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. 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. 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, e.g. ERROR). 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 () 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 will compile without complaint and work correctly either on SBCL or on a 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 "byte compiling top-level form:" output ought to be condensed. Perhaps any number of such consecutive lines ought to turn into a single "byte 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) 14: The ANSI syntax for non-STANDARD method combination types in CLOS is (DEFGENERIC FOO (X) (:METHOD-COMBINATION PROGN)) (DEFMETHOD FOO PROGN ((X BAR)) (PRINT 'NUMBER)) If you mess this up, omitting the PROGN qualifier in in DEFMETHOD, (DEFGENERIC FOO (X) (:METHOD-COMBINATION PROGN)) (DEFMETHOD FOO ((X BAR)) (PRINT 'NUMBER)) the error mesage is not easy to understand: INVALID-METHOD-ERROR was called outside the dynamic scope of a method combination function (inside the body of DEFINE-METHOD-COMBINATION or a method on the generic function COMPUTE-EFFECTIVE-METHOD). It would be better if it were more informative, a la The method combination type for this method (STANDARD) does not match the method combination type for the generic function (PROGN). Also, after you make the mistake of omitting the PROGN qualifier on a DEFMETHOD, doing a new DEFMETHOD with the correct qualifier no longer works: (DEFMETHOD FOO PROGN ((X BAR)) (PRINT 'NUMBER)) gives INVALID-METHOD-ERROR was called outside the dynamic scope of a method combination function (inside the body of DEFINE-METHOD-COMBINATION or a method on the generic function COMPUTE-EFFECTIVE-METHOD). This is not very helpful.. 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.) 18: from DTC on the CMU CL mailing list 25 Feb 2000: ;;; Compiler fails when this file is compiled. ;;; ;;; Problem shows up in delete-block within ir1util.lisp. The assertion ;;; (assert (member (functional-kind lambda) '(:let :mv-let :assignment))) ;;; fails within bind node branch. ;;; ;;; Note that if c::*check-consistency* is enabled then an un-reached ;;; entry is also reported. ;;; (defun foo (val) (declare (values nil)) nil) (defun bug (val) (multiple-value-call #'(lambda (res) (block nil (tagbody loop (when res (return nil)) (go loop)))) (foo val)) (catch 'ccc1 (throw 'ccc1 (block bbbb (tagbody (let ((ttt #'(lambda () (go cccc)))) (declare (special ttt)) (return-from bbbb nil)) cccc (return-from bbbb nil)))))) 19: (I *think* this is a bug. It certainly seems like strange behavior. But the ANSI spec is scary, dark, and deep..) (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) 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 "~" 12) munge12egnum NIL 23: When too many files are opened, OPEN will fail with an uninformative error message error in function OPEN: error opening #P"/tmp/foo.lisp": NIL instead of saying that too many files are open. 24: Right now, when COMPILE-FILE has a read error, it actually pops you into the debugger before giving up on the file. It should instead handle the error, perhaps issuing (and handling) a secondary error "caught ERROR: unrecoverable error during compilation" and then return with FAILURE-P true, 26: reported by Sam Steingold on the cmucl-imp mailing list 12 May 2000: Also, there is another bug: `array-displacement' should return an array or nil as first value (as per ANSI CL), while CMUCL declares it as returning an array as first value always. (Actually, I think the old CMU CL version in SBCL never returns NIL, i.e. it's not just a declaration problem, but the definition doesn't behave ANSIly.) 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. 29: some sort of bug in inlining and RETURN-FROM in sbcl-0.6.5: Compiling (DEFUN BAR? (X) (OR (NAR? X) (BLOCK USED-BY-SOME-Y? (FLET ((FROB (STK) (DOLIST (Y STK) (UNLESS (REJECTED? Y) (RETURN-FROM USED-BY-SOME-Y? T))))) (DECLARE (INLINE FROB)) (FROB (RSTK X)) (FROB (MRSTK X))) NIL))) gives error in function SB-KERNEL:ASSERT-ERROR: The assertion (EQ (SB-C::CONTINUATION-KIND SB-C::CONT) :BLOCK-START) failed. This is still present in sbcl-0.6.8. 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 # 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))) (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.) 38: DEFMETHOD doesn't check the syntax of &REST argument lists properly, accepting &REST even when it's not followed by an argument name: (DEFMETHOD FOO ((X T) &REST) NIL) 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: a: (fixed in sbcl-0.6.11.25) 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: (/ 1 0.0) (/ 1 0.0d0) (EXPT 10.0 1000) (EXPT 10.0d0 1000) PVE's regression tests want them to raise errors. SBCL generates the infinities instead, which may or may not be conforming behavior. 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. d: ELT signals SIMPLE-ERROR if its index argument isn't a valid index for its sequence argument, but should signal TYPE-ERROR instead. e: FILE-LENGTH is supposed to signal a type error when its argument is not a stream associated with a file, but doesn't. 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. 49: LOOP bugs reported by Peter Van Eynde July 25, 2000: a: (LOOP WITH (A B) DO (PRINT 1)) is a syntax error according to the definition of WITH clauses given in the ANSI spec, but compiles and runs happily in SBCL. b: a messy one involving package iteration: interpreted Form: (LET ((PACKAGE (MAKE-PACKAGE "LOOP-TEST"))) (INTERN "blah" PACKAGE) (LET ((BLAH2 (INTERN "blah2" PACKAGE))) (EXPORT BLAH2 PACKAGE)) (LIST (SORT (LOOP FOR SYM BEING EACH PRESENT-SYMBOL OF PACKAGE FOR SYM-NAME = (SYMBOL-NAME SYM) COLLECT SYM-NAME) (FUNCTION STRING<)) (SORT (LOOP FOR SYM BEING EACH EXTERNAL-SYMBOL OF PACKAGE FOR SYM-NAME = (SYMBOL-NAME SYM) COLLECT SYM-NAME) (FUNCTION STRING<)))) Should be: (("blah" "blah2") ("blah2")) SBCL: (("blah") ("blah2")) * (LET ((X 1)) (LOOP FOR I BY (INCF X) FROM X TO 10 COLLECT I)) doesn't work -- SBCL's LOOP says BY isn't allowed in a FOR clause. 50: type system errors reported by Peter Van Eynde July 25, 2000: a: (SUBTYPEP 'BIGNUM 'INTEGER) => NIL, NIL but should be (VALUES T T) instead. b: (SUBTYPEP 'EXTENDED-CHAR 'CHARACTER) => NIL, NIL but should be (VALUES T T) instead. c: (SUBTYPEP '(INTEGER (0) (0)) 'NIL) dies with nested errors. d: In general, the system doesn't like '(INTEGER (0) (0)) -- it blows up at the level of SPECIFIER-TYPE with "Lower bound (0) is greater than upper bound (0)." Probably SPECIFIER-TYPE should return NIL instead. e: (TYPEP 0 '(COMPLEX (EQL 0)) fails with "Component type for Complex is not numeric: (EQL 0)." This might be easy to fix; the type system already knows that (SUBTYPEP '(EQL 0) 'NUMBER) is true. f: The type system doesn't know about the condition system, so that e.g. (TYPEP 'SIMPLE-ERROR 'ERROR)=>NIL. g: The type system isn't all that smart about relationships between hairy types, as shown in the type.erg test results, e.g. (SUBTYPEP 'CONS '(NOT ATOM)) => NIL, NIL. 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.) 53: another error from Peter Van Eynde 5 September 2000: (FORMAT NIL "~F" "FOO") should work, but instead reports an error. PVE submitted a patch to deal with this bug, but it exposes other comparably serious bugs, so I didn't apply it. It looks as though the FORMAT code needs a fair amount of rewriting in order to comply with the various details of the ANSI spec. 54: The implementation of #'+ returns its single argument without type checking, e.g. (+ "illegal") => "illegal". 55: In sbcl-0.6.7, there is no doc string for CL:PUSH, probably because it's defined with the DEFMACRO-MUNDANELY macro and something is wrong with doc string setting in that macro. 56: Attempting to use COMPILE on something defined by DEFMACRO fails: (DEFMACRO FOO (X) (CONS X X)) (COMPILE 'FOO) Error in function C::GET-LAMBDA-TO-COMPILE: # was defined in a non-null environment. 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 59: CL:*DEFAULT-PATHNAME-DEFAULTS* doesn't behave as ANSI suggests (reflecting current working directory). And there's no supported way to update or query the current working directory (a la Unix "chdir" and "pwd"), which is functionality that ILISP needs (and currently gets with low-level hacks). 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) 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)) => # 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. 69: As reported by Martin Atzmueller on the sbcl-devel list 2000-11-22, > There remains one issue, that is a bug in SBCL: > According to my interpretation of the spec, the ":" and "@" modifiers > should appear _after_ the comma-seperated arguments. > Well, SBCL (and CMUCL for that matter) accept > (ASSERT (STRING= (FORMAT NIL "~:8D" 1) " 1")) > where the correct way (IMHO) should be > (ASSERT (STRING= (FORMAT NIL "~8:D" 1) " 1")) Probably SBCL should stop accepting the "~:8D"-style format arguments, or at least issue a warning. 70: (probably related to bug #65) 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. 74: As noted in the ANSI specification for COERCE, (COERCE 3 'COMPLEX) gives a result which isn't COMPLEX. The result type optimizer for COERCE doesn't know this, perhaps because it was written before ANSI threw this curveball: the optimizer thinks that COERCE always returns a result of the specified type. Thus while the interpreted function (DEFUN TRICKY (X) (TYPEP (COERCE X 'COMPLEX) 'COMPLEX)) returns the correct result, (TRICKY 3) => NIL the compiled function (COMPILE 'TRICKY) does not: (TRICKY 3) => T 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. 80: (fixed early Feb 2001 by MNA) 81: As reported by wbuss@TELDA.NET (Wolfhard Buss) on cmucl-help 2001-02-14, According to CLHS (loop with (a . b) of-type float = '(0.0 . 1.0) and (c . d) of-type float = '(2.0 . 3.0) return (list a b c d)) should evaluate to (0.0 1.0 2.0 3.0). cmucl-18c disagrees and invokes the debugger: "B is not of type list". SBCL does the same thing. 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 # and # 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. 84: (SUBTYPEP '(SATISFIES SOME-UNDEFINED-FUN) NIL)=>NIL,T (should be NIL,NIL) 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 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.) 93: In sbcl-0.6.11.26, (COMPILE 'IN-HOST-COMPILATION-MODE) in src/cold/shared.lisp doesn't correctly translate the interpreted function (defun in-host-compilation-mode (fn) (let ((*features* (cons :sb-xc-host *features*)) ;; the CROSS-FLOAT-INFINITY-KLUDGE, as documented in ;; base-target-features.lisp-expr: (*shebang-features* (set-difference *shebang-features* '(:sb-propagate-float-type :sb-propagate-fun-type)))) (with-additional-nickname ("SB-XC" "SB!XC") (funcall fn)))) No error is reported by the compiler, but when the function is executed, it causes an error TYPE-ERROR in SB-KERNEL::OBJECT-NOT-TYPE-ERROR-HANDLER: (:LINUX :X86 :IEEE-FLOATING-POINT :SB-CONSTRAIN-FLOAT-TYPE :SB-TEST :SB-INTERPRETER :SB-DOC :UNIX ...) is not of type SYMBOL. 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)))) 99: DESCRIBE interacts poorly with *PRINT-CIRCLE*, e.g. the output from (let ((*print-circle* t)) (describe (make-hash-table))) is weird. (This is likely a pretty-printer problem which happens to be exercised by DESCRIBE, not actually a DESCRIBE problem.) KNOWN BUGS RELATED TO THE IR1 INTERPRETER (Note: At some point, the pure interpreter (actually a semi-pure interpreter aka "the IR1 interpreter") will probably go away, replaced by constructs like (DEFUN EVAL (X) (FUNCALL (COMPILE NIL (LAMBDA ..))))) and at that time these bugs should either go away automatically or become more tractable to fix. Until then, they'll probably remain, since some of them aren't considered urgent, and the rest are too hard to fix as long as so many special cases remain. After the IR1 interpreter goes away is also the preferred time to start systematically exterminating cases where debugging functionality (backtrace, breakpoint, etc.) breaks down, since getting rid of the IR1 interpreter will reduce the number of special cases we need to support.) IR1-1: The FUNCTION special operator doesn't check properly whether its argument is a function name. E.g. (FUNCTION (X Y)) returns a value instead of failing with an error. (Later attempting to funcall the value does cause an error.) IR1-2: COMPILED-FUNCTION-P bogusly reports T for interpreted functions: * (DEFUN FOO (X) (- 12 X)) FOO * (COMPILED-FUNCTION-P #'FOO) T IR1-3: Executing (DEFVAR *SUPPRESS-P* T) (EVAL '(UNLESS *SUPPRESS-P* (EVAL-WHEN (:COMPILE-TOPLEVEL :LOAD-TOPLEVEL :EXECUTE) (FORMAT T "surprise!")))) prints "surprise!". Probably the entire EVAL-WHEN mechanism ought to be rewritten from scratch to conform to the ANSI definition, abandoning the *ALREADY-EVALED-THIS* hack which is used in sbcl-0.6.8.9 (and in the original CMU CL source, too). This should be easier to do -- though still nontrivial -- once the various IR1 interpreter special cases are gone. IR1-3a: EVAL-WHEN's idea of what's a toplevel form is even more screwed up than the example in IR1-3 would suggest, since COMPILE-FILE and COMPILE both print both "right now!" messages when compiling the following code, (LAMBDA (X) (COND (X (EVAL-WHEN (:COMPILE-TOPLEVEL :LOAD-TOPLEVEL :EXECUTE) (PRINT "yes! right now!")) "yes!") (T (EVAL-WHEN (:COMPILE-TOPLEVEL :LOAD-TOPLEVEL :EXECUTE) (PRINT "no! right now!")) "no!"))) and while EVAL doesn't print the "right now!" messages, the first FUNCALL on the value returned by EVAL causes both of them to be printed. IR1-4: 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.]