src/code/early-type.lisp

   1 ;;;; This software is part of the SBCL system. See the README file for
   2 ;;;; more information.
   3 ;;;;
   4 ;;;; This software is derived from the CMU CL system, which was
   5 ;;;; written at Carnegie Mellon University and released into the
   6 ;;;; public domain. The software is in the public domain and is
   7 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
   8 ;;;; files for more information.
   9
  10 (in-package "SB!KERNEL")
  11
  12 (!begin-collecting-cold-init-forms)
  13
  14 ;;;; representations of types
  15
  16 ;;; A HAIRY-TYPE represents anything too weird to be described
  17 ;;; reasonably or to be useful, such as NOT, SATISFIES, unknown types,
  18 ;;; and unreasonably complicated types involving AND. We just remember
  19 ;;; the original type spec.
  20 (defstruct (hairy-type (:include ctype
  21                                  (class-info (type-class-or-lose 'hairy))
  22                                  (enumerable t)
  23                                  (might-contain-other-types-p t))
  24                        (:copier nil)
  25                        #!+cmu (:pure nil))
  26   ;; the Common Lisp type-specifier of the type we represent
  27   (specifier nil :type t))
  28
  29 (!define-type-class hairy)
  30
  31 ;;; An UNKNOWN-TYPE is a type not known to the type system (not yet
  32 ;;; defined). We make this distinction since we don't want to complain
  33 ;;; about types that are hairy but defined.
  34 (defstruct (unknown-type (:include hairy-type)
  35                          (:copier nil)))
  36
  37 (defstruct (negation-type (:include ctype
  38                                     (class-info (type-class-or-lose 'negation))
  39                                     ;; FIXME: is this right?  It's
  40                                     ;; what they had before, anyway
  41                                     (enumerable t)
  42                                     (might-contain-other-types-p t))
  43                           (:copier nil)
  44                           #!+cmu (:pure nil))
  45   (type (missing-arg) :type ctype))
  46
  47 (!define-type-class negation)
  48
  49 ;;; ARGS-TYPE objects are used both to represent VALUES types and
  50 ;;; to represent FUNCTION types.
  51 (defstruct (args-type (:include ctype)
  52                       (:constructor nil)
  53                       (:copier nil))
  54   ;; Lists of the type for each required and optional argument.
  55   (required nil :type list)
  56   (optional nil :type list)
  57   ;; The type for the rest arg. NIL if there is no &REST arg.
  58   (rest nil :type (or ctype null))
  59   ;; true if &KEY arguments are specified
  60   (keyp nil :type boolean)
  61   ;; list of KEY-INFO structures describing the &KEY arguments
  62   (keywords nil :type list)
  63   ;; true if other &KEY arguments are allowed
  64   (allowp nil :type boolean))
  65
  66 (defun canonicalize-args-type-args (required optional rest &optional keyp)
  67   (when (eq rest *empty-type*)
  68     ;; or vice-versa?
  69     (setq rest nil))
  70   (loop with last-not-rest = nil
  71         for i from 0
  72         for opt in optional
  73         do (cond ((eq opt *empty-type*)
  74                   (return (values required (subseq optional i) rest)))
  75                  ((and (not keyp) (neq opt rest))
  76                   (setq last-not-rest i)))
  77         finally (return (values required
  78                                 (cond (keyp
  79                                        optional)
  80                                       (last-not-rest
  81                                        (subseq optional 0 (1+ last-not-rest))))
  82                                 rest))))
  83
  84 (defun parse-args-types (lambda-list-like-thing)
  85   (multiple-value-bind
  86         (required optional restp rest keyp keys allowp auxp aux
  87                   morep more-context more-count llk-p)
  88       (parse-lambda-list-like-thing lambda-list-like-thing :silent t)
  89     (declare (ignore aux morep more-context more-count))
  90     (when auxp
  91       (error "&AUX in a FUNCTION or VALUES type: ~S." lambda-list-like-thing))
  92     (let ((required (mapcar #'single-value-specifier-type required))
  93           (optional (mapcar #'single-value-specifier-type optional))
  94           (rest (when restp (single-value-specifier-type rest)))
  95           (keywords
  96            (collect ((key-info))
  97              (dolist (key keys)
  98                (unless (proper-list-of-length-p key 2)
  99                  (error "Keyword type description is not a two-list: ~S." key))
 100                (let ((kwd (first key)))
 101                  (when (find kwd (key-info) :key #'key-info-name)
 102                    (error "~@<repeated keyword ~S in lambda list: ~2I~_~S~:>"
 103                           kwd lambda-list-like-thing))
 104                  (key-info
 105                   (make-key-info
 106                    :name kwd
 107                    :type (single-value-specifier-type (second key))))))
 108              (key-info))))
 109       (multiple-value-bind (required optional rest)
 110           (canonicalize-args-type-args required optional rest keyp)
 111         (values required optional rest keyp keywords allowp llk-p)))))
 112
 113 (defstruct (values-type
 114             (:include args-type
 115                       (class-info (type-class-or-lose 'values)))
 116             (:constructor %make-values-type)
 117             (:copier nil)))
 118
 119 (defun-cached (make-values-type-cached
 120                :hash-bits 8
 121                :hash-function (lambda (req opt rest allowp)
 122                                 (logand (logxor
 123                                          (type-list-cache-hash req)
 124                                          (type-list-cache-hash opt)
 125                                          (if rest
 126                                              (type-hash-value rest)
 127                                              42)
 128                                          (sxhash allowp))
 129                                         #xFF)))
 130     ((required equal-but-no-car-recursion)
 131      (optional equal-but-no-car-recursion)
 132      (rest eq)
 133      (allowp eq))
 134   (%make-values-type :required required
 135                      :optional optional
 136                      :rest rest
 137                      :allowp allowp))
 138
 139 (defun make-values-type (&key required optional rest allowp)
 140   (multiple-value-bind (required optional rest)
 141       (canonicalize-args-type-args required optional rest)
 142     (cond ((and (null required)
 143                 (null optional)
 144                 (eq rest *universal-type*))
 145            *wild-type*)
 146           ((memq *empty-type* required)
 147            *empty-type*)
 148           (t (make-values-type-cached required optional
 149                                       rest allowp)))))
 150
 151 (!define-type-class values)
 152
 153 ;;; (SPECIFIER-TYPE 'FUNCTION) and its subtypes
 154 (defstruct (fun-type (:include args-type
 155                                (class-info (type-class-or-lose 'function)))
 156                      (:constructor
 157                       make-fun-type (&key required optional rest
 158                                           keyp keywords allowp
 159                                           wild-args
 160                                           returns
 161                                      &aux (rest (if (eq rest *empty-type*)
 162                                                     nil
 163                                                     rest)))))
 164   ;; true if the arguments are unrestrictive, i.e. *
 165   (wild-args nil :type boolean)
 166   ;; type describing the return values. This is a values type
 167   ;; when multiple values were specified for the return.
 168   (returns (missing-arg) :type ctype))
 169
 170 ;;; The CONSTANT-TYPE structure represents a use of the CONSTANT-ARG
 171 ;;; "type specifier", which is only meaningful in function argument
 172 ;;; type specifiers used within the compiler. (It represents something
 173 ;;; that the compiler knows to be a constant.)
 174 (defstruct (constant-type
 175             (:include ctype
 176                       (class-info (type-class-or-lose 'constant)))
 177             (:copier nil))
 178   ;; The type which the argument must be a constant instance of for this type
 179   ;; specifier to win.
 180   (type (missing-arg) :type ctype))
 181
 182 ;;; The NAMED-TYPE is used to represent *, T and NIL, the standard
 183 ;;; special cases, as well as other special cases needed to
 184 ;;; interpolate between regions of the type hierarchy, such as
 185 ;;; INSTANCE (which corresponds to all those classes with slots which
 186 ;;; are not funcallable), FUNCALLABLE-INSTANCE (those classes with
 187 ;;; slots which are funcallable) and EXTENDED-SEQUUENCE (non-LIST
 188 ;;; non-VECTOR classes which are also sequences).  These special cases
 189 ;;; are the ones that aren't really discussed by Baker in his
 190 ;;; "Decision Procedure for SUBTYPEP" paper.
 191 (defstruct (named-type (:include ctype
 192                                  (class-info (type-class-or-lose 'named)))
 193                        (:copier nil))
 194   (name nil :type symbol))
 195
 196 ;;; a list of all the float "formats" (i.e. internal representations;
 197 ;;; nothing to do with #'FORMAT), in order of decreasing precision
 198 (eval-when (:compile-toplevel :load-toplevel :execute)
 199   (defparameter *float-formats*
 200     '(long-float double-float single-float short-float)))
 201
 202 ;;; The type of a float format.
 203 (deftype float-format () `(member ,@*float-formats*))
 204
 205 ;;; A NUMERIC-TYPE represents any numeric type, including things
 206 ;;; such as FIXNUM.
 207 (defstruct (numeric-type (:include ctype
 208                                    (class-info (type-class-or-lose 'number)))
 209                          (:constructor %make-numeric-type)
 210                          (:copier nil))
 211   ;; the kind of numeric type we have, or NIL if not specified (just
 212   ;; NUMBER or COMPLEX)
 213   ;;
 214   ;; KLUDGE: A slot named CLASS for a non-CLASS value is bad.
 215   ;; Especially when a CLASS value *is* stored in another slot (called
 216   ;; CLASS-INFO:-). Perhaps this should be called CLASS-NAME? Also
 217   ;; weird that comment above says "Numeric-Type is used to represent
 218   ;; all numeric types" but this slot doesn't allow COMPLEX as an
 219   ;; option.. how does this fall into "not specified" NIL case above?
 220   ;; Perhaps someday we can switch to CLOS and make NUMERIC-TYPE
 221   ;; be an abstract base class and INTEGER-TYPE, RATIONAL-TYPE, and
 222   ;; whatnot be concrete subclasses..
 223   (class nil :type (member integer rational float nil) :read-only t)
 224   ;; "format" for a float type (i.e. type specifier for a CPU
 225   ;; representation of floating point, e.g. 'SINGLE-FLOAT -- nothing
 226   ;; to do with #'FORMAT), or NIL if not specified or not a float.
 227   ;; Formats which don't exist in a given implementation don't appear
 228   ;; here.
 229   (format nil :type (or float-format null) :read-only t)
 230   ;; Is this a complex numeric type?  Null if unknown (only in NUMBER).
 231   ;;
 232   ;; FIXME: I'm bewildered by FOO-P names for things not intended to
 233   ;; interpreted as truth values. Perhaps rename this COMPLEXNESS?
 234   (complexp :real :type (member :real :complex nil) :read-only t)
 235   ;; The upper and lower bounds on the value, or NIL if there is no
 236   ;; bound. If a list of a number, the bound is exclusive. Integer
 237   ;; types never have exclusive bounds, i.e. they may have them on
 238   ;; input, but they're canonicalized to inclusive bounds before we
 239   ;; store them here.
 240   (low nil :type (or number cons null) :read-only t)
 241   (high nil :type (or number cons null) :read-only t))
 242
 243 ;;; Impose canonicalization rules for NUMERIC-TYPE. Note that in some
 244 ;;; cases, despite the name, we return *EMPTY-TYPE* instead of a
 245 ;;; NUMERIC-TYPE.
 246 (defun make-numeric-type (&key class format (complexp :real) low high
 247                                enumerable)
 248   ;; if interval is empty
 249   (if (and low
 250            high
 251            (if (or (consp low) (consp high)) ; if either bound is exclusive
 252                (>= (type-bound-number low) (type-bound-number high))
 253                (> low high)))
 254       *empty-type*
 255       (multiple-value-bind (canonical-low canonical-high)
 256           (case class
 257             (integer
 258              ;; INTEGER types always have their LOW and HIGH bounds
 259              ;; represented as inclusive, not exclusive values.
 260              (values (if (consp low)
 261                          (1+ (type-bound-number low))
 262                          low)
 263                      (if (consp high)
 264                          (1- (type-bound-number high))
 265                          high)))
 266             (t
 267              ;; no canonicalization necessary
 268              (values low high)))
 269         (when (and (eq class 'rational)
 270                    (integerp canonical-low)
 271                    (integerp canonical-high)
 272                    (= canonical-low canonical-high))
 273           (setf class 'integer))
 274         (%make-numeric-type :class class
 275                             :format format
 276                             :complexp complexp
 277                             :low canonical-low
 278                             :high canonical-high
 279                             :enumerable enumerable))))
 280
 281 (defun modified-numeric-type (base
 282                               &key
 283                               (class      (numeric-type-class      base))
 284                               (format     (numeric-type-format     base))
 285                               (complexp   (numeric-type-complexp   base))
 286                               (low        (numeric-type-low        base))
 287                               (high       (numeric-type-high       base))
 288                               (enumerable (numeric-type-enumerable base)))
 289   (make-numeric-type :class class
 290                      :format format
 291                      :complexp complexp
 292                      :low low
 293                      :high high
 294                      :enumerable enumerable))
 295
 296 (defstruct (character-set-type
 297             (:include ctype
 298                       (class-info (type-class-or-lose 'character-set)))
 299             (:constructor %make-character-set-type)
 300             (:copier nil))
 301   (pairs (missing-arg) :type list :read-only t))
 302 (defun make-character-set-type (&key pairs)
 303   ; (aver (equal (mapcar #'car pairs)
 304   ;              (sort (mapcar #'car pairs) #'<)))
 305   ;; aver that the cars of the list elements are sorted into increasing order
 306   (aver (or (null pairs)
 307             (do ((p pairs (cdr p)))
 308                 ((null (cdr p)) t)
 309               (when (> (caar p) (caadr p)) (return nil)))))
 310   (let ((pairs (let (result)
 311                 (do ((pairs pairs (cdr pairs)))
 312                     ((null pairs) (nreverse result))
 313                   (destructuring-bind (low . high) (car pairs)
 314                     (loop for (low1 . high1) in (cdr pairs)
 315                           if (<= low1 (1+ high))
 316                           do (progn (setf high (max high high1))
 317                                     (setf pairs (cdr pairs)))
 318                           else do (return nil))
 319                     (cond
 320                       ((>= low sb!xc:char-code-limit))
 321                       ((< high 0))
 322                       (t (push (cons (max 0 low)
 323                                      (min high (1- sb!xc:char-code-limit)))
 324                                result))))))))
 325     (if (null pairs)
 326        *empty-type*
 327        (%make-character-set-type :pairs pairs))))
 328
 329 ;;; An ARRAY-TYPE is used to represent any array type, including
 330 ;;; things such as SIMPLE-BASE-STRING.
 331 (defstruct (array-type (:include ctype
 332                                  (class-info (type-class-or-lose 'array)))
 333                        (:constructor %make-array-type)
 334                        (:copier nil))
 335   ;; the dimensions of the array, or * if unspecified. If a dimension
 336   ;; is unspecified, it is *.
 337   (dimensions '* :type (or list (member *)))
 338   ;; Is this not a simple array type? (:MAYBE means that we don't know.)
 339   (complexp :maybe :type (member t nil :maybe))
 340   ;; the element type as originally specified
 341   (element-type (missing-arg) :type ctype)
 342   ;; the element type as it is specialized in this implementation
 343   (specialized-element-type *wild-type* :type ctype))
 344 (define-cached-synonym make-array-type)
 345
 346 ;;; A MEMBER-TYPE represent a use of the MEMBER type specifier. We
 347 ;;; bother with this at this level because MEMBER types are fairly
 348 ;;; important and union and intersection are well defined.
 349 (defstruct (member-type (:include ctype
 350                                   (class-info (type-class-or-lose 'member))
 351                                   (enumerable t))
 352                         (:copier nil)
 353                         (:constructor %make-member-type (xset fp-zeroes))
 354                         #-sb-xc-host (:pure nil))
 355   (xset (missing-arg) :type xset)
 356   (fp-zeroes (missing-arg) :type list))
 357 (defun make-member-type (&key xset fp-zeroes members)
 358   (unless xset
 359     (aver (not fp-zeroes))
 360     (setf xset (alloc-xset))
 361     (dolist (elt members)
 362       (if (fp-zero-p elt)
 363           (pushnew elt fp-zeroes)
 364           (add-to-xset elt xset))))
 365   ;; if we have a pair of zeros (e.g. 0.0d0 and -0.0d0), then we can
 366   ;; canonicalize to (DOUBLE-FLOAT 0.0d0 0.0d0), because numeric
 367   ;; ranges are compared by arithmetic operators (while MEMBERship is
 368   ;; compared by EQL).  -- CSR, 2003-04-23
 369   (let ((unpaired nil)
 370         (union-types nil))
 371     (do ((tail (cdr fp-zeroes) (cdr tail))
 372          (zero (car fp-zeroes) (car tail)))
 373         ((not zero))
 374       (macrolet ((frob (c)
 375                    `(let ((neg (neg-fp-zero zero)))
 376                       (if (member neg tail)
 377                           (push (ctype-of ,c) union-types)
 378                           (push zero unpaired)))))
 379         (etypecase zero
 380           (single-float (frob 0.0f0))
 381           (double-float (frob 0.0d0))
 382           #!+long-float
 383           (long-float (frob 0.0l0)))))
 384     ;; The actual member-type contains the XSET (with no FP zeroes),
 385     ;; and a list of unpaired zeroes.
 386     (let ((member-type (unless (and (xset-empty-p xset) (not unpaired))
 387                          (%make-member-type xset unpaired))))
 388       (cond (union-types
 389              (make-union-type t (if member-type
 390                                     (cons member-type union-types)
 391                                     union-types)))
 392             (member-type
 393              member-type)
 394             (t
 395              *empty-type*)))))
 396
 397 (defun member-type-size (type)
 398   (+ (length (member-type-fp-zeroes type))
 399      (xset-count (member-type-xset type))))
 400
 401 (defun member-type-member-p (x type)
 402   (if (fp-zero-p x)
 403       (and (member x (member-type-fp-zeroes type)) t)
 404       (xset-member-p x (member-type-xset type))))
 405
 406 (defun mapcar-member-type-members (function type)
 407   (declare (function function))
 408   (collect ((results))
 409     (map-xset (lambda (x)
 410                 (results (funcall function x)))
 411               (member-type-xset type))
 412     (dolist (zero (member-type-fp-zeroes type))
 413       (results (funcall function zero)))
 414     (results)))
 415
 416 (defun mapc-member-type-members (function type)
 417   (declare (function function))
 418   (map-xset function (member-type-xset type))
 419   (dolist (zero (member-type-fp-zeroes type))
 420     (funcall function zero)))
 421
 422 (defun member-type-members (type)
 423   (append (member-type-fp-zeroes type)
 424           (xset-members (member-type-xset type))))
 425
 426 ;;; A COMPOUND-TYPE is a type defined out of a set of types, the
 427 ;;; common parent of UNION-TYPE and INTERSECTION-TYPE.
 428 (defstruct (compound-type (:include ctype
 429                                     (might-contain-other-types-p t))
 430                           (:constructor nil)
 431                           (:copier nil))
 432   (types nil :type list :read-only t))
 433
 434 ;;; A UNION-TYPE represents a use of the OR type specifier which we
 435 ;;; couldn't canonicalize to something simpler. Canonical form:
 436 ;;;   1. All possible pairwise simplifications (using the UNION2 type
 437 ;;;      methods) have been performed. Thus e.g. there is never more
 438 ;;;      than one MEMBER-TYPE component. FIXME: As of sbcl-0.6.11.13,
 439 ;;;      this hadn't been fully implemented yet.
 440 ;;;   2. There are never any UNION-TYPE components.
 441 (defstruct (union-type (:include compound-type
 442                                  (class-info (type-class-or-lose 'union)))
 443                        (:constructor %make-union-type (enumerable types))
 444                        (:copier nil)))
 445 (define-cached-synonym make-union-type)
 446
 447 ;;; An INTERSECTION-TYPE represents a use of the AND type specifier
 448 ;;; which we couldn't canonicalize to something simpler. Canonical form:
 449 ;;;   1. All possible pairwise simplifications (using the INTERSECTION2
 450 ;;;      type methods) have been performed. Thus e.g. there is never more
 451 ;;;      than one MEMBER-TYPE component.
 452 ;;;   2. There are never any INTERSECTION-TYPE components: we've
 453 ;;;      flattened everything into a single INTERSECTION-TYPE object.
 454 ;;;   3. There are never any UNION-TYPE components. Either we should
 455 ;;;      use the distributive rule to rearrange things so that
 456 ;;;      unions contain intersections and not vice versa, or we
 457 ;;;      should just punt to using a HAIRY-TYPE.
 458 (defstruct (intersection-type (:include compound-type
 459                                         (class-info (type-class-or-lose
 460                                                      'intersection)))
 461                               (:constructor %make-intersection-type
 462                                             (enumerable types))
 463                               (:copier nil)))
 464
 465 ;;; Return TYPE converted to canonical form for a situation where the
 466 ;;; "type" '* (which SBCL still represents as a type even though ANSI
 467 ;;; CL defines it as a related but different kind of placeholder) is
 468 ;;; equivalent to type T.
 469 (defun type-*-to-t (type)
 470   (if (type= type *wild-type*)
 471       *universal-type*
 472       type))
 473
 474 ;;; A CONS-TYPE is used to represent a CONS type.
 475 (defstruct (cons-type (:include ctype (class-info (type-class-or-lose 'cons)))
 476                       (:constructor
 477                        %make-cons-type (car-type
 478                                         cdr-type))
 479                       (:copier nil))
 480   ;; the CAR and CDR element types (to support ANSI (CONS FOO BAR) types)
 481   ;;
 482   ;; FIXME: Most or all other type structure slots could also be :READ-ONLY.
 483   (car-type (missing-arg) :type ctype :read-only t)
 484   (cdr-type (missing-arg) :type ctype :read-only t))
 485 (defun make-cons-type (car-type cdr-type)
 486   (aver (not (or (eq car-type *wild-type*)
 487                  (eq cdr-type *wild-type*))))
 488   (if (or (eq car-type *empty-type*)
 489           (eq cdr-type *empty-type*))
 490       *empty-type*
 491       (%make-cons-type car-type cdr-type)))
 492
 493 (defun cons-type-length-info (type)
 494   (declare (type cons-type type))
 495   (do ((min 1 (1+ min))
 496        (cdr (cons-type-cdr-type type) (cons-type-cdr-type cdr)))
 497       ((not (cons-type-p cdr))
 498        (cond
 499          ((csubtypep cdr (specifier-type 'null))
 500           (values min t))
 501          ((csubtypep *universal-type* cdr)
 502           (values min nil))
 503          ((type/= (type-intersection (specifier-type 'cons) cdr) *empty-type*)
 504           (values min nil))
 505          ((type/= (type-intersection (specifier-type 'null) cdr) *empty-type*)
 506           (values min t))
 507          (t (values min :maybe))))
 508     ()))
 509
 510 \f
 511 ;;;; type utilities
 512
 513 ;;; Return the type structure corresponding to a type specifier. We
 514 ;;; pick off structure types as a special case.
 515 ;;;
 516 ;;; Note: VALUES-SPECIFIER-TYPE-CACHE-CLEAR must be called whenever a
 517 ;;; type is defined (or redefined).
 518 (defun-cached (values-specifier-type
 519                :hash-function (lambda (x)
 520                                 (logand (sxhash x) #x3FF))
 521                :hash-bits 10
 522                :init-wrapper !cold-init-forms)
 523               ((orig equal-but-no-car-recursion))
 524   (let ((u (uncross orig)))
 525     (or (info :type :builtin u)
 526         (let ((spec (typexpand u)))
 527           (cond
 528            ((and (not (eq spec u))
 529                  (info :type :builtin spec)))
 530            ((eq (info :type :kind spec) :instance)
 531             (find-classoid spec))
 532            ((typep spec 'classoid)
 533             (if (typep spec 'built-in-classoid)
 534                 (or (built-in-classoid-translation spec) spec)
 535                 spec))
 536            (t
 537             (when (and (atom spec)
 538                        (member spec '(and or not member eql satisfies values)))
 539               (error "The symbol ~S is not valid as a type specifier." spec))
 540             (let* ((lspec (if (atom spec) (list spec) spec))
 541                    (fun (info :type :translator (car lspec))))
 542               (cond (fun
 543                      (funcall fun lspec))
 544                     ((or (and (consp spec) (symbolp (car spec))
 545                               (not (info :type :builtin (car spec))))
 546                          (and (symbolp spec) (not (info :type :builtin spec))))
 547                      (when (and *type-system-initialized*
 548                                 (not (eq (info :type :kind spec)
 549                                          :forthcoming-defclass-type)))
 550                        (signal 'parse-unknown-type :specifier spec))
 551                      ;; (The RETURN-FROM here inhibits caching; this
 552                      ;; does not only make sense from a compiler
 553                      ;; diagnostics point of view but is also
 554                      ;; indispensable for proper workingness of
 555                      ;; VALID-TYPE-SPECIFIER-P.)
 556                      (return-from values-specifier-type
 557                        (make-unknown-type :specifier spec)))
 558                     (t
 559                      (error "bad thing to be a type specifier: ~S"
 560                             spec))))))))))
 561
 562 ;;; This is like VALUES-SPECIFIER-TYPE, except that we guarantee to
 563 ;;; never return a VALUES type.
 564 (defun specifier-type (x)
 565   (let ((res (values-specifier-type x)))
 566     (when (or (values-type-p res)
 567               ;; bootstrap magic :-(
 568               (and (named-type-p res)
 569                    (eq (named-type-name res) '*)))
 570       (error "VALUES type illegal in this context:~%  ~S" x))
 571     res))
 572
 573 (defun single-value-specifier-type (x)
 574   (if (eq x '*)
 575       *universal-type*
 576       (specifier-type x)))
 577
 578 (defun typexpand-1 (type-specifier &optional env)
 579   #!+sb-doc
 580   "Takes and expands a type specifier once like MACROEXPAND-1.
 581 Returns two values: the expansion, and a boolean that is true when
 582 expansion happened."
 583   (declare (type type-specifier type-specifier))
 584   (declare (ignore env))
 585   (multiple-value-bind (expander lspec)
 586       (let ((spec type-specifier))
 587         (cond ((and (symbolp spec) (info :type :builtin spec))
 588                ;; We do not expand builtins even though it'd be
 589                ;; possible to do so sometimes (e.g. STRING) for two
 590                ;; reasons:
 591                ;;
 592                ;; a) From a user's point of view, CL types are opaque.
 593                ;;
 594                ;; b) so (EQUAL (TYPEXPAND 'STRING) (TYPEXPAND-ALL 'STRING))
 595                (values nil nil))
 596               ((symbolp spec)
 597                (values (info :type :expander spec) (list spec)))
 598               ((and (consp spec) (symbolp (car spec)))
 599                (values (info :type :expander (car spec)) spec))
 600               (t nil)))
 601     (if expander
 602         (values (funcall expander lspec) t)
 603         (values type-specifier nil))))
 604
 605 (defun typexpand (type-specifier &optional env)
 606   #!+sb-doc
 607   "Takes and expands a type specifier repeatedly like MACROEXPAND.
 608 Returns two values: the expansion, and a boolean that is true when
 609 expansion happened."
 610   (declare (type type-specifier type-specifier))
 611   (multiple-value-bind (expansion flag)
 612       (typexpand-1 type-specifier env)
 613     (if flag
 614         (values (typexpand expansion env) t)
 615         (values expansion flag))))
 616
 617 (defun typexpand-all (type-specifier &optional env)
 618   #!+sb-doc
 619   "Takes and expands a type specifier recursively like MACROEXPAND-ALL."
 620   (declare (type type-specifier type-specifier))
 621   (declare (ignore env))
 622   ;; I first thought this would not be a good implementation because
 623   ;; it signals an error on e.g. (CONS 1 2) until I realized that
 624   ;; walking and calling TYPEXPAND would also result in errors, and
 625   ;; it actually makes sense.
 626   ;;
 627   ;; There's still a small problem in that
 628   ;;   (TYPEXPAND-ALL '(CONS * FIXNUM)) => (CONS T FIXNUM)
 629   ;; whereas walking+typexpand would result in (CONS * FIXNUM).
 630   ;;
 631   ;; Similiarly, (TYPEXPAND-ALL '(FUNCTION (&REST T) *)) => FUNCTION.
 632   (type-specifier (values-specifier-type type-specifier)))
 633
 634 (defun defined-type-name-p (name &optional env)
 635   #!+sb-doc
 636   "Returns T if NAME is known to name a type specifier, otherwise NIL."
 637   (declare (symbol name))
 638   (declare (ignore env))
 639   (and (info :type :kind name) t))
 640
 641 (defun valid-type-specifier-p (type-specifier &optional env)
 642   #!+sb-doc
 643   "Returns T if TYPE-SPECIFIER is a valid type specifier, otherwise NIL.
 644
 645 There may be different metrics on what constitutes a \"valid type
 646 specifier\" depending on context. If this function does not suit your
 647 exact need, you may be able to craft a particular solution using a
 648 combination of DEFINED-TYPE-NAME-P and the TYPEXPAND functions.
 649
 650 The definition of \"valid type specifier\" employed by this function
 651 is based on the following mnemonic:
 652
 653           \"Would TYPEP accept it as second argument?\"
 654
 655 Except that unlike TYPEP, this function fully supports compound
 656 FUNCTION type specifiers, and the VALUES type specifier, too.
 657
 658 In particular, VALID-TYPE-SPECIFIER-P will return NIL if
 659 TYPE-SPECIFIER is not a class, not a symbol that is known to name a
 660 type specifier, and not a cons that represents a known compound type
 661 specifier in a syntactically and recursively correct way.
 662
 663 Examples:
 664
 665   (valid-type-specifier-p '(cons * *))     => T
 666   (valid-type-specifier-p '#:foo)          => NIL
 667   (valid-type-specifier-p '(cons * #:foo)) => NIL
 668   (valid-type-specifier-p '(cons 1 *)      => NIL
 669
 670 Experimental."
 671   (declare (ignore env))
 672   (handler-case (prog1 t (values-specifier-type type-specifier))
 673     (parse-unknown-type () nil)
 674     (error () nil)))
 675
 676 ;;; Note that the type NAME has been (re)defined, updating the
 677 ;;; undefined warnings and VALUES-SPECIFIER-TYPE cache.
 678 (defun %note-type-defined (name)
 679   (declare (symbol name))
 680   (note-name-defined name :type)
 681   (when (boundp 'sb!kernel::*values-specifier-type-cache-vector*)
 682     (values-specifier-type-cache-clear))
 683   (values))
 684
 685 \f
 686 (!defun-from-collected-cold-init-forms !early-type-cold-init)