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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.
As of sbcl-0.7.5, sbcl's cross-compiler does run with
*TYPE-SYSTEM-INITIALIZED*; however, this bug remains.
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))
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.
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 2.5
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.
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:
c: (COERCE 'AND 'FUNCTION) returns something related to
(MACRO-FUNCTION 'AND), but ANSI says it should raise an error.
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:
d: (DEFGENERIC IF (X)) should signal a PROGRAM-ERROR, but instead
causes a COMPILER-ERROR.
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.
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".
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.
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.
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.
(partially alleviated in sbcl-0.7.9.32 by a fix by Matthew Danish to
make the temporary filename less easily guessable)
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.)
In fact, the type system is likely to depend on this inequality not
holding... * is not equivalent to T in many cases, such as
(VECTOR *) /= (VECTOR T).
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.
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.
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).
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.
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.
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.
(Since 0.7.8.23 macroexpanders are defined in a restricted version
of the lexical environment, containing no lexical variables and
functions, which seems to conform to ANSI and CLtL2, but signalling
a STYLE-WARNING for references to variables similar to locals might
be a good thing.)
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.
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.
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.
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"
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.
See also bugs #45.c and #183
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.
(Python LET-converts KIDIFY1 into KID-FROB, then tries to inline
expand KID-FROB into %ZEEP. Having partially done it, it sees a call
of KIDIFY1, which already does not exist. So it gives up on
expansion, leaving garbage consisting of infinished blocks of the
partially converted function.)
157:
Functions SUBTYPEP, TYPEP, UPGRADED-ARRAY-ELEMENT-TYPE, and
UPGRADED-COMPLEX-PART-TYPE should have an optional environment argument.
(reported by Alexey Dejneka sbcl-devel 2002-04-12)
162:
(reported by Robert E. Brown 2002-04-16)
When a function is called with too few arguments, causing the
debugger to be entered, the uninitialized slots in the bad call frame
seem to cause GCish problems, being interpreted as tagged data even
though they're not. In particular, executing ROOM in the
debugger at that point causes AVER failures:
* (machine-type)
"X86"
* (lisp-implementation-version)
"0.7.2.12"
* (typep 10)
...
0] (room)
...
failed AVER: "(SAP= CURRENT END)"
(Christophe Rhodes reports that this doesn't occur on the SPARC, which
isn't too surprising since there are many differences in stack
implementation and GC conservatism between the X86 and other ports.)
167:
In sbcl-0.7.3.11, compiling the (illegal) code
(in-package :cl-user)
(defmethod prove ((uustk uustk))
(zap ((frob () nil))
(frob)))
gives the (not terribly clear) error message
; caught ERROR:
; (during macroexpansion of (DEFMETHOD PROVE ...))
; can't get template for (FROB NIL NIL)
The problem seems to be that the code walker used by the DEFMETHOD
macro is unhappy with the illegal syntax in the method body, and
is giving an unclear error message.
173:
The compiler sometimes tries to constant-fold expressions before
it checks to see whether they can be reached. This can lead to
bogus warnings about errors in the constant folding, e.g. in code
like
(WHEN X
(WRITE-STRING (> X 0) "+" "0"))
compiled in a context where the compiler can prove that X is NIL,
and the compiler complains that (> X 0) causes a type error because
NIL isn't a valid argument to #'>. Until sbcl-0.7.4.10 or so this
caused a full WARNING, which made the bug really annoying because then
COMPILE and COMPILE-FILE returned FAILURE-P=T for perfectly legal
code. Since then the warning has been downgraded to STYLE-WARNING,
so it's still a bug but at least it's a little less annoying.
178: "AVER failure compiling confused THEs in FUNCALL"
In sbcl-0.7.4.24, compiling
(defun bug178 (x)
(funcall (the function (the standard-object x))))
gives
failed AVER:
"(AND (EQ (IR2-CONTINUATION-PRIMITIVE-TYPE 2CONT) FUNCTION-PTYPE) (EQ CHECK T))"
This variant compiles OK, though:
(defun bug178alternative (x)
(funcall (the nil x)))
(since 0.7.8.9 it does not signal an error; see also bug 199)
183: "IEEE floating point issues"
Even where floating point handling is being dealt with relatively
well (as of sbcl-0.7.5, on sparc/sunos and alpha; see bug #146), the
accrued-exceptions and current-exceptions part of the fp control
word don't seem to bear much relation to reality. E.g. on
SPARC/SunOS:
* (/ 1.0 0.0)
debugger invoked on condition of type DIVISION-BY-ZERO:
arithmetic error DIVISION-BY-ZERO signalled
0] (sb-vm::get-floating-point-modes)
(:TRAPS (:OVERFLOW :INVALID :DIVIDE-BY-ZERO)
:ROUNDING-MODE :NEAREST
:CURRENT-EXCEPTIONS NIL
:ACCRUED-EXCEPTIONS (:INEXACT)
:FAST-MODE NIL)
0] abort
* (sb-vm::get-floating-point-modes)
(:TRAPS (:OVERFLOW :INVALID :DIVIDE-BY-ZERO)
:ROUNDING-MODE :NEAREST
:CURRENT-EXCEPTIONS (:INEXACT)
:ACCRUED-EXCEPTIONS (:INEXACT)
:FAST-MODE NIL)
187: "type inference confusion around DEFTRANSFORM time"
(reported even more verbosely on sbcl-devel 2002-06-28 as "strange
bug in DEFTRANSFORM")
After the file below is compiled and loaded in sbcl-0.7.5, executing
(TCX (MAKE-ARRAY 4 :FILL-POINTER 2) 0)
at the REPL returns an adjustable vector, which is wrong. Presumably
somehow the DERIVE-TYPE information for the output values of %WAD is
being mispropagated as a type constraint on the input values of %WAD,
and so causing the type test to be optimized away. It's unclear how
hand-expanding the DEFTRANSFORM would change this, but it suggests
the DEFTRANSFORM machinery (or at least the way DEFTRANSFORMs are
invoked at a particular phase) is involved.
(cl:in-package :sb-c)
(eval-when (:compile-toplevel)
;;; standin for %DATA-VECTOR-AND-INDEX
(defknown %dvai (array index)
(values t t)
(foldable flushable))
(deftransform %dvai ((array index)
(vector t)
*
:important t)
(let* ((atype (continuation-type array))
(eltype (array-type-specialized-element-type atype)))
(when (eq eltype *wild-type*)
(give-up-ir1-transform
"specialized array element type not known at compile-time"))
(when (not (array-type-complexp atype))
(give-up-ir1-transform "SIMPLE array!"))
`(if (array-header-p array)
(%wad array index nil)
(values array index))))
;;; standin for %WITH-ARRAY-DATA
(defknown %wad (array index (or index null))
(values (simple-array * (*)) index index index)
(foldable flushable))
;;; (Commenting out this optimizer causes the bug to go away.)
(defoptimizer (%wad derive-type) ((array start end))
(let ((atype (continuation-type array)))
(when (array-type-p atype)
(values-specifier-type
`(values (simple-array ,(type-specifier
(array-type-specialized-element-type atype))
(*))
index index index)))))
) ; EVAL-WHEN
(defun %wad (array start end)
(format t "~&in %WAD~%")
(%with-array-data array start end))
(cl:in-package :cl-user)
(defun tcx (v i)
(declare (type (vector t) v))
(declare (notinline sb-kernel::%with-array-data))
;; (Hand-expending DEFTRANSFORM %DVAI here also causes the bug to
;; go away.)
(sb-c::%dvai v i))
188: "compiler performance fiasco involving type inference and UNION-TYPE"
(In sbcl-0.7.6.10, DEFTRANSFORM CONCATENATE was commented out until this
bug could be fixed properly, so you won't see the bug unless you restore
the DEFTRANSFORM by hand.) In sbcl-0.7.5.11 on a 700 MHz Pentium III,
(time (compile
nil
'(lambda ()
(declare (optimize (safety 3)))
(declare (optimize (compilation-speed 2)))
(declare (optimize (speed 1) (debug 1) (space 1)))
(let ((fn "if-this-file-exists-the-universe-is-strange"))
(load fn :if-does-not-exist nil)
(load (concatenate 'string fn ".lisp") :if-does-not-exist nil)
(load (concatenate 'string fn ".fasl") :if-does-not-exist nil)
(load (concatenate 'string fn ".misc-garbage")
:if-does-not-exist nil)))))
reports
134.552 seconds of real time
133.35156 seconds of user run time
0.03125 seconds of system run time
[Run times include 2.787 seconds GC run time.]
0 page faults and
246883368 bytes consed.
BACKTRACE from Ctrl-C in the compilation shows that the compiler is
thinking about type relationships involving types like
#<UNION-TYPE
(OR (INTEGER 576 576)
(INTEGER 1192 1192)
(INTEGER 2536 2536)
(INTEGER 1816 1816)
(INTEGER 2752 2752)
(INTEGER 1600 1600)
(INTEGER 2640 2640)
(INTEGER 1808 1808)
(INTEGER 1296 1296)
...)>)[:EXTERNAL]
190: "PPC/Linux pipe? buffer? bug"
In sbcl-0.7.6, the run-program.test.sh test script sometimes hangs
on the PPC/Linux platform, waiting for a zombie env process. This
is a classic symptom of buffer filling and deadlock, but it seems
only sporadically reproducible.
191: "Miscellaneous PCL deficiencies"
(reported by Alexey Dejneka sbcl-devel 2002-08-04)
a. DEFCLASS does not inform the compiler about generated
functions. Compiling a file with
(DEFCLASS A-CLASS ()
((A-CLASS-X)))
(DEFUN A-CLASS-X (A)
(WITH-SLOTS (A-CLASS-X) A
A-CLASS-X))
results in a STYLE-WARNING:
undefined-function
SB-SLOT-ACCESSOR-NAME::|COMMON-LISP-USER A-CLASS-X slot READER|
APD's fix for this was checked in to sbcl-0.7.6.20, but Pierre
Mai points out that the declamation of functions is in fact
incorrect in some cases (most notably for structure
classes). This means that at present erroneous attempts to use
WITH-SLOTS and the like on classes with metaclass STRUCTURE-CLASS
won't get the corresponding STYLE-WARNING.
c. the examples in CLHS 7.6.5.1 (regarding generic function lambda
lists and &KEY arguments) do not signal errors when they should.
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
(see bug 203)
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)))))