0.7.1.44:

[sbcl.git] / BUGS

REPORTING BUGS

Bugs can be reported on the help mailing list
  sbcl-help@lists.sourceforge.net
or on the development mailing list
  sbcl-devel@lists.sourceforge.net

Please include enough information in a bug report that someone reading
it can reproduce the problem, i.e. don't write
     Subject: apparent bug in PRINT-OBJECT (or *PRINT-LENGTH*?)
     PRINT-OBJECT doesn't seem to work with *PRINT-LENGTH*. Is this a bug?
but instead
     Subject: apparent bug in PRINT-OBJECT (or *PRINT-LENGTH*?)
     In sbcl-1.2.3 running under OpenBSD 4.5 on my Alpha box, when
     I compile and load the file
       (DEFSTRUCT (FOO (:PRINT-OBJECT (LAMBDA (X Y)
                                        (LET ((*PRINT-LENGTH* 4))
                                          (PRINT X Y)))))
         X Y)
     then at the command line type
       (MAKE-FOO)
     the program loops endlessly instead of printing the object.


NOTES:

There is also some information on bugs in the manual page and
in the TODO file. Eventually more such information may move here.

The gaps in the number sequence belong to old bug descriptions which
have gone away (typically because they were fixed, but sometimes for
other reasons, e.g. because they were moved elsewhere).


KNOWN BUGS OF NO SPECIAL CLASS:

2:
  DEFSTRUCT almost certainly should overwrite the old LAYOUT information
  instead of just punting when a contradictory structure definition
  is loaded. As it is, if you redefine DEFSTRUCTs in a way which 
  changes their layout, you probably have to rebuild your entire
  program, even if you know or guess enough about the internals of
  SBCL to wager that this (undefined in ANSI) operation would be safe.

3:
  ANSI specifies that a type mismatch in a structure slot
  initialization value should not cause a warning.
WORKAROUND:
  This one might not be fixed for a while because while we're big
  believers in ANSI compatibility and all, (1) there's no obvious
  simple way to do it (short of disabling all warnings for type
  mismatches everywhere), and (2) there's a good portable
  workaround, and (3) by their own reasoning, it looks as though
  ANSI may have gotten it wrong. ANSI justifies this specification
  by saying 
    The restriction against issuing a warning for type mismatches
    between a slot-initform and the corresponding slot's :TYPE
    option is necessary because a slot-initform must be specified
    in order to specify slot options; in some cases, no suitable
    default may exist.
  However, in SBCL (as in CMU CL or, for that matter, any compiler
  which really understands Common Lisp types) a suitable default
  does exist, in all cases, because the compiler understands the
  concept of functions which never return (i.e. has return type NIL).
  Thus, as a portable workaround, you can use a call to some
  known-never-to-return function as the default. E.g.
    (DEFSTRUCT FOO
      (BAR (ERROR "missing :BAR argument")
           :TYPE SOME-TYPE-TOO-HAIRY-TO-CONSTRUCT-AN-INSTANCE-OF))
  or 
    (DECLAIM (FTYPE (FUNCTION () NIL) MISSING-ARG))
    (DEFUN REQUIRED-ARG () ; workaround for SBCL non-ANSI slot init typing
      (ERROR "missing required argument")) 
    (DEFSTRUCT FOO
      (BAR (REQUIRED-ARG) :TYPE TRICKY-TYPE-OF-SOME-SORT)
      (BLETCH (REQUIRED-ARG) :TYPE TRICKY-TYPE-OF-SOME-SORT)
      (N-REFS-SO-FAR 0 :TYPE (INTEGER 0)))
  Such code should compile without complaint and work correctly either
  on SBCL or on any other completely compliant Common Lisp system.

6:
  bogus warnings about undefined functions for magic functions like
  SB!C::%%DEFUN and SB!C::%DEFCONSTANT when cross-compiling files
  like src/code/float.lisp. Fixing this will probably require
  straightening out enough bootstrap consistency issues that
  the cross-compiler can run with *TYPE-SYSTEM-INITIALIZED*.
  Instead, the cross-compiler runs in a slightly flaky state
  which is sane enough to compile SBCL itself, but which is
  also unstable in several ways, including its inability
  to really grok function declarations.

7:
  The "compiling top-level form:" output ought to be condensed.
  Perhaps any number of such consecutive lines ought to turn into a
  single "compiling top-level forms:" line.

10:
  The way that the compiler munges types with arguments together
  with types with no arguments (in e.g. TYPE-EXPAND) leads to
  weirdness visible to the user:
        (DEFTYPE FOO () 'FIXNUM)
        (TYPEP 11 'FOO) => T
        (TYPEP 11 '(FOO)) => T, which seems weird
        (TYPEP 11 'FIXNUM) => T
        (TYPEP 11 '(FIXNUM)) signals an error, as it should
  The situation is complicated by the presence of Common Lisp types
  like UNSIGNED-BYTE (which can either be used in list form or alone)
  so I'm not 100% sure that the behavior above is actually illegal.
  But I'm 90+% sure, and the following related behavior,
        (TYPEP 11 'AND) => T
  treating the bare symbol AND as equivalent to '(AND), is specifically
  forbidden (by the ANSI specification of the AND type).

11:
  It would be nice if the
        caught ERROR:
          (during macroexpansion)
  said what macroexpansion was at fault, e.g.
        caught ERROR:
          (during macroexpansion of IN-PACKAGE,
          during macroexpansion of DEFFOO)

15:
  (SUBTYPEP '(FUNCTION (T BOOLEAN) NIL)
            '(FUNCTION (FIXNUM FIXNUM) NIL)) => T, T
  (Also, when this is fixed, we can enable the code in PROCLAIM which 
  checks for incompatible FTYPE redeclarations.)

19:
  (I *think* this is a bug. It certainly seems like strange behavior. But
  the ANSI spec is scary, dark, and deep.. -- WHN)
    (FORMAT NIL  "~,1G" 1.4) => "1.    "
    (FORMAT NIL "~3,1G" 1.4) => "1.    "

20:
  from Marco Antoniotti on cmucl-imp mailing list 1 Mar 2000:
        (defclass ccc () ())
        (setf (find-class 'ccc1) (find-class 'ccc))
        (defmethod zut ((c ccc1)) 123)
  In sbcl-0.7.1.13, this gives an error, 
        There is no class named CCC1.
  DTC's recommended workaround from the mailing list 3 Mar 2000:
        (setf (pcl::find-class 'ccc1) (pcl::find-class 'ccc))

22:
  The ANSI spec, in section "22.3.5.2 Tilde Less-Than-Sign: Logical Block",
  says that an error is signalled if ~W, ~_, ~<...~:>, ~I, or ~:T is used
  inside "~<..~>" (without the colon modifier on the closing syntax).
  However, SBCL doesn't do this:
        * (FORMAT T "~<munge~wegnum~>" 12)
        munge12egnum
        NIL

27:
  Sometimes (SB-EXT:QUIT) fails with 
        Argh! maximum interrupt nesting depth (4096) exceeded, exiting
        Process inferior-lisp exited abnormally with code 1
  I haven't noticed a repeatable case of this yet.

31:
  In some cases the compiler believes type declarations on array
  elements without checking them, e.g.
        (DECLAIM (OPTIMIZE (SAFETY 3) (SPEED 1) (SPACE 1)))
        (DEFSTRUCT FOO A B)
        (DEFUN BAR (X)
          (DECLARE (TYPE (SIMPLE-ARRAY CONS 1) X))
          (WHEN (CONSP (AREF X 0))
            (PRINT (AREF X 0))))
        (BAR (VECTOR (MAKE-FOO :A 11 :B 12)))
  prints
        #S(FOO :A 11 :B 12) 
  in SBCL 0.6.5 (and also in CMU CL 18b). This does not happen for
  all cases, e.g. the type assumption *is* checked if the array
  elements are declared to be of some structure type instead of CONS.

32:
  The printer doesn't report closures very well. This is true in 
  CMU CL 18b as well:
    (PRINT #'CLASS-NAME)
  gives
    #<Closure Over Function "DEFUN STRUCTURE-SLOT-ACCESSOR" {134D1A1}>
  It would be nice to make closures have a settable name slot,
  and make things like DEFSTRUCT and FLET, which create closures,
  set helpful values into this slot.

33:
  And as long as we're wishing, it would be awfully nice if INSPECT could
  also report on closures, telling about the values of the bound variables.

35:
  The compiler assumes that any time a function of declared FTYPE
  doesn't signal an error, its arguments were of the declared type.
  E.g. compiling and loading
    (DECLAIM (OPTIMIZE (SAFETY 3)))
    (DEFUN FACTORIAL (X) (GAMMA (1+ X)))
    (DEFUN GAMMA (X) X)
    (DECLAIM (FTYPE (FUNCTION (UNSIGNED-BYTE)) FACTORIAL))
    (DEFUN FOO (X)
      (COND ((> (FACTORIAL X) 1.0E6)
             (FORMAT T "too big~%"))
            ((INTEGERP X)
             (FORMAT T "exactly ~S~%" (FACTORIAL X)))
            (T
             (FORMAT T "approximately ~S~%" (FACTORIAL X)))))
  then executing
    (FOO 1.5)
  will cause the INTEGERP case to be selected, giving bogus output a la
    exactly 1.33..
  This violates the "declarations are assertions" principle.
  According to the ANSI spec, in the section "System Class FUNCTION",
  this is a case of "lying to the compiler", but the lying is done
  by the code which calls FACTORIAL with non-UNSIGNED-BYTE arguments,
  not by the unexpectedly general definition of FACTORIAL. In any case,
  "declarations are assertions" means that lying to the compiler should
  cause an error to be signalled, and should not cause a bogus
  result to be returned. Thus, the compiler should not assume
  that arbitrary functions check their argument types. (It might
  make sense to add another flag (CHECKED?) to DEFKNOWN to 
  identify functions which *do* check their argument types.)
  (Also, verify that the compiler handles declared function
  return types as assertions.)

41:
  TYPEP of VALUES types is sometimes implemented very inefficiently, e.g. in 
        (DEFTYPE INDEXOID () '(INTEGER 0 1000))
        (DEFUN FOO (X)
          (DECLARE (TYPE INDEXOID X))
          (THE (VALUES INDEXOID)
            (VALUES X)))
  where the implementation of the type check in function FOO 
  includes a full call to %TYPEP. There are also some fundamental problems
  with the interpretation of VALUES types (inherited from CMU CL, and
  from the ANSI CL standard) as discussed on the cmucl-imp@cons.org
  mailing list, e.g. in Robert Maclachlan's post of 21 Jun 2000.

42:
  The definitions of SIGCONTEXT-FLOAT-REGISTER and
  %SET-SIGCONTEXT-FLOAT-REGISTER in x86-vm.lisp say they're not
  supported on FreeBSD because the floating point state is not saved,
  but at least as of FreeBSD 4.0, the floating point state *is* saved,
  so they could be supported after all. Very likely 
  SIGCONTEXT-FLOATING-POINT-MODES could now be supported, too.

43:
  (as discussed by Douglas Crosher on the cmucl-imp mailing list ca. 
  Aug. 10, 2000): CMUCL currently interprets 'member as '(member); same
  issue with 'union, 'and, 'or etc. So even though according to the
  ANSI spec, bare 'MEMBER, 'AND, and 'OR are not legal types, CMUCL
  (and now SBCL) interpret them as legal types.

44:
  ANSI specifies DEFINE-SYMBOL-MACRO, but it's not defined in SBCL.
  CMU CL added it ca. Aug 13, 2000, after some discussion on the mailing
  list, and it is probably possible to use substantially the same 
  patches to add it to SBCL.

45:
  a slew of floating-point-related errors reported by Peter Van Eynde
  on July 25, 2000:
        b: SBCL's value for LEAST-POSITIVE-SHORT-FLOAT is bogus, and 
           should probably be 1.4012985e-45. In SBCL,
           (/ LEAST-POSITIVE-SHORT-FLOAT 2) returns a number smaller
           than LEAST-POSITIVE-SHORT-FLOAT. Similar problems 
           exist for LEAST-NEGATIVE-SHORT-FLOAT, LEAST-POSITIVE-LONG-FLOAT,
           and LEAST-NEGATIVE-LONG-FLOAT.
        c: Many expressions generate floating infinity on x86/Linux:
                (/ 1 0.0)
                (/ 1 0.0d0)
                (EXPT 10.0 1000)
                (EXPT 10.0d0 1000)
           PVE's regression tests want them to raise errors. sbcl-0.7.0.5
           on x86/Linux generates the infinities instead. That might or
           might not be conforming behavior, but it's also inconsistent,
           which is almost certainly wrong. (Inconsistency: (/ 1 0.0)
           should give the same result as (/ 1.0 0.0), but instead (/ 1 0.0)
           generates SINGLE-FLOAT-POSITIVE-INFINITY and (/ 1.0 0.0)
           signals an error.
        d: (in section12.erg) various forms a la 
                (FLOAT 1 DOUBLE-FLOAT-EPSILON)
           don't give the right behavior.

46:
  type safety errors reported by Peter Van Eynde July 25, 2000:
        a: (COERCE (QUOTE (A B C)) (QUOTE (VECTOR * 4)))
           => #(A B C)
           In general lengths of array type specifications aren't
           checked by COERCE, so it fails when the spec is
           (VECTOR 4), (STRING 2), (SIMPLE-BIT-VECTOR 3), or whatever.
        b: CONCATENATE has the same problem of not checking the length
           of specified output array types. MAKE-SEQUENCE and MAP and
           MERGE also have the same problem.
        c: (COERCE 'AND 'FUNCTION) returns something related to
           (MACRO-FUNCTION 'AND), but ANSI says it should raise an error.
        f: (FLOAT-RADIX 2/3) should signal an error instead of 
           returning 2.
        g: (LOAD "*.lsp") should signal FILE-ERROR.
        h: (MAKE-CONCATENATED-STREAM (MAKE-STRING-OUTPUT-STREAM))
           should signal TYPE-ERROR.
        i: MAKE-TWO-WAY-STREAM doesn't check that its arguments can
           be used for input and output as needed. It should fail with
           TYPE-ERROR when handed e.g. the results of
           MAKE-STRING-INPUT-STREAM or MAKE-STRING-OUTPUT-STREAM in
           the inappropriate positions, but doesn't.
        j: (PARSE-NAMESTRING (COERCE (LIST #\f #\o #\o (CODE-CHAR 0) #\4 #\8)
                            (QUOTE STRING)))
           should probably signal an error instead of making a pathname with
           a null byte in it.
        k: READ-BYTE is supposed to signal TYPE-ERROR when its argument is 
           not a binary input stream, but instead cheerfully reads from
           character streams, e.g. (MAKE-STRING-INPUT-STREAM "abc").

47:
  DEFCLASS bugs reported by Peter Van Eynde July 25, 2000:
        a: (DEFCLASS FOO () (A B A)) should signal a PROGRAM-ERROR, and
           doesn't.
        b: (DEFCLASS FOO () (A B A) (:DEFAULT-INITARGS X A X B)) should
           signal a PROGRAM-ERROR, and doesn't.
        c: (DEFCLASS FOO07 NIL ((A :ALLOCATION :CLASS :ALLOCATION :CLASS))),
           and other DEFCLASS forms with duplicate specifications in their
           slots, should signal a PROGRAM-ERROR, and doesn't.
        d: (DEFGENERIC IF (X)) should signal a PROGRAM-ERROR, but instead
           causes a COMPILER-ERROR.

48:
  SYMBOL-MACROLET bugs reported by Peter Van Eynde July 25, 2000:
        a: (SYMBOL-MACROLET ((T TRUE)) ..) should probably signal
           PROGRAM-ERROR, but SBCL accepts it instead.
        b: SYMBOL-MACROLET should refuse to bind something which is
           declared as a global variable, signalling PROGRAM-ERROR.
        c: SYMBOL-MACROLET should signal PROGRAM-ERROR if something
           it binds is declared SPECIAL inside.

50:
  type system errors reported by Peter Van Eynde July 25, 2000:
        g: The type system [still] isn't all that smart about relationships
           between hairy types. [The original example from PVE was
           (SUBTYPEP 'CONS '(NOT ATOM)) => NIL, NIL, which was fixed
           by CSR in sbcl-0.7.1.28, but there are still
           plenty of corner cases out there: (SUBTYPEP 'ATOM 'LIST)
           returns NIL, NIL in sbcl-0.7.1.31.]

51:
  miscellaneous errors reported by Peter Van Eynde July 25, 2000:
        a: (PROGN
            (DEFGENERIC FOO02 (X))
            (DEFMETHOD FOO02 ((X NUMBER)) T)
            (LET ((M (FIND-METHOD (FUNCTION FOO02)
                                  NIL
                                  (LIST (FIND-CLASS (QUOTE NUMBER))))))
              (REMOVE-METHOD (FUNCTION FOO02) M)
              (DEFGENERIC FOO03 (X))
              (ADD-METHOD (FUNCTION FOO03) M)))
           should give an error, but SBCL allows it.
        b: READ should probably return READER-ERROR, not the bare 
           arithmetic error, when input a la "1/0" or "1e1000" causes
           an arithmetic error.

52:
  It has been reported (e.g. by Peter Van Eynde) that there are 
  several metaobject protocol "errors". (In order to fix them, we might
  need to document exactly what metaobject protocol specification
  we're following -- the current code is just inherited from PCL.)

54:
  The implementation of #'+ returns its single argument without
  type checking, e.g. (+ "illegal") => "illegal".

58:
  (SUBTYPEP '(AND ZILCH INTEGER) 'ZILCH) => NIL, NIL
  Note: I looked into fixing this in 0.6.11.15, but gave up. The
  problem seems to be that there are two relevant type methods for
  the subtypep operation, HAIRY :COMPLEX-SUBTYPEP-ARG2 and
  INTERSECTION :COMPLEX-SUBTYPEP-ARG1, and only the first is
  called. This could be fixed, but type dispatch is messy and
  confusing enough already, I don't want to complicate it further.
  Perhaps someday we can make CLOS cross-compiled (instead of compiled
  after bootstrapping) so that we don't need to have the type system
  available before CLOS, and then we can rewrite the type methods to
  CLOS methods, and then expressing the solutions to stuff like this
  should become much more straightforward. -- WHN 2001-03-14

60:
  The debugger LIST-LOCATIONS command doesn't work properly.

61:
  Compiling and loading
    (DEFUN FAIL (X) (THROW 'FAIL-TAG X))
    (FAIL 12)
  then requesting a BACKTRACE at the debugger prompt gives no information
  about where in the user program the problem occurred.

62:
  The compiler is supposed to do type inference well enough that 
  the declaration in
    (TYPECASE X
      ((SIMPLE-ARRAY SINGLE-FLOAT)
       (LOCALLY
         (DECLARE (TYPE (SIMPLE-ARRAY SINGLE-FLOAT) X))
         ..))
      ..)
  is redundant. However, as reported by Juan Jose Garcia Ripoll for
  CMU CL, it sometimes doesn't. Adding declarations is a pretty good
  workaround for the problem for now, but can't be done by the TYPECASE
  macros themselves, since it's too hard for the macro to detect
  assignments to the variable within the clause. 
    Note: The compiler *is* smart enough to do the type inference in
  many cases. This case, derived from a couple of MACROEXPAND-1
  calls on Ripoll's original test case,
    (DEFUN NEGMAT (A)
      (DECLARE (OPTIMIZE SPEED (SAFETY 0)))
      (COND ((TYPEP A '(SIMPLE-ARRAY SINGLE-FLOAT)) NIL
             (LET ((LENGTH (ARRAY-TOTAL-SIZE A)))
               (LET ((I 0) (G2554 LENGTH))
                 (DECLARE (TYPE REAL G2554) (TYPE REAL I))
                 (TAGBODY
                  SB-LOOP::NEXT-LOOP
                  (WHEN (>= I G2554) (GO SB-LOOP::END-LOOP))
                  (SETF (ROW-MAJOR-AREF A I) (- (ROW-MAJOR-AREF A I)))
                  (GO SB-LOOP::NEXT-LOOP)
                  SB-LOOP::END-LOOP))))))
  demonstrates the problem; but the problem goes away if the TAGBODY
  and GO forms are removed (leaving the SETF in ordinary, non-looping
  code), or if the TAGBODY and GO forms are retained, but the 
  assigned value becomes 0.0 instead of (- (ROW-MAJOR-AREF A I)).

63:
  Paul Werkowski wrote on cmucl-imp@cons.org 2000-11-15
    I am looking into this problem that showed up on the cmucl-help
    list. It seems to me that the "implementation specific environment
    hacking functions" found in pcl/walker.lisp are completely messed
    up. The good thing is that they appear to be barely used within
    PCL and the munged environment object is passed to cmucl only
    in calls to macroexpand-1, which is probably why this case fails.
  SBCL uses essentially the same code, so if the environment hacking
  is screwed up, it affects us too.

64:
  Using the pretty-printer from the command prompt gives funny
  results, apparently because the pretty-printer doesn't know
  about user's command input, including the user's carriage return
  that the user, and therefore the pretty-printer thinks that
  the new output block should start indented 2 or more characters
  rightward of the correct location.

65:
  (probably related to bug #70; maybe related to bug #109)
  As reported by Carl Witty on submit@bugs.debian.org 1999-05-08,
  compiling this file
(in-package "CL-USER")
(defun equal-terms (termx termy)
  (labels
    ((alpha-equal-bound-term-lists (listx listy)
       (or (and (null listx) (null listy))
           (and listx listy
                (let ((bindings-x (bindings-of-bound-term (car listx)))
                      (bindings-y (bindings-of-bound-term (car listy))))
                  (if (and (null bindings-x) (null bindings-y))
                      (alpha-equal-terms (term-of-bound-term (car listx))
                                         (term-of-bound-term (car listy)))
                      (and (= (length bindings-x) (length bindings-y))
                           (prog2
                               (enter-binding-pairs (bindings-of-bound-term (car listx))
                                                    (bindings-of-bound-term (car listy)))
                               (alpha-equal-terms (term-of-bound-term (car listx))
                                                  (term-of-bound-term (car listy)))
                             (exit-binding-pairs (bindings-of-bound-term (car listx))
                                                 (bindings-of-bound-term (car listy)))))))
                (alpha-equal-bound-term-lists (cdr listx) (cdr listy)))))

     (alpha-equal-terms (termx termy)
       (if (and (variable-p termx)
                (variable-p termy))
           (equal-bindings (id-of-variable-term termx)
                           (id-of-variable-term termy))
           (and (equal-operators-p (operator-of-term termx) (operator-of-term termy))
                (alpha-equal-bound-term-lists (bound-terms-of-term termx)
                                              (bound-terms-of-term termy))))))

    (or (eq termx termy)
        (and termx termy
             (with-variable-invocation (alpha-equal-terms termx termy))))))
  causes an assertion failure
    The assertion (EQ (C::LAMBDA-TAIL-SET C::CALLER)
                      (C::LAMBDA-TAIL-SET (C::LAMBDA-HOME C::CALLEE))) failed.

  Bob Rogers reports (1999-07-28 on cmucl-imp@cons.org) a smaller test
  case with the same problem:
(defun parse-fssp-alignment ()
  ;; Given an FSSP alignment file named by the argument . . .
  (labels ((get-fssp-char ()
             (get-fssp-char))
           (read-fssp-char ()
             (get-fssp-char)))
    ;; Stub body, enough to tickle the bug.
    (list (read-fssp-char)
          (read-fssp-char))))

66:
  ANSI specifies that the RESULT-TYPE argument of CONCATENATE must be
  a subtype of SEQUENCE, but CONCATENATE doesn't check this properly:
    (CONCATENATE 'SIMPLE-ARRAY #(1 2) '(3)) => #(1 2 3)
  This also leads to funny behavior when derived type specifiers
  are used, as originally reported by Milan Zamazal for CMU CL (on the
  Debian bugs mailing list (?) 2000-02-27), then reported by Martin
  Atzmueller for SBCL (2000-10-01 on sbcl-devel@lists.sourceforge.net):
    (DEFTYPE FOO () 'SIMPLE-ARRAY)
    (CONCATENATE 'FOO #(1 2) '(3)) 
      => #<ARRAY-TYPE SIMPLE-ARRAY> is a bad type specifier for
           sequence functions.
  The derived type specifier FOO should act the same way as the 
  built-in type SIMPLE-ARRAY here, but it doesn't. That problem
  doesn't seem to exist for sequence types:
    (DEFTYPE BAR () 'SIMPLE-VECTOR)
    (CONCATENATE 'BAR #(1 2) '(3)) => #(1 2 3)

67:
  As reported by Winton Davies on a CMU CL mailing list 2000-01-10,
  and reported for SBCL by Martin Atzmueller 2000-10-20: (TRACE GETHASH)
  crashes SBCL. In general tracing anything which is used in the 
  implementation of TRACE is likely to have the same problem.

68: 
  As reported by Daniel Solaz on cmucl-help@cons.org 2000-11-23,
  SXHASH returns the same value for all non-STRUCTURE-OBJECT instances,
  notably including all PCL instances. There's a limit to how much
  SXHASH can do to return unique values for instances, but at least
  it should probably look at the class name, the way that it does
  for STRUCTURE-OBJECTs.

70:
  (probably related to bug #65; maybe related to bug #109)
  The compiler doesn't like &OPTIONAL arguments in LABELS and FLET
  forms. E.g.
    (DEFUN FIND-BEFORE (ITEM SEQUENCE &KEY (TEST #'EQL))
      (LABELS ((FIND-ITEM (OBJ SEQ TEST &OPTIONAL (VAL NIL))
                 (LET ((ITEM (FIRST SEQ)))
                   (COND ((NULL SEQ)
                          (VALUES NIL NIL))
                         ((FUNCALL TEST OBJ ITEM)
                          (VALUES VAL SEQ))
                         (T     
                          (FIND-ITEM OBJ (REST SEQ) TEST (NCONC VAL `(,ITEM))))))))
      (FIND-ITEM ITEM SEQUENCE TEST)))
  from David Young's bug report on cmucl-help@cons.org 30 Nov 2000
  causes sbcl-0.6.9 to fail with
    error in function SB-KERNEL:ASSERT-ERROR:
       The assertion (EQ (SB-C::LAMBDA-TAIL-SET SB-C::CALLER)
                         (SB-C::LAMBDA-TAIL-SET
                          (SB-C::LAMBDA-HOME SB-C::CALLEE))) failed.

71: 
  (DECLAIM (OPTIMIZE ..)) doesn't work. E.g. even after 
  (DECLAIM (OPTIMIZE (SPEED 3))), things are still optimized with
  the previous SPEED policy. This bug will probably get fixed in
  0.6.9.x in a general cleanup of optimization policy.

72:
  (DECLAIM (OPTIMIZE ..)) doesn't work properly inside LOCALLY forms.

75:
  As reported by Martin Atzmueller on sbcl-devel 26 Dec 2000,
  ANSI says that WITH-OUTPUT-TO-STRING should have a keyword
  :ELEMENT-TYPE, but in sbcl-0.6.9 this is not defined for
  WITH-OUTPUT-TO-STRING.

78:
  ANSI says in one place that type declarations can be abbreviated even
  when the type name is not a symbol, e.g.
    (DECLAIM ((VECTOR T) *FOOVECTOR*))
  SBCL doesn't support this. But ANSI says in another place that this
  isn't allowed. So it's not clear this is a bug after all. (See the
  e-mail on cmucl-help@cons.org on 2001-01-16 and 2001-01-17 from WHN
  and Pierre Mai.)

79:
  as pointed out by Dan Barlow on sbcl-devel 2000-07-02:
  The PICK-TEMPORARY-FILE-NAME utility used by LOAD-FOREIGN uses
  an easily guessable temporary filename in a way which might open
  applications using LOAD-FOREIGN to hijacking by malicious users
  on the same machine. Incantations for doing this safely are
  floating around the net in various "how to write secure programs
  despite Unix" documents, and it would be good to (1) fix this in 
  LOAD-FOREIGN, and (2) hunt for any other code which uses temporary
  files and make it share the same new safe logic.

82: 
  Functions are assigned names based on the context in which they're
  defined. This is less than ideal for the functions which are
  used to implement CLOS methods. E.g. the output of 
  (DESCRIBE 'PRINT-OBJECT) lists functions like 
        #<FUNCTION "DEF!STRUCT (TRACE-INFO (:MAKE-LOAD-FORM-FUN SB-KERNEL:JUST-DUMP-IT-NORMALLY) (:PRINT-OBJECT #))" {1020E49}> 
  and
        #<FUNCTION "MACROLET ((FORCE-DELAYED-DEF!METHODS NIL #))" {1242871}>
  It would be better if these functions' names always identified
  them as methods, and identified their generic functions and
  specializers.

83:
  RANDOM-INTEGER-EXTRA-BITS=10 may not be large enough for the RANDOM
  RNG to be high quality near RANDOM-FIXNUM-MAX; it looks as though
  the mean of the distribution can be systematically O(0.1%) wrong.
  Just increasing R-I-E-B is probably not a good solution, since
  it would decrease efficiency more than is probably necessary. Perhaps
  using some sort of accept/reject method would be better.

85:
  Internally the compiler sometimes evaluates
    (sb-kernel:type/= (specifier-type '*) (specifier-type t))
  (I stumbled across this when I added an
    (assert (not (eq type1 *wild-type*)))
  in the NAMED :SIMPLE-= type method.) '* isn't really a type, and
  in a type context should probably be translated to T, and so it's
  probably wrong to ask whether it's equal to the T type and then (using
  the EQ type comparison in the NAMED :SIMPLE-= type method) return NIL.
  (I haven't tried to investigate this bug enough to guess whether
  there might be any user-level symptoms.)

90: 
  a latent cross-compilation/bootstrapping bug: The cross-compilation
  host's CL:CHAR-CODE-LIMIT is used in target code in readtable.lisp
  and possibly elsewhere. Instead, we should use the target system's
  CHAR-CODE-LIMIT. This will probably cause problems if we try to 
  bootstrap on a system which uses a different value of CHAR-CODE-LIMIT
  than SBCL does.

91:
  (subtypep '(or (integer -1 1)
                 unsigned-byte)
            '(or (rational -1 7)
                 unsigned-byte
                 (integer -1 1))) => NIL,T
  An analogous problem with SINGLE-FLOAT and REAL types was fixed in 
  sbcl-0.6.11.22, but some peculiarites of the RATIO type make it 
  awkward to generalize the fix to INTEGER and RATIONAL. It's not 
  clear what's the best fix. (See the "bug in type handling" discussion
  on cmucl-imp ca. 2001-03-22 and ca. 2001-02-12.)

94a: 
  Inconsistencies between derived and declared VALUES return types for
  DEFUN aren't checked very well. E.g. the logic which successfully
  catches problems like
    (declaim (ftype (function (fixnum) float) foo))
    (defun foo (x)
      (declare (type integer x))
      (values x)) ; wrong return type, detected, gives warning, good!
  fails to catch
    (declaim (ftype (function (t) (values t t)) bar))
    (defun bar (x)
      (values x)) ; wrong number of return values, no warning, bad!
  The cause of this is seems to be that (1) the internal function 
  VALUES-TYPES-EQUAL-OR-INTERSECT used to make the check handles its
  arguments symmetrically, and (2) when the type checking code was
  written back when when SBCL's code was still CMU CL, the intent
  was that this case
    (declaim (ftype (function (t) t) bar))
    (defun bar (x)
      (values x x)) ; wrong number of return values; should give warning?
  not be warned for, because a two-valued return value is considered
  to be compatible with callers who expects a single value to be
  returned. That intent is probably not appropriate for modern ANSI
  Common Lisp, but fixing this might be complicated because of other
  divergences between auld-style and new-style handling of
  multiple-VALUES types. (Some issues related to this were discussed
  on cmucl-imp at some length sometime in 2000.)

95:
  The facility for dumping a running Lisp image to disk gets confused
  when run without the PURIFY option, and creates an unnecessarily large
  core file (apparently representing memory usage up to the previous
  high-water mark). Moreover, when the file is loaded, it confuses the
  GC, so that thereafter memory usage can never be reduced below that
  level.

96:
  The TRACE facility can't be used on some kinds of functions.
  (Basically, the breakpoint facility was incompletely implemented
  in the X86 port of CMU CL, and hasn't been fixed in SBCL.)

98:
  In sbcl-0.6.11.41 (and in all earlier SBCL, and in CMU
  CL), out-of-line structure slot setters are horribly inefficient
  whenever the type of the slot is declared, because out-of-line
  structure slot setters are implemented as closures to save space,
  so the compiler doesn't compile the type test into code, but
  instead just saves the type in a lexical closure and interprets it
  at runtime.
    A proper solution involves deciding whether it's really worth
  saving space by implementing structure slot accessors as closures.
  (If it's not worth it, the problem vanishes automatically. If it
  is worth it, there are hacks we could use to force type tests to
  be compiled anyway, and even shared. E.g. we could implement
  an EQUAL hash table mapping from types to compiled type tests, 
  and save the appropriate compiled type test as part of each lexical
  closure; or we could make the lexical closures be placeholders
  which overwrite their old definition as a lexical closure with
  a new compiled definition the first time that they're called.)
    As a workaround for the problem, #'(SETF FOO) expressions can
  be replaced with (EFFICIENT-SETF-FUNCTION FOO), where
(defmacro efficient-setf-function (place-function-name)
  (or #+sbcl (and (sb-impl::info :function :accessor-for place-function-name)
                  ;; a workaround for the problem, encouraging the
                  ;; inline expansion of the structure accessor, so
                  ;; that the compiler can optimize its type test
                  (let ((new-value (gensym "NEW-VALUE-"))
                        (structure-value (gensym "STRUCTURE-VALUE-")))
                    `(lambda (,new-value ,structure-value)
                       (setf (,place-function-name ,structure-value)
                             ,new-value))))
      ;; no problem, can just use the ordinary expansion
      `(function (setf ,place-function-name))))

100:
  There's apparently a bug in CEILING optimization which caused 
  Douglas Crosher to patch the CMU CL version. Martin Atzmueller
  applied the patches to SBCL and they didn't seem to cause problems
  (as reported sbcl-devel 2001-05-04). However, since the patches
  modify nontrivial code which was apparently written incorrectly
  the first time around, until regression tests are written I'm not 
  comfortable merging the patches in the CVS version of SBCL.

102:
  As reported by Arthur Lemmens sbcl-devel 2001-05-05, ANSI
  requires that SYMBOL-MACROLET refuse to rebind special variables,
  but SBCL doesn't do this. (Also as reported by AL in the same
  message, SBCL depended on this nonconforming behavior to build
  itself, because of the way that **CURRENT-SEGMENT** was implemented.
  As of sbcl-0.6.12.x, this dependence on the nonconforming behavior
  has been fixed, but the nonconforming behavior remains.)

104:
  (DESCRIBE 'SB-ALIEN:DEF-ALIEN-TYPE) reports the macro argument list
  incorrectly:
        DEF-ALIEN-TYPE is
          an external symbol
          in #<PACKAGE "SB-ALIEN">.
        Macro-function: #<FUNCTION "DEF!MACRO DEF-ALIEN-TYPE" {19F4A39}>
          Macro arguments:  (#:whole-470 #:environment-471)
          On Sat, May 26, 2001 09:45:57 AM CDT it was compiled from:
          /usr/stuff/sbcl/src/code/host-alieneval.lisp
            Created: Monday, March 12, 2001 07:47:43 AM CST

108:
  (TIME (ROOM T)) reports more than 200 Mbytes consed even for
  a clean, just-started SBCL system. And it seems to be right:
  (ROOM T) can bring a small computer to its knees for a *long*
  time trying to GC afterwards. Surely there's some more economical
  way to implement (ROOM T).

109:
  reported by Martin Atzmueller 2001-06-25; originally from CMU CL bugs
  collection:
    ;;; This file fails to compile.
    ;;; Maybe this bug is related to bugs #65, #70 in the BUGS file.
    (in-package :cl-user)
    (defun tst2 ()
      (labels 
          ((eff (&key trouble)
             (eff)
             ;; nil
             ;; Uncomment and it works
             ))
        (eff)))
  In SBCL 0.6.12.42, the problem is
    internal error, failed AVER:
      "(COMMON-LISP:EQ (SB!C::LAMBDA-TAIL-SET SB!C::CALLER)
                  (SB!C::LAMBDA-TAIL-SET (SB!C::LAMBDA-HOME SB!C::CALLEE)))"

110:
  reported by Martin Atzmueller 2001-06-25; originally from CMU CL bugs
  collection:
    ;;; The compiler is flushing the argument type test, and the default
    ;;; case in the cond, so that calling with say a fixnum 0 causes a
    ;;; SIGBUS.
    (declaim (optimize (safety 2) (speed 3)))
    (defun tst (x)
      (declare (type (or string stream) x))
      (cond ((typep x 'string) 'string)
            ((typep x 'stream) 'stream)
            (t
             'none)))
  The symptom in sbcl-0.6.12.42 on OpenBSD is actually (TST 0)=>STREAM
  (not the SIGBUS reported in the comment) but that's broken too; 
  type declarations are supposed to be treated as assertions unless
  SAFETY 0, so we should be getting a TYPE-ERROR.

113:
  reported by Martin Atzmueller 2001-06-25; originally from CMU CL bugs
  collection:
    (in-package :cl-user)
    ;;; From: David Gadbois <gadbois@cyc.com>
    ;;;
    ;;; Logical pathnames aren't externalizable.
    ;;; Test case:
    (let ((tempfile "/tmp/test.lisp"))
      (setf (logical-pathname-translations "XXX")
            '(("XXX:**;*.*" "/tmp/**/*.*")))
      (with-open-file (out tempfile :direction :output)
        (write-string "(defvar *path* #P\"XXX:XXX;FOO.LISP\")" out))
      (compile-file tempfile))
  The error message in sbcl-0.6.12.42 is
    ; caught ERROR:
    ;   (while making load form for #<SB-IMPL::LOGICAL-HOST "XXX">)
    ; A logical host can't be dumped as a constant: #<SB-IMPL::LOGICAL-HOST "XXX">

115:
  reported by Martin Atzmueller 2001-06-25; originally from CMU CL bugs
  collection:
    (in-package :cl-user)
    ;;; The following invokes a compiler error.
    (declaim (optimize (speed 2) (debug 3)))
    (defun tst ()
      (flet ((m1 ()
               (unwind-protect nil)))
        (if (catch nil)
          (m1)
          (m1))))
  The error message in sbcl-0.6.12.42 is
    internal error, failed AVER:
      "(COMMON-LISP:EQ (SB!C::TN-ENVIRONMENT SB!C:TN) SB!C::TN-ENV)"

117:
  When the compiler inline expands functions, it may be that different
  kinds of return values are generated from different code branches.
  E.g. an inline expansion of POSITION generates integer results 
  from one branch, and NIL results from another. When that inline
  expansion is used in a context where only one of those results
  is acceptable, e.g.
    (defun foo (x)
      (aref *a1* (position x *a2*)))
  and the compiler can't prove that the unacceptable branch is 
  never taken, then bogus type mismatch warnings can be generated.
  If you need to suppress the type mismatch warnings, you can
  suppress the inline expansion,
    (defun foo (x)
      #+sbcl (declare (notinline position)) ; to suppress bug 117 bogowarnings
      (aref *a1* (position x *a2*)))
  or, sometimes, suppress them by declaring the result to be of an
  appropriate type,
    (defun foo (x)
      (aref *a1* (the integer (position x *a2*))))

  This is not a new compiler problem in 0.7.0, but the new compiler
  transforms for FIND, POSITION, FIND-IF, and POSITION-IF make it 
  more conspicuous. If you don't need performance from these functions,
  and the bogus warnings are a nuisance for you, you can return to
  your pre-0.7.0 state of grace with
    #+sbcl (declaim (notinline find position find-if position-if)) ; bug 117..

118:
   as reported by Eric Marsden on cmucl-imp@cons.org 2001-08-14:
     (= (FLOAT 1 DOUBLE-FLOAT-EPSILON)
        (+ (FLOAT 1 DOUBLE-FLOAT-EPSILON) DOUBLE-FLOAT-EPSILON)) => T
   when of course it should be NIL. (He says it only fails for X86,
   not SPARC; dunno about Alpha.)

   Also, "the same problem exists for LONG-FLOAT-EPSILON,
   DOUBLE-FLOAT-NEGATIVE-EPSILON, LONG-FLOAT-NEGATIVE-EPSILON (though
   for the -negative- the + is replaced by a - in the test)."

   Raymond Toy comments that this is tricky on the X86 since its FPU
   uses 80-bit precision internally.

120a:
   The compiler incorrectly figures the return type of 
        (DEFUN FOO (FRAME UP-FRAME)
          (IF (OR (NOT FRAME)
                  T)
              FRAME
              "BAR"))
   as NIL.

   This problem exists in CMU CL 18c too. When I reported it on
   cmucl-imp@cons.org, Raymond Toy replied 23 Aug 2001 with 
   a partial explanation, but no fix has been found yet.

120b:
   Even in sbcl-0.pre7.x, which is supposed to be free of the old
   non-ANSI behavior of treating the function return type inferred
   from the current function definition as a declaration of the
   return type from any function of that name, the return type of NIL
   is attached to FOO in 120a above, and used to optimize code which
   calls FOO. 

122:
   There was some sort of screwup in handling of
   (IF (NOT (IGNORE-ERRORS ..))). E.g.
        (defun foo1i ()
          (if (not (ignore-errors
                     (make-pathname :host "foo" :directory "!bla" :name "bar")))
              (print "ok")
              (error "notunlessnot")))
   The (NOT (IGNORE-ERRORS ..)) form evaluates to T, so this should be
   printing "ok", but instead it's going to the ERROR. This problem
   seems to've been introduced by MNA's HANDLER-CASE patch (sbcl-devel
   2001-07-17) and as a workaround (put in sbcl-0.pre7.14.flaky4.12)
   I reverted back to the old weird HANDLER-CASE code. However, I
   think the problem looks like a compiler bug in handling RETURN-FROM,
   so I left the MNA-patched code in HANDLER-CASE (suppressed with
   #+NIL) and I'd like to go back to see whether this really is
   a compiler bug before I delete this BUGS entry.

123:
   The *USE-IMPLEMENTATION-TYPES* hack causes bugs, particularly
     (IN-PACKAGE :SB-KERNEL)
     (TYPE= (SPECIFIER-TYPE '(VECTOR T))
            (SPECIFIER-TYPE '(VECTOR UNDEFTYPE)))
   Then because of this, the compiler bogusly optimizes
        (TYPEP #(11) '(SIMPLE-ARRAY UNDEF-TYPE 1))
   to T. Unfortunately, just setting *USE-IMPLEMENTATION-TYPES* to 
   NIL around sbcl-0.pre7.14.flaky4.12 didn't work: the compiler complained
   about type mismatches (probably harmlessly, another instance of bug 117);
   and then cold init died with a segmentation fault.

124:
   As of version 0.pre7.14, SBCL's implementation of MACROLET makes
   the entire lexical environment at the point of MACROLET available
   in the bodies of the macroexpander functions. In particular, it 
   allows the function bodies (which run at compile time) to try to 
   access lexical variables (which are only defined at runtime).
   It doesn't even issue a warning, which is bad.
  
   The SBCL behavior arguably conforms to the ANSI spec (since the
   spec says that the behavior is undefined, ergo anything conforms).
   However, it would be better to issue a compile-time error.
   Unfortunately I (WHN) don't see any simple way to detect this
   condition in order to issue such an error, so for the meantime
   SBCL just does this weird broken "conforming" thing.

   The ANSI standard says, in the definition of the special operator
   MACROLET,
       The macro-expansion functions defined by MACROLET are defined
       in the lexical environment in which the MACROLET form appears.
       Declarations and MACROLET and SYMBOL-MACROLET definitions affect
       the local macro definitions in a MACROLET, but the consequences
       are undefined if the local macro definitions reference any
       local variable or function bindings that are visible in that
       lexical environment. 
   Then it seems to contradict itself by giving the example
        (defun foo (x flag)
           (macrolet ((fudge (z)
                         ;The parameters x and flag are not accessible
                         ; at this point; a reference to flag would be to
                         ; the global variable of that name.
                         ` (if flag (* ,z ,z) ,z)))
            ;The parameters x and flag are accessible here.
             (+ x
                (fudge x)
                (fudge (+ x 1)))))
   The comment "a reference to flag would be to the global variable
   of the same name" sounds like good behavior for the system to have.
   but actual specification quoted above says that the actual behavior
   is undefined.

125:
   (as reported by Gabe Garza on cmucl-help 2001-09-21)
        (defvar *tmp* 3)
        (defun test-pred (x y)
          (eq x y))
        (defun test-case ()
          (let* ((x *tmp*)
                 (func (lambda () x)))
            (print (eq func func))
            (print (test-pred func func))
            (delete func (list func))))
   Now calling (TEST-CASE) gives output
     NIL
     NIL
     (#<FUNCTION {500A9EF9}>)
   Evidently Python thinks of the lambda as a code transformation so
   much that it forgets that it's also an object.

126:
  (fixed in 0.pre7.41)

127:
  The DEFSTRUCT section of the ANSI spec, in the :CONC-NAME section,
  specifies a precedence rule for name collisions between slot accessors of
  structure classes related by inheritance. As of 0.7.0, SBCL still 
  doesn't follow it.

129:
  insufficient syntax checking in MACROLET:
   (defun foo (x)
     (macrolet ((defmacro bar (z) `(+ z z)))
       (bar x)))
  shouldn't compile without error (because of the extra DEFMACRO symbol).

131:
  As of sbcl-0.pre7.86.flaky7.3, the cross-compiler, and probably 
  the CL:COMPILE function (which is based on the same %COMPILE 
  mechanism) get confused by 
(defun sxhash (x)
  (labels ((sxhash-number (x)
             (etypecase x
               (fixnum (sxhash x)) ; through DEFTRANSFORM
               (integer (sb!bignum:sxhash-bignum x))
               (single-float (sxhash x)) ; through DEFTRANSFORM
               (double-float (sxhash x)) ; through DEFTRANSFORM
               #!+long-float (long-float (error "stub: no LONG-FLOAT"))
               (ratio (let ((result 127810327))
                        (declare (type fixnum result))
                        (mixf result (sxhash-number (numerator x)))
                        (mixf result (sxhash-number (denominator x)))
                        result))
               (complex (let ((result 535698211))
                          (declare (type fixnum result))
                          (mixf result (sxhash-number (realpart x)))
                          (mixf result (sxhash-number (imagpart x)))
                          result))))
           (sxhash-recurse (x &optional (depthoid +max-hash-depthoid+))
             (declare (type index depthoid))
             (typecase x
               (list
                (if (plusp depthoid)
                    (mix (sxhash-recurse (car x) (1- depthoid))
                         (sxhash-recurse (cdr x) (1- depthoid)))
                    261835505))
               (instance
                (if (typep x 'structure-object)
                    (logxor 422371266
                            (sxhash ; through DEFTRANSFORM
                             (class-name (layout-class (%instance-layout x)))))
                    309518995))
               (symbol (sxhash x)) ; through DEFTRANSFORM
               (number (sxhash-number x))
               (array
                (typecase x
                  (simple-string (sxhash x)) ; through DEFTRANSFORM
                  (string (%sxhash-substring x))
                  (bit-vector (let ((result 410823708))
                                (declare (type fixnum result))
                                (dotimes (i (min depthoid (length x)))
                                  (mixf result (aref x i)))
                                result))
                  (t (logxor 191020317 (sxhash (array-rank x))))))
               (character
                (logxor 72185131
                        (sxhash (char-code x)))) ; through DEFTRANSFORM
               (t 42))))
    (sxhash-recurse x)))
  complaining "function called with two arguments, but wants exactly
  one" about SXHASH-RECURSE. (This might not be strictly a new bug, 
  since IIRC post-fork CMU CL has also had problems with &OPTIONAL
  arguments in FLET/LABELS: it might be an old Python bug which is 
  only exercised by the new arrangement of the SBCL compiler.)

135:
  Ideally, uninterning a symbol would allow it, and its associated
  FDEFINITION and PROCLAIM data, to be reclaimed by the GC. However, 
  at least as of sbcl-0.7.0, this isn't the case. Information about
  FDEFINITIONs and PROCLAIMed properties is stored in globaldb.lisp
  essentially in ordinary (non-weak) hash tables keyed by symbols.
  Thus, once a system has an entry in this system, it tends to live
  forever, even when it is uninterned and all other references to it
  are lost. 

136:
  (reported by Arnaud Rouanet on cmucl-imp 2001-12-18)
    (defmethod foo ((x integer))
      x)
    (defmethod foo :around ((x integer))
      (let ((x (1+ x)))
        (call-next-method)))
  Now (FOO 3) should return 3, but instead it returns 4.
    
137:
  (SB-DEBUG:BACKTRACE) output should start with something
  including the name BACKTRACE, not (as in 0.pre7.88)
  just "0: (\"hairy arg processor\" ...)". Until about
  sbcl-0.pre7.109, the names in BACKTRACE were all screwed
  up compared to the nice useful names in sbcl-0.6.13.
  Around sbcl-0.pre7.109, they were mostly fixed by using
  NAMED-LAMBDA to implement DEFUN. However, there are still
  some screwups left, e.g. as of sbcl-0.pre7.109, there are
  still some functions named "hairy arg processor" and
  "SB-INT:&MORE processor".

140:
  (reported by Alexey Dejneka sbcl-devel 2002-01-03)

  SUBTYPEP does not work well with redefined classes:
  ---
  * (defclass a () ())
  #<STANDARD-CLASS A>
  * (defclass b () ())
  #<STANDARD-CLASS B>
  * (subtypep 'b 'a)
  NIL
  T
  * (defclass b (a) ())
  #<STANDARD-CLASS B>
  * (subtypep 'b 'a)
  T
  T
  * (defclass b () ())
  #<STANDARD-CLASS B>
   
  ;;; And now...
  * (subtypep 'b 'a)
  T
  T

  This is probably due to underzealous clearing of the type caches; a
  brute-force solution in that case would be to make a defclass expand
  into something that included a call to SB-KERNEL::CLEAR-TYPE-CACHES,
  but there may be a better solution.

141: 
  Pretty-printing nested backquotes doesn't work right, as 
  reported by Alexey Dejneka sbcl-devel 2002-01-13:
  * '``(FOO ,@',@S)
  ``(FOO SB-IMPL::BACKQ-COMMA-AT S)
  * (lisp-implementation-version)
  "0.pre7.129"

142:
  (as reported by Lynn Quam on cmucl-imp ca. 2002-01-16)
  %NATURALIZE-C-STRING conses a lot, like 16 bytes per byte
  of the naturalized string. We could probably port the patches
  from the cmucl-imp mailing list.

143:
  (reported by Jesse Bouwman 2001-10-24 through the unfortunately
  prominent SourceForge web/db bug tracking system, which is 
  unfortunately not a reliable way to get a timely response from
  the SBCL maintainers)
      In the course of trying to build a test case for an 
    application error, I encountered this behavior: 
      If you start up sbcl, and then lay on CTRL-C for a 
    minute or two, the lisp process will eventually say: 
         %PRIMITIVE HALT called; the party is over. 
    and throw you into the monitor. If I start up lisp, 
    attach to the process with strace, and then do the same 
    (abusive) thing, I get instead: 
         access failure in heap page not marked as write-protected 
    and the monitor again. I don't know enough to have the 
    faintest idea of what is going on here. 
      This is with sbcl 6.12, uname -a reports: 
         Linux prep 2.2.19 #4 SMP Tue Apr 24 13:59:52 CDT 2001 i686 unknown 
  I (WHN) have verified that the same thing occurs on sbcl-0.pre7.141
  under OpenBSD 2.9 on my X86 laptop. Do be patient when you try it:
  it took more than two minutes (but less than five) for me.

144: 
  (This was once known as IR1-4, but it lived on even after the
  IR1 interpreter went to the big bit bucket in the sky.)
  The system accepts DECLAIM in most places where DECLARE would be 
  accepted, without even issuing a warning. ANSI allows this, but since
  it's fairly easy to mistype DECLAIM instead of DECLARE, and the
  meaning is rather different, and it's unlikely that the user
  has a good reason for doing DECLAIM not at top level, it would be 
  good to issue a STYLE-WARNING when this happens. A possible
  fix would be to issue STYLE-WARNINGs for DECLAIMs not at top level,
  or perhaps to issue STYLE-WARNINGs for any EVAL-WHEN not at top level.
  [This is considered an IR1-interpreter-related bug because until
  EVAL-WHEN is rewritten, which won't happen until after the IR1
  interpreter is gone, the system's notion of what's a top-level form
  and what's not will remain too confused to fix this problem.]

145:
  ANSI allows types `(COMPLEX ,FOO) to use very hairy values for
  FOO, e.g. (COMPLEX (AND REAL (SATISFIES ODDP))). The old CMU CL
  COMPLEX implementation didn't deal with this, and hasn't been
  upgraded to do so. (This doesn't seem to be a high priority
  conformance problem, since seems hard to construct useful code
  where it matters.)

146:
  Floating point errors are reported poorly. E.g. on x86 OpenBSD
  with sbcl-0.7.1, 
        * (expt 2.0 12777)
        debugger invoked on condition of type SB-KERNEL:FLOATING-POINT-EXCEPTION:
          An arithmetic error SB-KERNEL:FLOATING-POINT-EXCEPTION was signalled.
        No traps are enabled? How can this be?
  It should be possible to be much more specific (overflow, division
  by zero, etc.) and of course the "How can this be?" should be fixable.

147:
  (reported by Alexey Dejneka sbcl-devel 2002-01-28)
  Compiling a file containing
    (deftype digit () '(member #\1))
    (defun parse-num (string ind)
      (flet ((digs ()
               (let (old-index)
                 (if (and (< ind ind)
                          (typep (char string ind) 'digit))
                     nil))))))
  in sbcl-0.7.1 causes the compiler to fail with
    internal error, failed AVER: "(= (LENGTH (BLOCK-SUCC CALL-BLOCK)) 1)" 
  This problem seems to have been introduced by the sbcl-0.pre7.* compiler
  changes, since 0.pre7.73 and 0.6.13 don't suffer from it. A related
  test case is
    (defun parse-num (index)
      (let (num x)
        (flet ((digs ()
                 (setq num index))
               (z ()
                 (let ()
                   (setq x nil))))
          (when (and (digs) (digs)) x))))
  In sbcl-0.7.1, this second test case failed with the same
    internal error, failed AVER: "(= (LENGTH (BLOCK-SUCC CALL-BLOCK)) 1)" 
  After the APD patches in sbcl-0.7.1.2 (new consistency check in
  TARGET-IF-DESIRABLE, plus a fix in meta-vmdef.lisp to keep the
  new consistency check from failing routinely) this second test case
  failed in FIND-IN-PHYSENV instead. Fixes in sbcl-0.7.1.3 (not
  closing over unreferenced variables) made this second test case
  compile without error, but the original test case still fails.
 
  Another way to get rid of the DEFTYPE without changing the symptom
  of the bug is
    (defvar *ch*)
    (defun parse-num (string ind)
      (flet ((digs ()
               (let ()
                 (if (and (< ind ind)
                          (sb-int:memq *ch* '(#\1)))
                     nil))))))
  In sbcl-0.7.1.3, this fails with
    internal error, failed AVER: "(= (LENGTH (BLOCK-SUCC CALL-BLOCK)) 1)" 
  The problem occurs while the inline expansion of MEMQ,
  #<LAMBDA :%DEBUG-NAME "varargs entry point for SB-C::.ANONYMOUS.">
  is being LET-converted after having its second REF deleted, leaving
  it with only one entry in LEAF-REFS.
  
148:
  In sbcl-0.7.1.3 on x86, COMPILE-FILE on the file
    (in-package :cl-user)
    (defvar *thing*)
    (defvar *zoom*)
    (defstruct foo bar bletch)
    (defun %zeep ()
      (labels ((kidify1 (kid)
                 )
               (kid-frob (kid)
                 (if *thing*
                    (setf sweptm
                           (m+ (frobnicate kid)
                                     sweptm))
                    (kidify1 kid))))
      (declare (inline kid-frob))
      (map nil
           #'kid-frob
           (the simple-vector (foo-bar perd)))))
  fails with
    debugger invoked on condition of type TYPE-ERROR:
      The value NIL is not of type SB-C::NODE.
  The location of this failure has moved around as various related
  issues were cleaned up. As of sbcl-0.7.1.9, it occurs in 
  NODE-BLOCK called by LAMBDA-COMPONENT called by IR2-CONVERT-CLOSURE.

151:
  From the ANSI description of GET-DISPATCH-MACRO-CHARACTER, it
  should return NIL when there is no definition, e.g.
    (GET-DISPATCH-MACRO-CHARACTER #\# #\{) => NIL
  Instead, in sbcl-0.7.1.17 it returns
    #<FUNCTION "top level local call SB!IMPL::DISPATCH-CHAR-ERROR">

153:
  (essentially the same problem as a CMU CL bug reported by Martin
  Cracauer on cmucl-imp 2002-02-19)
  There is a hole in structure slot type checking. Compiling and LOADing
    (declaim (optimize safety))
    (defstruct foo
      (bla 0 :type fixnum))
    (defun f ()
      (let ((foo (make-foo)))
        (setf (foo-bla foo) '(1 . 1))
        (format t "Is ~a of type ~a a cons? => ~a~%"
                (foo-bla foo)
                (type-of (foo-bla foo))
                (consp (foo-bla foo)))))
    (f)
  should signal an error, but in sbcl-0.7.1.21 instead gives the output
    Is (1 . 1) of type CONS a cons? => NIL
  without signalling an error.

154:
  There's some sort of problem with aborting back out of the debugger
  after a %DETECT-STACK-EXHAUSTION error in sbcl-0.7.1.38. In some cases
  telling the debugger to ABORT doesn't get you back to the main REPL,
  but instead just gives you another stack exhaustion error. The problem
  doesn't occur in the trivial case
    * (defun frob () (frob) (frob))
    FROB
    * (frob)
  but it has happened in more complicated cases (which I haven't
  figured out how to reproduce).

DEFUNCT CATEGORIES OF BUGS
  IR1-#:
    These labels were used for bugs related to the old IR1 interpreter.
    The # values reached 6 before the category was closed down.