X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcode%2Flate-type.lisp;h=8a4e03b81c480dfd10a9038d7f9329dea1cb056d;hb=4dbc52ee4f9a4f566701f1d33e7916e8491b918b;hp=96b5a817c78787dabe4fc3cfcb9810dfeb043a81;hpb=8e1b4cac0a0f045542ac071c60c323f1fd14c328;p=sbcl.git diff --git a/src/code/late-type.lisp b/src/code/late-type.lisp index 96b5a81..8a4e03b 100644 --- a/src/code/late-type.lisp +++ b/src/code/late-type.lisp @@ -65,21 +65,29 @@ ;;; This is used by !DEFINE-SUPERCLASSES to define the SUBTYPE-ARG1 ;;; method. INFO is a list of conses ;;; (SUPERCLASS-CLASS . {GUARD-TYPE-SPECIFIER | NIL}). -;;; This will never be called with a hairy type as TYPE2, since the -;;; hairy type TYPE2 method gets first crack. (defun !has-superclasses-complex-subtypep-arg1 (type1 type2 info) - (values - (and (sb!xc:typep type2 'sb!xc:class) - (dolist (x info nil) - (when (or (not (cdr x)) - (csubtypep type1 (specifier-type (cdr x)))) - (return - (or (eq type2 (car x)) - (let ((inherits (layout-inherits (class-layout (car x))))) - (dotimes (i (length inherits) nil) - (when (eq type2 (layout-class (svref inherits i))) - (return t))))))))) - t)) + ;; If TYPE2 might be concealing something related to our class + ;; hierarchy + (if (type-might-contain-other-types-p type2) + ;; too confusing, gotta punt + (values nil nil) + ;; ordinary case expected by old CMU CL code, where the taxonomy + ;; of TYPE2's representation accurately reflects the taxonomy of + ;; the underlying set + (values + ;; FIXME: This old CMU CL code probably deserves a comment + ;; explaining to us mere mortals how it works... + (and (sb!xc:typep type2 'sb!xc:class) + (dolist (x info nil) + (when (or (not (cdr x)) + (csubtypep type1 (specifier-type (cdr x)))) + (return + (or (eq type2 (car x)) + (let ((inherits (layout-inherits (class-layout (car x))))) + (dotimes (i (length inherits) nil) + (when (eq type2 (layout-class (svref inherits i))) + (return t))))))))) + t))) ;;; This function takes a list of specs, each of the form ;;; (SUPERCLASS-NAME &OPTIONAL GUARD). @@ -560,8 +568,7 @@ (eq type1 *empty-type*) (eq type2 *wild-type*)) (values t t)) - ((or (eq type1 *wild-type*) - (eq type2 *empty-type*)) + ((eq type1 *wild-type*) (values nil t)) (t (!invoke-type-method :simple-subtypep :complex-subtypep-arg2 @@ -633,6 +640,8 @@ (declare (type ctype type1 type2)) (cond ((eq type1 type2) type1) + ((csubtypep type1 type2) type2) + ((csubtypep type2 type1) type1) ((or (union-type-p type1) (union-type-p type2)) ;; Unions of UNION-TYPE should have the UNION-TYPE-TYPES @@ -685,6 +694,9 @@ ((type1 eq) (type2 eq)) (declare (type ctype type1 type2)) (cond ((eq type1 type2) + ;; FIXME: For some reason, this doesn't catch e.g. type1 = + ;; type2 = (SPECIFIER-TYPE + ;; 'SOME-UNKNOWN-TYPE). Investigate. - CSR, 2002-04-10 type1) ((or (intersection-type-p type1) (intersection-type-p type2)) @@ -744,7 +756,17 @@ (let ((res (specifier-type spec))) (unless (unknown-type-p res) (setf (info :type :builtin spec) res) - (setf (info :type :kind spec) :primitive)))) + ;; KLUDGE: the three copies of this idiom in this file (and + ;; the one in class.lisp as at sbcl-0.7.4.1x) should be + ;; coalesced, or perhaps the error-detecting code that + ;; disallows redefinition of :PRIMITIVE types should be + ;; rewritten to use *TYPE-SYSTEM-FINALIZED* (rather than + ;; *TYPE-SYSTEM-INITIALIZED*). The effect of this is not to + ;; cause redefinition errors when precompute-types is called + ;; for a second time while building the target compiler using + ;; the cross-compiler. -- CSR, trying to explain why this + ;; isn't completely wrong, 2002-06-07 + (setf (info :type :kind spec) #+sb-xc-host :defined #-sb-xc-host :primitive)))) (values)) ;;;; general TYPE-UNION and TYPE-INTERSECTION operations @@ -800,6 +822,7 @@ (defun simplified-compound-types (input-types %compound-type-p simplify2) (let ((simplified-types (make-array (length input-types) :fill-pointer 0 + :adjustable t :element-type 'ctype ;; (This INITIAL-ELEMENT shouldn't ;; matter, but helps avoid type @@ -836,6 +859,16 @@ #+sb-xc-host (coerce types 'list) #-sb-xc-host (coerce-to-list types))))) +(defun maybe-distribute-one-union (union-type types) + (let* ((intersection (apply #'type-intersection types)) + (union (mapcar (lambda (x) (type-intersection x intersection)) + (union-type-types union-type)))) + (if (notany (lambda (x) (or (hairy-type-p x) + (intersection-type-p x))) + union) + union + nil))) + (defun type-intersection (&rest input-types) (let ((simplified-types (simplified-compound-types input-types #'intersection-type-p @@ -847,11 +880,17 @@ ;; always achieve that by the distributive rule. But we don't want ;; to just apply the distributive rule, since it would be too easy ;; to end up with unreasonably huge type expressions. So instead - ;; we punt to HAIRY-TYPE when this comes up. + ;; we try to generate a simple type by distributing the union; if + ;; the type can't be made simple, we punt to HAIRY-TYPE. (if (and (> (length simplified-types) 1) (some #'union-type-p simplified-types)) - (make-hairy-type - :specifier `(and ,@(map 'list #'type-specifier simplified-types))) + (let* ((first-union (find-if #'union-type-p simplified-types)) + (other-types (coerce (remove first-union simplified-types) 'list)) + (distributed (maybe-distribute-one-union first-union other-types))) + (if distributed + (apply #'type-union distributed) + (make-hairy-type + :specifier `(and ,@(map 'list #'type-specifier simplified-types))))) (make-compound-type-or-something #'%make-intersection-type simplified-types (some #'type-enumerable @@ -879,7 +918,7 @@ (macrolet ((frob (name var) `(progn (setq ,var (make-named-type :name ',name)) - (setf (info :type :kind ',name) :primitive) + (setf (info :type :kind ',name) #+sb-xc-host :defined #-sb-xc-host :primitive) (setf (info :type :builtin ',name) ,var)))) ;; KLUDGE: In ANSI, * isn't really the name of a type, it's just a ;; special symbol which can be stuck in some places where an @@ -892,7 +931,7 @@ (frob t *universal-type*)) (setf *universal-fun-type* (make-fun-type :wild-args t - :returns *wild-type*))) + :returns *wild-type*))) (!define-type-method (named :simple-=) (type1 type2) ;; FIXME: BUG 85: This assertion failed when I added it in @@ -906,26 +945,45 @@ (values (or (eq type1 *empty-type*) (eq type2 *wild-type*)) t)) (!define-type-method (named :complex-subtypep-arg1) (type1 type2) - (aver (not (eq type1 *wild-type*))) ; * isn't really a type. - ;; FIXME: Why does this (old CMU CL) assertion hold? Perhaps 'cause - ;; the HAIRY-TYPE COMPLEX-SUBTYPEP-ARG2 method takes precedence over - ;; this COMPLEX-SUBTYPE-ARG1 method? (I miss CLOS..) - (aver (not (hairy-type-p type2))) - ;; Besides the old CMU CL assertion above, we also need to avoid - ;; compound types, else we could get into trouble with - ;; (SUBTYPEP T '(OR (SATISFIES FOO) (SATISFIES BAR))) - ;; or - ;; (SUBTYPEP T '(AND (SATISFIES FOO) (SATISFIES BAR))). - (aver (not (compound-type-p type2))) - ;; Then, since TYPE2 is reasonably tractable, we're good to go. - (values (eq type1 *empty-type*) t)) + ;; This AVER causes problems if we write accurate methods for the + ;; union (and possibly intersection) types which then delegate to + ;; us; while a user shouldn't get here, because of the odd status of + ;; *wild-type* a type-intersection executed by the compiler can. - + ;; CSR, 2002-04-10 + ;; + ;; (aver (not (eq type1 *wild-type*))) ; * isn't really a type. + (cond ((eq type1 *empty-type*) + t) + (;; When TYPE2 might be the universal type in disguise + (type-might-contain-other-types-p type2) + ;; Now that the UNION and HAIRY COMPLEX-SUBTYPEP-ARG2 methods + ;; can delegate to us (more or less as CALL-NEXT-METHOD) when + ;; they're uncertain, we can't just barf on COMPOUND-TYPE and + ;; HAIRY-TYPEs as we used to. Instead we deal with the + ;; problem (where at least part of the problem is cases like + ;; (SUBTYPEP T '(SATISFIES FOO)) + ;; or + ;; (SUBTYPEP T '(AND (SATISFIES FOO) (SATISFIES BAR))) + ;; where the second type is a hairy type like SATISFIES, or + ;; is a compound type which might contain a hairy type) by + ;; returning uncertainty. + (values nil nil)) + (t + ;; By elimination, TYPE1 is the universal type. + (aver (or (eq type1 *wild-type*) (eq type1 *universal-type*))) + ;; This case would have been picked off by the SIMPLE-SUBTYPEP + ;; method, and so shouldn't appear here. + (aver (not (eq type2 *universal-type*))) + ;; Since TYPE2 is not EQ *UNIVERSAL-TYPE* and is not the + ;; universal type in disguise, TYPE2 is not a superset of TYPE1. + (values nil t)))) (!define-type-method (named :complex-subtypep-arg2) (type1 type2) (aver (not (eq type2 *wild-type*))) ; * isn't really a type. (cond ((eq type2 *universal-type*) (values t t)) ((hairy-type-p type1) - (values nil nil)) + (invoke-complex-subtypep-arg1-method type1 type2)) (t ;; FIXME: This seems to rely on there only being 2 or 3 ;; HAIRY-TYPE values, and the exclusion of various @@ -971,18 +1029,111 @@ complement-type2))) (if intersection2 (values (eq intersection2 *empty-type*) t) - (values nil nil)))) + (invoke-complex-subtypep-arg1-method type1 type2)))) (t - (values nil nil))))) + (invoke-complex-subtypep-arg1-method type1 type2))))) + +(!define-type-method (hairy :complex-subtypep-arg1) (type1 type2) + ;; "Incrementally extended heuristic algorithms tend inexorably toward the + ;; incomprehensible." -- http://www.unlambda.com/~james/lambda/lambda.txt + (let ((hairy-spec (hairy-type-specifier type1))) + (cond ((and (consp hairy-spec) (eq (car hairy-spec) 'not)) + ;; You may not believe this. I couldn't either. But then I + ;; sat down and drew lots of Venn diagrams. Comments + ;; involving a and b refer to the call (subtypep '(not a) + ;; 'b) -- CSR, 2002-02-27. + (block nil + ;; (Several logical truths in this block are true as + ;; long as b/=T. As of sbcl-0.7.1.28, it seems + ;; impossible to construct a case with b=T where we + ;; actually reach this type method, but we'll test for + ;; and exclude this case anyway, since future + ;; maintenance might make it possible for it to end up + ;; in this code.) + (multiple-value-bind (equal certain) + (type= type2 (specifier-type t)) + (unless certain + (return (values nil nil))) + (when equal + (return (values t t)))) + (let ((complement-type1 (specifier-type (cadr hairy-spec)))) + ;; Do the special cases first, in order to give us a + ;; chance if subtype/supertype relationships are hairy. + (multiple-value-bind (equal certain) + (type= complement-type1 type2) + ;; If a = b, ~a is not a subtype of b (unless b=T, + ;; which was excluded above). + (unless certain + (return (values nil nil))) + (when equal + (return (values nil t)))) + ;; KLUDGE: ANSI requires that the SUBTYPEP result + ;; between any two built-in atomic type specifiers + ;; never be uncertain. This is hard to do cleanly for + ;; the built-in types whose definitions include + ;; (NOT FOO), i.e. CONS and RATIO. However, we can do + ;; it with this hack, which uses our global knowledge + ;; that our implementation of the type system uses + ;; disjoint implementation types to represent disjoint + ;; sets (except when types are contained in other types). + ;; (This is a KLUDGE because it's fragile. Various + ;; changes in internal representation in the type + ;; system could make it start confidently returning + ;; incorrect results.) -- WHN 2002-03-08 + (unless (or (type-might-contain-other-types-p complement-type1) + (type-might-contain-other-types-p type2)) + ;; Because of the way our types which don't contain + ;; other types are disjoint subsets of the space of + ;; possible values, (SUBTYPEP '(NOT AA) 'B)=NIL when + ;; AA and B are simple (and B is not T, as checked above). + (return (values nil t))) + ;; The old (TYPE= TYPE1 TYPE2) branch would never be + ;; taken, as TYPE1 and TYPE2 will only be equal if + ;; they're both NOT types, and then the + ;; :SIMPLE-SUBTYPEP method would be used instead. + ;; But a CSUBTYPEP relationship might still hold: + (multiple-value-bind (equal certain) + (csubtypep complement-type1 type2) + ;; If a is a subtype of b, ~a is not a subtype of b + ;; (unless b=T, which was excluded above). + (unless certain + (return (values nil nil))) + (when equal + (return (values nil t)))) + (multiple-value-bind (equal certain) + (csubtypep type2 complement-type1) + ;; If b is a subtype of a, ~a is not a subtype of b. + ;; (FIXME: That's not true if a=T. Do we know at + ;; this point that a is not T?) + (unless certain + (return (values nil nil))) + (when equal + (return (values nil t)))) + ;; old CSR comment ca. 0.7.2, now obsoleted by the + ;; SIMPLE-CTYPE? KLUDGE case above: + ;; Other cases here would rely on being able to catch + ;; all possible cases, which the fragility of this + ;; type system doesn't inspire me; for instance, if a + ;; is type= to ~b, then we want T, T; if this is not + ;; the case and the types are disjoint (have an + ;; intersection of *empty-type*) then we want NIL, T; + ;; else if the union of a and b is the + ;; *universal-type* then we want T, T. So currently we + ;; still claim to be unsure about e.g. (subtypep '(not + ;; fixnum) 'single-float). + ))) + (t + (values nil nil))))) -(!define-type-method (hairy :complex-subtypep-arg1 :complex-=) (type1 type2) +(!define-type-method (hairy :complex-=) (type1 type2) (declare (ignore type1 type2)) (values nil nil)) (!define-type-method (hairy :simple-intersection2 :complex-intersection2) (type1 type2) - (declare (ignore type1 type2)) - nil) + (if (type= type1 type2) + type1 + nil)) (!define-type-method (hairy :simple-=) (type1 type2) (if (equal (hairy-type-specifier type1) @@ -995,9 +1146,11 @@ ;; Check legality of arguments. (destructuring-bind (not typespec) whole (declare (ignore not)) - (specifier-type typespec)) ; must be legal typespec - ;; Create object. - (make-hairy-type :specifier whole)) + (let ((spec (type-specifier (specifier-type typespec)))) ; must be legal typespec + (if (and (listp spec) (eq (car spec) 'not)) + ;; canonicalize (not (not foo)) + (specifier-type (cadr spec)) + (make-hairy-type :specifier whole))))) (!def-type-translator satisfies (&whole whole fun) (declare (ignore fun)) @@ -1047,8 +1200,8 @@ `(unsigned-byte ,high-length)) (t `(mod ,(1+ high))))) - ((and (= low sb!vm:*target-most-negative-fixnum*) - (= high sb!vm:*target-most-positive-fixnum*)) + ((and (= low sb!xc:most-negative-fixnum) + (= high sb!xc:most-positive-fixnum)) 'fixnum) ((and (= low (lognot high)) (= high-count high-length) @@ -1269,7 +1422,7 @@ >= > t))))))) (!cold-init-forms - (setf (info :type :kind 'number) :primitive) + (setf (info :type :kind 'number) #+sb-xc-host :defined #-sb-xc-host :primitive) (setf (info :type :builtin 'number) (make-numeric-type :complexp nil))) @@ -1348,9 +1501,9 @@ ;; an intersection type like (AND REAL (SATISFIES ODDP)), ;; in which case we fall through the logic above and ;; end up here, stumped. - (error "~@" typespec))))))))) + (bug "~@<(known bug #145): The type ~S is too hairy to be + used for a COMPLEX component.~:@>" + typespec))))))))) ;;; If X is *, return NIL, otherwise return the bound, which must be a ;;; member of TYPE or a one-element list of a member of TYPE. @@ -1374,21 +1527,27 @@ (lb (if (consp l) (1+ (car l)) l)) (h (canonicalized-bound high 'integer)) (hb (if (consp h) (1- (car h)) h))) - (when (and hb lb (< hb lb)) - (error "Lower bound ~S is greater than upper bound ~S." l h)) - (make-numeric-type :class 'integer - :complexp :real - :enumerable (not (null (and l h))) - :low lb - :high hb))) + (if (and hb lb (< hb lb)) + ;; previously we threw an error here: + ;; (error "Lower bound ~S is greater than upper bound ~S." l h)) + ;; but ANSI doesn't say anything about that, so: + (specifier-type 'nil) + (make-numeric-type :class 'integer + :complexp :real + :enumerable (not (null (and l h))) + :low lb + :high hb)))) (defmacro !def-bounded-type (type class format) `(!def-type-translator ,type (&optional (low '*) (high '*)) (let ((lb (canonicalized-bound low ',type)) (hb (canonicalized-bound high ',type))) - (unless (numeric-bound-test* lb hb <= <) - (error "Lower bound ~S is not less than upper bound ~S." low high)) - (make-numeric-type :class ',class :format ',format :low lb :high hb)))) + (if (not (numeric-bound-test* lb hb <= <)) + ;; as above, previously we did + ;; (error "Lower bound ~S is not less than upper bound ~S." low high)) + ;; but it is correct to do + (specifier-type 'nil) + (make-numeric-type :class ',class :format ',format :low lb :high hb))))) (!def-bounded-type rational rational nil) @@ -1657,13 +1816,23 @@ (array-type-element-type type))) (!define-type-method (array :simple-=) (type1 type2) - (values (and (equal (array-type-dimensions type1) - (array-type-dimensions type2)) - (eq (array-type-complexp type1) - (array-type-complexp type2)) - (type= (specialized-element-type-maybe type1) - (specialized-element-type-maybe type2))) - t)) + (if (or (unknown-type-p (array-type-element-type type1)) + (unknown-type-p (array-type-element-type type2))) + (multiple-value-bind (equalp certainp) + (type= (array-type-element-type type1) + (array-type-element-type type2)) + ;; by its nature, the call to TYPE= should never return NIL, + ;; T, as we don't know what the UNKNOWN-TYPE will grow up to + ;; be. -- CSR, 2002-08-19 + (aver (not (and (not equalp) certainp))) + (values equalp certainp)) + (values (and (equal (array-type-dimensions type1) + (array-type-dimensions type2)) + (eq (array-type-complexp type1) + (array-type-complexp type2)) + (type= (specialized-element-type-maybe type1) + (specialized-element-type-maybe type2))) + t))) (!define-type-method (array :unparse) (type) (let ((dims (array-type-dimensions type)) @@ -1769,10 +1938,28 @@ (eq complexp2 :maybe) (eq complexp1 complexp2))) (values nil t)) - ;; If either element type is wild, then they intersect. - ;; Otherwise, the types must be identical. - ((or (eq (array-type-element-type type1) *wild-type*) - (eq (array-type-element-type type2) *wild-type*) + ;; Old comment: + ;; + ;; If either element type is wild, then they intersect. + ;; Otherwise, the types must be identical. + ;; + ;; FIXME: There seems to have been a fair amount of + ;; confusion about the distinction between requested element + ;; type and specialized element type; here is one of + ;; them. If we request an array to hold objects of an + ;; unknown type, we can do no better than represent that + ;; type as an array specialized on wild-type. We keep the + ;; requested element-type in the -ELEMENT-TYPE slot, and + ;; *WILD-TYPE* in the -SPECIALIZED-ELEMENT-TYPE. So, here, + ;; we must test for the SPECIALIZED slot being *WILD-TYPE*, + ;; not just the ELEMENT-TYPE slot. Maybe the return value + ;; in that specific case should be T, NIL? Or maybe this + ;; function should really be called + ;; ARRAY-TYPES-COULD-POSSIBLY-INTERSECT? In any case, this + ;; was responsible for bug #123, and this whole issue could + ;; do with a rethink and/or a rewrite. -- CSR, 2002-08-21 + ((or (eq (array-type-specialized-element-type type1) *wild-type*) + (eq (array-type-specialized-element-type type2) *wild-type*) (type= (specialized-element-type-maybe type1) (specialized-element-type-maybe type2))) @@ -1848,7 +2035,8 @@ ;;; subtype of the MEMBER type. (!define-type-method (member :complex-subtypep-arg2) (type1 type2) (cond ((not (type-enumerable type1)) (values nil t)) - ((types-equal-or-intersect type1 type2) (values nil nil)) + ((types-equal-or-intersect type1 type2) + (invoke-complex-subtypep-arg1-method type1 type2)) (t (values nil t)))) (!define-type-method (member :simple-intersection2) (type1 type2) @@ -1992,27 +2180,96 @@ 'list `(or ,@(mapcar #'type-specifier (union-type-types type))))) +;;; Two union types are equal if they are each subtypes of each +;;; other. We need to be this clever because our complex subtypep +;;; methods are now more accurate; we don't get infinite recursion +;;; because the simple-subtypep method delegates to complex-subtypep +;;; of the individual types of type1. - CSR, 2002-04-09 +;;; +;;; Previous comment, now obsolete, but worth keeping around because +;;; it is true, though too strong a condition: +;;; ;;; Two union types are equal if their subtypes are equal sets. (!define-type-method (union :simple-=) (type1 type2) - (type=-set (union-type-types type1) - (union-type-types type2))) + (multiple-value-bind (subtype certain?) + (csubtypep type1 type2) + (if subtype + (csubtypep type2 type1) + ;; we might as well become as certain as possible. + (if certain? + (values nil t) + (multiple-value-bind (subtype certain?) + (csubtypep type2 type1) + (declare (ignore subtype)) + (values nil certain?)))))) + +(!define-type-method (union :complex-=) (type1 type2) + (declare (ignore type1)) + (if (some #'hairy-type-p (union-type-types type2)) + (values nil nil) + (values nil t))) -;;; Similarly, a union type is a subtype of another if every element -;;; of TYPE1 is a subtype of some element of TYPE2. -(!define-type-method (union :simple-subtypep) (type1 type2) +;;; Similarly, a union type is a subtype of another if and only if +;;; every element of TYPE1 is a subtype of TYPE2. +(defun union-simple-subtypep (type1 type2) (every/type (swapped-args-fun #'union-complex-subtypep-arg2) type2 (union-type-types type1))) +(!define-type-method (union :simple-subtypep) (type1 type2) + (union-simple-subtypep type1 type2)) + (defun union-complex-subtypep-arg1 (type1 type2) (every/type (swapped-args-fun #'csubtypep) type2 (union-type-types type1))) + (!define-type-method (union :complex-subtypep-arg1) (type1 type2) (union-complex-subtypep-arg1 type1 type2)) (defun union-complex-subtypep-arg2 (type1 type2) - (any/type #'csubtypep type1 (union-type-types type2))) + (multiple-value-bind (sub-value sub-certain?) + ;; was: (any/type #'csubtypep type1 (union-type-types type2)), + ;; which turns out to be too restrictive, causing bug 91. + ;; + ;; the following reimplementation might look dodgy. It is + ;; dodgy. It depends on the union :complex-= method not doing + ;; very much work -- certainly, not using subtypep. Reasoning: + (progn + ;; At this stage, we know that type2 is a union type and type1 + ;; isn't. We might as well check this, though: + (aver (union-type-p type2)) + (aver (not (union-type-p type1))) + ;; A is a subset of (B1 u B2) + ;; <=> A n (B1 u B2) = A + ;; <=> (A n B1) u (A n B2) = A + ;; + ;; But, we have to be careful not to delegate this type= to + ;; something that could invoke subtypep, which might get us + ;; back here -> stack explosion. We therefore ensure that the + ;; second type (which is the one that's dispatched on) is + ;; either a union type (where we've ensured that the complex-= + ;; method will not call subtypep) or something with no union + ;; types involved, in which case we'll never come back here. + ;; + ;; If we don't do this, then e.g. + ;; (SUBTYPEP '(MEMBER 3) '(OR (SATISFIES FOO) (SATISFIES BAR))) + ;; would loop infinitely, as the member :complex-= method is + ;; implemented in terms of subtypep. + ;; + ;; Ouch. - CSR, 2002-04-10 + (type= type1 + (apply #'type-union + (mapcar (lambda (x) (type-intersection type1 x)) + (union-type-types type2))))) + (if sub-certain? + (values sub-value sub-certain?) + ;; The ANY/TYPE expression above is a sufficient condition for + ;; subsetness, but not a necessary one, so we might get a more + ;; certain answer by this CALL-NEXT-METHOD-ish step when the + ;; ANY/TYPE expression is uncertain. + (invoke-complex-subtypep-arg1-method type1 type2)))) + (!define-type-method (union :complex-subtypep-arg2) (type1 type2) (union-complex-subtypep-arg2 type1 type2)) @@ -2030,9 +2287,19 @@ ;; CSUBTYPEP, in order to avoid possibly invoking any methods which ;; might in turn invoke (TYPE-INTERSECTION2 TYPE1 TYPE2) and thus ;; cause infinite recursion. - (cond ((union-complex-subtypep-arg2 type1 type2) + ;; + ;; Within this method, type2 is guaranteed to be a union type: + (aver (union-type-p type2)) + ;; Make sure to call only the applicable methods... + (cond ((and (union-type-p type1) + (union-simple-subtypep type1 type2)) type1) + ((and (union-type-p type1) + (union-simple-subtypep type2 type1)) type2) + ((and (not (union-type-p type1)) + (union-complex-subtypep-arg2 type1 type2)) type1) - ((union-complex-subtypep-arg1 type2 type1) + ((and (not (union-type-p type1)) + (union-complex-subtypep-arg1 type2 type1)) type2) (t ;; KLUDGE: This code accumulates a sequence of TYPE-UNION2