;;;; This software is part of the SBCL system. See the README file for
;;;; more information.

;;;; This software is derived from software originally released by Xerox
;;;; Corporation. Copyright and release statements follow. Later modifications
;;;; to the software are in the public domain and are provided with
;;;; absolutely no warranty. See the COPYING and CREDITS files for more
;;;; information.

;;;; copyright information from original PCL sources:
;;;;
;;;; Copyright (c) 1985, 1986, 1987, 1988, 1989, 1990 Xerox Corporation.
;;;; All rights reserved.
;;;;
;;;; Use and copying of this software and preparation of derivative works based
;;;; upon this software are permitted. Any distribution of this software or
;;;; derivative works must comply with all applicable United States export
;;;; control laws.
;;;;
;;;; This software is made available AS IS, and Xerox Corporation makes no
;;;; warranty about the software, its performance or its conformity to any
;;;; specification.

(in-package "SB-PCL")

#|

The CommonLoops evaluator is meta-circular.

Most of the code in PCL is methods on generic functions, including
most of the code that actually implements generic functions and method
lookup.

So, we have a classic bootstrapping problem. The solution to this is
to first get a cheap implementation of generic functions running,
these are called early generic functions. These early generic
functions and the corresponding early methods and early method lookup
are used to get enough of the system running that it is possible to
create real generic functions and methods and implement real method
lookup. At that point (done in the file FIXUP) the function
!FIX-EARLY-GENERIC-FUNCTIONS is called to convert all the early generic
functions to real generic functions.

The cheap generic functions are built using the same
FUNCALLABLE-INSTANCE objects that real generic functions are made out of.
This means that as PCL is being bootstrapped, the cheap generic
function objects which are being created are the same objects which
will later be real generic functions. This is good because:
  - we don't cons garbage structure, and
  - we can keep pointers to the cheap generic function objects
    during booting because those pointers will still point to
    the right object after the generic functions are all fixed up.

This file defines the DEFMETHOD macro and the mechanism used to expand
it. This includes the mechanism for processing the body of a method.
DEFMETHOD basically expands into a call to LOAD-DEFMETHOD, which
basically calls ADD-METHOD to add the method to the generic function.
These expansions can be loaded either during bootstrapping or when PCL
is fully up and running.

An important effect of this arrangement is it means we can compile
files with DEFMETHOD forms in them in a completely running PCL, but
then load those files back in during bootstrapping. This makes
development easier. It also means there is only one set of code for
processing DEFMETHOD. Bootstrapping works by being sure to have
LOAD-METHOD be careful to call only primitives which work during
bootstrapping.

|#

(declaim (notinline make-a-method
                    add-named-method
                    ensure-generic-function-using-class
                    add-method
                    remove-method))

(defvar *!early-functions*
        '((make-a-method early-make-a-method
                         real-make-a-method)
          (add-named-method early-add-named-method
                            real-add-named-method)
          ))

;;; For each of the early functions, arrange to have it point to its
;;; early definition. Do this in a way that makes sure that if we
;;; redefine one of the early definitions the redefinition will take
;;; effect. This makes development easier.
(dolist (fns *!early-functions*)
  (let ((name (car fns))
        (early-name (cadr fns)))
    (setf (gdefinition name)
            (set-fun-name
             (lambda (&rest args)
               (apply (fdefinition early-name) args))
             name))))

;;; *!GENERIC-FUNCTION-FIXUPS* is used by !FIX-EARLY-GENERIC-FUNCTIONS
;;; to convert the few functions in the bootstrap which are supposed
;;; to be generic functions but can't be early on.
(defvar *!generic-function-fixups*
  '((add-method
     ((generic-function method)  ;lambda-list
      (standard-generic-function method) ;specializers
      real-add-method))          ;method-function
    (remove-method
     ((generic-function method)
      (standard-generic-function method)
      real-remove-method))
    (get-method
     ((generic-function qualifiers specializers &optional (errorp t))
      (standard-generic-function t t)
      real-get-method))
    (ensure-generic-function-using-class
     ((generic-function fun-name
                        &key generic-function-class environment
                        &allow-other-keys)
      (generic-function t)
      real-ensure-gf-using-class--generic-function)
     ((generic-function fun-name
                        &key generic-function-class environment
                        &allow-other-keys)
      (null t)
      real-ensure-gf-using-class--null))
    (make-method-lambda
     ((proto-generic-function proto-method lambda-expression environment)
      (standard-generic-function standard-method t t)
      real-make-method-lambda))
    (make-method-initargs-form
     ((proto-generic-function proto-method
                              lambda-expression
                              lambda-list environment)
      (standard-generic-function standard-method t t t)
      real-make-method-initargs-form))
    (compute-effective-method
     ((generic-function combin applicable-methods)
      (generic-function standard-method-combination t)
      standard-compute-effective-method))))

(defmacro defgeneric (fun-name lambda-list &body options)
  (declare (type list lambda-list))
  (unless (legal-fun-name-p fun-name)
    (error 'simple-program-error
           :format-control "illegal generic function name ~S"
           :format-arguments (list fun-name)))
  (check-gf-lambda-list lambda-list)
  (let ((initargs ())
        (methods ()))
    (flet ((duplicate-option (name)
             (error 'simple-program-error
                    :format-control "The option ~S appears more than once."
                    :format-arguments (list name)))
           (expand-method-definition (qab) ; QAB = qualifiers, arglist, body
             (let* ((arglist-pos (position-if #'listp qab))
                    (arglist (elt qab arglist-pos))
                    (qualifiers (subseq qab 0 arglist-pos))
                    (body (nthcdr (1+ arglist-pos) qab)))
               `(push (defmethod ,fun-name ,@qualifiers ,arglist ,@body)
                      (generic-function-initial-methods (fdefinition ',fun-name))))))
      (macrolet ((initarg (key) `(getf initargs ,key)))
        (dolist (option options)
          (let ((car-option (car option)))
            (case car-option
              (declare
               (when (and
                      (consp (cadr option))
                      (member (first (cadr option))
                              ;; FIXME: this list is slightly weird.
                              ;; ANSI (on the DEFGENERIC page) in one
                              ;; place allows only OPTIMIZE; in
                              ;; another place gives this list of
                              ;; disallowed declaration specifiers.
                              ;; This seems to be the only place where
                              ;; the FUNCTION declaration is
                              ;; mentioned; TYPE seems to be missing.
                              ;; Very strange.  -- CSR, 2002-10-21
                              '(declaration ftype function
                                inline notinline special)))
                 (error 'simple-program-error
                        :format-control "The declaration specifier ~S ~
                                         is not allowed inside DEFGENERIC."
                        :format-arguments (list (cadr option))))
               (push (cadr option) (initarg :declarations)))
              (:method-combination
               (when (initarg car-option)
                 (duplicate-option car-option))
               (unless (symbolp (cadr option))
                 (error 'simple-program-error
                        :format-control "METHOD-COMBINATION name not a ~
                                         symbol: ~S"
                        :format-arguments (list (cadr option))))
               (setf (initarg car-option)
                     `',(cdr option)))
              (:argument-precedence-order
               (let* ((required (parse-lambda-list lambda-list))
                      (supplied (cdr option)))
                 (unless (= (length required) (length supplied))
                   (error 'simple-program-error
                          :format-control "argument count discrepancy in ~
                                           :ARGUMENT-PRECEDENCE-ORDER clause."
                          :format-arguments nil))
                 (when (set-difference required supplied)
                   (error 'simple-program-error
                          :format-control "unequal sets for ~
                                           :ARGUMENT-PRECEDENCE-ORDER clause: ~
                                           ~S and ~S"
                          :format-arguments (list required supplied)))
                 (setf (initarg car-option)
                       `',(cdr option))))
              ((:documentation :generic-function-class :method-class)
               (unless (proper-list-of-length-p option 2)
                 (error "bad list length for ~S" option))
               (if (initarg car-option)
                   (duplicate-option car-option)
                   (setf (initarg car-option) `',(cadr option))))
              (:method
               (push (cdr option) methods))
              (t
               ;; ANSI requires that unsupported things must get a
               ;; PROGRAM-ERROR.
               (error 'simple-program-error
                      :format-control "unsupported option ~S"
                      :format-arguments (list option))))))

        (when (initarg :declarations)
          (setf (initarg :declarations)
                `',(initarg :declarations))))
      `(progn
         (eval-when (:compile-toplevel :load-toplevel :execute)
           (compile-or-load-defgeneric ',fun-name))
         (load-defgeneric ',fun-name ',lambda-list
                          (sb-c:source-location) ,@initargs)
        ,@(mapcar #'expand-method-definition methods)
        (fdefinition ',fun-name)))))

(defun compile-or-load-defgeneric (fun-name)
  (proclaim-as-fun-name fun-name)
  (note-name-defined fun-name :function)
  (unless (eq (info :function :where-from fun-name) :declared)
    (setf (info :function :where-from fun-name) :defined)
    (setf (info :function :type fun-name)
          (specifier-type 'function))))

(defun load-defgeneric (fun-name lambda-list source-location &rest initargs)
  (when (fboundp fun-name)
    (style-warn "redefining ~S in DEFGENERIC" fun-name)
    (let ((fun (fdefinition fun-name)))
      (when (generic-function-p fun)
        (loop for method in (generic-function-initial-methods fun)
              do (remove-method fun method))
        (setf (generic-function-initial-methods fun) '()))))
  (apply #'ensure-generic-function
         fun-name
         :lambda-list lambda-list
         :definition-source source-location
         initargs))

(define-condition generic-function-lambda-list-error
    (reference-condition simple-program-error)
  ()
  (:default-initargs :references (list '(:ansi-cl :section (3 4 2)))))

(defun check-gf-lambda-list (lambda-list)
  (flet ((ensure (arg ok)
           (unless ok
             (error 'generic-function-lambda-list-error
                    :format-control
                    "~@<invalid ~S ~_in the generic function lambda list ~S~:>"
                    :format-arguments (list arg lambda-list)))))
    (multiple-value-bind (required optional restp rest keyp keys allowp
                          auxp aux morep more-context more-count)
        (parse-lambda-list lambda-list)
      (declare (ignore required)) ; since they're no different in a gf ll
      (declare (ignore restp rest)) ; since they're no different in a gf ll
      (declare (ignore allowp)) ; since &ALLOW-OTHER-KEYS is fine either way
      (declare (ignore aux)) ; since we require AUXP=NIL
      (declare (ignore more-context more-count)) ; safely ignored unless MOREP
      ;; no defaults allowed for &OPTIONAL arguments
      (dolist (i optional)
        (ensure i (or (symbolp i)
                      (and (consp i) (symbolp (car i)) (null (cdr i))))))
      ;; no defaults allowed for &KEY arguments
      (when keyp
        (dolist (i keys)
          (ensure i (or (symbolp i)
                        (and (consp i)
                             (or (symbolp (car i))
                                 (and (consp (car i))
                                      (symbolp (caar i))
                                      (symbolp (cadar i))
                                      (null (cddar i))))
                             (null (cdr i)))))))
      ;; no &AUX allowed
      (when auxp
        (error "&AUX is not allowed in a generic function lambda list: ~S"
               lambda-list))
      ;; Oh, *puhlease*... not specifically as per section 3.4.2 of
      ;; the ANSI spec, but the CMU CL &MORE extension does not
      ;; belong here!
      (aver (not morep)))))

(defmacro defmethod (&rest args &environment env)
  (multiple-value-bind (name qualifiers lambda-list body)
      (parse-defmethod args)
    (multiple-value-bind (proto-gf proto-method)
        (prototypes-for-make-method-lambda name)
      (expand-defmethod name
                        proto-gf
                        proto-method
                        qualifiers
                        lambda-list
                        body
                        env))))

(defun prototypes-for-make-method-lambda (name)
  (if (not (eq *boot-state* 'complete))
      (values nil nil)
      (let ((gf? (and (fboundp name)
                      (gdefinition name))))
        (if (or (null gf?)
                (not (generic-function-p gf?)))
            (values (class-prototype (find-class 'standard-generic-function))
                    (class-prototype (find-class 'standard-method)))
            (values gf?
                    (class-prototype (or (generic-function-method-class gf?)
                                         (find-class 'standard-method))))))))

;;; Take a name which is either a generic function name or a list specifying
;;; a SETF generic function (like: (SETF <generic-function-name>)). Return
;;; the prototype instance of the method-class for that generic function.
;;;
;;; If there is no generic function by that name, this returns the
;;; default value, the prototype instance of the class
;;; STANDARD-METHOD. This default value is also returned if the spec
;;; names an ordinary function or even a macro. In effect, this leaves
;;; the signalling of the appropriate error until load time.
;;;
;;; Note: During bootstrapping, this function is allowed to return NIL.
(defun method-prototype-for-gf (name)
  (let ((gf? (and (fboundp name)
                  (gdefinition name))))
    (cond ((neq *boot-state* 'complete) nil)
          ((or (null gf?)
               (not (generic-function-p gf?)))          ; Someone else MIGHT
                                                        ; error at load time.
           (class-prototype (find-class 'standard-method)))
          (t
            (class-prototype (or (generic-function-method-class gf?)
                                 (find-class 'standard-method)))))))

(defun expand-defmethod (name
                         proto-gf
                         proto-method
                         qualifiers
                         lambda-list
                         body
                         env)
  (multiple-value-bind (method-lambda unspecialized-lambda-list specializers)
      (add-method-declarations name qualifiers lambda-list body env)
    (multiple-value-bind (method-function-lambda initargs)
        (make-method-lambda proto-gf proto-method method-lambda env)
      (let ((initargs-form (make-method-initargs-form proto-gf
                                                      proto-method
                                                      method-function-lambda
                                                      initargs
                                                      env)))
        `(progn
          ;; Note: We could DECLAIM the ftype of the generic function
          ;; here, since ANSI specifies that we create it if it does
          ;; not exist. However, I chose not to, because I think it's
          ;; more useful to support a style of programming where every
          ;; generic function has an explicit DEFGENERIC and any typos
          ;; in DEFMETHODs are warned about. Otherwise
          ;;
          ;;   (DEFGENERIC FOO-BAR-BLETCH ((X T)))
          ;;   (DEFMETHOD FOO-BAR-BLETCH ((X HASH-TABLE)) ..)
          ;;   (DEFMETHOD FOO-BRA-BLETCH ((X SIMPLE-VECTOR)) ..)
          ;;   (DEFMETHOD FOO-BAR-BLETCH ((X VECTOR)) ..)
          ;;   (DEFMETHOD FOO-BAR-BLETCH ((X ARRAY)) ..)
          ;;   (DEFMETHOD FOO-BAR-BLETCH ((X LIST)) ..)
          ;;
          ;; compiles without raising an error and runs without
          ;; raising an error (since SIMPLE-VECTOR cases fall through
          ;; to VECTOR) but still doesn't do what was intended. I hate
          ;; that kind of bug (code which silently gives the wrong
          ;; answer), so we don't do a DECLAIM here. -- WHN 20000229
          ,(make-defmethod-form name qualifiers specializers
                                unspecialized-lambda-list
                                (if proto-method
                                    (class-name (class-of proto-method))
                                    'standard-method)
                                initargs-form))))))

(defun interned-symbol-p (x)
  (and (symbolp x) (symbol-package x)))

(defun make-defmethod-form
    (name qualifiers specializers unspecialized-lambda-list
     method-class-name initargs-form)
  (let (fn
        fn-lambda)
    (if (and (interned-symbol-p (fun-name-block-name name))
             (every #'interned-symbol-p qualifiers)
             (every (lambda (s)
                      (if (consp s)
                          (and (eq (car s) 'eql)
                               (constantp (cadr s))
                               (let ((sv (constant-form-value (cadr s))))
                                 (or (interned-symbol-p sv)
                                     (integerp sv)
                                     (and (characterp sv)
                                          (standard-char-p sv)))))
                          (interned-symbol-p s)))
                    specializers)
             (consp initargs-form)
             (eq (car initargs-form) 'list*)
             (memq (cadr initargs-form) '(:function))
             (consp (setq fn (caddr initargs-form)))
             (eq (car fn) 'function)
             (consp (setq fn-lambda (cadr fn)))
             (eq (car fn-lambda) 'lambda))
        (let* ((specls (mapcar (lambda (specl)
                                 (if (consp specl)
                                     `(,(car specl) ,(eval (cadr specl)))
                                   specl))
                               specializers))
               (mname `(,(if (eq (cadr initargs-form) :function)
                             'slow-method 'fast-method)
                        ,name ,@qualifiers ,specls)))
          `(progn
             (defun ,mname ,(cadr fn-lambda)
               ,@(cddr fn-lambda))
             ,(make-defmethod-form-internal
               name qualifiers `',specls
               unspecialized-lambda-list method-class-name
               `(list* ,(cadr initargs-form)
                       #',mname
                       ,@(cdddr initargs-form)))))
        (make-defmethod-form-internal
         name qualifiers
         `(list ,@(mapcar (lambda (specializer)
                            (if (consp specializer)
                                ``(,',(car specializer)
                                      ,,(cadr specializer))
                                `',specializer))
                          specializers))
         unspecialized-lambda-list
         method-class-name
         initargs-form))))

(defun make-defmethod-form-internal
    (name qualifiers specializers-form unspecialized-lambda-list
     method-class-name initargs-form)
  `(load-defmethod
    ',method-class-name
    ',name
    ',qualifiers
    ,specializers-form
    ',unspecialized-lambda-list
    ,initargs-form
    (sb-c:source-location)))

(defmacro make-method-function (method-lambda &environment env)
  (make-method-function-internal method-lambda env))

(defun make-method-function-internal (method-lambda &optional env)
  (multiple-value-bind (proto-gf proto-method)
      (prototypes-for-make-method-lambda nil)
    (multiple-value-bind (method-function-lambda initargs)
        (make-method-lambda proto-gf proto-method method-lambda env)
      (make-method-initargs-form proto-gf
                                 proto-method
                                 method-function-lambda
                                 initargs
                                 env))))

(defun add-method-declarations (name qualifiers lambda-list body env)
  (declare (ignore env))
  (multiple-value-bind (parameters unspecialized-lambda-list specializers)
      (parse-specialized-lambda-list lambda-list)
    (multiple-value-bind (real-body declarations documentation)
        (parse-body body)
      (values `(lambda ,unspecialized-lambda-list
                 ,@(when documentation `(,documentation))
                 ;; (Old PCL code used a somewhat different style of
                 ;; list for %METHOD-NAME values. Our names use
                 ;; ,@QUALIFIERS instead of ,QUALIFIERS so that the
                 ;; method names look more like what you see in a
                 ;; DEFMETHOD form.)
                 ;;
                 ;; FIXME: As of sbcl-0.7.0.6, code elsewhere, at
                 ;; least the code to set up named BLOCKs around the
                 ;; bodies of methods, depends on the function's base
                 ;; name being the first element of the %METHOD-NAME
                 ;; list. It would be good to remove this dependency,
                 ;; perhaps by building the BLOCK here, or by using
                 ;; another declaration (e.g. %BLOCK-NAME), so that
                 ;; our method debug names are free to have any format,
                 ;; e.g. (:METHOD PRINT-OBJECT :AROUND (CLOWN T)).
                 ;;
                 ;; Further, as of sbcl-0.7.9.10, the code to
                 ;; implement NO-NEXT-METHOD is coupled to the form of
                 ;; this declaration; see the definition of
                 ;; CALL-NO-NEXT-METHOD (and the passing of
                 ;; METHOD-NAME-DECLARATION arguments around the
                 ;; various CALL-NEXT-METHOD logic).
                 (declare (%method-name (,name
                                         ,@qualifiers
                                         ,specializers)))
                 (declare (%method-lambda-list ,@lambda-list))
                 ,@declarations
                 ,@real-body)
              unspecialized-lambda-list specializers))))

(defun real-make-method-initargs-form (proto-gf proto-method
                                       method-lambda initargs env)
  (declare (ignore proto-gf proto-method))
  (unless (and (consp method-lambda)
               (eq (car method-lambda) 'lambda))
    (error "The METHOD-LAMBDA argument to MAKE-METHOD-FUNCTION, ~S, ~
            is not a lambda form."
           method-lambda))
  (make-method-initargs-form-internal method-lambda initargs env))

(unless (fboundp 'make-method-initargs-form)
  (setf (gdefinition 'make-method-initargs-form)
        (symbol-function 'real-make-method-initargs-form)))

(defun real-make-method-lambda (proto-gf proto-method method-lambda env)
  (declare (ignore proto-gf proto-method))
  (make-method-lambda-internal method-lambda env))

;;; a helper function for creating Python-friendly type declarations
;;; in DEFMETHOD forms
(defun parameter-specializer-declaration-in-defmethod (parameter specializer)
  (cond ((and (consp specializer)
              (eq (car specializer) 'eql))
         ;; KLUDGE: ANSI, in its wisdom, says that
         ;; EQL-SPECIALIZER-FORMs in EQL specializers are evaluated at
         ;; DEFMETHOD expansion time. Thus, although one might think
         ;; that in
         ;;   (DEFMETHOD FOO ((X PACKAGE)
         ;;                   (Y (EQL 12))
         ;;      ..))
         ;; the PACKAGE and (EQL 12) forms are both parallel type
         ;; names, they're not, as is made clear when you do
         ;;   (DEFMETHOD FOO ((X PACKAGE)
         ;;                   (Y (EQL 'BAR)))
         ;;     ..)
         ;; where Y needs to be a symbol named "BAR", not some cons
         ;; made by (CONS 'QUOTE 'BAR). I.e. when the
         ;; EQL-SPECIALIZER-FORM is (EQL 'X), it requires an argument
         ;; to be of type (EQL X). It'd be easy to transform one to
         ;; the other, but it'd be somewhat messier to do so while
         ;; ensuring that the EQL-SPECIALIZER-FORM is only EVAL'd
         ;; once. (The new code wouldn't be messy, but it'd require a
         ;; big transformation of the old code.) So instead we punt.
         ;; -- WHN 20000610
         '(ignorable))
        ((member specializer
                 ;; KLUDGE: For some low-level implementation
                 ;; classes, perhaps because of some problems related
                 ;; to the incomplete integration of PCL into SBCL's
                 ;; type system, some specializer classes can't be
                 ;; declared as argument types. E.g.
                 ;;   (DEFMETHOD FOO ((X SLOT-OBJECT))
                 ;;     (DECLARE (TYPE SLOT-OBJECT X))
                 ;;     ..)
                 ;; loses when
                 ;;   (DEFSTRUCT BAR A B)
                 ;;   (FOO (MAKE-BAR))
                 ;; perhaps because of the way that STRUCTURE-OBJECT
                 ;; inherits both from SLOT-OBJECT and from
                 ;; SB-KERNEL:INSTANCE. In an effort to sweep such
                 ;; problems under the rug, we exclude these problem
                 ;; cases by blacklisting them here. -- WHN 2001-01-19
                 (list 'slot-object #+nil (find-class 'slot-object)))
         '(ignorable))
        ((not (eq *boot-state* 'complete))
         ;; KLUDGE: PCL, in its wisdom, sometimes calls methods with
         ;; types which don't match their specializers. (Specifically,
         ;; it calls ENSURE-CLASS-USING-CLASS (T NULL) with a non-NULL
         ;; second argument.) Hopefully it only does this kind of
         ;; weirdness when bootstrapping.. -- WHN 20000610
         '(ignorable))
        ((typep specializer 'eql-specializer)
         `(type (eql ,(eql-specializer-object specializer)) ,parameter))
        ((var-globally-special-p parameter)
         ;; KLUDGE: Don't declare types for global special variables
         ;; -- our rebinding magic for SETQ cases don't work right
         ;; there.
         ;;
         ;; FIXME: It would be better to detect the SETQ earlier and
         ;; skip declarations for specials only when needed, not
         ;; always.
         ;;
         ;; --NS 2004-10-14
         '(ignorable))
        (t
         ;; Otherwise, we can usually make Python very happy.
         ;;
         ;; KLUDGE: Since INFO doesn't work right for class objects here,
         ;; and they are valid specializers, see if the specializer is
         ;; a named class, and use the name in that case -- otherwise
         ;; the class instance is ok, since info will just return NIL, NIL.
         ;;
         ;; We still need to deal with the class case too, but at
         ;; least #.(find-class 'integer) and integer as equivalent
         ;; specializers with this.
         (let* ((specializer-nameoid
                 (if (and (typep specializer 'class)
                          (let ((name (class-name specializer)))
                            (and name (symbolp name)
                                 (eq specializer (find-class name nil)))))
                     (class-name specializer)
                     specializer))
                (kind (info :type :kind specializer-nameoid)))

           (flet ((specializer-nameoid-class ()
                    (typecase specializer-nameoid
                      (symbol (find-class specializer-nameoid nil))
                      (class specializer-nameoid)
                      (class-eq-specializer
                       (specializer-class specializer-nameoid))
                      (t nil))))
             (ecase kind
               ((:primitive) `(type ,specializer-nameoid ,parameter))
               ((:defined)
                (let ((class (specializer-nameoid-class)))
                  ;; CLASS can be null here if the user has
                  ;; erroneously tried to use a defined type as a
                  ;; specializer; it can be a non-BUILT-IN-CLASS if
                  ;; the user defines a type and calls (SETF
                  ;; FIND-CLASS) in a consistent way.
                 (when (and class (typep class 'built-in-class))
                   `(type ,specializer-nameoid ,parameter))))
              ((:instance nil)
               (let ((class (specializer-nameoid-class)))
                 (cond
                   (class
                    (if (typep class '(or built-in-class structure-class))
                        `(type ,class ,parameter)
                        ;; don't declare CLOS classes as parameters;
                        ;; it's too expensive.
                        '(ignorable)))
                   (t
                    ;; we can get here, and still not have a failure
                    ;; case, by doing MOP programming like (PROGN
                    ;; (ENSURE-CLASS 'FOO) (DEFMETHOD BAR ((X FOO))
                    ;; ...)).  Best to let the user know we haven't
                    ;; been able to extract enough information:
                    (style-warn
                     "~@<can't find type for specializer ~S in ~S.~@:>"
                     specializer-nameoid
                     'parameter-specializer-declaration-in-defmethod)
                    '(ignorable)))))
              ((:forthcoming-defclass-type)
               '(ignorable))))))))

;;; For passing a list (groveled by the walker) of the required
;;; parameters whose bindings are modified in the method body to the
;;; optimized-slot-value* macros.
(define-symbol-macro %parameter-binding-modified ())

(defun make-method-lambda-internal (method-lambda &optional env)
  (unless (and (consp method-lambda) (eq (car method-lambda) 'lambda))
    (error "The METHOD-LAMBDA argument to MAKE-METHOD-LAMBDA, ~S, ~
            is not a lambda form."
           method-lambda))
  (multiple-value-bind (real-body declarations documentation)
      (parse-body (cddr method-lambda))
    (let* ((name-decl (get-declaration '%method-name declarations))
           (sll-decl (get-declaration '%method-lambda-list declarations))
           (method-name (when (consp name-decl) (car name-decl)))
           (generic-function-name (when method-name (car method-name)))
           (specialized-lambda-list (or sll-decl (cadr method-lambda))))
      (multiple-value-bind (parameters lambda-list specializers)
          (parse-specialized-lambda-list specialized-lambda-list)
        (let* ((required-parameters
                (mapcar (lambda (r s) (declare (ignore s)) r)
                        parameters
                        specializers))
               (slots (mapcar #'list required-parameters))
               (calls (list nil))
               (class-declarations
                `(declare
                  ;; These declarations seem to be used by PCL to pass
                  ;; information to itself; when I tried to delete 'em
                  ;; ca. 0.6.10 it didn't work. I'm not sure how
                  ;; they work, but note the (VAR-DECLARATION '%CLASS ..)
                  ;; expression in CAN-OPTIMIZE-ACCESS1. -- WHN 2000-12-30
                  ,@(remove nil
                            (mapcar (lambda (a s) (and (symbolp s)
                                                       (neq s t)
                                                       `(%class ,a ,s)))
                                    parameters
                                    specializers))
                  ;; These TYPE declarations weren't in the original
                  ;; PCL code, but the Python compiler likes them a
                  ;; lot. (We're telling the compiler about our
                  ;; knowledge of specialized argument types so that
                  ;; it can avoid run-time type dispatch overhead,
                  ;; which can be a huge win for Python.)
                  ;;
                  ;; KLUDGE: when I tried moving these to
                  ;; ADD-METHOD-DECLARATIONS, things broke.  No idea
                  ;; why.  -- CSR, 2004-06-16
                  ,@(mapcar #'parameter-specializer-declaration-in-defmethod
                            parameters
                            specializers)))
               (method-lambda
                ;; Remove the documentation string and insert the
                ;; appropriate class declarations. The documentation
                ;; string is removed to make it easy for us to insert
                ;; new declarations later, they will just go after the
                ;; CADR of the method lambda. The class declarations
                ;; are inserted to communicate the class of the method's
                ;; arguments to the code walk.
                `(lambda ,lambda-list
                   ;; The default ignorability of method parameters
                   ;; doesn't seem to be specified by ANSI. PCL had
                   ;; them basically ignorable but was a little
                   ;; inconsistent. E.g. even though the two
                   ;; method definitions
                   ;;   (DEFMETHOD FOO ((X T) (Y T)) "Z")
                   ;;   (DEFMETHOD FOO ((X T) Y) "Z")
                   ;; are otherwise equivalent, PCL treated Y as
                   ;; ignorable in the first definition but not in the
                   ;; second definition. We make all required
                   ;; parameters ignorable as a way of systematizing
                   ;; the old PCL behavior. -- WHN 2000-11-24
                   (declare (ignorable ,@required-parameters))
                   ,class-declarations
                   ,@declarations
                   (block ,(fun-name-block-name generic-function-name)
                     ,@real-body)))
               (constant-value-p (and (null (cdr real-body))
                                      (constantp (car real-body))))
               (constant-value (and constant-value-p
                                    (constant-form-value (car real-body))))
               (plist (and constant-value-p
                           (or (typep constant-value
                                      '(or number character))
                               (and (symbolp constant-value)
                                    (symbol-package constant-value)))
                           (list :constant-value constant-value)))
               (applyp (dolist (p lambda-list nil)
                         (cond ((memq p '(&optional &rest &key))
                                (return t))
                               ((eq p '&aux)
                                (return nil))))))
          (multiple-value-bind
                (walked-lambda call-next-method-p closurep
                               next-method-p-p setq-p
                               parameters-setqd)
              (walk-method-lambda method-lambda
                                  required-parameters
                                  env
                                  slots
                                  calls)
            (multiple-value-bind (walked-lambda-body
                                  walked-declarations
                                  walked-documentation)
                (parse-body (cddr walked-lambda))
              (declare (ignore walked-documentation))
              (when (some #'cdr slots)
                (multiple-value-bind (slot-name-lists call-list)
                    (slot-name-lists-from-slots slots calls)
                  (setq plist
                        `(,@(when slot-name-lists
                                  `(:slot-name-lists ,slot-name-lists))
                            ,@(when call-list
                                    `(:call-list ,call-list))
                            ,@plist))
                  (setq walked-lambda-body
                        `((pv-binding (,required-parameters
                                       ,slot-name-lists
                                       (load-time-value
                                        (intern-pv-table
                                         :slot-name-lists ',slot-name-lists
                                         :call-list ',call-list)))
                            ,@walked-lambda-body)))))
              (when (and (memq '&key lambda-list)
                         (not (memq '&allow-other-keys lambda-list)))
                (let ((aux (memq '&aux lambda-list)))
                  (setq lambda-list (nconc (ldiff lambda-list aux)
                                           (list '&allow-other-keys)
                                           aux))))
              (values `(lambda (.method-args. .next-methods.)
                         (simple-lexical-method-functions
                             (,lambda-list .method-args. .next-methods.
                                           :call-next-method-p
                                           ,call-next-method-p
                                           :next-method-p-p ,next-method-p-p
                                           :setq-p ,setq-p
                                           ;; we need to pass this along
                                           ;; so that NO-NEXT-METHOD can
                                           ;; be given a suitable METHOD
                                           ;; argument; we need the
                                           ;; QUALIFIERS and SPECIALIZERS
                                           ;; inside the declaration to
                                           ;; give to FIND-METHOD.
                                           :method-name-declaration ,name-decl
                                           :closurep ,closurep
                                           :applyp ,applyp)
                           ,@walked-declarations
                           (locally
                               (declare (disable-package-locks
                                         %parameter-binding-modified))
                             (symbol-macrolet ((%parameter-binding-modified
                                                ',@parameters-setqd))
                               (declare (enable-package-locks
                                         %parameter-binding-modified))
                               ,@walked-lambda-body))))
                      `(,@(when plist
                                `(plist ,plist))
                          ,@(when documentation
                                  `(:documentation ,documentation)))))))))))

(unless (fboundp 'make-method-lambda)
  (setf (gdefinition 'make-method-lambda)
        (symbol-function 'real-make-method-lambda)))

(defmacro simple-lexical-method-functions ((lambda-list
                                            method-args
                                            next-methods
                                            &rest lmf-options)
                                           &body body)
  `(progn
     ,method-args ,next-methods
     (bind-simple-lexical-method-functions (,method-args ,next-methods
                                                         ,lmf-options)
         (bind-args (,lambda-list ,method-args)
           ,@body))))

(defmacro fast-lexical-method-functions ((lambda-list
                                          next-method-call
                                          args
                                          rest-arg
                                          &rest lmf-options)
                                         &body body)
  `(bind-fast-lexical-method-functions (,args ,rest-arg ,next-method-call ,lmf-options)
     (bind-args (,(nthcdr (length args) lambda-list) ,rest-arg)
       ,@body)))

(defmacro bind-simple-lexical-method-functions
    ((method-args next-methods (&key call-next-method-p next-method-p-p setq-p
                                     closurep applyp method-name-declaration))
     &body body
     &environment env)
  (if (not (or call-next-method-p setq-p closurep next-method-p-p applyp))
      `(locally
           ,@body)
      `(let ((.next-method. (car ,next-methods))
             (,next-methods (cdr ,next-methods)))
         (declare (ignorable .next-method. ,next-methods))
         (flet (,@(and call-next-method-p
                       `((call-next-method
                          (&rest cnm-args)
                          ,@(if (safe-code-p env)
                                `((%check-cnm-args cnm-args
                                                   ,method-args
                                                   ',method-name-declaration))
                                nil)
                          (if .next-method.
                              (funcall (if (std-instance-p .next-method.)
                                           (method-function .next-method.)
                                           .next-method.) ; for early methods
                                       (or cnm-args ,method-args)
                                       ,next-methods)
                              (apply #'call-no-next-method
                                     ',method-name-declaration
                                     (or cnm-args ,method-args))))))
                ,@(and next-method-p-p
                       '((next-method-p ()
                          (not (null .next-method.))))))
           ,@body))))

(defun call-no-next-method (method-name-declaration &rest args)
  (destructuring-bind (name) method-name-declaration
    (destructuring-bind (name &rest qualifiers-and-specializers) name
      ;; KLUDGE: inefficient traversal, but hey.  This should only
      ;; happen on the slow error path anyway.
      (let* ((qualifiers (butlast qualifiers-and-specializers))
             (specializers (car (last qualifiers-and-specializers)))
             (method (find-method (gdefinition name) qualifiers specializers)))
        (apply #'no-next-method
               (method-generic-function method)
               method
               args)))))

(defstruct (method-call (:copier nil))
  (function #'identity :type function)
  call-method-args)
(defstruct (constant-method-call (:copier nil) (:include method-call))
  value)

#-sb-fluid (declaim (sb-ext:freeze-type method-call))

(defmacro invoke-method-call1 (function args cm-args)
  `(let ((.function. ,function)
         (.args. ,args)
         (.cm-args. ,cm-args))
     (if (and .cm-args. (null (cdr .cm-args.)))
         (funcall .function. .args. (car .cm-args.))
         (apply .function. .args. .cm-args.))))

(defmacro invoke-method-call (method-call restp &rest required-args+rest-arg)
  `(invoke-method-call1 (method-call-function ,method-call)
                        ,(if restp
                             `(list* ,@required-args+rest-arg)
                             `(list ,@required-args+rest-arg))
                        (method-call-call-method-args ,method-call)))

(defstruct (fast-method-call (:copier nil))
  (function #'identity :type function)
  pv-cell
  next-method-call
  arg-info)
(defstruct (constant-fast-method-call
             (:copier nil) (:include fast-method-call))
  value)

#-sb-fluid (declaim (sb-ext:freeze-type fast-method-call))

;; The two variants of INVOKE-FAST-METHOD-CALL differ in how REST-ARGs
;; are handled. The first one will get REST-ARG as a single list (as
;; the last argument), and will thus need to use APPLY. The second one
;; will get them as a &MORE argument, so we can pass the arguments
;; directly with MULTIPLE-VALUE-CALL and %MORE-ARG-VALUES.

(defmacro invoke-fast-method-call (method-call restp &rest required-args+rest-arg)
  `(,(if restp 'apply 'funcall) (fast-method-call-function ,method-call)
                                (fast-method-call-pv-cell ,method-call)
                                (fast-method-call-next-method-call ,method-call)
                                ,@required-args+rest-arg))

(defmacro invoke-fast-method-call/more (method-call
                                        more-context
                                        more-count
                                        &rest required-args)
  (macrolet ((generate-call (n)
               ``(funcall (fast-method-call-function ,method-call)
                          (fast-method-call-pv-cell ,method-call)
                          (fast-method-call-next-method-call ,method-call)
                          ,@required-args
                          ,@(loop for x below ,n
                                  collect `(sb-c::%more-arg ,more-context ,x)))))
    ;; The cases with only small amounts of required arguments passed
    ;; are probably very common, and special-casing speeds them up by
    ;; a factor of 2 with very little effect on the other
    ;; cases. Though it'd be nice to have the generic case be equally
    ;; fast.
    `(case ,more-count
       (0 ,(generate-call 0))
       (1 ,(generate-call 1))
       (t (multiple-value-call (fast-method-call-function ,method-call)
            (values (fast-method-call-pv-cell ,method-call))
            (values (fast-method-call-next-method-call ,method-call))
            ,@required-args
            (sb-c::%more-arg-values ,more-context 0 ,more-count))))))

(defstruct (fast-instance-boundp (:copier nil))
  (index 0 :type fixnum))

#-sb-fluid (declaim (sb-ext:freeze-type fast-instance-boundp))

(eval-when (:compile-toplevel :load-toplevel :execute)
  (defvar *allow-emf-call-tracing-p* nil)
  (defvar *enable-emf-call-tracing-p* #-sb-show nil #+sb-show t))

;;;; effective method functions

(defvar *emf-call-trace-size* 200)
(defvar *emf-call-trace* nil)
(defvar *emf-call-trace-index* 0)

;;; This function was in the CMU CL version of PCL (ca Debian 2.4.8)
;;; without explanation. It appears to be intended for debugging, so
;;; it might be useful someday, so I haven't deleted it.
;;; But it isn't documented and isn't used for anything now, so
;;; I've conditionalized it out of the base system. -- WHN 19991213
#+sb-show
(defun show-emf-call-trace ()
  (when *emf-call-trace*
    (let ((j *emf-call-trace-index*)
          (*enable-emf-call-tracing-p* nil))
      (format t "~&(The oldest entries are printed first)~%")
      (dotimes-fixnum (i *emf-call-trace-size*)
        (let ((ct (aref *emf-call-trace* j)))
          (when ct (print ct)))
        (incf j)
        (when (= j *emf-call-trace-size*)
          (setq j 0))))))

(defun trace-emf-call-internal (emf format args)
  (unless *emf-call-trace*
    (setq *emf-call-trace* (make-array *emf-call-trace-size*)))
  (setf (aref *emf-call-trace* *emf-call-trace-index*)
        (list* emf format args))
  (incf *emf-call-trace-index*)
  (when (= *emf-call-trace-index* *emf-call-trace-size*)
    (setq *emf-call-trace-index* 0)))

(defmacro trace-emf-call (emf format args)
  (when *allow-emf-call-tracing-p*
    `(when *enable-emf-call-tracing-p*
       (trace-emf-call-internal ,emf ,format ,args))))

(defmacro invoke-effective-method-function-fast
    (emf restp &key required-args rest-arg more-arg)
  `(progn
     (trace-emf-call ,emf ,restp (list ,@required-args rest-arg))
     ,(if more-arg
          `(invoke-fast-method-call/more ,emf
                                         ,@more-arg
                                         ,@required-args)
          `(invoke-fast-method-call ,emf
                                    ,restp
                                    ,@required-args
                                    ,@rest-arg))))

(defun effective-method-optimized-slot-access-clause
    (emf restp required-args)
  ;; "What," you may wonder, "do these next two clauses do?" In that
  ;; case, you are not a PCL implementor, for they considered this to
  ;; be self-documenting.:-| Or CSR, for that matter, since he can
  ;; also figure it out by looking at it without breaking stride. For
  ;; the rest of us, though: From what the code is doing with .SLOTS.
  ;; and whatnot, evidently it's implementing SLOT-VALUEish and
  ;; GET-SLOT-VALUEish things. Then we can reason backwards and
  ;; conclude that setting EMF to a FIXNUM is an optimized way to
  ;; represent these slot access operations.
  (when (not restp)
    (let ((length (length required-args)))
      (cond ((= 1 length)
             `((fixnum
                (let* ((.slots. (get-slots-or-nil
                                 ,(car required-args)))
                       (value (when .slots. (clos-slots-ref .slots. ,emf))))
                  (if (eq value +slot-unbound+)
                      (slot-unbound-internal ,(car required-args)
                                             ,emf)
                      value)))))
            ((= 2 length)
             `((fixnum
                (let ((.new-value. ,(car required-args))
                      (.slots. (get-slots-or-nil
                                ,(cadr required-args))))
                  (when .slots.
                    (setf (clos-slots-ref .slots. ,emf) .new-value.)))))))
      ;; (In cmucl-2.4.8 there was a commented-out third ,@(WHEN
      ;; ...) clause here to handle SLOT-BOUNDish stuff. Since
      ;; there was no explanation and presumably the code is 10+
      ;; years stale, I simply deleted it. -- WHN)
      )))

;;; Before SBCL 0.9.16.7 instead of
;;; INVOKE-NARROW-EFFECTIVE-METHOD-FUNCTION we passed a (THE (OR
;;; FUNCTION METHOD-CALL FAST-METHOD-CALL) EMF) form as the EMF. Now,
;;; to make less work for the compiler we take a path that doesn't
;;; involve the slot-accessor clause (where EMF is a FIXNUM) at all.
(macrolet ((def (name &optional narrow)
             `(defmacro ,name (emf restp &key required-args rest-arg more-arg)
                (unless (constantp restp)
                  (error "The RESTP argument is not constant."))
                (setq restp (constant-form-value restp))
                (with-unique-names (emf-n)
                  `(locally
                       (declare (optimize (sb-c:insert-step-conditions 0)))
                     (let ((,emf-n ,emf))
                       (trace-emf-call ,emf-n ,restp (list ,@required-args ,@rest-arg))
                       (etypecase ,emf-n
                         (fast-method-call
                          ,(if more-arg
                               `(invoke-fast-method-call/more ,emf-n
                                                              ,@more-arg
                                                              ,@required-args)
                               `(invoke-fast-method-call ,emf-n
                                                         ,restp
                                                         ,@required-args
                                                         ,@rest-arg)))
                         ,@,(unless narrow
                              `(effective-method-optimized-slot-access-clause
                                emf-n restp required-args))
                         (method-call
                          (invoke-method-call ,emf-n ,restp ,@required-args
                                              ,@rest-arg))
                         (function
                          ,(if restp
                               `(apply ,emf-n ,@required-args ,@rest-arg)
                               `(funcall ,emf-n ,@required-args
                                         ,@rest-arg))))))))))
  (def invoke-effective-method-function nil)
  (def invoke-narrow-effective-method-function t))

(defun invoke-emf (emf args)
  (trace-emf-call emf t args)
  (etypecase emf
    (fast-method-call
     (let* ((arg-info (fast-method-call-arg-info emf))
            (restp (cdr arg-info))
            (nreq (car arg-info)))
       (if restp
           (apply (fast-method-call-function emf)
                  (fast-method-call-pv-cell emf)
                  (fast-method-call-next-method-call emf)
                  args)
           (cond ((null args)
                  (if (eql nreq 0)
                      (invoke-fast-method-call emf nil)
                      (error 'simple-program-error
                             :format-control "invalid number of arguments: 0"
                             :format-arguments nil)))
                 ((null (cdr args))
                  (if (eql nreq 1)
                      (invoke-fast-method-call emf nil (car args))
                      (error 'simple-program-error
                             :format-control "invalid number of arguments: 1"
                             :format-arguments nil)))
                 ((null (cddr args))
                  (if (eql nreq 2)
                      (invoke-fast-method-call emf nil (car args) (cadr args))
                      (error 'simple-program-error
                             :format-control "invalid number of arguments: 2"
                             :format-arguments nil)))
                 (t
                  (apply (fast-method-call-function emf)
                         (fast-method-call-pv-cell emf)
                         (fast-method-call-next-method-call emf)
                         args))))))
    (method-call
     (apply (method-call-function emf)
            args
            (method-call-call-method-args emf)))
    (fixnum
     (cond ((null args)
            (error 'simple-program-error
                   :format-control "invalid number of arguments: 0"
                   :format-arguments nil))
           ((null (cdr args))
            (let* ((slots (get-slots (car args)))
                   (value (clos-slots-ref slots emf)))
              (if (eq value +slot-unbound+)
                  (slot-unbound-internal (car args) emf)
                  value)))
           ((null (cddr args))
            (setf (clos-slots-ref (get-slots (cadr args)) emf)
                  (car args)))
           (t (error 'simple-program-error
                     :format-control "invalid number of arguments"
                     :format-arguments nil))))
    (fast-instance-boundp
     (if (or (null args) (cdr args))
         (error 'simple-program-error
                :format-control "invalid number of arguments"
                :format-arguments nil)
         (let ((slots (get-slots (car args))))
           (not (eq (clos-slots-ref slots (fast-instance-boundp-index emf))
                    +slot-unbound+)))))
    (function
     (apply emf args))))


(defmacro fast-call-next-method-body ((args next-method-call rest-arg)
                                      method-name-declaration
                                      cnm-args)
  `(if ,next-method-call
       ,(let ((call `(invoke-narrow-effective-method-function
                      ,next-method-call
                      ,(not (null rest-arg))
                      :required-args ,args
                      :rest-arg ,(when rest-arg (list rest-arg)))))
             `(if ,cnm-args
                  (bind-args ((,@args
                               ,@(when rest-arg
                                       `(&rest ,rest-arg)))
                              ,cnm-args)
                    ,call)
                  ,call))
       (call-no-next-method ',method-name-declaration
                            ,@args
                            ,@(when rest-arg
                                    `(,rest-arg)))))

(defmacro bind-fast-lexical-method-functions
    ((args rest-arg next-method-call (&key
                                      call-next-method-p
                                      setq-p
                                      method-name-declaration
                                      next-method-p-p
                                      closurep
                                      applyp))
     &body body
     &environment env)
  (let* ((all-params (append args (when rest-arg (list rest-arg))))
         (rebindings (when (or setq-p call-next-method-p)
                       (mapcar (lambda (x) (list x x)) all-params))))
    (if (not (or call-next-method-p setq-p closurep next-method-p-p applyp))
        `(locally
             ,@body)
        `(flet (,@(when call-next-method-p
                        `((call-next-method (&rest cnm-args)
                            (declare (muffle-conditions code-deletion-note)
                                     (optimize (sb-c:insert-step-conditions 0)))
                           ,@(if (safe-code-p env)
                                 `((%check-cnm-args cnm-args (list ,@args)
                                                    ',method-name-declaration))
                                 nil)
                           (fast-call-next-method-body (,args
                                                        ,next-method-call
                                                        ,rest-arg)
                                                        ,method-name-declaration
                                                       cnm-args))))
                ,@(when next-method-p-p
                        `((next-method-p ()
                           (declare (optimize (sb-c:insert-step-conditions 0)))
                           (not (null ,next-method-call))))))
           (let ,rebindings
             ,@(when rebindings `((declare (ignorable ,@all-params))))
             ,@body)))))

;;; CMUCL comment (Gerd Moellmann):
;;;
;;; The standard says it's an error if CALL-NEXT-METHOD is called with
;;; arguments, and the set of methods applicable to those arguments is
;;; different from the set of methods applicable to the original
;;; method arguments.  (According to Barry Margolin, this rule was
;;; probably added to ensure that before and around methods are always
;;; run before primary methods.)
;;;
;;; This could be optimized for the case that the generic function
;;; doesn't have hairy methods, does have standard method combination,
;;; is a standard generic function, there are no methods defined on it
;;; for COMPUTE-APPLICABLE-METHODS and probably a lot more of such
;;; preconditions.  That looks hairy and is probably not worth it,
;;; because this check will never be fast.
(defun %check-cnm-args (cnm-args orig-args method-name-declaration)
  (when cnm-args
    (let* ((gf (fdefinition (caar method-name-declaration)))
           (omethods (compute-applicable-methods gf orig-args))
           (nmethods (compute-applicable-methods gf cnm-args)))
      (unless (equal omethods nmethods)
        (error "~@<The set of methods ~S applicable to argument~P ~
                ~{~S~^, ~} to call-next-method is different from ~
                the set of methods ~S applicable to the original ~
                method argument~P ~{~S~^, ~}.~@:>"
               nmethods (length cnm-args) cnm-args omethods
               (length orig-args) orig-args)))))

(defmacro bind-args ((lambda-list args) &body body)
  (let ((args-tail '.args-tail.)
        (key '.key.)
        (state 'required))
    (flet ((process-var (var)
             (if (memq var lambda-list-keywords)
                 (progn
                   (case var
                     (&optional       (setq state 'optional))
                     (&key            (setq state 'key))
                     (&allow-other-keys)
                     (&rest           (setq state 'rest))
                     (&aux            (setq state 'aux))
                     (otherwise
                      (error
                       "encountered the non-standard lambda list keyword ~S"
                       var)))
                   nil)
                 (case state
                   (required `((,var (pop ,args-tail))))
                   (optional (cond ((not (consp var))
                                    `((,var (when ,args-tail
                                              (pop ,args-tail)))))
                                   ((null (cddr var))
                                    `((,(car var) (if ,args-tail
                                                      (pop ,args-tail)
                                                      ,(cadr var)))))
                                   (t
                                    `((,(caddr var) (not (null ,args-tail)))
                                      (,(car var) (if ,args-tail
                                                      (pop ,args-tail)
                                                      ,(cadr var)))))))
                   (rest `((,var ,args-tail)))
                   (key (cond ((not (consp var))
                               `((,var (car
                                        (get-key-arg-tail ,(keywordicate var)
                                                          ,args-tail)))))
                              ((null (cddr var))
                               (multiple-value-bind (keyword variable)
                                   (if (consp (car var))
                                       (values (caar var)
                                               (cadar var))
                                       (values (keywordicate (car var))
                                               (car var)))
                                 `((,key (get-key-arg-tail ',keyword
                                                           ,args-tail))
                                   (,variable (if ,key
                                                  (car ,key)
                                                  ,(cadr var))))))
                              (t
                               (multiple-value-bind (keyword variable)
                                   (if (consp (car var))
                                       (values (caar var)
                                               (cadar var))
                                       (values (keywordicate (car var))
                                               (car var)))
                                 `((,key (get-key-arg-tail ',keyword
                                                           ,args-tail))
                                   (,(caddr var) (not (null,key)))
                                   (,variable (if ,key
                                                  (car ,key)
                                                  ,(cadr var))))))))
                   (aux `(,var))))))
      (let ((bindings (mapcan #'process-var lambda-list)))
        `(let* ((,args-tail ,args)
                ,@bindings
                (.dummy0.
                 ,@(when (eq state 'optional)
                     `((unless (null ,args-tail)
                         (error 'simple-program-error
                                :format-control "surplus arguments: ~S"
                                :format-arguments (list ,args-tail)))))))
           (declare (ignorable ,args-tail .dummy0.))
           ,@body)))))

(defun get-key-arg-tail (keyword list)
  (loop for (key . tail) on list by #'cddr
        when (null tail) do
          ;; FIXME: Do we want to export this symbol? Or maybe use an
          ;; (ERROR 'SIMPLE-PROGRAM-ERROR) form?
          (sb-c::%odd-key-args-error)
        when (eq key keyword)
          return tail))

(defun walk-method-lambda (method-lambda required-parameters env slots calls)
  (let (;; flag indicating that CALL-NEXT-METHOD should be in the
        ;; method definition
        (call-next-method-p nil)
        ;; flag indicating that #'CALL-NEXT-METHOD was seen in the
        ;; body of a method
        (closurep nil)
        ;; flag indicating that NEXT-METHOD-P should be in the method
        ;; definition
        (next-method-p-p nil)
        ;; a list of all required parameters whose bindings might be
        ;; modified in the method body.
        (parameters-setqd nil))
    (flet ((walk-function (form context env)
             (cond ((not (eq context :eval)) form)
                   ;; FIXME: Jumping to a conclusion from the way it's used
                   ;; above, perhaps CONTEXT should be called SITUATION
                   ;; (after the term used in the ANSI specification of
                   ;; EVAL-WHEN) and given modern ANSI keyword values
                   ;; like :LOAD-TOPLEVEL.
                   ((not (listp form)) form)
                   ((eq (car form) 'call-next-method)
                    (setq call-next-method-p t)
                    form)
                   ((eq (car form) 'next-method-p)
                    (setq next-method-p-p t)
                    form)
                   ((memq (car form) '(setq multiple-value-setq))
                    ;; FIXME: this is possibly a little strong as
                    ;; conditions go.  Ideally we would want to detect
                    ;; which, if any, of the method parameters are
                    ;; being set, and communicate that information to
                    ;; e.g. SPLIT-DECLARATIONS.  However, the brute
                    ;; force method doesn't really cost much; a little
                    ;; loss of discrimination over IGNORED variables
                    ;; should be all.  -- CSR, 2004-07-01
                    ;;
                    ;; As of 2006-09-18 modified parameter bindings
                    ;; are now tracked with more granularity than just
                    ;; one SETQ-P flag, in order to disable SLOT-VALUE
                    ;; optimizations for parameters that are SETQd.
                    ;; The old binary SETQ-P flag is still used for
                    ;; all other purposes, since as noted above, the
                    ;; extra cost is minimal. -- JES, 2006-09-18
                    ;;
                    ;; The walker will split (SETQ A 1 B 2) to
                    ;; separate (SETQ A 1) and (SETQ B 2) forms, so we
                    ;; only need to handle the simple case of SETQ
                    ;; here.
                    (let ((vars (if (eq (car form) 'setq)
                                    (list (second form))
                                    (second form))))
                      (dolist (var vars)
                        ;; Note that we don't need to check for
                        ;; %VARIABLE-REBINDING declarations like is
                        ;; done in CAN-OPTIMIZE-ACCESS1, since the
                        ;; bindings that will have that declation will
                        ;; never be SETQd.
                        (when (var-declaration '%class var env)
                          ;; If a parameter binding is shadowed by
                          ;; another binding it won't have a %CLASS
                          ;; declaration anymore, and this won't get
                          ;; executed.
                          (pushnew var parameters-setqd))))
                    form)
                   ((and (eq (car form) 'function)
                         (cond ((eq (cadr form) 'call-next-method)
                                (setq call-next-method-p t)
                                (setq closurep t)
                                form)
                               ((eq (cadr form) 'next-method-p)
                                (setq next-method-p-p t)
                                (setq closurep t)
                                form)
                               (t nil))))
                   ((and (memq (car form)
                               '(slot-value set-slot-value slot-boundp))
                         (constantp (caddr form)))
                    (let ((parameter (can-optimize-access form
                                                          required-parameters
                                                          env)))
                      (let ((fun (ecase (car form)
                                   (slot-value #'optimize-slot-value)
                                   (set-slot-value #'optimize-set-slot-value)
                                   (slot-boundp #'optimize-slot-boundp))))
                        (funcall fun slots parameter form))))
                   (t form))))

      (let ((walked-lambda (walk-form method-lambda env #'walk-function)))
        ;;; FIXME: the walker's rewriting of the source code causes
        ;;; trouble when doing code coverage. The rewrites should be
        ;;; removed, and the same operations done using
        ;;; compiler-macros or tranforms.
        (values (if (sb-c:policy env (= sb-c:store-coverage-data 0))
                    walked-lambda
                    method-lambda)
                call-next-method-p
                closurep
                next-method-p-p
                (not (null parameters-setqd))
                parameters-setqd)))))

(defun generic-function-name-p (name)
  (and (legal-fun-name-p name)
       (fboundp name)
       (if (eq *boot-state* 'complete)
           (standard-generic-function-p (gdefinition name))
           (funcallable-instance-p (gdefinition name)))))

(defun method-plist-value (method key &optional default)
  (let ((plist (if (consp method)
                   (getf (early-method-initargs method) 'plist)
                   (object-plist method))))
    (getf plist key default)))

(defun (setf method-plist-value) (new-value method key &optional default)
  (if (consp method)
      (setf (getf (getf (early-method-initargs method) 'plist) key default)
            new-value)
      (setf (getf (object-plist method) key default) new-value)))

(defun load-defmethod
    (class name quals specls ll initargs source-location)
  (setq initargs (copy-tree initargs))
  (setf (getf (getf initargs 'plist) :name)
        (make-method-spec name quals specls))
  (load-defmethod-internal class name quals specls
                           ll initargs source-location))

(defun load-defmethod-internal
    (method-class gf-spec qualifiers specializers lambda-list
                  initargs source-location)
  (when (and (eq *boot-state* 'complete)
             (fboundp gf-spec))
    (let* ((gf (fdefinition gf-spec))
           (method (and (generic-function-p gf)
                        (generic-function-methods gf)
                        (find-method gf
                                     qualifiers
                                     (parse-specializers specializers)
                                     nil))))
      (when method
        (style-warn "redefining ~S~{ ~S~} ~S in DEFMETHOD"
                    gf-spec qualifiers specializers))))
  (let ((method (apply #'add-named-method
                       gf-spec qualifiers specializers lambda-list
                       :definition-source source-location
                       initargs)))
    (unless (or (eq method-class 'standard-method)
                (eq (find-class method-class nil) (class-of method)))
      ;; FIXME: should be STYLE-WARNING?
      (format *error-output*
              "~&At the time the method with qualifiers ~:S and~%~
               specializers ~:S on the generic function ~S~%~
               was compiled, the method-class for that generic function was~%~
               ~S. But, the method class is now ~S, this~%~
               may mean that this method was compiled improperly.~%"
              qualifiers specializers gf-spec
              method-class (class-name (class-of method))))
    method))

(defun make-method-spec (gf-spec qualifiers unparsed-specializers)
  `(slow-method ,gf-spec ,@qualifiers ,unparsed-specializers))

(defun initialize-method-function (initargs method)
  (let* ((mf (getf initargs :function))
         (mff (and (typep mf '%method-function)
                   (%method-function-fast-function mf)))
         (plist (getf initargs 'plist))
         (name (getf plist :name)))
    (when name
      (when mf
        (setq mf (set-fun-name mf name)))
      (when (and mff (consp name) (eq (car name) 'slow-method))
        (let ((fast-name `(fast-method ,@(cdr name))))
          (set-fun-name mff fast-name))))
    (when plist
      (let ((plist plist))
        (let ((snl (getf plist :slot-name-lists))
              (cl (getf plist :call-list)))
          (when (or snl cl)
            (setf (method-plist-value method :pv-table)
                  (intern-pv-table :slot-name-lists snl :call-list cl))))))))

(defun analyze-lambda-list (lambda-list)
  (flet (;; FIXME: Is this redundant with SB-C::MAKE-KEYWORD-FOR-ARG?
         (parse-key-arg (arg)
           (if (listp arg)
               (if (listp (car arg))
                   (caar arg)
                   (keywordicate (car arg)))
               (keywordicate arg))))
    (let ((nrequired 0)
          (noptional 0)
          (keysp nil)
          (restp nil)
          (nrest 0)
          (allow-other-keys-p nil)
          (keywords ())
          (keyword-parameters ())
          (state 'required))
      (dolist (x lambda-list)
        (if (memq x lambda-list-keywords)
            (case x
              (&optional         (setq state 'optional))
              (&key              (setq keysp t
                                       state 'key))
              (&allow-other-keys (setq allow-other-keys-p t))
              (&rest             (setq restp t
                                       state 'rest))
              (&aux           (return t))
              (otherwise
                (error "encountered the non-standard lambda list keyword ~S"
                       x)))
            (ecase state
              (required  (incf nrequired))
              (optional  (incf noptional))
              (key       (push (parse-key-arg x) keywords)
                         (push x keyword-parameters))
              (rest      (incf nrest)))))
      (when (and restp (zerop nrest))
        (error "Error in lambda-list:~%~
                After &REST, a DEFGENERIC lambda-list ~
                must be followed by at least one variable."))
      (values nrequired noptional keysp restp allow-other-keys-p
              (reverse keywords)
              (reverse keyword-parameters)))))

(defun keyword-spec-name (x)
  (let ((key (if (atom x) x (car x))))
    (if (atom key)
        (keywordicate key)
        (car key))))

(defun ftype-declaration-from-lambda-list (lambda-list name)
  (multiple-value-bind (nrequired noptional keysp restp allow-other-keys-p
                                  keywords keyword-parameters)
      (analyze-lambda-list lambda-list)
    (declare (ignore keyword-parameters))
    (let* ((old (info :function :type name)) ;FIXME:FDOCUMENTATION instead?
           (old-ftype (if (fun-type-p old) old nil))
           (old-restp (and old-ftype (fun-type-rest old-ftype)))
           (old-keys (and old-ftype
                          (mapcar #'key-info-name
                                  (fun-type-keywords
                                   old-ftype))))
           (old-keysp (and old-ftype (fun-type-keyp old-ftype)))
           (old-allowp (and old-ftype
                            (fun-type-allowp old-ftype)))
           (keywords (union old-keys (mapcar #'keyword-spec-name keywords))))
      `(function ,(append (make-list nrequired :initial-element t)
                          (when (plusp noptional)
                            (append '(&optional)
                                    (make-list noptional :initial-element t)))
                          (when (or restp old-restp)
                            '(&rest t))
                          (when (or keysp old-keysp)
                            (append '(&key)
                                    (mapcar (lambda (key)
                                              `(,key t))
                                            keywords)
                                    (when (or allow-other-keys-p old-allowp)
                                      '(&allow-other-keys)))))
                 *))))

(defun defgeneric-declaration (spec lambda-list)
  `(ftype ,(ftype-declaration-from-lambda-list lambda-list spec) ,spec))

;;;; early generic function support

(defvar *!early-generic-functions* ())

(defun ensure-generic-function (fun-name
                                &rest all-keys
                                &key environment source-location
                                &allow-other-keys)
  (declare (ignore environment))
  (let ((existing (and (fboundp fun-name)
                       (gdefinition fun-name))))
    (cond ((and existing
                (eq *boot-state* 'complete)
                (null (generic-function-p existing)))
           (generic-clobbers-function fun-name)
           (fmakunbound fun-name)
           (apply #'ensure-generic-function fun-name all-keys))
          (t
           (apply #'ensure-generic-function-using-class
                  existing fun-name all-keys)))))

(defun generic-clobbers-function (fun-name)
  (cerror "Replace the function binding"
          'simple-program-error
          :format-control "~S already names an ordinary function or a macro."
          :format-arguments (list fun-name)))

(defvar *sgf-wrapper*
  (boot-make-wrapper (early-class-size 'standard-generic-function)
                     'standard-generic-function))

(defvar *sgf-slots-init*
  (mapcar (lambda (canonical-slot)
            (if (memq (getf canonical-slot :name) '(arg-info source))
                +slot-unbound+
                (let ((initfunction (getf canonical-slot :initfunction)))
                  (if initfunction
                      (funcall initfunction)
                      +slot-unbound+))))
          (early-collect-inheritance 'standard-generic-function)))

(defvar *sgf-method-class-index*
  (!bootstrap-slot-index 'standard-generic-function 'method-class))

(defun early-gf-p (x)
  (and (fsc-instance-p x)
       (eq (clos-slots-ref (get-slots x) *sgf-method-class-index*)
           +slot-unbound+)))

(defvar *sgf-methods-index*
  (!bootstrap-slot-index 'standard-generic-function 'methods))

(defmacro early-gf-methods (gf)
  `(clos-slots-ref (get-slots ,gf) *sgf-methods-index*))

(defun safe-generic-function-methods (generic-function)
  (if (eq (class-of generic-function) *the-class-standard-generic-function*)
      (clos-slots-ref (get-slots generic-function) *sgf-methods-index*)
      (generic-function-methods generic-function)))

(defvar *sgf-arg-info-index*
  (!bootstrap-slot-index 'standard-generic-function 'arg-info))

(defmacro early-gf-arg-info (gf)
  `(clos-slots-ref (get-slots ,gf) *sgf-arg-info-index*))

(defvar *sgf-dfun-state-index*
  (!bootstrap-slot-index 'standard-generic-function 'dfun-state))

(defstruct (arg-info
            (:conc-name nil)
            (:constructor make-arg-info ())
            (:copier nil))
  (arg-info-lambda-list :no-lambda-list)
  arg-info-precedence
  arg-info-metatypes
  arg-info-number-optional
  arg-info-key/rest-p
  arg-info-keys   ;nil        no &KEY or &REST allowed
                  ;(k1 k2 ..) Each method must accept these &KEY arguments.
                  ;T          must have &KEY or &REST

  gf-info-simple-accessor-type ; nil, reader, writer, boundp
  (gf-precompute-dfun-and-emf-p nil) ; set by set-arg-info

  gf-info-static-c-a-m-emf
  (gf-info-c-a-m-emf-std-p t)
  gf-info-fast-mf-p)

#-sb-fluid (declaim (sb-ext:freeze-type arg-info))

(defun arg-info-valid-p (arg-info)
  (not (null (arg-info-number-optional arg-info))))

(defun arg-info-applyp (arg-info)
  (or (plusp (arg-info-number-optional arg-info))
      (arg-info-key/rest-p arg-info)))

(defun arg-info-number-required (arg-info)
  (length (arg-info-metatypes arg-info)))

(defun arg-info-nkeys (arg-info)
  (count-if (lambda (x) (neq x t)) (arg-info-metatypes arg-info)))

(defun create-gf-lambda-list (lambda-list)
  ;;; Create a gf lambda list from a method lambda list
  (loop for x in lambda-list
        collect (if (consp x) (list (car x)) x)
        if (eq x '&key) do (loop-finish)))

(defun set-arg-info (gf &key new-method (lambda-list nil lambda-list-p)
                        argument-precedence-order)
  (let* ((arg-info (if (eq *boot-state* 'complete)
                       (gf-arg-info gf)
                       (early-gf-arg-info gf)))
         (methods (if (eq *boot-state* 'complete)
                      (generic-function-methods gf)
                      (early-gf-methods gf)))
         (was-valid-p (integerp (arg-info-number-optional arg-info)))
         (first-p (and new-method (null (cdr methods)))))
    (when (and (not lambda-list-p) methods)
      (setq lambda-list (gf-lambda-list gf)))
    (when (or lambda-list-p
              (and first-p
                   (eq (arg-info-lambda-list arg-info) :no-lambda-list)))
      (multiple-value-bind (nreq nopt keysp restp allow-other-keys-p keywords)
          (analyze-lambda-list lambda-list)
        (when (and methods (not first-p))
          (let ((gf-nreq (arg-info-number-required arg-info))
                (gf-nopt (arg-info-number-optional arg-info))
                (gf-key/rest-p (arg-info-key/rest-p arg-info)))
            (unless (and (= nreq gf-nreq)
                         (= nopt gf-nopt)
                         (eq (or keysp restp) gf-key/rest-p))
              (error "The lambda-list ~S is incompatible with ~
                     existing methods of ~S."
                     lambda-list gf))))
        (setf (arg-info-lambda-list arg-info)
              (if lambda-list-p
                  lambda-list
                   (create-gf-lambda-list lambda-list)))
        (when (or lambda-list-p argument-precedence-order
                  (null (arg-info-precedence arg-info)))
          (setf (arg-info-precedence arg-info)
                (compute-precedence lambda-list nreq argument-precedence-order)))
        (setf (arg-info-metatypes arg-info) (make-list nreq))
        (setf (arg-info-number-optional arg-info) nopt)
        (setf (arg-info-key/rest-p arg-info) (not (null (or keysp restp))))
        (setf (arg-info-keys arg-info)
              (if lambda-list-p
                  (if allow-other-keys-p t keywords)
                  (arg-info-key/rest-p arg-info)))))
    (when new-method
      (check-method-arg-info gf arg-info new-method))
    (set-arg-info1 gf arg-info new-method methods was-valid-p first-p)
    arg-info))

(defun check-method-arg-info (gf arg-info method)
  (multiple-value-bind (nreq nopt keysp restp allow-other-keys-p keywords)
      (analyze-lambda-list (if (consp method)
                               (early-method-lambda-list method)
                               (method-lambda-list method)))
    (flet ((lose (string &rest args)
             (error 'simple-program-error
                    :format-control "~@<attempt to add the method~2I~_~S~I~_~
                                     to the generic function~2I~_~S;~I~_~
                                     but ~?~:>"
                    :format-arguments (list method gf string args)))
           (comparison-description (x y)
             (if (> x y) "more" "fewer")))
      (let ((gf-nreq (arg-info-number-required arg-info))
            (gf-nopt (arg-info-number-optional arg-info))
            (gf-key/rest-p (arg-info-key/rest-p arg-info))
            (gf-keywords (arg-info-keys arg-info)))
        (unless (= nreq gf-nreq)
          (lose
           "the method has ~A required arguments than the generic function."
           (comparison-description nreq gf-nreq)))
        (unless (= nopt gf-nopt)
          (lose
           "the method has ~A optional arguments than the generic function."
           (comparison-description nopt gf-nopt)))
        (unless (eq (or keysp restp) gf-key/rest-p)
          (lose
           "the method and generic function differ in whether they accept~_~
            &REST or &KEY arguments."))
        (when (consp gf-keywords)
          (unless (or (and restp (not keysp))
                      allow-other-keys-p
                      (every (lambda (k) (memq k keywords)) gf-keywords))
            (lose "the method does not accept each of the &KEY arguments~2I~_~
                   ~S."
                  gf-keywords)))))))

(defvar *sm-specializers-index*
  (!bootstrap-slot-index 'standard-method 'specializers))
(defvar *sm-%function-index*
  (!bootstrap-slot-index 'standard-method '%function))
(defvar *sm-qualifiers-index*
  (!bootstrap-slot-index 'standard-method 'qualifiers))
(defvar *sm-plist-index*
  (!bootstrap-slot-index 'standard-method 'plist))

;;; FIXME: we don't actually need this; we could test for the exact
;;; class and deal with it as appropriate.  In fact we probably don't
;;; need it anyway because we only use this for METHOD-SPECIALIZERS on
;;; the standard reader method for METHOD-SPECIALIZERS.  Probably.
(dolist (s '(specializers %function plist))
  (aver (= (symbol-value (intern (format nil "*SM-~A-INDEX*" s)))
           (!bootstrap-slot-index 'standard-reader-method s)
           (!bootstrap-slot-index 'standard-writer-method s)
           (!bootstrap-slot-index 'standard-boundp-method s))))

(defun safe-method-specializers (method)
  (let ((standard-method-classes
         (list *the-class-standard-method*
               *the-class-standard-reader-method*
               *the-class-standard-writer-method*
               *the-class-standard-boundp-method*))
        (class (class-of method)))
    (if (member class standard-method-classes)
        (clos-slots-ref (get-slots method) *sm-specializers-index*)
        (method-specializers method))))
(defun safe-method-fast-function (method)
  (let ((mf (safe-method-function method)))
    (and (typep mf '%method-function)
         (%method-function-fast-function mf))))
(defun safe-method-function (method)
  (let ((standard-method-classes
         (list *the-class-standard-method*
               *the-class-standard-reader-method*
               *the-class-standard-writer-method*
               *the-class-standard-boundp-method*))
        (class (class-of method)))
    (if (member class standard-method-classes)
        (clos-slots-ref (get-slots method) *sm-%function-index*)
        (method-function method))))
(defun safe-method-qualifiers (method)
  (let ((standard-method-classes
         (list *the-class-standard-method*
               *the-class-standard-reader-method*
               *the-class-standard-writer-method*
               *the-class-standard-boundp-method*))
        (class (class-of method)))
    (if (member class standard-method-classes)
        (clos-slots-ref (get-slots method) *sm-qualifiers-index*)
        (method-qualifiers method))))

(defun set-arg-info1 (gf arg-info new-method methods was-valid-p first-p)
  (let* ((existing-p (and methods (cdr methods) new-method))
         (nreq (length (arg-info-metatypes arg-info)))
         (metatypes (if existing-p
                        (arg-info-metatypes arg-info)
                        (make-list nreq)))
         (type (if existing-p
                   (gf-info-simple-accessor-type arg-info)
                   nil)))
    (when (arg-info-valid-p arg-info)
      (dolist (method (if new-method (list new-method) methods))
        (let* ((specializers (if (or (eq *boot-state* 'complete)
                                     (not (consp method)))
                                 (safe-method-specializers method)
                                 (early-method-specializers method t)))
               (class (if (or (eq *boot-state* 'complete) (not (consp method)))
                          (class-of method)
                          (early-method-class method)))
               (new-type
                (when (and class
                           (or (not (eq *boot-state* 'complete))
                               (eq (generic-function-method-combination gf)
                                   *standard-method-combination*)))
                  (cond ((or (eq class *the-class-standard-reader-method*)
                             (eq class *the-class-global-reader-method*))
                         'reader)
                        ((or (eq class *the-class-standard-writer-method*)
                             (eq class *the-class-global-writer-method*))
                         'writer)
                        ((or (eq class *the-class-standard-boundp-method*)
                             (eq class *the-class-global-boundp-method*))
                         'boundp)))))
          (setq metatypes (mapcar #'raise-metatype metatypes specializers))
          (setq type (cond ((null type) new-type)
                           ((eq type new-type) type)
                           (t nil)))))
      (setf (arg-info-metatypes arg-info) metatypes)
      (setf (gf-info-simple-accessor-type arg-info) type)))
  (when (or (not was-valid-p) first-p)
    (multiple-value-bind (c-a-m-emf std-p)
        (if (early-gf-p gf)
            (values t t)
            (compute-applicable-methods-emf gf))
      (setf (gf-info-static-c-a-m-emf arg-info) c-a-m-emf)
      (setf (gf-info-c-a-m-emf-std-p arg-info) std-p)
      (unless (gf-info-c-a-m-emf-std-p arg-info)
        (setf (gf-info-simple-accessor-type arg-info) t))))
  (unless was-valid-p
    (let ((name (if (eq *boot-state* 'complete)
                    (generic-function-name gf)
                    (!early-gf-name gf))))
      (setf (gf-precompute-dfun-and-emf-p arg-info)
            (cond
              ((and (consp name)
                    (member (car name)
                            *internal-pcl-generalized-fun-name-symbols*))
                nil)
              (t (let* ((symbol (fun-name-block-name name))
                        (package (symbol-package symbol)))
                   (and (or (eq package *pcl-package*)
                            (memq package (package-use-list *pcl-package*)))
                        ;; FIXME: this test will eventually be
                        ;; superseded by the *internal-pcl...* test,
                        ;; above.  While we are in a process of
                        ;; transition, however, it should probably
                        ;; remain.
                        (not (find #\Space (symbol-name symbol))))))))))
  (setf (gf-info-fast-mf-p arg-info)
        (or (not (eq *boot-state* 'complete))
            (let* ((method-class (generic-function-method-class gf))
                   (methods (compute-applicable-methods
                             #'make-method-lambda
                             (list gf (class-prototype method-class)
                                   '(lambda) nil))))
              (and methods (null (cdr methods))
                   (let ((specls (method-specializers (car methods))))
                     (and (classp (car specls))
                          (eq 'standard-generic-function
                              (class-name (car specls)))
                          (classp (cadr specls))
                          (eq 'standard-method
                              (class-name (cadr specls)))))))))
  arg-info)

;;; This is the early definition of ENSURE-GENERIC-FUNCTION-USING-CLASS.
;;;
;;; The STATIC-SLOTS field of the funcallable instances used as early
;;; generic functions is used to store the early methods and early
;;; discriminator code for the early generic function. The static
;;; slots field of the fins contains a list whose:
;;;    CAR    -   a list of the early methods on this early gf
;;;    CADR   -   the early discriminator code for this method
(defun ensure-generic-function-using-class (existing spec &rest keys
                                            &key (lambda-list nil
                                                              lambda-list-p)
                                            argument-precedence-order
                                            source-location
                                            &allow-other-keys)
  (declare (ignore keys))
  (cond ((and existing (early-gf-p existing))
         (when lambda-list-p
           (set-arg-info existing :lambda-list lambda-list))
         existing)
        ((assoc spec *!generic-function-fixups* :test #'equal)
         (if existing
             (make-early-gf spec lambda-list lambda-list-p existing
                            argument-precedence-order source-location)
             (error "The function ~S is not already defined." spec)))
        (existing
         (error "~S should be on the list ~S."
                spec
                '*!generic-function-fixups*))
        (t
         (pushnew spec *!early-generic-functions* :test #'equal)
         (make-early-gf spec lambda-list lambda-list-p nil
                        argument-precedence-order source-location))))

(defun make-early-gf (spec &optional lambda-list lambda-list-p
                      function argument-precedence-order source-location)
  (let ((fin (allocate-standard-funcallable-instance
              *sgf-wrapper* *sgf-slots-init*)))
    (set-funcallable-instance-function
     fin
     (or function
         (if (eq spec 'print-object)
             #'(lambda (instance stream)
                 (print-unreadable-object (instance stream :identity t)
                   (format stream "std-instance")))
             #'(lambda (&rest args)
                 (declare (ignore args))
                 (error "The function of the funcallable-instance ~S~
                         has not been set." fin)))))
    (setf (gdefinition spec) fin)
    (!bootstrap-set-slot 'standard-generic-function fin 'name spec)
    (!bootstrap-set-slot 'standard-generic-function
                         fin
                         'source
                         source-location)
    (set-fun-name fin spec)
    (let ((arg-info (make-arg-info)))
      (setf (early-gf-arg-info fin) arg-info)
      (when lambda-list-p
        (proclaim (defgeneric-declaration spec lambda-list))
        (if argument-precedence-order
            (set-arg-info fin
                          :lambda-list lambda-list
                          :argument-precedence-order argument-precedence-order)
            (set-arg-info fin :lambda-list lambda-list))))
    fin))

(defun safe-gf-dfun-state (generic-function)
  (if (eq (class-of generic-function) *the-class-standard-generic-function*)
      (clos-slots-ref (get-slots generic-function) *sgf-dfun-state-index*)
      (gf-dfun-state generic-function)))
(defun (setf safe-gf-dfun-state) (new-value generic-function)
  (if (eq (class-of generic-function) *the-class-standard-generic-function*)
      (setf (clos-slots-ref (get-slots generic-function)
                            *sgf-dfun-state-index*)
            new-value)
      (setf (gf-dfun-state generic-function) new-value)))

(defun set-dfun (gf &optional dfun cache info)
  (when cache
    (setf (cache-owner cache) gf))
  (let ((new-state (if (and dfun (or cache info))
                       (list* dfun cache info)
                       dfun)))
    (if (eq *boot-state* 'complete)
        (setf (safe-gf-dfun-state gf) new-state)
        (setf (clos-slots-ref (get-slots gf) *sgf-dfun-state-index*)
              new-state)))
  dfun)

(defun gf-dfun-cache (gf)
  (let ((state (if (eq *boot-state* 'complete)
                   (safe-gf-dfun-state gf)
                   (clos-slots-ref (get-slots gf) *sgf-dfun-state-index*))))
    (typecase state
      (function nil)
      (cons (cadr state)))))

(defun gf-dfun-info (gf)
  (let ((state (if (eq *boot-state* 'complete)
                   (safe-gf-dfun-state gf)
                   (clos-slots-ref (get-slots gf) *sgf-dfun-state-index*))))
    (typecase state
      (function nil)
      (cons (cddr state)))))

(defvar *sgf-name-index*
  (!bootstrap-slot-index 'standard-generic-function 'name))

(defun !early-gf-name (gf)
  (clos-slots-ref (get-slots gf) *sgf-name-index*))

(defun gf-lambda-list (gf)
  (let ((arg-info (if (eq *boot-state* 'complete)
                      (gf-arg-info gf)
                      (early-gf-arg-info gf))))
    (if (eq :no-lambda-list (arg-info-lambda-list arg-info))
        (let ((methods (if (eq *boot-state* 'complete)
                           (generic-function-methods gf)
                           (early-gf-methods gf))))
          (if (null methods)
              (progn
                (warn "no way to determine the lambda list for ~S" gf)
                nil)
              (let* ((method (car (last methods)))
                     (ll (if (consp method)
                             (early-method-lambda-list method)
                             (method-lambda-list method))))
                (create-gf-lambda-list ll))))
        (arg-info-lambda-list arg-info))))

(defmacro real-ensure-gf-internal (gf-class all-keys env)
  `(progn
     (cond ((symbolp ,gf-class)
            (setq ,gf-class (find-class ,gf-class t ,env)))
           ((classp ,gf-class))
           (t
            (error "The :GENERIC-FUNCTION-CLASS argument (~S) was neither a~%~
                    class nor a symbol that names a class."
                   ,gf-class)))
     (unless (class-finalized-p ,gf-class)
       (if (class-has-a-forward-referenced-superclass-p ,gf-class)
           ;; FIXME: reference MOP documentation -- this is an
           ;; additional requirement on our users
           (error "The generic function class ~S is not finalizeable" ,gf-class)
           (finalize-inheritance ,gf-class)))
     (remf ,all-keys :generic-function-class)
     (remf ,all-keys :environment)
     (let ((combin (getf ,all-keys :method-combination '.shes-not-there.)))
       (unless (eq combin '.shes-not-there.)
         (setf (getf ,all-keys :method-combination)
               (find-method-combination (class-prototype ,gf-class)
                                        (car combin)
                                        (cdr combin)))))
    (let ((method-class (getf ,all-keys :method-class '.shes-not-there.)))
      (unless (eq method-class '.shes-not-there.)
        (setf (getf ,all-keys :method-class)
              (cond ((classp method-class)
                     method-class)
                    (t (find-class method-class t ,env))))))))

(defun real-ensure-gf-using-class--generic-function
       (existing
        fun-name
        &rest all-keys
        &key environment (lambda-list nil lambda-list-p)
        (generic-function-class 'standard-generic-function)
        &allow-other-keys)
  (real-ensure-gf-internal generic-function-class all-keys environment)
  ;; KLUDGE: the above macro does SETQ on GENERIC-FUNCTION-CLASS,
  ;; which is what makes the next line work
  (unless (eq (class-of existing) generic-function-class)
    (change-class existing generic-function-class))
  (prog1
      (apply #'reinitialize-instance existing all-keys)
    (when lambda-list-p
      (proclaim (defgeneric-declaration fun-name lambda-list)))))

(defun real-ensure-gf-using-class--null
       (existing
        fun-name
        &rest all-keys
        &key environment (lambda-list nil lambda-list-p)
             (generic-function-class 'standard-generic-function)
        &allow-other-keys)
  (declare (ignore existing))
  (real-ensure-gf-internal generic-function-class all-keys environment)
  (prog1
      (setf (gdefinition fun-name)
            (apply #'make-instance generic-function-class
                   :name fun-name all-keys))
    (when lambda-list-p
      (proclaim (defgeneric-declaration fun-name lambda-list)))))

(defun safe-gf-arg-info (generic-function)
  (if (eq (class-of generic-function) *the-class-standard-generic-function*)
      (clos-slots-ref (fsc-instance-slots generic-function)
                      *sgf-arg-info-index*)
      (gf-arg-info generic-function)))

;;; FIXME: this function took on a slightly greater role than it
;;; previously had around 2005-11-02, when CSR fixed the bug whereby
;;; having more than one subclass of standard-generic-function caused
;;; the whole system to die horribly through a metacircle in
;;; GF-ARG-INFO.  The fix is to be slightly more disciplined about
;;; calling accessor methods -- we call GET-GENERIC-FUN-INFO when
;;; computing discriminating functions, so we need to be careful about
;;; having a base case for the recursion, and we provide that with the
;;; STANDARD-GENERIC-FUNCTION case below.  However, we are not (yet)
;;; as disciplined as CLISP's CLOS/MOP, and it would be nice to get to
;;; that stage, where all potentially dangerous cases are enumerated
;;; and stopped.  -- CSR, 2005-11-02.
(defun get-generic-fun-info (gf)
  ;; values   nreq applyp metatypes nkeys arg-info
  (multiple-value-bind (applyp metatypes arg-info)
      (let* ((arg-info (if (early-gf-p gf)
                           (early-gf-arg-info gf)
                           (safe-gf-arg-info gf)))
             (metatypes (arg-info-metatypes arg-info)))
        (values (arg-info-applyp arg-info)
                metatypes
                arg-info))
    (values (length metatypes) applyp metatypes
            (count-if (lambda (x) (neq x t)) metatypes)
            arg-info)))

(defun early-make-a-method (class qualifiers arglist specializers initargs doc
                            &key slot-name object-class method-class-function)
  (let ((parsed ())
        (unparsed ()))
    ;; Figure out whether we got class objects or class names as the
    ;; specializers and set parsed and unparsed appropriately. If we
    ;; got class objects, then we can compute unparsed, but if we got
    ;; class names we don't try to compute parsed.
    ;;
    ;; Note that the use of not symbolp in this call to every should be
    ;; read as 'classp' we can't use classp itself because it doesn't
    ;; exist yet.
    (if (every (lambda (s) (not (symbolp s))) specializers)
        (setq parsed specializers
              unparsed (mapcar (lambda (s)
                                 (if (eq s t) t (class-name s)))
                               specializers))
        (setq unparsed specializers
              parsed ()))
    (let ((result
           (list :early-method

                 (getf initargs :function)
                 (let ((mf (getf initargs :function)))
                   (aver mf)
                   (and (typep mf '%method-function)
                        (%method-function-fast-function mf)))

                 ;; the parsed specializers. This is used by
                 ;; EARLY-METHOD-SPECIALIZERS to cache the parse.
                 ;; Note that this only comes into play when there is
                 ;; more than one early method on an early gf.
                 parsed

                 ;; A list to which REAL-MAKE-A-METHOD can be applied
                 ;; to make a real method corresponding to this early
                 ;; one.
                 (append
                  (list class qualifiers arglist unparsed
                        initargs doc)
                  (when slot-name
                    (list :slot-name slot-name :object-class object-class
                          :method-class-function method-class-function))))))
      (initialize-method-function initargs result)
      result)))

(defun real-make-a-method
       (class qualifiers lambda-list specializers initargs doc
        &rest args &key slot-name object-class method-class-function)
  (setq specializers (parse-specializers specializers))
  (if method-class-function
      (let* ((object-class (if (classp object-class) object-class
                               (find-class object-class)))
             (slots (class-direct-slots object-class))
             (slot-definition (find slot-name slots
                                    :key #'slot-definition-name)))
        (aver slot-name)
        (aver slot-definition)
        (let ((initargs (list* :qualifiers qualifiers :lambda-list lambda-list
                               :specializers specializers :documentation doc
                               :slot-definition slot-definition
                               :slot-name slot-name initargs)))
          (apply #'make-instance
                 (apply method-class-function object-class slot-definition
                        initargs)
                 initargs)))
      (apply #'make-instance class :qualifiers qualifiers
             :lambda-list lambda-list :specializers specializers
             :documentation doc (append args initargs))))

(defun early-method-function (early-method)
  (values (cadr early-method) (caddr early-method)))

(defun early-method-class (early-method)
  (find-class (car (fifth early-method))))

(defun early-method-standard-accessor-p (early-method)
  (let ((class (first (fifth early-method))))
    (or (eq class 'standard-reader-method)
        (eq class 'standard-writer-method)
        (eq class 'standard-boundp-method))))

(defun early-method-standard-accessor-slot-name (early-method)
  (eighth (fifth early-method)))

;;; Fetch the specializers of an early method. This is basically just
;;; a simple accessor except that when the second argument is t, this
;;; converts the specializers from symbols into class objects. The
;;; class objects are cached in the early method, this makes
;;; bootstrapping faster because the class objects only have to be
;;; computed once.
;;;
;;; NOTE:
;;;  The second argument should only be passed as T by
;;;  early-lookup-method. This is to implement the rule that only when
;;;  there is more than one early method on a generic function is the
;;;  conversion from class names to class objects done. This
;;;  corresponds to the fact that we are only allowed to have one
;;;  method on any generic function up until the time classes exist.
(defun early-method-specializers (early-method &optional objectsp)
  (if (and (listp early-method)
           (eq (car early-method) :early-method))
      (cond ((eq objectsp t)
             (or (fourth early-method)
                 (setf (fourth early-method)
                       (mapcar #'find-class (cadddr (fifth early-method))))))
            (t
             (fourth (fifth early-method))))
      (error "~S is not an early-method." early-method)))

(defun early-method-qualifiers (early-method)
  (second (fifth early-method)))

(defun early-method-lambda-list (early-method)
  (third (fifth early-method)))

(defun early-method-initargs (early-method)
  (fifth (fifth early-method)))

(defun (setf early-method-initargs) (new-value early-method)
  (setf (fifth (fifth early-method)) new-value))

(defun early-add-named-method (generic-function-name
                               qualifiers
                               specializers
                               arglist
                               &rest initargs)
  (let* (;; we don't need to deal with the :generic-function-class
         ;; argument here because the default,
         ;; STANDARD-GENERIC-FUNCTION, is right for all early generic
         ;; functions.  (See REAL-ADD-NAMED-METHOD)
         (gf (ensure-generic-function generic-function-name))
         (existing
           (dolist (m (early-gf-methods gf))
             (when (and (equal (early-method-specializers m) specializers)
                        (equal (early-method-qualifiers m) qualifiers))
               (return m))))
         (new (make-a-method 'standard-method
                             qualifiers
                             arglist
                             specializers
                             initargs
                             ())))
    (when existing (remove-method gf existing))
    (add-method gf new)))

;;; This is the early version of ADD-METHOD. Later this will become a
;;; generic function. See !FIX-EARLY-GENERIC-FUNCTIONS which has
;;; special knowledge about ADD-METHOD.
(defun add-method (generic-function method)
  (when (not (fsc-instance-p generic-function))
    (error "Early ADD-METHOD didn't get a funcallable instance."))
  (when (not (and (listp method) (eq (car method) :early-method)))
    (error "Early ADD-METHOD didn't get an early method."))
  (push method (early-gf-methods generic-function))
  (set-arg-info generic-function :new-method method)
  (unless (assoc (!early-gf-name generic-function)
                 *!generic-function-fixups*
                 :test #'equal)
    (update-dfun generic-function)))

;;; This is the early version of REMOVE-METHOD. See comments on
;;; the early version of ADD-METHOD.
(defun remove-method (generic-function method)
  (when (not (fsc-instance-p generic-function))
    (error "An early remove-method didn't get a funcallable instance."))
  (when (not (and (listp method) (eq (car method) :early-method)))
    (error "An early remove-method didn't get an early method."))
  (setf (early-gf-methods generic-function)
        (remove method (early-gf-methods generic-function)))
  (set-arg-info generic-function)
  (unless (assoc (!early-gf-name generic-function)
                 *!generic-function-fixups*
                 :test #'equal)
    (update-dfun generic-function)))

;;; This is the early version of GET-METHOD. See comments on the early
;;; version of ADD-METHOD.
(defun get-method (generic-function qualifiers specializers
                                    &optional (errorp t))
  (if (early-gf-p generic-function)
      (or (dolist (m (early-gf-methods generic-function))
            (when (and (or (equal (early-method-specializers m nil)
                                  specializers)
                           (equal (early-method-specializers m t)
                                  specializers))
                       (equal (early-method-qualifiers m) qualifiers))
              (return m)))
          (if errorp
              (error "can't get early method")
              nil))
      (real-get-method generic-function qualifiers specializers errorp)))

(defun !fix-early-generic-functions ()
  (let ((accessors nil))
    ;; Rearrange *!EARLY-GENERIC-FUNCTIONS* to speed up
    ;; FIX-EARLY-GENERIC-FUNCTIONS.
    (dolist (early-gf-spec *!early-generic-functions*)
      (when (every #'early-method-standard-accessor-p
                   (early-gf-methods (gdefinition early-gf-spec)))
        (push early-gf-spec accessors)))
    (dolist (spec (nconc accessors
                         '(accessor-method-slot-name
                           generic-function-methods
                           method-specializers
                           specializerp
                           specializer-type
                           specializer-class
                           slot-definition-location
                           slot-definition-name
                           class-slots
                           gf-arg-info
                           class-precedence-list
                           slot-boundp-using-class
                           (setf slot-value-using-class)
                           slot-value-using-class
                           structure-class-p
                           standard-class-p
                           funcallable-standard-class-p
                           specializerp)))
      (/show spec)
      (setq *!early-generic-functions*
            (cons spec
                  (delete spec *!early-generic-functions* :test #'equal))))

    (dolist (early-gf-spec *!early-generic-functions*)
      (/show early-gf-spec)
      (let* ((gf (gdefinition early-gf-spec))
             (methods (mapcar (lambda (early-method)
                                (let ((args (copy-list (fifth
                                                        early-method))))
                                  (setf (fourth args)
                                        (early-method-specializers
                                         early-method t))
                                  (apply #'real-make-a-method args)))
                              (early-gf-methods gf))))
        (setf (generic-function-method-class gf) *the-class-standard-method*)
        (setf (generic-function-method-combination gf)
              *standard-method-combination*)
        (set-methods gf methods)))

    (dolist (fn *!early-functions*)
      (/show fn)
      (setf (gdefinition (car fn)) (fdefinition (caddr fn))))

    (dolist (fixup *!generic-function-fixups*)
      (/show fixup)
      (let* ((fspec (car fixup))
             (gf (gdefinition fspec))
             (methods (mapcar (lambda (method)
                                (let* ((lambda-list (first method))
                                       (specializers (second method))
                                       (method-fn-name (third method))
                                       (fn-name (or method-fn-name fspec))
                                       (fn (fdefinition fn-name))
                                       (initargs
                                        (list :function
                                              (set-fun-name
                                               (lambda (args next-methods)
                                                 (declare (ignore
                                                           next-methods))
                                                 (apply fn args))
                                               `(call ,fn-name)))))
                                  (declare (type function fn))
                                  (make-a-method 'standard-method
                                                 ()
                                                 lambda-list
                                                 specializers
                                                 initargs
                                                 nil)))
                              (cdr fixup))))
        (setf (generic-function-method-class gf) *the-class-standard-method*)
        (setf (generic-function-method-combination gf)
              *standard-method-combination*)
        (set-methods gf methods))))
  (/show "leaving !FIX-EARLY-GENERIC-FUNCTIONS"))

;;; PARSE-DEFMETHOD is used by DEFMETHOD to parse the &REST argument
;;; into the 'real' arguments. This is where the syntax of DEFMETHOD
;;; is really implemented.
(defun parse-defmethod (cdr-of-form)
  (declare (list cdr-of-form))
  (let ((name (pop cdr-of-form))
        (qualifiers ())
        (spec-ll ()))
    (loop (if (and (car cdr-of-form) (atom (car cdr-of-form)))
              (push (pop cdr-of-form) qualifiers)
              (return (setq qualifiers (nreverse qualifiers)))))
    (setq spec-ll (pop cdr-of-form))
    (values name qualifiers spec-ll cdr-of-form)))

(defun parse-specializers (specializers)
  (declare (list specializers))
  (flet ((parse (spec)
           (let ((result (specializer-from-type spec)))
             (if (specializerp result)
                 result
                 (if (symbolp spec)
                     (error "~S was used as a specializer,~%~
                             but is not the name of a class."
                            spec)
                     (error "~S is not a legal specializer." spec))))))
    (mapcar #'parse specializers)))

(defun unparse-specializers (specializers-or-method)
  (if (listp specializers-or-method)
      (flet ((unparse (spec)
               (if (specializerp spec)
                   (let ((type (specializer-type spec)))
                     (if (and (consp type)
                              (eq (car type) 'class))
                         (let* ((class (cadr type))
                                (class-name (class-name class)))
                           (if (eq class (find-class class-name nil))
                               class-name
                               type))
                         type))
                   (error "~S is not a legal specializer." spec))))
        (mapcar #'unparse specializers-or-method))
      (unparse-specializers (method-specializers specializers-or-method))))

(defun parse-method-or-spec (spec &optional (errorp t))
  (let (gf method name temp)
    (if (method-p spec)
        (setq method spec
              gf (method-generic-function method)
              temp (and gf (generic-function-name gf))
              name (if temp
                       (make-method-spec temp
                                         (method-qualifiers method)
                                         (unparse-specializers
                                          (method-specializers method)))
                       (make-symbol (format nil "~S" method))))
        (multiple-value-bind (gf-spec quals specls)
            (parse-defmethod spec)
          (and (setq gf (and (or errorp (fboundp gf-spec))
                             (gdefinition gf-spec)))
               (let ((nreq (compute-discriminating-function-arglist-info gf)))
                 (setq specls (append (parse-specializers specls)
                                      (make-list (- nreq (length specls))
                                                 :initial-element
                                                 *the-class-t*)))
                 (and
                   (setq method (get-method gf quals specls errorp))
                   (setq name
                         (make-method-spec
                          gf-spec quals (unparse-specializers specls))))))))
    (values gf method name)))

(defun extract-parameters (specialized-lambda-list)
  (multiple-value-bind (parameters ignore1 ignore2)
      (parse-specialized-lambda-list specialized-lambda-list)
    (declare (ignore ignore1 ignore2))
    parameters))

(defun extract-lambda-list (specialized-lambda-list)
  (multiple-value-bind (ignore1 lambda-list ignore2)
      (parse-specialized-lambda-list specialized-lambda-list)
    (declare (ignore ignore1 ignore2))
    lambda-list))

(defun extract-specializer-names (specialized-lambda-list)
  (multiple-value-bind (ignore1 ignore2 specializers)
      (parse-specialized-lambda-list specialized-lambda-list)
    (declare (ignore ignore1 ignore2))
    specializers))

(defun extract-required-parameters (specialized-lambda-list)
  (multiple-value-bind (ignore1 ignore2 ignore3 required-parameters)
      (parse-specialized-lambda-list specialized-lambda-list)
    (declare (ignore ignore1 ignore2 ignore3))
    required-parameters))

(define-condition specialized-lambda-list-error
    (reference-condition simple-program-error)
  ()
  (:default-initargs :references (list '(:ansi-cl :section (3 4 3)))))

(defun parse-specialized-lambda-list
    (arglist
     &optional supplied-keywords (allowed-keywords '(&optional &rest &key &aux))
     &aux (specialized-lambda-list-keywords
           '(&optional &rest &key &allow-other-keys &aux)))
  (let ((arg (car arglist)))
    (cond ((null arglist) (values nil nil nil nil))
          ((eq arg '&aux)
           (values nil arglist nil nil))
          ((memq arg lambda-list-keywords)
           ;; non-standard lambda-list-keywords are errors.
           (unless (memq arg specialized-lambda-list-keywords)
             (error 'specialized-lambda-list-error
                    :format-control "unknown specialized-lambda-list ~
                                     keyword ~S~%"
                    :format-arguments (list arg)))
           ;; no multiple &rest x &rest bla specifying
           (when (memq arg supplied-keywords)
             (error 'specialized-lambda-list-error
                    :format-control "multiple occurrence of ~
                                     specialized-lambda-list keyword ~S~%"
                    :format-arguments (list arg)))
           ;; And no placing &key in front of &optional, either.
           (unless (memq arg allowed-keywords)
             (error 'specialized-lambda-list-error
                    :format-control "misplaced specialized-lambda-list ~
                                     keyword ~S~%"
                    :format-arguments (list arg)))
           ;; When we are at a lambda-list keyword, the parameters
           ;; don't include the lambda-list keyword; the lambda-list
           ;; does include the lambda-list keyword; and no
           ;; specializers are allowed to follow the lambda-list
           ;; keywords (at least for now).
           (multiple-value-bind (parameters lambda-list)
               (parse-specialized-lambda-list (cdr arglist)
                                              (cons arg supplied-keywords)
                                              (if (eq arg '&key)
                                                  (cons '&allow-other-keys
                                                        (cdr (member arg allowed-keywords)))
                                                (cdr (member arg allowed-keywords))))
             (when (and (eq arg '&rest)
                        (or (null lambda-list)
                            (memq (car lambda-list)
                                  specialized-lambda-list-keywords)
                            (not (or (null (cadr lambda-list))
                                     (memq (cadr lambda-list)
                                           specialized-lambda-list-keywords)))))
               (error 'specialized-lambda-list-error
                      :format-control
                      "in a specialized-lambda-list, excactly one ~
                       variable must follow &REST.~%"
                      :format-arguments nil))
             (values parameters
                     (cons arg lambda-list)
                     ()
                     ())))
          (supplied-keywords
           ;; After a lambda-list keyword there can be no specializers.
           (multiple-value-bind (parameters lambda-list)
               (parse-specialized-lambda-list (cdr arglist)
                                              supplied-keywords
                                              allowed-keywords)
             (values (cons (if (listp arg) (car arg) arg) parameters)
                     (cons arg lambda-list)
                     ()
                     ())))
          (t
           (multiple-value-bind (parameters lambda-list specializers required)
               (parse-specialized-lambda-list (cdr arglist))
             (values (cons (if (listp arg) (car arg) arg) parameters)
                     (cons (if (listp arg) (car arg) arg) lambda-list)
                     (cons (if (listp arg) (cadr arg) t) specializers)
                     (cons (if (listp arg) (car arg) arg) required)))))))

(setq *boot-state* 'early)

;;; FIXME: In here there was a #-CMU definition of SYMBOL-MACROLET
;;; which used %WALKER stuff. That suggests to me that maybe the code
;;; walker stuff was only used for implementing stuff like that; maybe
;;; it's not needed any more? Hunt down what it was used for and see.

(defmacro with-slots (slots instance &body body)
  (let ((in (gensym)))
    `(let ((,in ,instance))
       (declare (ignorable ,in))
       ,@(let ((instance (if (and (consp instance) (eq (car instance) 'the))
                             (third instance)
                             instance)))
           (and (symbolp instance)
                `((declare (%variable-rebinding ,in ,instance)))))
       ,in
       (symbol-macrolet ,(mapcar (lambda (slot-entry)
                                   (let ((var-name
                                          (if (symbolp slot-entry)
                                              slot-entry
                                              (car slot-entry)))
                                         (slot-name
                                          (if (symbolp slot-entry)
                                              slot-entry
                                              (cadr slot-entry))))
                                     `(,var-name
                                       (slot-value ,in ',slot-name))))
                                 slots)
                        ,@body))))

(defmacro with-accessors (slots instance &body body)
  (let ((in (gensym)))
    `(let ((,in ,instance))
       (declare (ignorable ,in))
       ,@(let ((instance (if (and (consp instance) (eq (car instance) 'the))
                             (third instance)
                             instance)))
           (and (symbolp instance)
                `((declare (%variable-rebinding ,in ,instance)))))
       ,in
       (symbol-macrolet ,(mapcar (lambda (slot-entry)
                                   (let ((var-name (car slot-entry))
                                         (accessor-name (cadr slot-entry)))
                                     `(,var-name (,accessor-name ,in))))
                                 slots)
          ,@body))))