[sbcl.git] / src / code / defstruct.lisp

;;;; that part of DEFSTRUCT implementation which is needed not just 
;;;; in the target Lisp but also in the cross-compilation host

;;;; This software is part of the SBCL system. See the README file for
;;;; more information.
;;;;
;;;; This software is derived from the CMU CL system, which was
;;;; written at Carnegie Mellon University and released into the
;;;; public domain. The software is in the public domain and is
;;;; provided with absolutely no warranty. See the COPYING and CREDITS
;;;; files for more information.

(in-package "SB!KERNEL")

(/show0 "code/defstruct.lisp 15")
\f
;;;; getting LAYOUTs

;;; Return the compiler layout for NAME. (The class referred to by
;;; NAME must be a structure-like class.)
(defun compiler-layout-or-lose (name)
  #+sb-xc (/show0 "entering COMPILER-LAYOUT-OR-LOSE")
  (let ((res (info :type :compiler-layout name)))
    (cond ((not res)
           (error "Class is not yet defined or was undefined: ~S" name))
          ((not (typep (layout-info res) 'defstruct-description))
           (error "Class is not a structure class: ~S" name))
          (t res))))

;;; Delay looking for compiler-layout until the constructor is being
;;; compiled, since it doesn't exist until after the EVAL-WHEN (COMPILE)
;;; stuff is compiled.
(sb!xc:defmacro %delayed-get-compiler-layout (name)
  `',(compiler-layout-or-lose name))

;;; Get layout right away.
(sb!xc:defmacro compile-time-find-layout (name)
  (find-layout name))

;;; re. %DELAYED-GET-COMPILER-LAYOUT and COMPILE-TIME-FIND-LAYOUT, above..
;;;
;;; FIXME: Perhaps both should be defined with DEFMACRO-MUNDANELY?
;;; FIXME: Do we really need both? If so, their names and implementations
;;; should probably be tweaked to be more parallel.
\f
;;;; DEFSTRUCT-DESCRIPTION

;;; The DEFSTRUCT-DESCRIPTION structure holds compile-time information
;;; about a structure type.
(def!struct (defstruct-description
             (:conc-name dd-)
             (:make-load-form-fun just-dump-it-normally)
             #-sb-xc-host (:pure t)
             (:constructor make-defstruct-description (name)))
  ;; name of the structure
  (name (missing-arg) :type symbol)
  ;; documentation on the structure
  (doc nil :type (or string null))
  ;; prefix for slot names. If NIL, none.
  (conc-name (symbolicate name "-") :type (or symbol null))
  ;; the name of the primary standard keyword constructor, or NIL if none
  (default-constructor nil :type (or symbol null))
  ;; all the explicit :CONSTRUCTOR specs, with name defaulted
  (constructors () :type list)
  ;; name of copying function
  (copier-name (symbolicate "COPY-" name) :type (or symbol null))
  ;; name of type predicate
  (predicate-name (symbolicate name "-P") :type (or symbol null))
  ;; the arguments to the :INCLUDE option, or NIL if no included
  ;; structure
  (include nil :type list)
  ;; properties used to define structure-like classes with an
  ;; arbitrary superclass and that may not have STRUCTURE-CLASS as the
  ;; metaclass. Syntax is:
  ;;    (superclass-name metaclass-name metaclass-constructor)
  (alternate-metaclass nil :type list)
  ;; a list of DEFSTRUCT-SLOT-DESCRIPTION objects for all slots
  ;; (including included ones)
  (slots () :type list)
  ;; number of elements we've allocated (See also RAW-LENGTH.)
  (length 0 :type index)
  ;; General kind of implementation.
  (type 'structure :type (member structure vector list
                                 funcallable-structure))

  ;; The next three slots are for :TYPE'd structures (which aren't
  ;; classes, DD-CLASS-P = NIL)
  ;;
  ;; vector element type
  (element-type t)
  ;; T if :NAMED was explicitly specified, NIL otherwise
  (named nil :type boolean)
  ;; any INITIAL-OFFSET option on this direct type
  (offset nil :type (or index null))

  ;; the argument to the PRINT-FUNCTION option, or NIL if a
  ;; PRINT-FUNCTION option was given with no argument, or 0 if no
  ;; PRINT-FUNCTION option was given
  (print-function 0 :type (or cons symbol (member 0)))
  ;; the argument to the PRINT-OBJECT option, or NIL if a PRINT-OBJECT
  ;; option was given with no argument, or 0 if no PRINT-OBJECT option
  ;; was given
  (print-object 0 :type (or cons symbol (member 0)))
  ;; the index of the raw data vector and the number of words in it,
  ;; or NIL and 0 if not allocated (either because this structure
  ;; has no raw slots, or because we're still parsing it and haven't
  ;; run across any raw slots yet)
  (raw-index nil :type (or index null))
  (raw-length 0 :type index)
  ;; the value of the :PURE option, or :UNSPECIFIED. This is only
  ;; meaningful if DD-CLASS-P = T.
  (pure :unspecified :type (member t nil :substructure :unspecified)))
(def!method print-object ((x defstruct-description) stream)
  (print-unreadable-object (x stream :type t)
    (prin1 (dd-name x) stream)))

;;; Does DD describe a structure with a class?
(defun dd-class-p (dd)
  (member (dd-type dd)
          '(structure funcallable-structure)))

;;; a type name which can be used when declaring things which operate
;;; on structure instances
(defun dd-declarable-type (dd)
  (if (dd-class-p dd)
      ;; Native classes are known to the type system, and we can
      ;; declare them as types.
      (dd-name dd)
      ;; Structures layered on :TYPE LIST or :TYPE VECTOR aren't part
      ;; of the type system, so all we can declare is the underlying
      ;; LIST or VECTOR type.
      (dd-type dd)))

(defun dd-layout-or-lose (dd)
  (compiler-layout-or-lose (dd-name dd)))
\f
;;;; DEFSTRUCT-SLOT-DESCRIPTION

;;; A DEFSTRUCT-SLOT-DESCRIPTION holds compile-time information about
;;; a structure slot.
(def!struct (defstruct-slot-description
             (:make-load-form-fun just-dump-it-normally)
             (:conc-name dsd-)
             (:copier nil)
             #-sb-xc-host (:pure t))
  ;; string name of slot
  %name 
  ;; its position in the implementation sequence
  (index (missing-arg) :type fixnum)
  ;; the name of the accessor function
  ;;
  ;; (CMU CL had extra complexity here ("..or NIL if this accessor has
  ;; the same name as an inherited accessor (which we don't want to
  ;; shadow)") but that behavior doesn't seem to be specified by (or
  ;; even particularly consistent with) ANSI, so it's gone in SBCL.)
  (accessor-name nil)
  default                       ; default value expression
  (type t)                      ; declared type specifier
  ;; If this object does not describe a raw slot, this value is T.
  ;;
  ;; If this object describes a raw slot, this value is the type of the
  ;; value that the raw slot holds. Mostly. (KLUDGE: If the raw slot has
  ;; type (UNSIGNED-BYTE 32), the value here is UNSIGNED-BYTE, not
  ;; (UNSIGNED-BYTE 32).)
  (raw-type t :type (member t single-float double-float
                            #!+long-float long-float
                            complex-single-float complex-double-float
                            #!+long-float complex-long-float
                            unsigned-byte))
  (read-only nil :type (member t nil)))
(def!method print-object ((x defstruct-slot-description) stream)
  (print-unreadable-object (x stream :type t)
    (prin1 (dsd-name x) stream)))

;;; Return the name of a defstruct slot as a symbol. We store it as a
;;; string to avoid creating lots of worthless symbols at load time.
(defun dsd-name (dsd)
  (intern (string (dsd-%name dsd))
          (if (dsd-accessor-name dsd)
              (symbol-package (dsd-accessor-name dsd))
              (sane-package))))
\f
;;;; typed (non-class) structures

;;; Return a type specifier we can use for testing :TYPE'd structures.
(defun dd-lisp-type (defstruct)
  (ecase (dd-type defstruct)
    (list 'list)
    (vector `(simple-array ,(dd-element-type defstruct) (*)))))
\f
;;;; shared machinery for inline and out-of-line slot accessor functions

;;; an alist mapping from raw slot type to the operator used to access
;;; the raw slot
;;;
;;; FIXME: should be shared 
(eval-when (:compile-toplevel :load-toplevel :execute)
  (defvar *raw-type->rawref-fun-name*
    '(;; The compiler thinks that the raw data vector is a vector of
      ;; unsigned bytes, so if the slot we want to access actually *is*
      ;; an unsigned byte, it'll access the slot for us even if we don't
      ;; lie to it at all.
      (unsigned-byte . aref)
      ;; "A lie can travel halfway round the world while the truth is
      ;; putting on its shoes." -- Mark Twain
      (single-float . %raw-ref-single)
      (double-float . %raw-ref-double)
      #!+long-float (long-float . %raw-ref-long)
      (complex-single-float . %raw-ref-complex-single)
      (complex-double-float . %raw-ref-complex-double)
      #!+long-float (complex-long-float . %raw-ref-complex-long))))
\f
;;;; generating out-of-line slot accessor functions

;;; FIXME: Ideally, the presence of the type checks in the functions
;;; here would be conditional on the optimization policy at the point
;;; of expansion of DEFSTRUCT. (For now we're just doing the simpler
;;; thing, putting in the type checks unconditionally.)

;;; Return (VALUES SLOT-READER-FUN SLOT-WRITER-FUN).
(defun slot-accessor-funs (dd dsd)

  #+sb-xc (/show0 "entering SLOT-ACCESSOR-FUNS")

  ;; various code generators
  ;;
  ;; Note: They're only minimally parameterized, and cavalierly grab
  ;; things like INSTANCE and DSD-INDEX from the namespace they're
  ;; expanded in.
  (macrolet (;; code shared between funcallable instance case and the
             ;; ordinary STRUCTURE-OBJECT case: Handle native
             ;; structures with LAYOUTs and (possibly) raw slots.
             (%native-slot-accessor-funs (dd-ref-fun-name)
               (let ((instance-type-check-form
                      '(%check-structure-type-from-layout instance layout)))
                 (/show "macroexpanding %NATIVE-SLOT-ACCESSOR-FUNS" dd-ref-fun-name instance-type-check-form)
                 `(let ((layout (dd-layout-or-lose dd))
                        (dsd-raw-type (dsd-raw-type dsd)))
                    #+sb-xc (/show0 "in %NATIVE-SLOT-ACCESSOR-FUNS macroexpanded code")
                    ;; Map over all the possible RAW-TYPEs, compiling
                    ;; a different closure-function for each one, so
                    ;; that once the COND over RAW-TYPEs happens (at
                    ;; the time closure is allocated) there are no
                    ;; more decisions to be made and things execute
                    ;; reasonably efficiently.
                    (cond
                     ;; nonraw slot case
                     ((eql dsd-raw-type t)
                      #+sb-xc (/show0 "in nonraw slot case")
                      (%slotplace-accessor-funs
                       (,dd-ref-fun-name instance dsd-index)
                       ,instance-type-check-form))
                     ;; raw slot cases
                     ,@(mapcar (lambda (raw-type-and-rawref-fun-name)
                                 (destructuring-bind (raw-type
                                                      . rawref-fun-name)
                                     raw-type-and-rawref-fun-name
                                   `((equal dsd-raw-type ',raw-type)
                                     #+sb-xc (/show0 "in raw slot case")
                                     (let ((raw-index (dd-raw-index dd)))
                                       (%slotplace-accessor-funs
                                        (,rawref-fun-name (,dd-ref-fun-name
                                                           instance
                                                           raw-index)
                                                          dsd-index)
                                        ,instance-type-check-form)))))
                               *raw-type->rawref-fun-name*)
                     ;; oops
                     (t
                      (error "internal error: unexpected DSD-RAW-TYPE ~S"
                             dsd-raw-type))))))
             ;; code shared between DEFSTRUCT :TYPE LIST and
             ;; DEFSTRUCT :TYPE VECTOR cases: Handle the "typed
             ;; structure" case, with no LAYOUTs and no raw slots.
             (%colontyped-slot-accessor-funs () (error "stub")) 
             ;; the common structure of the raw-slot and not-raw-slot
             ;; cases, defined in terms of the writable SLOTPLACE. All
             ;; possible flavors of slot access should be able to pass
             ;; through here.
             (%slotplace-accessor-funs (slotplace instance-type-check-form)
               (/show "macroexpanding %SLOTPLACE-ACCESSOR-FUNS" slotplace instance-type-check-form)
               `(values (lambda (instance)
                          (/noshow0 "in %SLOTPLACE-ACCESSOR-FUNS-defined reader")
                          ,instance-type-check-form
                          (/noshow0 "back from INSTANCE-TYPE-CHECK-FORM")
                          ,slotplace)
                        (let ((typecheckfun (typespec-typecheckfun dsd-type)))
                          (lambda (new-value instance)
                            (/noshow0 "in %SLOTPLACE-ACCESSOR-FUNS-defined writer")
                            ,instance-type-check-form
                            (/noshow0 "back from INSTANCE-TYPE-CHECK-FORM")
                            (funcall typecheckfun new-value)
                            (/noshow0 "back from TYPECHECKFUN")
                            (setf ,slotplace new-value))))))

    (let ((dsd-index (dsd-index dsd))
          (dsd-type (dsd-type dsd)))
            
      #+sb-xc (/show0 "got DSD-TYPE=..")
      #+sb-xc (/hexstr dsd-type)
      (ecase (dd-type dd)

        ;; native structures
        (structure
         #+sb-xc (/show0 "case of DSD-TYPE = STRUCTURE")
         (%native-slot-accessor-funs %instance-ref))
                                     
        ;; structures with the :TYPE option

        ;; FIXME: Worry about these later..
        #|
        ;; In :TYPE LIST and :TYPE VECTOR structures, ANSI specifies the
        ;; layout completely, so that raw slots are impossible.
        (list
         (dd-type-slot-accessor-funs nth-but-with-sane-arg-order
                                 `(%check-structure-type-from-dd
                                 :maybe-raw-p nil))
        (vector
         (dd-type-slot-accessor-funs aref
                                 :maybe-raw-p nil)))
        |#
        ))))
\f
;;;; baby steps for the new out-of-line slot accessor functions
;;;;
;;;; REMOVEME after new structure code works

#|
(in-package :sb-kernel)

(defstruct foo
  ;; vanilla slots
  a
  (b 5 :type package :read-only t)
  ;; raw slots
  (x 5 :type (unsigned-byte 32))
  (y 5.0 :type single-float :read-only t))

(load "/usr/stuff/sbcl/src/cold/chill")
(cl-user:fasl "/usr/stuff/sbcl/src/code/typecheckfuns")
(cl-user:fasl "/usr/stuff/outsacc")

(let* ((foo-layout (compiler-layout-or-lose 'foo))
       (foo-dd (layout-info foo-layout))
       (foo-dsds (dd-slots foo-dd))
       (foo-a-dsd (find "A" foo-dsds :test #'string= :key #'dsd-%name))
       (foo-b-dsd (find "B" foo-dsds :test #'string= :key #'dsd-%name))
       (foo-x-dsd (find "X" foo-dsds :test #'string= :key #'dsd-%name))
       (foo-y-dsd (find "X" foo-dsds :test #'string= :key #'dsd-%name))
       (foo (make-foo :a 'avalue
                      :b (find-package :cl)
                      :x 50)))
  (declare (type layout foo-layout))
  (declare (type defstruct-description foo-dd))
  (declare (type defstruct-slot-description foo-a-dsd))

  (cl-user:/show foo)

  (multiple-value-bind (foo-a-reader foo-a-writer)
      (slot-accessor-funs foo-dd foo-a-dsd)

    ;; basic functionality
    (cl-user:/show foo-a-reader)
    (cl-user:/show (funcall foo-a-reader foo))
    (aver (eql (funcall foo-a-reader foo) 'avalue))
    (cl-user:/show foo-a-writer)
    (cl-user:/show (funcall foo-a-writer 'replacedavalue foo))
    (cl-user:/show "new" (funcall foo-a-reader foo))
    (aver (eql (funcall foo-a-reader foo) 'replacedavalue))

    ;; type checks on FOO-ness of instance argument
    (cl-user:/show (nth-value 1 (ignore-errors (funcall foo-a-reader 3))))
    (aver (typep (nth-value 1 (ignore-errors (funcall foo-a-reader 3)))
                 'type-error))
    (aver (typep (nth-value 1 (ignore-errors (funcall foo-a-writer 3 4)))
                 'type-error)))

  ;; type checks on written slot value
  (multiple-value-bind (foo-b-reader foo-b-writer)
      (slot-accessor-funs foo-dd foo-b-dsd)
    (cl-user:/show "old" (funcall foo-b-reader foo))
    (aver (not (eql (funcall foo-b-reader foo) (find-package :cl-user))))
    (funcall foo-b-writer (find-package :cl-user) foo)    
    (cl-user:/show "new" (funcall foo-b-reader foo))
    (aver (eql (funcall foo-b-reader foo) (find-package :cl-user)))
    (aver (typep (nth-value 1 (ignore-errors (funcall foo-b-writer 5 foo)))
                 'type-error))
    (aver (eql (funcall foo-b-reader foo) (find-package :cl-user))))

  ;; raw slots
  (cl-user:/describe foo-x-dsd)
  (cl-user:/describe foo-y-dsd)
  (multiple-value-bind (foo-x-reader foo-x-writer)
      (slot-accessor-funs foo-dd foo-x-dsd)
    (multiple-value-bind (foo-y-reader foo-y-writer)
        (slot-accessor-funs foo-dd foo-y-dsd)

      ;; basic functionality for (UNSIGNED-BYTE 32) slot
      (cl-user:/show foo-x-reader)
      (cl-user:/show (funcall foo-x-reader foo))
      (aver (eql (funcall foo-x-reader foo) 50))
      (cl-user:/show foo-x-writer)
      (cl-user:/show (funcall foo-x-writer 14 foo))
      (cl-user:/show "new" (funcall foo-x-reader foo))
      (aver (eql (funcall foo-x-reader foo) 14)))

      ;; type check for (UNSIGNED-BYTE 32) slot
      (/show "to do: type check X")

      ;; SINGLE-FLOAT slot
      (/show "to do: Y")))
|#
\f
;;;; the legendary DEFSTRUCT macro itself (both CL:DEFSTRUCT and its
;;;; close personal friend SB!XC:DEFSTRUCT)

;;; Return a list of forms to install PRINT and MAKE-LOAD-FORM funs,
;;; mentioning them in the expansion so that they can be compiled.
(defun class-method-definitions (defstruct)
  (let ((name (dd-name defstruct)))
    `((locally
        ;; KLUDGE: There's a FIND-CLASS DEFTRANSFORM for constant
        ;; class names which creates fast but non-cold-loadable,
        ;; non-compact code. In this context, we'd rather have
        ;; compact, cold-loadable code. -- WHN 19990928
        (declare (notinline sb!xc:find-class))
        #+sb-xc (/show0 "beginning CLASS-METHOD-DEFINITIONS forms")
        ,@(let ((pf (dd-print-function defstruct))
                (po (dd-print-object defstruct))
                (x (gensym))
                (s (gensym)))
            ;; Giving empty :PRINT-OBJECT or :PRINT-FUNCTION options
            ;; leaves PO or PF equal to NIL. The user-level effect is
            ;; to generate a PRINT-OBJECT method specialized for the type,
            ;; implementing the default #S structure-printing behavior.
            (when (or (eq pf nil) (eq po nil))
              (setf pf '(default-structure-print)
                    po 0))
            (flet (;; Given an arg from a :PRINT-OBJECT or :PRINT-FUNCTION
                   ;; option, return the value to pass as an arg to FUNCTION.
                   (farg (oarg)
                     (destructuring-bind (fun-name) oarg
                       fun-name)))
              (cond ((not (eql pf 0))
                     `((def!method print-object ((,x ,name) ,s)
                         (funcall #',(farg pf) ,x ,s *current-level*))))
                    ((not (eql po 0))
                     `((def!method print-object ((,x ,name) ,s)
                         (funcall #',(farg po) ,x ,s))))
                    (t nil))))
        ,@(let ((pure (dd-pure defstruct)))
            (cond ((eq pure t)
                   `((setf (layout-pure (class-layout
                                         (sb!xc:find-class ',name)))
                           t)))
                  ((eq pure :substructure)
                   `((setf (layout-pure (class-layout
                                         (sb!xc:find-class ',name)))
                           0)))))
        ,@(let ((def-con (dd-default-constructor defstruct)))
            (when (and def-con (not (dd-alternate-metaclass defstruct)))
              `((setf (structure-class-constructor (sb!xc:find-class ',name))
                      #',def-con))))
        #+sb-xc (/show0 "done with CLASS-METHOD-DEFINITIONS forms")))))
;;; FIXME: I really would like to make structure accessors less
;;; special, just ordinary inline functions. (Or perhaps inline
;;; functions with special compact implementations of their
;;; expansions, to avoid bloating the system.)

;;; shared logic for CL:DEFSTRUCT and SB!XC:DEFSTRUCT
(defmacro !expander-for-defstruct (name-and-options
                                   slot-descriptions
                                   expanding-into-code-for-xc-host-p)
  `(let ((name-and-options ,name-and-options)
         (slot-descriptions ,slot-descriptions)
         (expanding-into-code-for-xc-host-p
          ,expanding-into-code-for-xc-host-p))
     (let* ((dd (parse-defstruct-name-and-options-and-slot-descriptions
                 name-and-options
                 slot-descriptions))
            (name (dd-name dd)))
       (if (dd-class-p dd)
           (let ((inherits (inherits-for-structure dd)))
             `(progn
                (/show0 "beginning macroexpanded DEFSTRUCT code")
                (eval-when (:compile-toplevel :load-toplevel :execute)
                  (%compiler-defstruct ',dd ',inherits))
                (/show0 "back from %COMPILER-DEFSTRUCT")
                (%defstruct ',dd ',inherits)
                (/show0 "back from %DEFSTRUCT")
                ,@(unless expanding-into-code-for-xc-host-p
                    (append #|(raw-accessor-definitions dd)|# ; REMOVEME
                            (predicate-definitions dd)
                            ;; FIXME: We've inherited from CMU CL nonparallel
                            ;; code for creating copiers for typed and untyped
                            ;; structures. This should be fixed.
                                        ;(copier-definition dd)
                            (constructor-definitions dd)
                            (class-method-definitions dd)))
                (/show0 "done with macroexpanded DEFSTRUCT code")
                ',name))
           `(progn
              (/show0 "beginning macroexpanded typed DEFSTRUCT code")
              (eval-when (:compile-toplevel :load-toplevel :execute)
                (setf (info :typed-structure :info ',name) ',dd))
              ,@(unless expanding-into-code-for-xc-host-p
                  (append (typed-accessor-definitions dd)
                          (typed-predicate-definitions dd)
                          (typed-copier-definitions dd)
                          (constructor-definitions dd)))
              (/show0 "done with macroexpanded typed DEFSTRUCT code")
              ',name)))))

(sb!xc:defmacro defstruct (name-and-options &rest slot-descriptions)
  #!+sb-doc
  "DEFSTRUCT {Name | (Name Option*)} {Slot | (Slot [Default] {Key Value}*)}
   Define the structure type Name. Instances are created by MAKE-<name>, 
   which takes &KEY arguments allowing initial slot values to the specified.
   A SETF'able function <name>-<slot> is defined for each slot to read and
   write slot values. <name>-p is a type predicate.

   Popular DEFSTRUCT options (see manual for others):

   (:CONSTRUCTOR Name)
   (:PREDICATE Name)
       Specify the name for the constructor or predicate.

   (:CONSTRUCTOR Name Lambda-List)
       Specify the name and arguments for a BOA constructor
       (which is more efficient when keyword syntax isn't necessary.)

   (:INCLUDE Supertype Slot-Spec*)
       Make this type a subtype of the structure type Supertype. The optional
       Slot-Specs override inherited slot options.

   Slot options:

   :TYPE Type-Spec
       Asserts that the value of this slot is always of the specified type.

   :READ-ONLY {T | NIL}
       If true, no setter function is defined for this slot."
    (!expander-for-defstruct name-and-options slot-descriptions nil))
#+sb-xc-host
(defmacro sb!xc:defstruct (name-and-options &rest slot-descriptions)
  #!+sb-doc
  "Cause information about a target structure to be built into the
  cross-compiler."
  (!expander-for-defstruct name-and-options slot-descriptions t))
\f
;;;; functions to generate code for various parts of DEFSTRUCT definitions

;;; REMOVEME: no longer used
#|
;;; Return forms to define readers and writers for raw slots as inline
;;; functions.
(defun raw-accessor-definitions (dd)
  (let* ((name (dd-name dd))
         (dtype (dd-declarable-type dd)))
    (collect ((res))
      (dolist (slot (dd-slots dd))
        (let ((slot-type (dsd-type slot))
              (accessor-name (dsd-accessor-name slot))
              (argname (gensym "ARG"))
              (nvname (gensym "NEW-VALUE-")))
          (multiple-value-bind (accessor offset data)
              (slot-accessor-form dd slot argname)
            ;; When accessor exists and is raw
            (when (and accessor-name
                       (not (eq accessor-name '%instance-ref)))
              (res `(/show0 "doing one slot, ACCESSOR-NAME=.."))
              (res `(/hexstr ',accessor-name))
              (res `(declaim (inline ,accessor-name)))
              (res `(/show0 "done with reader DECLAIM INLINE"))
              (res `(declaim (ftype (function (,dtype) ,slot-type)
                                    ,accessor-name)))
              (res `(/show0 "done with reader DECLAIM FTYPE, doing DEFUN"))
              (res `(defun ,accessor-name (,argname)
                      ;; Note: The DECLARE here might seem redundant
                      ;; with the DECLAIM FTYPE above, but it's not:
                      ;; If we're not at toplevel, the PROCLAIM inside
                      ;; the DECLAIM doesn't get executed until after
                      ;; this function is compiled.
                      (declare (type ,dtype ,argname))
                      (truly-the ,slot-type (,accessor ,data ,offset))))
              (unless (dsd-read-only slot)
                (res `(/show0 "doing writer DECLAIM INLINE"))
                (res `(declaim (inline (setf ,accessor-name))))
                (res `(/show0 "doing writer DECLAIM FTYPE"))
                (res `(declaim (ftype (function (,slot-type ,dtype) ,slot-type)
                                      (setf ,accessor-name))))
                ;; FIXME: I rewrote this somewhat from the CMU CL definition.
                ;; Do some basic tests to make sure that reading and writing
                ;; raw slots still works correctly.
                (res `(/show0 "doing writer DEFUN"))
                (res `(defun (setf ,accessor-name) (,nvname ,argname)
                        (declare (type ,dtype ,argname))
                        (setf (,accessor ,data ,offset) ,nvname)
                        ,nvname)))
              (res `(/show0 "done with one slot"))))))
      `((/show0 "beginning RAW-ACCESSOR-DEFINITIONS forms")
        ,@(res)
        (/show0 "done with RAW-ACCESSOR-DEFINITIONS forms")))))
|#

;;; Return a list of forms which create a predicate for an untyped DEFSTRUCT.
(defun predicate-definitions (dd)
  (let ((pred (dd-predicate-name dd))
        (argname (gensym "ARG")))
    (and pred
         `((/show0 "beginning PREDICATE-DEFINITIONS forms")
           (protect-cl ',pred)
           (declaim (inline ,pred))
           (defun ,pred (,argname)
             (declare (optimize (speed 3) (safety 0)))
             (typep-to-layout ,argname
                              (compile-time-find-layout ,(dd-name dd))))
           (/show0 "done with PREDICATE-DEFINITIONS forms")))))

;;; Return a list of forms which create a predicate function for a typed
;;; DEFSTRUCT.
(defun typed-predicate-definitions (defstruct)
  (let ((name (dd-name defstruct))
        (predicate-name (dd-predicate-name defstruct))
        (argname (gensym)))
    (when (and predicate-name (dd-named defstruct))
      (let ((ltype (dd-lisp-type defstruct)))
        `((defun ,predicate-name (,argname)
            (and (typep ,argname ',ltype)
                 (eq (elt (the ,ltype ,argname)
                          ,(cdr (car (last (find-name-indices defstruct)))))
                     ',name))))))))

;;; FIXME: We've inherited from CMU CL code to do typed structure copiers
;;; in a completely different way than untyped structure copiers. Fix this.
;;; (This function was my first attempt to fix this, but I stopped before
;;; figuring out how to install it completely and remove the parallel
;;; code which simply SETF's the FDEFINITION of the DD-COPIER name.
#|
;;; Return the copier definition for an untyped DEFSTRUCT.
(defun copier-definition (dd)
  (when (dd-copier dd)
    (let ((argname (gensym)))
      `(progn
         (protect-cl ',(dd-copier dd))
         (defun ,(dd-copier dd) (,argname)
           (declare (type ,(dd-name dd) ,argname))
           (copy-structure ,argname))))))
|#

;;; Return a list of forms to create a copier function of a typed DEFSTRUCT.
(defun typed-copier-definitions (defstruct)
  (when (dd-copier-name defstruct)
    `((setf (fdefinition ',(dd-copier-name defstruct)) #'copy-seq)
      (declaim (ftype function ,(dd-copier-name defstruct))))))

;;; Return a list of function definitions for accessing and setting
;;; the slots of a typed DEFSTRUCT. The functions are proclaimed to be
;;; inline, and the types of their arguments and results are declared
;;; as well. We count on the compiler to do clever things with ELT.
(defun typed-accessor-definitions (defstruct)
  (collect ((stuff))
    (let ((ltype (dd-lisp-type defstruct)))
      (dolist (slot (dd-slots defstruct))
        (let ((name (dsd-accessor-name slot))
              (index (dsd-index slot))
              (slot-type `(and ,(dsd-type slot)
                               ,(dd-element-type defstruct))))
          (stuff `(proclaim '(inline ,name (setf ,name))))
          ;; FIXME: The arguments in the next two DEFUNs should be
          ;; gensyms. (Otherwise e.g. if NEW-VALUE happened to be the
          ;; name of a special variable, things could get weird.)
          (stuff `(defun ,name (structure)
                    (declare (type ,ltype structure))
                    (the ,slot-type (elt structure ,index))))
          (unless (dsd-read-only slot)
            (stuff
             `(defun (setf ,name) (new-value structure)
                (declare (type ,ltype structure) (type ,slot-type new-value))
                (setf (elt structure ,index) new-value)))))))
    (stuff)))
\f
;;;; parsing

(defun require-no-print-options-so-far (defstruct)
  (unless (and (eql (dd-print-function defstruct) 0)
               (eql (dd-print-object defstruct) 0))
    (error "No more than one of the following options may be specified:
  :PRINT-FUNCTION, :PRINT-OBJECT, :TYPE")))

;;; Parse a single DEFSTRUCT option and store the results in DD.
(defun parse-1-dd-option (option dd)
  (let ((args (rest option))
        (name (dd-name dd)))
    (case (first option)
      (:conc-name
       (destructuring-bind (conc-name) args
         (setf (dd-conc-name dd)
               (if (symbolp conc-name)
                   conc-name
                   (make-symbol (string conc-name))))))
      (:constructor
       (destructuring-bind (&optional (cname (symbolicate "MAKE-" name))
                                      &rest stuff)
           args
         (push (cons cname stuff) (dd-constructors dd))))
      (:copier
       (destructuring-bind (&optional (copier (symbolicate "COPY-" name)))
           args
         (setf (dd-copier-name dd) copier)))
      (:predicate
       (destructuring-bind (&optional (predicate-name (symbolicate name "-P")))
           args
         (setf (dd-predicate-name dd) predicate-name)))
      (:include
       (when (dd-include dd)
         (error "more than one :INCLUDE option"))
       (setf (dd-include dd) args))
      (:print-function
       (require-no-print-options-so-far dd)
       (setf (dd-print-function dd)
             (the (or symbol cons) args)))
      (:print-object
       (require-no-print-options-so-far dd)
       (setf (dd-print-object dd)
             (the (or symbol cons) args)))
      (:type
       (destructuring-bind (type) args
         (cond ((member type '(list vector))
                (setf (dd-element-type dd) t)
                (setf (dd-type dd) type))
               ((and (consp type) (eq (first type) 'vector))
                (destructuring-bind (vector vtype) type
                  (declare (ignore vector))
                  (setf (dd-element-type dd) vtype)
                  (setf (dd-type dd) 'vector)))
               (t
                (error "~S is a bad :TYPE for DEFSTRUCT." type)))))
      (:named
       (error "The DEFSTRUCT option :NAMED takes no arguments."))
      (:initial-offset
       (destructuring-bind (offset) args
         (setf (dd-offset dd) offset)))
      (:pure
       (destructuring-bind (fun) args
         (setf (dd-pure dd) fun)))
      (t (error "unknown DEFSTRUCT option:~%  ~S" option)))))

;;; Given name and options, return a DD holding that info.
(eval-when (:compile-toplevel :load-toplevel :execute)
(defun parse-defstruct-name-and-options (name-and-options)
  (destructuring-bind (name &rest options) name-and-options
    (aver name) ; A null name doesn't seem to make sense here.
    (let ((dd (make-defstruct-description name)))
      (dolist (option options)
        (cond ((eq option :named)
               (setf (dd-named dd) t))
              ((consp option)
               (parse-1-dd-option option dd))
              ((member option '(:conc-name :constructor :copier :predicate))
               (parse-1-dd-option (list option) dd))
              (t
               (error "unrecognized DEFSTRUCT option: ~S" option))))

      (case (dd-type dd)
        (structure
         (when (dd-offset dd)
           (error ":OFFSET can't be specified unless :TYPE is specified."))
         (unless (dd-include dd)
           ;; FIXME: It'd be cleaner to treat no-:INCLUDE as defaulting
           ;; to :INCLUDE STRUCTURE-OBJECT, and then let the general-case
           ;; (INCF (DD-LENGTH DD) (DD-LENGTH included-DD)) logic take
           ;; care of this. (Except that the :TYPE VECTOR and :TYPE
           ;; LIST cases, with their :NAMED and un-:NAMED flavors,
           ;; make that messy, alas.)
           (incf (dd-length dd))))
        (t
         (require-no-print-options-so-far dd)
         (when (dd-named dd)
           (incf (dd-length dd)))
         (let ((offset (dd-offset dd)))
           (when offset (incf (dd-length dd) offset)))))

      (when (dd-include dd)
        (do-dd-inclusion-stuff dd))

      dd)))

;;; Given name and options and slot descriptions (and possibly doc
;;; string at the head of slot descriptions) return a DD holding that
;;; info.
(defun parse-defstruct-name-and-options-and-slot-descriptions
    (name-and-options slot-descriptions)
  (let ((result (parse-defstruct-name-and-options (if (atom name-and-options)
                                                      (list name-and-options)
                                                      name-and-options))))
    (when (stringp (car slot-descriptions))
      (setf (dd-doc result) (pop slot-descriptions)))
    (dolist (slot-description slot-descriptions)
      (allocate-1-slot result (parse-1-dsd result slot-description)))
    result))

) ; EVAL-WHEN
\f
;;;; stuff to parse slot descriptions

;;; Parse a slot description for DEFSTRUCT, add it to the description
;;; and return it. If supplied, SLOT is a pre-initialized DSD
;;; that we modify to get the new slot. This is supplied when handling
;;; included slots.
(defun parse-1-dsd (defstruct spec &optional
                    (slot (make-defstruct-slot-description :%name ""
                                                           :index 0
                                                           :type t)))
  (multiple-value-bind (name default default-p type type-p read-only ro-p)
      (cond
       ((listp spec)
        (destructuring-bind
            (name
             &optional (default nil default-p)
             &key (type nil type-p) (read-only nil ro-p))
            spec
          (values name
                  default default-p
                  (uncross type) type-p
                  read-only ro-p)))
       (t
        (when (keywordp spec)
          (style-warn "Keyword slot name indicates probable syntax ~
                       error in DEFSTRUCT: ~S."
                      spec))
        spec))

    (when (find name (dd-slots defstruct) :test #'string= :key #'dsd-%name)
      (error 'simple-program-error
             :format-control "duplicate slot name ~S"
             :format-arguments (list name)))
    (setf (dsd-%name slot) (string name))
    (setf (dd-slots defstruct) (nconc (dd-slots defstruct) (list slot)))

    (let ((accessor-name (symbolicate (or (dd-conc-name defstruct) "") name))
          (predicate-name (dd-predicate-name defstruct)))
      (setf (dsd-accessor-name slot) accessor-name)
      (when (eql accessor-name predicate-name)
        ;; Some adventurous soul has named a slot so that its accessor
        ;; collides with the structure type predicate. ANSI doesn't
        ;; specify what to do in this case. As of 2001-09-04, Martin
        ;; Atzmueller reports that CLISP and Lispworks both give
        ;; priority to the slot accessor, so that the predicate is
        ;; overwritten. We might as well do the same (as well as
        ;; signalling a warning).
        (style-warn
         "~@<The structure accessor name ~S is the same as the name of the ~
          structure type predicate. ANSI doesn't specify what to do in ~
          this case. We'll overwrite the type predicate with the slot ~
          accessor, but you can't rely on this behavior, so it'd be wise to ~
          remove the ambiguity in your code.~@:>"
         accessor-name)
        (setf (dd-predicate-name defstruct) nil)))

    (when default-p
      (setf (dsd-default slot) default))
    (when type-p
      (setf (dsd-type slot)
            (if (eq (dsd-type slot) t)
                type
                `(and ,(dsd-type slot) ,type))))
    (when ro-p
      (if read-only
          (setf (dsd-read-only slot) t)
          (when (dsd-read-only slot)
            (error "Slot ~S is :READ-ONLY in parent and must be :READ-ONLY in subtype ~S."
                   name
                   (dsd-name slot)))))
    slot))

;;; When a value of type TYPE is stored in a structure, should it be
;;; stored in a raw slot? Return (VALUES RAW? RAW-TYPE WORDS), where
;;;   RAW? is true if TYPE should be stored in a raw slot.
;;;   RAW-TYPE is the raw slot type, or NIL if no raw slot.
;;;   WORDS is the number of words in the raw slot, or NIL if no raw slot.
(defun structure-raw-slot-type-and-size (type)
  (/noshow "in STRUCTURE-RAW-SLOT-TYPE-AND-SIZE" type (sb!xc:subtypep type 'fixnum))
  (cond #+nil
        (;; FIXME: For now we suppress raw slots, since there are various
         ;; issues about the way that the cross-compiler handles them.
         (not (boundp '*dummy-placeholder-to-stop-compiler-warnings*))
         (values nil nil nil))
        ((and (sb!xc:subtypep type '(unsigned-byte 32))
              (multiple-value-bind (fixnum? fixnum-certain?)
                  (sb!xc:subtypep type 'fixnum)
                (/noshow fixnum? fixnum-certain?)
                ;; (The extra test for FIXNUM-CERTAIN? here is
                ;; intended for bootstrapping the system. In
                ;; particular, in sbcl-0.6.2, we set up LAYOUT before
                ;; FIXNUM is defined, and so could bogusly end up
                ;; putting INDEX-typed values into raw slots if we
                ;; didn't test FIXNUM-CERTAIN?.)
                (and (not fixnum?) fixnum-certain?)))
         (values t 'unsigned-byte 1))
        ((sb!xc:subtypep type 'single-float)
         (values t 'single-float 1))
        ((sb!xc:subtypep type 'double-float)
         (values t 'double-float 2))
        #!+long-float
        ((sb!xc:subtypep type 'long-float)
         (values t 'long-float #!+x86 3 #!+sparc 4))
        ((sb!xc:subtypep type '(complex single-float))
         (values t 'complex-single-float 2))
        ((sb!xc:subtypep type '(complex double-float))
         (values t 'complex-double-float 4))
        #!+long-float
        ((sb!xc:subtypep type '(complex long-float))
         (values t 'complex-long-float #!+x86 6 #!+sparc 8))
        (t
         (values nil nil nil))))

;;; Allocate storage for a DSD in DD. This is where we decide whether
;;; a slot is raw or not. If raw, and we haven't allocated a raw-index
;;; yet for the raw data vector, then do it. Raw objects are aligned
;;; on the unit of their size.
(defun allocate-1-slot (dd dsd)
  #+sb-xc (/show0 "entering ALLOCATE-1-SLOT")
  (multiple-value-bind (raw? raw-type words)
      (if (eq (dd-type dd) 'structure)
          (structure-raw-slot-type-and-size (dsd-type dsd))
          (values nil nil nil))
    (/noshow "ALLOCATE-1-SLOT" dsd raw? raw-type words)
    (cond ((not raw?)
           (setf (dsd-index dsd) (dd-length dd))
           (incf (dd-length dd)))
          (t
           (unless (dd-raw-index dd)
             (setf (dd-raw-index dd) (dd-length dd))
             (incf (dd-length dd)))
           (let ((off (rem (dd-raw-length dd) words)))
             (unless (zerop off)
               (incf (dd-raw-length dd) (- words off))))
           (setf (dsd-raw-type dsd) raw-type)
           (setf (dsd-index dsd) (dd-raw-length dd))
           (incf (dd-raw-length dd) words))))
  #+sb-xc (/show0 "leaving ALLOCATE-1-SLOT")
  (values))

(defun typed-structure-info-or-lose (name)
  (or (info :typed-structure :info name)
      (error ":TYPE'd DEFSTRUCT ~S not found for inclusion." name)))

;;; Process any included slots pretty much like they were specified.
;;; Also inherit various other attributes.
(defun do-dd-inclusion-stuff (dd)
  (destructuring-bind (included-name &rest modified-slots) (dd-include dd)
    (let* ((type (dd-type dd))
           (included-structure
            (if (dd-class-p dd)
                (layout-info (compiler-layout-or-lose included-name))
                (typed-structure-info-or-lose included-name))))

      ;; checks on legality
      (unless (and (eq type (dd-type included-structure))
                   (type= (specifier-type (dd-element-type included-structure))
                          (specifier-type (dd-element-type dd))))
        (error ":TYPE option mismatch between structures ~S and ~S"
               (dd-name dd) included-name))
      (let ((included-class (sb!xc:find-class included-name nil)))
        (when included-class
          ;; It's not particularly well-defined to :INCLUDE any of the
          ;; CMU CL INSTANCE weirdosities like CONDITION or
          ;; GENERIC-FUNCTION, and it's certainly not ANSI-compliant.
          (let* ((included-layout (class-layout included-class))
                 (included-dd (layout-info included-layout)))
            (when (and (dd-alternate-metaclass included-dd)
                       ;; As of sbcl-0.pre7.73, anyway, STRUCTURE-OBJECT
                       ;; is represented with an ALTERNATE-METACLASS. But
                       ;; it's specifically OK to :INCLUDE (and PCL does)
                       ;; so in this one case, it's OK to include
                       ;; something with :ALTERNATE-METACLASS after all.
                       (not (eql included-name 'structure-object)))
              (error "can't :INCLUDE class ~S (has alternate metaclass)"
                     included-name)))))

      (incf (dd-length dd) (dd-length included-structure))
      (when (dd-class-p dd)
        (let ((mc (rest (dd-alternate-metaclass included-structure))))
          (when (and mc (not (dd-alternate-metaclass dd)))
            (setf (dd-alternate-metaclass dd)
                  (cons included-name mc))))
        (when (eq (dd-pure dd) :unspecified)
          (setf (dd-pure dd) (dd-pure included-structure)))
        (setf (dd-raw-index dd) (dd-raw-index included-structure))
        (setf (dd-raw-length dd) (dd-raw-length included-structure)))

      (dolist (included-slot (dd-slots included-structure))
        (let* ((included-name (dsd-name included-slot))
               (modified (or (find included-name modified-slots
                                   :key #'(lambda (x) (if (atom x) x (car x)))
                                   :test #'string=)
                             `(,included-name))))
          (parse-1-dsd dd
                       modified
                       (copy-structure included-slot)))))))
\f
;;;; various helper functions for setting up DEFSTRUCTs

;;; This function is called at macroexpand time to compute the INHERITS
;;; vector for a structure type definition.
(defun inherits-for-structure (info)
  (declare (type defstruct-description info))
  (let* ((include (dd-include info))
         (superclass-opt (dd-alternate-metaclass info))
         (super
          (if include
              (compiler-layout-or-lose (first include))
              (class-layout (sb!xc:find-class
                             (or (first superclass-opt)
                                 'structure-object))))))
    (if (eq (dd-name info) 'ansi-stream)
        ;; a hack to add the CL:STREAM class as a mixin for ANSI-STREAMs
        (concatenate 'simple-vector
                     (layout-inherits super)
                     (vector super
                             (class-layout (sb!xc:find-class 'stream))))
        (concatenate 'simple-vector
                     (layout-inherits super)
                     (vector super)))))

;;; Do miscellaneous (LOAD EVAL) time actions for the structure
;;; described by DD. Create the class & LAYOUT, checking for
;;; incompatible redefinition. Define those functions which are
;;; sufficiently stereotyped that we can implement them as standard
;;; closures.
(defun %defstruct (dd inherits)
  (declare (type defstruct-description dd))

  #+sb-xc (/show0 "entering %DEFSTRUCT")

  ;; We set up LAYOUTs even in the cross-compilation host.
  (multiple-value-bind (class layout old-layout)
      (ensure-structure-class dd inherits "current" "new")
    (cond ((not old-layout)
           (unless (eq (class-layout class) layout)
             (register-layout layout)))
          (t
           (let ((old-dd (layout-info old-layout)))
             (when (defstruct-description-p old-dd)
               (dolist (slot (dd-slots old-dd))
                 (fmakunbound (dsd-accessor-name slot))
                 (unless (dsd-read-only slot)
                   (fmakunbound `(setf ,(dsd-accessor-name slot)))))))
           (%redefine-defstruct class old-layout layout)
           (setq layout (class-layout class))))
    (setf (sb!xc:find-class (dd-name dd)) class)

    ;; It doesn't make sense to do these in the cross-compilation host.
    #-sb-xc-host
    (progn
      #+sb-xc (/show0 "doing #+SB-XC stuff in %DEFSTRUCT")
      (remhash (dd-name dd) *typecheckfuns*)
      (%target-defstruct dd layout)
      (when (dd-doc dd)
        (setf (fdocumentation (dd-name dd) 'type)
              (dd-doc dd)))
      #+sb-xc (/show0 "done with #+SB-XC stuff in %DEFSTRUCT")
      ))

  #+sb-xc (/show0 "leaving %DEFSTRUCT")
  (values))
\f
;;; Return a form describing the writable place used for this slot
;;; in the instance named INSTANCE-NAME.
(defun %accessor-place-form (dd dsd instance-name)
  (let (;; the operator that we'll use to access a typed slot or, in
        ;; the case of a raw slot, to read the vector of raw slots
        (ref (ecase (dd-type dd)
               (structure '%instance-ref)
               (list 'nth-but-with-sane-arg-order)
               (vector 'aref)))
        (raw-type (dsd-raw-type dsd)))
    (if (eq raw-type t) ; if not raw slot
        `(,ref ,instance-name ,(dsd-index dsd))
        (let (;; the operator that we'll use to access one value in
              ;; the raw data vector
              (rawref (ecase raw-type
                        ;; The compiler thinks that the raw data
                        ;; vector is a vector of unsigned bytes, so if
                        ;; the slot we want to access actually *is* an
                        ;; unsigned byte, it'll access the slot for
                        ;; us even if we don't lie to it at all.
                        (unsigned-byte 'aref)
                        ;; "A lie can travel halfway round the world while
                        ;; the truth is putting on its shoes." -- Mark Twain
                        (single-float '%raw-ref-single)
                        (double-float '%raw-ref-double)
                        #!+long-float (long-float '%raw-ref-long)
                        (complex-single-float '%raw-ref-complex-single)
                        (complex-double-float '%raw-ref-complex-double)
                        #!+long-float (complex-long-float
                                       '%raw-ref-complex-long))))
          `(,rawref (,ref ,instance-name ,(dd-raw-index dd))
                    ,(dsd-index dsd))))))

;;; Return inline expansion designators (i.e. values suitable for
;;; (INFO :FUNCTION :INLINE-EXPANSSION-DESIGNATOR ..)) for the reader
;;; and writer functions of the slot described by DSD.
(defun accessor-inline-expansion-designators (dd dsd)
  (values (lambda ()
            `(lambda (instance)
               (declare (type ,(dd-name dd) instance))
               (truly-the ,(dsd-type dsd)
                          ,(%accessor-place-form dd dsd 'instance))))
          (lambda ()
            `(lambda (new-value instance)
               (declare (type ,(dsd-type dsd) new-value))
               (declare (type ,(dd-name dd) structure-object))
               (setf ,(%accessor-place-form dd dsd 'instance) new-value)))))

;;; core compile-time setup of any class with a LAYOUT, used even by
;;; !DEFSTRUCT-WITH-ALTERNATE-METACLASS weirdosities
(defun %compiler-set-up-layout (dd
                                &optional
                                ;; Several special cases (STRUCTURE-OBJECT
                                ;; itself, and structures with alternate
                                ;; metaclasses) call this function directly,
                                ;; and they're all at the base of the
                                ;; instance class structure, so this is
                                ;; a handy default.
                                (inherits (vector (find-layout t)
                                                  (find-layout 'instance))))

  (/show "entering %COMPILER-SET-UP-LAYOUT for" (dd-name dd))

  (multiple-value-bind (class layout old-layout)
      (multiple-value-bind (clayout clayout-p)
          (info :type :compiler-layout (dd-name dd))
        (ensure-structure-class dd
                                inherits
                                (if clayout-p "previously compiled" "current")
                                "compiled"
                                :compiler-layout clayout))
    (cond (old-layout
           (/show "non-NIL" old-layout)
           (undefine-structure (layout-class old-layout))
           (when (and (class-subclasses class)
                      (not (eq layout old-layout)))
             (collect ((subs))
                      (dohash (class layout (class-subclasses class))
                        (declare (ignore layout))
                        (undefine-structure class)
                        (subs (class-proper-name class)))
                      (when (subs)
                        (warn "removing old subclasses of ~S:~%  ~S"
                              (sb!xc:class-name class)
                              (subs))))))
          (t
           (unless (eq (class-layout class) layout)
             (register-layout layout :invalidate nil))
           (setf (sb!xc:find-class (dd-name dd)) class)))

    ;; At this point the class should be set up in the INFO database.
    ;; But the logic that enforces this is a little tangled and
    ;; scattered, so it's not obvious, so let's check.
    (aver (sb!xc:find-class (dd-name dd) nil))

    (setf (info :type :compiler-layout (dd-name dd)) layout))

  (/show0 "leaving %COMPILER-SET-UP-LAYOUT")

  (values))

;;; Do (COMPILE LOAD EVAL)-time actions for the normal (not
;;; ALTERNATE-LAYOUT) DEFSTRUCT described by DD.
(defun %compiler-defstruct (dd inherits)
  (declare (type defstruct-description dd))
  #+sb-xc (/show0 "entering %COMPILER-DEFSTRUCT")

  (%compiler-set-up-layout dd inherits)

  (let* ((dd-name (dd-name dd))
         (dtype (dd-declarable-type dd))
         (class (sb!xc:find-class dd-name)))

    (let ((copier-name (dd-copier-name dd)))
      (when copier-name
        (sb!xc:proclaim `(ftype (function (,dtype) ,dtype) ,copier-name))))

    (let ((predicate-name (dd-predicate-name dd)))
      (when predicate-name
        (sb!xc:proclaim `(ftype (function (t) t) ,predicate-name))))

    (dolist (dsd (dd-slots dd))
      (let* ((accessor-name (dsd-accessor-name dsd))
             (dsd-type (dsd-type dsd)))
        (when accessor-name
          (multiple-value-bind (reader-designator writer-designator)
              (accessor-inline-expansion-designators dd dsd)
            (sb!xc:proclaim `(ftype (function (,dtype) ,dsd-type)
                                    ,accessor-name))
            (setf (info :function
                        :inline-expansion-designator
                        accessor-name)
                  reader-designator
                  (info :function :inlinep accessor-name)
                  :inline)
            (unless (dsd-read-only dsd)
              (let ((setf-accessor-name `(setf ,accessor-name)))
                (sb!xc:proclaim
                 `(ftype (function (,dsd-type ,dtype) ,dsd-type)
                         ,setf-accessor-name))
                (setf (info :function
                            :inline-expansion-designator
                            setf-accessor-name)
                      writer-designator
                      (info :function :inlinep setf-accessor-name)
                      :inline))))))))

  #+sb-xc (/show0 "leaving %COMPILER-DEFSTRUCT")
  (values))
\f
;;;; redefinition stuff

;;; Compare the slots of OLD and NEW, returning 3 lists of slot names:
;;;   1. Slots which have moved,
;;;   2. Slots whose type has changed,
;;;   3. Deleted slots.
(defun compare-slots (old new)
  (let* ((oslots (dd-slots old))
         (nslots (dd-slots new))
         (onames (mapcar #'dsd-name oslots))
         (nnames (mapcar #'dsd-name nslots)))
    (collect ((moved)
              (retyped))
      (dolist (name (intersection onames nnames))
        (let ((os (find name oslots :key #'dsd-name))
              (ns (find name nslots :key #'dsd-name)))
          (unless (subtypep (dsd-type ns) (dsd-type os))
            (/noshow "found retyped slots" ns os (dsd-type ns) (dsd-type os))
            (retyped name))
          (unless (and (= (dsd-index os) (dsd-index ns))
                       (eq (dsd-raw-type os) (dsd-raw-type ns)))
            (moved name))))
      (values (moved)
              (retyped)
              (set-difference onames nnames)))))

;;; If we are redefining a structure with different slots than in the
;;; currently loaded version, give a warning and return true.
(defun redefine-structure-warning (class old new)
  (declare (type defstruct-description old new)
           (type sb!xc:class class)
           (ignore class))
  (let ((name (dd-name new)))
    (multiple-value-bind (moved retyped deleted) (compare-slots old new)
      (when (or moved retyped deleted)
        (warn
         "incompatibly redefining slots of structure class ~S~@
          Make sure any uses of affected accessors are recompiled:~@
          ~@[  These slots were moved to new positions:~%    ~S~%~]~
          ~@[  These slots have new incompatible types:~%    ~S~%~]~
          ~@[  These slots were deleted:~%    ~S~%~]"
         name moved retyped deleted)
        t))))

;;; This function is called when we are incompatibly redefining a
;;; structure CLASS to have the specified NEW-LAYOUT. We signal an
;;; error with some proceed options and return the layout that should
;;; be used.
(defun %redefine-defstruct (class old-layout new-layout)
  (declare (type sb!xc:class class) (type layout old-layout new-layout))
  #+sb-xc (/show0 "entering %REDEFINE-DEFSTRUCT")
  (let ((name (class-proper-name class)))
    (restart-case
        (error "redefining class ~S incompatibly with the current definition"
               name)
      (continue ()
        :report "Invalidate current definition."
        (warn "Previously loaded ~S accessors will no longer work." name)
        (register-layout new-layout))
      (clobber-it ()
        :report "Smash current layout, preserving old code."
        (warn "Any old ~S instances will be in a bad way.~@
               I hope you know what you're doing..."
              name)
        (register-layout new-layout :invalidate nil
                         :destruct-layout old-layout))))
  #+sb-xc (/show0 "leaving %REDEFINE-DEFSTRUCT")
  (values))

;;; This is called when we are about to define a structure class. It
;;; returns a (possibly new) class object and the layout which should
;;; be used for the new definition (may be the current layout, and
;;; also might be an uninstalled forward referenced layout.) The third
;;; value is true if this is an incompatible redefinition, in which
;;; case it is the old layout.
(defun ensure-structure-class (info inherits old-context new-context
                                    &key compiler-layout)
  (multiple-value-bind (class old-layout)
      (destructuring-bind
          (&optional
           name
           (class 'sb!xc:structure-class)
           (constructor 'make-structure-class))
          (dd-alternate-metaclass info)
        (declare (ignore name))
        (insured-find-class (dd-name info)
                            (if (eq class 'sb!xc:structure-class)
                              (lambda (x)
                                (typep x 'sb!xc:structure-class))
                              (lambda (x)
                                (sb!xc:typep x (sb!xc:find-class class))))
                            (fdefinition constructor)))
    (setf (class-direct-superclasses class)
          (if (eq (dd-name info) 'ansi-stream)
              ;; a hack to add CL:STREAM as a superclass mixin to ANSI-STREAMs
              (list (layout-class (svref inherits (1- (length inherits))))
                    (layout-class (svref inherits (- (length inherits) 2))))
              (list (layout-class (svref inherits (1- (length inherits)))))))
    (let ((new-layout (make-layout :class class
                                   :inherits inherits
                                   :depthoid (length inherits)
                                   :length (dd-length info)
                                   :info info))
          (old-layout (or compiler-layout old-layout)))
      (cond
       ((not old-layout)
        (values class new-layout nil))
       (;; This clause corresponds to an assertion in REDEFINE-LAYOUT-WARNING
        ;; of classic CMU CL. I moved it out to here because it was only
        ;; exercised in this code path anyway. -- WHN 19990510
        (not (eq (layout-class new-layout) (layout-class old-layout)))
        (error "shouldn't happen: weird state of OLD-LAYOUT?"))
       ((not *type-system-initialized*)
        (setf (layout-info old-layout) info)
        (values class old-layout nil))
       ((redefine-layout-warning old-context
                                 old-layout
                                 new-context
                                 (layout-length new-layout)
                                 (layout-inherits new-layout)
                                 (layout-depthoid new-layout))
        (values class new-layout old-layout))
       (t
        (let ((old-info (layout-info old-layout)))
          (typecase old-info
            ((or defstruct-description)
             (cond ((redefine-structure-warning class old-info info)
                    (values class new-layout old-layout))
                   (t
                    (setf (layout-info old-layout) info)
                    (values class old-layout nil))))
            (null
             (setf (layout-info old-layout) info)
             (values class old-layout nil))
            (t
             (error "shouldn't happen! strange thing in LAYOUT-INFO:~%  ~S"
                    old-layout)
             (values class new-layout old-layout)))))))))

;;; Blow away all the compiler info for the structure CLASS. Iterate
;;; over this type, clearing the compiler structure type info, and
;;; undefining all the associated functions.
(defun undefine-structure (class)
  #+sb-xc (/show0 "entering UNDEFINE-STRUCTURE")
  (let ((info (layout-info (class-layout class))))
    (when (defstruct-description-p info)
      (let ((type (dd-name info)))
        (remhash type *typecheckfuns*)
        (setf (info :type :compiler-layout type) nil)
        (undefine-fun-name (dd-copier-name info))
        (undefine-fun-name (dd-predicate-name info))
        (dolist (slot (dd-slots info))
          (let ((fun (dsd-accessor-name slot)))
            (undefine-fun-name fun)
            (unless (dsd-read-only slot)
              (undefine-fun-name `(setf ,fun))))))
      ;; Clear out the SPECIFIER-TYPE cache so that subsequent
      ;; references are unknown types.
      (values-specifier-type-cache-clear)))
  #+sb-xc (/show0 "leaving UNDEFINE-STRUCTURE")
  (values))
\f
;;; Return a list of pairs (name . index). Used for :TYPE'd
;;; constructors to find all the names that we have to splice in &
;;; where. Note that these types don't have a layout, so we can't look
;;; at LAYOUT-INHERITS.
(defun find-name-indices (defstruct)
  (collect ((res))
    (let ((infos ()))
      (do ((info defstruct
                 (typed-structure-info-or-lose (first (dd-include info)))))
          ((not (dd-include info))
           (push info infos))
        (push info infos))

      (let ((i 0))
        (dolist (info infos)
          (incf i (or (dd-offset info) 0))
          (when (dd-named info)
            (res (cons (dd-name info) i)))
          (setq i (dd-length info)))))

    (res)))
\f
;;;; slot accessors for raw slots

;;; Return info about how to read/write a slot in the value stored in
;;; OBJECT. This is also used by constructors (since we can't safely
;;; use the accessor function, since some slots are read-only). If
;;; supplied, DATA is a variable holding the raw-data vector.
;;;
;;; returned values:
;;; 1. accessor function name (SETFable)
;;; 2. index to pass to accessor.
;;; 3. object form to pass to accessor
(defun slot-accessor-form (defstruct slot object &optional data)
  (let ((rtype (dsd-raw-type slot)))
    (values
     (ecase rtype
       (single-float '%raw-ref-single)
       (double-float '%raw-ref-double)
       #!+long-float
       (long-float '%raw-ref-long)
       (complex-single-float '%raw-ref-complex-single)
       (complex-double-float '%raw-ref-complex-double)
       #!+long-float
       (complex-long-float '%raw-ref-complex-long)
       (unsigned-byte 'aref)
       ((t) '%instance-ref))
     (case rtype
       #!+long-float
       (complex-long-float
        (truncate (dsd-index slot) #!+x86 6 #!+sparc 8))
       #!+long-float
       (long-float
        (truncate (dsd-index slot) #!+x86 3 #!+sparc 4))
       (double-float
        (ash (dsd-index slot) -1))
       (complex-double-float
        (ash (dsd-index slot) -2))
       (complex-single-float
        (ash (dsd-index slot) -1))
       (t
        (dsd-index slot)))
     (cond
      ((eq rtype t) object)
      (data)
      (t
       `(truly-the (simple-array (unsigned-byte 32) (*))
                   (%instance-ref ,object ,(dd-raw-index defstruct))))))))
\f
;;; These functions are called to actually make a constructor after we
;;; have processed the arglist. The correct variant (according to the
;;; DD-TYPE) should be called. The function is defined with the
;;; specified name and arglist. VARS and TYPES are used for argument
;;; type declarations. VALUES are the values for the slots (in order.)
;;;
;;; This is split three ways because:
;;;   * LIST & VECTOR structures need "name" symbols stuck in at
;;;     various weird places, whereas STRUCTURE structures have
;;;     a LAYOUT slot.
;;;   * We really want to use LIST to make list structures, instead of
;;;     MAKE-LIST/(SETF ELT).
;;;   * STRUCTURE structures can have raw slots that must also be
;;;     allocated and indirectly referenced. We use SLOT-ACCESSOR-FORM
;;;     to compute how to set the slots, which deals with raw slots.
(defun create-vector-constructor (dd cons-name arglist vars types values)
  (let ((temp (gensym))
        (etype (dd-element-type dd)))
    `(defun ,cons-name ,arglist
       (declare ,@(mapcar #'(lambda (var type) `(type (and ,type ,etype) ,var))
                          vars types))
       (let ((,temp (make-array ,(dd-length dd)
                                :element-type ',(dd-element-type dd))))
         ,@(mapcar #'(lambda (x)
                       `(setf (aref ,temp ,(cdr x))  ',(car x)))
                   (find-name-indices dd))
         ,@(mapcar #'(lambda (dsd value)
                       `(setf (aref ,temp ,(dsd-index dsd)) ,value))
                   (dd-slots dd) values)
         ,temp))))
(defun create-list-constructor (dd cons-name arglist vars types values)
  (let ((vals (make-list (dd-length dd) :initial-element nil)))
    (dolist (x (find-name-indices dd))
      (setf (elt vals (cdr x)) `',(car x)))
    (loop for dsd in (dd-slots dd) and val in values do
      (setf (elt vals (dsd-index dsd)) val))

    `(defun ,cons-name ,arglist
       (declare ,@(mapcar #'(lambda (var type) `(type ,type ,var))
                          vars types))
       (list ,@vals))))
(defun create-structure-constructor (dd cons-name arglist vars types values)
  (let* ((temp (gensym))
         (raw-index (dd-raw-index dd))
         (n-raw-data (when raw-index (gensym))))
    `(defun ,cons-name ,arglist
       (declare ,@(mapcar #'(lambda (var type) `(type ,type ,var))
                          vars types))
       (let ((,temp (truly-the ,(dd-name dd)
                               (%make-instance ,(dd-length dd))))
             ,@(when n-raw-data
                 `((,n-raw-data
                    (make-array ,(dd-raw-length dd)
                                :element-type '(unsigned-byte 32))))))
         (setf (%instance-layout ,temp)
               (%delayed-get-compiler-layout ,(dd-name dd)))
         ,@(when n-raw-data
             `((setf (%instance-ref ,temp ,raw-index) ,n-raw-data)))
         ,@(mapcar (lambda (dsd value)
                     (multiple-value-bind (accessor index data)
                         (slot-accessor-form dd dsd temp n-raw-data)
                       `(setf (,accessor ,data ,index) ,value)))
                   (dd-slots dd)
                   values)
         ,temp))))

;;; Create a default (non-BOA) keyword constructor.
(defun create-keyword-constructor (defstruct creator)
  (collect ((arglist (list '&key))
            (types)
            (vals))
    (dolist (slot (dd-slots defstruct))
      (let ((dum (gensym))
            (name (dsd-name slot)))
        (arglist `((,(keywordicate name) ,dum) ,(dsd-default slot)))
        (types (dsd-type slot))
        (vals dum)))
    (funcall creator
             defstruct (dd-default-constructor defstruct)
             (arglist) (vals) (types) (vals))))

;;; Given a structure and a BOA constructor spec, call CREATOR with
;;; the appropriate args to make a constructor.
(defun create-boa-constructor (defstruct boa creator)
  (multiple-value-bind (req opt restp rest keyp keys allowp aux)
      (sb!kernel:parse-lambda-list (second boa))
    (collect ((arglist)
              (vars)
              (types))
      (labels ((get-slot (name)
                 (let ((res (find name (dd-slots defstruct)
                                  :test #'string=
                                  :key #'dsd-name)))
                   (if res
                       (values (dsd-type res) (dsd-default res))
                       (values t nil))))
               (do-default (arg)
                 (multiple-value-bind (type default) (get-slot arg)
                   (arglist `(,arg ,default))
                   (vars arg)
                   (types type))))
        (dolist (arg req)
          (arglist arg)
          (vars arg)
          (types (get-slot arg)))
        
        (when opt
          (arglist '&optional)
          (dolist (arg opt)
            (cond ((consp arg)
                   (destructuring-bind
                       (name &optional (def (nth-value 1 (get-slot name))))
                       arg
                     (arglist `(,name ,def))
                     (vars name)
                     (types (get-slot name))))
                  (t
                   (do-default arg)))))

        (when restp
          (arglist '&rest rest)
          (vars rest)
          (types 'list))

        (when keyp
          (arglist '&key)
          (dolist (key keys)
            (if (consp key)
                (destructuring-bind (wot &optional (def nil def-p)) key
                  (let ((name (if (consp wot)
                                  (destructuring-bind (key var) wot
                                    (declare (ignore key))
                                    var)
                                  wot)))
                    (multiple-value-bind (type slot-def) (get-slot name)
                      (arglist `(,wot ,(if def-p def slot-def)))
                      (vars name)
                      (types type))))
                (do-default key))))

        (when allowp (arglist '&allow-other-keys))

        (when aux
          (arglist '&aux)
          (dolist (arg aux)
            (let* ((arg (if (consp arg) arg (list arg)))
                   (var (first arg)))
              (arglist arg)
              (vars var)
              (types (get-slot var))))))

      (funcall creator defstruct (first boa)
               (arglist) (vars) (types)
               (mapcar #'(lambda (slot)
                           (or (find (dsd-name slot) (vars) :test #'string=)
                               (dsd-default slot)))
                       (dd-slots defstruct))))))

;;; Grovel the constructor options, and decide what constructors (if
;;; any) to create.
(defun constructor-definitions (defstruct)
  (let ((no-constructors nil)
        (boas ())
        (defaults ())
        (creator (ecase (dd-type defstruct)
                   (structure #'create-structure-constructor)
                   (vector #'create-vector-constructor)
                   (list #'create-list-constructor))))
    (dolist (constructor (dd-constructors defstruct))
      (destructuring-bind (name &optional (boa-ll nil boa-p)) constructor
        (declare (ignore boa-ll))
        (cond ((not name) (setq no-constructors t))
              (boa-p (push constructor boas))
              (t (push name defaults)))))

    (when no-constructors
      (when (or defaults boas)
        (error "(:CONSTRUCTOR NIL) combined with other :CONSTRUCTORs"))
      (return-from constructor-definitions ()))

    (unless (or defaults boas)
      (push (symbolicate "MAKE-" (dd-name defstruct)) defaults))

    (collect ((res))
      (when defaults
        (let ((cname (first defaults)))
          (setf (dd-default-constructor defstruct) cname)
          (res (create-keyword-constructor defstruct creator))
          (dolist (other-name (rest defaults))
            (res `(setf (fdefinition ',other-name) (fdefinition ',cname)))
            (res `(declaim (ftype function ',other-name))))))

      (dolist (boa boas)
        (res (create-boa-constructor defstruct boa creator)))

      `((/show0 "beginning CONSTRUCTOR-DEFINITIONS forms")
        ,@(res)
        (/show0 "done with CONSTRUCTOR-DEFINITIONS forms")))))
\f
;;;; instances with ALTERNATE-METACLASS
;;;;
;;;; The CMU CL support for structures with ALTERNATE-METACLASS was a
;;;; fairly general extension embedded in the main DEFSTRUCT code, and
;;;; the result was an fairly impressive mess as ALTERNATE-METACLASS
;;;; extension mixed with ANSI CL generality (e.g. :TYPE and :INCLUDE)
;;;; and CMU CL implementation hairiness (esp. raw slots). This SBCL
;;;; version is much less ambitious, noticing that ALTERNATE-METACLASS
;;;; is only used to implement CONDITION, STANDARD-INSTANCE, and
;;;; GENERIC-FUNCTION, and defining a simple specialized
;;;; separate-from-DEFSTRUCT macro to provide only enough
;;;; functionality to support those.
;;;;
;;;; KLUDGE: The defining macro here is so specialized that it's ugly
;;;; in its own way. It also violates once-and-only-once by knowing
;;;; much about structures and layouts that is already known by the
;;;; main DEFSTRUCT macro. Hopefully it will go away presently
;;;; (perhaps when CL:CLASS and SB-PCL:CLASS meet) as per FIXME below.
;;;; -- WHN 2001-10-28
;;;; 
;;;; FIXME: There seems to be no good reason to shoehorn CONDITION,
;;;; STANDARD-INSTANCE, and GENERIC-FUNCTION into mutated structures
;;;; instead of just implementing them as primitive objects. (This
;;;; reduced-functionality macro seems pretty close to the
;;;; functionality of DEFINE-PRIMITIVE-OBJECT..)

(defun make-dd-with-alternate-metaclass (&key (class-name (missing-arg))
                                              (superclass-name (missing-arg))
                                              (metaclass-name (missing-arg))
                                              (dd-type (missing-arg))
                                              metaclass-constructor
                                              slot-names)
  (let* ((dd (make-defstruct-description class-name))
         (conc-name (concatenate 'string (symbol-name class-name) "-"))
         (dd-slots (let ((reversed-result nil)
                         ;; The index starts at 1 for ordinary
                         ;; named slots because slot 0 is
                         ;; magical, used for LAYOUT in
                         ;; CONDITIONs or for something (?) in
                         ;; funcallable instances.
                         (index 1))
                     (dolist (slot-name slot-names)
                       (push (make-defstruct-slot-description
                              :%name (symbol-name slot-name)
                              :index index
                              :accessor-name (symbolicate conc-name slot-name))
                             reversed-result)
                       (incf index))
                     (nreverse reversed-result))))
    (setf (dd-alternate-metaclass dd) (list superclass-name
                                            metaclass-name
                                            metaclass-constructor)
          (dd-slots dd) dd-slots
          (dd-length dd) (1+ (length slot-names))
          (dd-type dd) dd-type)
    dd))

(sb!xc:defmacro !defstruct-with-alternate-metaclass
    (class-name &key
                (slot-names (missing-arg))
                (boa-constructor (missing-arg))
                (superclass-name (missing-arg))
                (metaclass-name (missing-arg))
                (metaclass-constructor (missing-arg))
                (dd-type (missing-arg))
                predicate
                (runtime-type-checks-p t))

  (declare (type (and list (not null)) slot-names))
  (declare (type (and symbol (not null))
                 boa-constructor
                 superclass-name
                 metaclass-name
                 metaclass-constructor))
  (declare (type symbol predicate))
  (declare (type (member structure funcallable-structure) dd-type))

  (/show "entering !DEFSTRUCT-WITH-ALTERNATE-METACLASS expander" class-name)
  (let* ((dd (make-dd-with-alternate-metaclass
              :class-name class-name
              :slot-names slot-names
              :superclass-name superclass-name
              :metaclass-name metaclass-name
              :metaclass-constructor metaclass-constructor
              :dd-type dd-type))
         (conc-name (concatenate 'string (symbol-name class-name) "-"))
         (dd-slots (dd-slots dd))
         (dd-length (1+ (length slot-names)))
         (object-gensym (gensym "OBJECT"))
         (new-value-gensym (gensym "NEW-VALUE-"))
         (delayed-layout-form `(%delayed-get-compiler-layout ,class-name)))
    (multiple-value-bind (raw-maker-form raw-reffer-operator)
        (ecase dd-type
          (structure
           (values `(let ((,object-gensym (%make-instance ,dd-length)))
                      (setf (%instance-layout ,object-gensym)
                            ,delayed-layout-form)
                      ,object-gensym)
                   '%instance-ref))
          (funcallable-structure
           (values `(%make-funcallable-instance ,dd-length
                                                ,delayed-layout-form)
                   '%funcallable-instance-info)))
      (/show dd raw-maker-form raw-reffer-operator)
      `(progn

         (eval-when (:compile-toplevel :load-toplevel :execute)
           (%compiler-set-up-layout ',dd))

         ;; slot readers and writers
         (declaim (inline ,@(mapcar #'dsd-accessor-name dd-slots)))
         ,@(mapcar (lambda (dsd)
                     `(defun ,(dsd-accessor-name dsd) (,object-gensym)
                        ,@(when runtime-type-checks-p
                            `((declare (type ,class-name ,object-gensym))))
                        (,raw-reffer-operator ,object-gensym
                                              ,(dsd-index dsd))))
                   dd-slots)
         (declaim (inline ,@(mapcar (lambda (dsd)
                                      `(setf ,(dsd-accessor-name dsd)))
                                    dd-slots)))
         ,@(mapcar (lambda (dsd)
                     `(defun (setf ,(dsd-accessor-name dsd)) (,new-value-gensym
                                                              ,object-gensym)
                        ,@(when runtime-type-checks-p
                            `((declare (type ,class-name ,object-gensym))))
                        (setf (,raw-reffer-operator ,object-gensym
                                                    ,(dsd-index dsd))
                              ,new-value-gensym)))
                   dd-slots)

         ;; constructor
         (defun ,boa-constructor ,slot-names
           (let ((,object-gensym ,raw-maker-form))
             ,@(mapcar (lambda (slot-name)
                         (let ((dsd (find (symbol-name slot-name) dd-slots
                                          :key #'dsd-%name
                                          :test #'string=)))
                           `(setf (,(dsd-accessor-name dsd) ,object-gensym)
                                  ,slot-name)))
                       slot-names)
             ,object-gensym))
                              
         ;; predicate
         ,@(when predicate
             ;; Just delegate to the compiler's type optimization
             ;; code, which knows how to generate inline type tests
             ;; for the whole CMU CL INSTANCE menagerie.
             `(defun ,predicate (,object-gensym)
                (typep ,object-gensym ',class-name)))))))
\f
;;;; finalizing bootstrapping

;;; Set up DD and LAYOUT for STRUCTURE-OBJECT class itself.
;;;
;;; Ordinary structure classes effectively :INCLUDE STRUCTURE-OBJECT
;;; when they have no explicit :INCLUDEs, so (1) it needs to be set up
;;; before we can define ordinary structure classes, and (2) it's
;;; special enough (and simple enough) that we just build it by hand
;;; instead of trying to generalize the ordinary DEFSTRUCT code.
(defun !set-up-structure-object-class ()
  (/show0 "entering !SET-UP-STRUCTURE-OBJECT-CLASS")
  (let ((dd (make-defstruct-description 'structure-object)))
    (setf
     ;; Note: This has an ALTERNATE-METACLASS only because of blind
     ;; clueless imitation of the CMU CL code -- dunno if or why it's
     ;; needed. -- WHN 
     (dd-alternate-metaclass dd) '(instance)
     (dd-slots dd) nil
     (dd-length dd) 1
     (dd-type dd) 'structure)
    (/show0 "about to %COMPILER-SET-UP-LAYOUT")
    (%compiler-set-up-layout dd))
  (/show0 "leaving !SET-UP-STRUCTURE-OBJECT-CLASS"))
(!set-up-structure-object-class)

;;; early structure predeclarations: Set up DD and LAYOUT for ordinary
;;; (non-ALTERNATE-METACLASS) structures which are needed early.
(dolist (args
         '#.(sb-cold:read-from-file
             "src/code/early-defstruct-args.lisp-expr"))
  (let* ((dd (parse-defstruct-name-and-options-and-slot-descriptions
              (first args)
              (rest args)))
         (inherits (inherits-for-structure dd)))
    (%compiler-defstruct dd inherits)))

(/show0 "code/defstruct.lisp end of file")