object.
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