condition.lisp

;;;; stuff originally from CMU CL's error.lisp which can or should
;;;; come late (mostly related to the CONDITION class itself)
;;;;

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

(in-package "SB!KERNEL")

;;;; miscellaneous support utilities

;;; Signalling an error when trying to print an error condition is
;;; generally a PITA, so whatever the failure encountered when
;;; wondering about FILE-POSITION within a condition printer, 'tis
;;; better silently to give up than to try to complain.
(defun file-position-or-nil-for-error (stream &optional (pos nil posp))
  ;; Arguably FILE-POSITION shouldn't be signalling errors at all; but
  ;; "NIL if this cannot be determined" in the ANSI spec doesn't seem
  ;; absolutely unambiguously to prohibit errors when, e.g., STREAM
  ;; has been closed so that FILE-POSITION is a nonsense question. So
  ;; my (WHN) impression is that the conservative approach is to
  ;; IGNORE-ERRORS. (I encountered this failure from within a homebrew
  ;; defsystemish operation where the ERROR-STREAM had been CL:CLOSEd,
  ;; I think by nonlocally exiting through a WITH-OPEN-FILE, by the
  ;; time an error was reported.)
  (if posp
      (ignore-errors (file-position stream pos))
      (ignore-errors (file-position stream))))

;;;; the CONDITION class

(/show0 "condition.lisp 20")

(eval-when (:compile-toplevel :load-toplevel :execute)

(/show0 "condition.lisp 24")

(def!struct (condition-classoid (:include classoid)
                                (:constructor make-condition-classoid))
  ;; list of CONDITION-SLOT structures for the direct slots of this
  ;; class
  (slots nil :type list)
  ;; list of CONDITION-SLOT structures for all of the effective class
  ;; slots of this class
  (class-slots nil :type list)
  ;; report function or NIL
  (report nil :type (or function null))
  ;; list of alternating initargs and initforms
  (default-initargs () :type list)
  ;; class precedence list as a list of CLASS objects, with all
  ;; non-CONDITION classes removed
  (cpl () :type list)
  ;; a list of all the effective instance allocation slots of this
  ;; class that have a non-constant initform or default-initarg.
  ;; Values for these slots must be computed in the dynamic
  ;; environment of MAKE-CONDITION.
  (hairy-slots nil :type list))

(/show0 "condition.lisp 49")

) ; EVAL-WHEN

(!defstruct-with-alternate-metaclass condition
  :slot-names (actual-initargs assigned-slots)
  :boa-constructor %make-condition-object
  :superclass-name t
  :metaclass-name condition-classoid
  :metaclass-constructor make-condition-classoid
  :dd-type structure)

(defun make-condition-object (actual-initargs)
  (%make-condition-object actual-initargs nil))

(defstruct (condition-slot (:copier nil))
  (name (missing-arg) :type symbol)
  ;; list of all applicable initargs
  (initargs (missing-arg) :type list)
  ;; names of reader and writer functions
  (readers (missing-arg) :type list)
  (writers (missing-arg) :type list)
  ;; true if :INITFORM was specified
  (initform-p (missing-arg) :type (member t nil))
  ;; If this is a function, call it with no args. Otherwise, it's the
  ;; actual value.
  (initform (missing-arg) :type t)
  ;; allocation of this slot, or NIL until defaulted
  (allocation nil :type (member :instance :class nil))
  ;; If ALLOCATION is :CLASS, this is a cons whose car holds the value.
  (cell nil :type (or cons null))
  ;; slot documentation
  (documentation nil :type (or string null)))

;;; KLUDGE: It's not clear to me why CONDITION-CLASS has itself listed
;;; in its CPL, while other classes derived from CONDITION-CLASS don't
;;; have themselves listed in their CPLs. This behavior is inherited
;;; from CMU CL, and didn't seem to be explained there, and I haven't
;;; figured out whether it's right. -- WHN 19990612
(eval-when (:compile-toplevel :load-toplevel :execute)
  (/show0 "condition.lisp 103")
  (let ((condition-class (locally
                           ;; KLUDGE: There's a DEFTRANSFORM
                           ;; FIND-CLASSOID for constant class names
                           ;; which creates fast but
                           ;; non-cold-loadable, non-compact code. In
                           ;; this context, we'd rather have compact,
                           ;; cold-loadable code. -- WHN 19990928
                           (declare (notinline find-classoid))
                           (find-classoid 'condition))))
    (setf (condition-classoid-cpl condition-class)
          (list condition-class)))
  (/show0 "condition.lisp 103"))

(setf (condition-classoid-report (locally
                                   ;; KLUDGE: There's a DEFTRANSFORM
                                   ;; FIND-CLASSOID for constant class
                                   ;; names which creates fast but
                                   ;; non-cold-loadable, non-compact
                                   ;; code. In this context, we'd
                                   ;; rather have compact,
                                   ;; cold-loadable code. -- WHN
                                   ;; 19990928
                                   (declare (notinline find-classoid))
                                   (find-classoid 'condition)))
      (lambda (cond stream)
        (format stream "Condition ~S was signalled." (type-of cond))))

(eval-when (:compile-toplevel :load-toplevel :execute)

(defun find-condition-layout (name parent-types)
  (let* ((cpl (remove-duplicates
               (reverse
                (reduce #'append
                        (mapcar (lambda (x)
                                  (condition-classoid-cpl
                                   (find-classoid x)))
                                parent-types)))))
         (cond-layout (info :type :compiler-layout 'condition))
         (olayout (info :type :compiler-layout name))
         ;; FIXME: Does this do the right thing in case of multiple
         ;; inheritance? A quick look at DEFINE-CONDITION didn't make
         ;; it obvious what ANSI intends to be done in the case of
         ;; multiple inheritance, so it's not actually clear what the
         ;; right thing is..
         (new-inherits
          (order-layout-inherits (concatenate 'simple-vector
                                              (layout-inherits cond-layout)
                                              (mapcar #'classoid-layout cpl)))))
    (if (and olayout
             (not (mismatch (layout-inherits olayout) new-inherits)))
        olayout
        (make-layout :classoid (make-undefined-classoid name)
                     :inherits new-inherits
                     :depthoid -1
                     :length (layout-length cond-layout)))))

) ; EVAL-WHEN

;;; FIXME: ANSI's definition of DEFINE-CONDITION says
;;;   Condition reporting is mediated through the PRINT-OBJECT method
;;;   for the condition type in question, with *PRINT-ESCAPE* always
;;;   being nil. Specifying (:REPORT REPORT-NAME) in the definition of
;;;   a condition type C is equivalent to:
;;;     (defmethod print-object ((x c) stream)
;;;       (if *print-escape* (call-next-method) (report-name x stream)))
;;; The current code doesn't seem to quite match that.
(def!method print-object ((x condition) stream)
  (if *print-escape*
      (if (and (typep x 'simple-condition) (slot-value x 'format-control))
          (print-unreadable-object (x stream :type t :identity t)
            (write (simple-condition-format-control x)
                   :stream stream
                   :lines 1))
          (print-unreadable-object (x stream :type t :identity t)))
      ;; KLUDGE: A comment from CMU CL here said
      ;;   7/13/98 BUG? CPL is not sorted and results here depend on order of
      ;;   superclasses in define-condition call!
      (dolist (class (condition-classoid-cpl (classoid-of x))
                     (error "no REPORT? shouldn't happen!"))
        (let ((report (condition-classoid-report class)))
          (when report
            (return (funcall report x stream)))))))

;;;; slots of CONDITION objects

(defvar *empty-condition-slot* '(empty))

(defun find-slot-default (class slot)
  (let ((initargs (condition-slot-initargs slot))
        (cpl (condition-classoid-cpl class)))
    (dolist (class cpl)
      (let ((default-initargs (condition-classoid-default-initargs class)))
        (dolist (initarg initargs)
          (let ((val (getf default-initargs initarg *empty-condition-slot*)))
            (unless (eq val *empty-condition-slot*)
              (return-from find-slot-default
                           (if (functionp val)
                               (funcall val)
                               val)))))))

    (if (condition-slot-initform-p slot)
        (let ((initform (condition-slot-initform slot)))
          (if (functionp initform)
              (funcall initform)
              initform))
        (error "unbound condition slot: ~S" (condition-slot-name slot)))))

(defun find-condition-class-slot (condition-class slot-name)
  (dolist (sclass
           (condition-classoid-cpl condition-class)
           (error "There is no slot named ~S in ~S."
                  slot-name condition-class))
    (dolist (slot (condition-classoid-slots sclass))
      (when (eq (condition-slot-name slot) slot-name)
        (return-from find-condition-class-slot slot)))))

(defun condition-writer-function (condition new-value name)
  (dolist (cslot (condition-classoid-class-slots
                  (layout-classoid (%instance-layout condition)))
                 (setf (getf (condition-assigned-slots condition) name)
                       new-value))
    (when (eq (condition-slot-name cslot) name)
      (return (setf (car (condition-slot-cell cslot)) new-value)))))

(defun condition-reader-function (condition name)
  (let ((class (layout-classoid (%instance-layout condition))))
    (dolist (cslot (condition-classoid-class-slots class))
      (when (eq (condition-slot-name cslot) name)
        (return-from condition-reader-function
                     (car (condition-slot-cell cslot)))))
    (let ((val (getf (condition-assigned-slots condition) name
                     *empty-condition-slot*)))
      (if (eq val *empty-condition-slot*)
          (let ((actual-initargs (condition-actual-initargs condition))
                (slot (find-condition-class-slot class name)))
            (unless slot
              (error "missing slot ~S of ~S" name condition))
            (do ((initargs actual-initargs (cddr initargs)))
                ((endp initargs)
                 (setf (getf (condition-assigned-slots condition) name)
                       (find-slot-default class slot)))
              (when (member (car initargs) (condition-slot-initargs slot))
                (return-from condition-reader-function
                  (setf (getf (condition-assigned-slots condition)
                              name)
                        (cadr initargs))))))
          val))))

;;;; MAKE-CONDITION

(defun make-condition (type &rest args)
  #!+sb-doc
  "Make an instance of a condition object using the specified initargs."
  ;; Note: ANSI specifies no exceptional situations in this function.
  ;; signalling simple-type-error would not be wrong.
  (let* ((type (or (and (symbolp type) (find-classoid type nil))
                    type))
         (class (typecase type
                  (condition-classoid type)
                  (class
                   ;; Punt to CLOS.
                   (return-from make-condition (apply #'make-instance type args)))
                  (classoid
                   (error 'simple-type-error
                          :datum type
                          :expected-type 'condition-class
                          :format-control "~S is not a condition class."
                          :format-arguments (list type)))
                  (t
                   (error 'simple-type-error
                          :datum type
                          :expected-type 'condition-class
                          :format-control "Bad type argument:~%  ~S"
                          :format-arguments (list type)))))
         (res (make-condition-object args)))
    (setf (%instance-layout res) (classoid-layout class))
    ;; Set any class slots with initargs present in this call.
    (dolist (cslot (condition-classoid-class-slots class))
      (dolist (initarg (condition-slot-initargs cslot))
        (let ((val (getf args initarg *empty-condition-slot*)))
          (unless (eq val *empty-condition-slot*)
            (setf (car (condition-slot-cell cslot)) val)))))
    ;; Default any slots with non-constant defaults now.
    (dolist (hslot (condition-classoid-hairy-slots class))
      (when (dolist (initarg (condition-slot-initargs hslot) t)
              (unless (eq (getf args initarg *empty-condition-slot*)
                          *empty-condition-slot*)
                (return nil)))
        (setf (getf (condition-assigned-slots res) (condition-slot-name hslot))
              (find-slot-default class hslot))))
    res))

;;;; DEFINE-CONDITION

(eval-when (:compile-toplevel :load-toplevel :execute)
(defun %compiler-define-condition (name direct-supers layout
                                   all-readers all-writers)
  (with-single-package-locked-error
      (:symbol name "defining ~A as a condition")
    (sb!xc:proclaim `(ftype (function (t) t) ,@all-readers))
    (sb!xc:proclaim `(ftype (function (t t) t) ,@all-writers))
    (multiple-value-bind (class old-layout)
        (insured-find-classoid name
                               #'condition-classoid-p
                               #'make-condition-classoid)
      (setf (layout-classoid layout) class)
      (setf (classoid-direct-superclasses class)
            (mapcar #'find-classoid direct-supers))
      (cond ((not old-layout)
             (register-layout layout))
            ((not *type-system-initialized*)
             (setf (layout-classoid old-layout) class)
             (setq layout old-layout)
             (unless (eq (classoid-layout class) layout)
               (register-layout layout)))
            ((redefine-layout-warning "current"
                                      old-layout
                                      "new"
                                      (layout-length layout)
                                      (layout-inherits layout)
                                      (layout-depthoid layout)
                                      (layout-n-untagged-slots layout))
             (register-layout layout :invalidate t))
            ((not (classoid-layout class))
             (register-layout layout)))

      (setf (layout-info layout)
            (locally
                ;; KLUDGE: There's a FIND-CLASS DEFTRANSFORM for constant class
                ;; names which creates fast but non-cold-loadable, non-compact
                ;; code. In this context, we'd rather have compact, cold-loadable
                ;; code. -- WHN 19990928
                (declare (notinline find-classoid))
              (layout-info (classoid-layout (find-classoid 'condition)))))

      (setf (find-classoid name) class)

      ;; Initialize CPL slot.
      (setf (condition-classoid-cpl class)
            (remove-if-not #'condition-classoid-p
                           (std-compute-class-precedence-list class)))))
  (values))
) ; EVAL-WHEN

;;; Compute the effective slots of CLASS, copying inherited slots and
;;; destructively modifying direct slots.
;;;
;;; FIXME: It'd be nice to explain why it's OK to destructively modify
;;; direct slots. Presumably it follows from the semantics of
;;; inheritance and redefinition of conditions, but finding the cite
;;; and documenting it here would be good. (Or, if this is not in fact
;;; ANSI-compliant, fixing it would also be good.:-)
(defun compute-effective-slots (class)
  (collect ((res (copy-list (condition-classoid-slots class))))
    (dolist (sclass (cdr (condition-classoid-cpl class)))
      (dolist (sslot (condition-classoid-slots sclass))
        (let ((found (find (condition-slot-name sslot) (res)
                           :key #'condition-slot-name)))
          (cond (found
                 (setf (condition-slot-initargs found)
                       (union (condition-slot-initargs found)
                              (condition-slot-initargs sslot)))
                 (unless (condition-slot-initform-p found)
                   (setf (condition-slot-initform-p found)
                         (condition-slot-initform-p sslot))
                   (setf (condition-slot-initform found)
                         (condition-slot-initform sslot)))
                 (unless (condition-slot-allocation found)
                   (setf (condition-slot-allocation found)
                         (condition-slot-allocation sslot))))
                (t
                 (res (copy-structure sslot)))))))
    (res)))

;;; Early definitions of slot accessor creators.
;;;
;;; Slot accessors must be generic functions, but ANSI does not seem
;;; to specify any of them, and we cannot support it before end of
;;; warm init. So we use ordinary functions inside SBCL, and switch to
;;; GFs only at the end of building.
(declaim (notinline install-condition-slot-reader
                    install-condition-slot-writer))
(defun install-condition-slot-reader (name condition slot-name)
  (declare (ignore condition))
  (setf (fdefinition name)
        (lambda (condition)
          (condition-reader-function condition slot-name))))
(defun install-condition-slot-writer (name condition slot-name)
  (declare (ignore condition))
  (setf (fdefinition name)
        (lambda (new-value condition)
          (condition-writer-function condition new-value slot-name))))

(defvar *define-condition-hooks* nil)

(defun %define-condition (name parent-types layout slots documentation
                          report default-initargs all-readers all-writers
                          source-location)
  (with-single-package-locked-error
      (:symbol name "defining ~A as a condition")
    (%compiler-define-condition name parent-types layout all-readers all-writers)
    (sb!c:with-source-location (source-location)
      (setf (layout-source-location layout)
            source-location))
    (let ((class (find-classoid name)))
      (setf (condition-classoid-slots class) slots)
      (setf (condition-classoid-report class) report)
      (setf (condition-classoid-default-initargs class) default-initargs)
      (setf (fdocumentation name 'type) documentation)

      (dolist (slot slots)

        ;; Set up reader and writer functions.
        (let ((slot-name (condition-slot-name slot)))
          (dolist (reader (condition-slot-readers slot))
            (install-condition-slot-reader reader name slot-name))
          (dolist (writer (condition-slot-writers slot))
            (install-condition-slot-writer writer name slot-name))))

      ;; Compute effective slots and set up the class and hairy slots
      ;; (subsets of the effective slots.)
      (let ((eslots (compute-effective-slots class))
            (e-def-initargs
             (reduce #'append
                     (mapcar #'condition-classoid-default-initargs
                           (condition-classoid-cpl class)))))
        (dolist (slot eslots)
          (ecase (condition-slot-allocation slot)
            (:class
             (unless (condition-slot-cell slot)
               (setf (condition-slot-cell slot)
                     (list (if (condition-slot-initform-p slot)
                               (let ((initform (condition-slot-initform slot)))
                                 (if (functionp initform)
                                     (funcall initform)
                                     initform))
                               *empty-condition-slot*))))
             (push slot (condition-classoid-class-slots class)))
            ((:instance nil)
             (setf (condition-slot-allocation slot) :instance)
             (when (or (functionp (condition-slot-initform slot))
                       (dolist (initarg (condition-slot-initargs slot) nil)
                         (when (functionp (getf e-def-initargs initarg))
                           (return t))))
               (push slot (condition-classoid-hairy-slots class)))))))
      (when (boundp '*define-condition-hooks*)
        (dolist (fun *define-condition-hooks*)
          (funcall fun class))))
    name))

(defmacro define-condition (name (&rest parent-types) (&rest slot-specs)
                                 &body options)
  #!+sb-doc
  "DEFINE-CONDITION Name (Parent-Type*) (Slot-Spec*) Option*
   Define NAME as a condition type. This new type inherits slots and its
   report function from the specified PARENT-TYPEs. A slot spec is a list of:
     (slot-name :reader <rname> :initarg <iname> {Option Value}*

   The DEFINE-CLASS slot options :ALLOCATION, :INITFORM, [slot] :DOCUMENTATION
   and :TYPE and the overall options :DEFAULT-INITARGS and
   [type] :DOCUMENTATION are also allowed.

   The :REPORT option is peculiar to DEFINE-CONDITION. Its argument is either
   a string or a two-argument lambda or function name. If a function, the
   function is called with the condition and stream to report the condition.
   If a string, the string is printed.

   Condition types are classes, but (as allowed by ANSI and not as described in
   CLtL2) are neither STANDARD-OBJECTs nor STRUCTURE-OBJECTs. WITH-SLOTS and
   SLOT-VALUE may not be used on condition objects."
  (let* ((parent-types (or parent-types '(condition)))
         (layout (find-condition-layout name parent-types))
         (documentation nil)
         (report nil)
         (default-initargs ()))
    (collect ((slots)
              (all-readers nil append)
              (all-writers nil append))
      (dolist (spec slot-specs)
        (when (keywordp spec)
          (warn "Keyword slot name indicates probable syntax error:~%  ~S"
                spec))
        (let* ((spec (if (consp spec) spec (list spec)))
               (slot-name (first spec))
               (allocation :instance)
               (initform-p nil)
               documentation
               initform)
          (collect ((initargs)
                    (readers)
                    (writers))
            (do ((options (rest spec) (cddr options)))
                ((null options))
              (unless (and (consp options) (consp (cdr options)))
                (error "malformed condition slot spec:~%  ~S." spec))
              (let ((arg (second options)))
                (case (first options)
                  (:reader (readers arg))
                  (:writer (writers arg))
                  (:accessor
                   (readers arg)
                   (writers `(setf ,arg)))
                  (:initform
                   (when initform-p
                     (error "more than one :INITFORM in ~S" spec))
                   (setq initform-p t)
                   (setq initform arg))
                  (:initarg (initargs arg))
                  (:allocation
                   (setq allocation arg))
                  (:documentation
                   (when documentation
                     (error "more than one :DOCUMENTATION in ~S" spec))
                   (unless (stringp arg)
                     (error "slot :DOCUMENTATION argument is not a string: ~S"
                            arg))
                   (setq documentation arg))
                  (:type)
                  (t
                   (error "unknown slot option:~%  ~S" (first options))))))

            (all-readers (readers))
            (all-writers (writers))
            (slots `(make-condition-slot
                     :name ',slot-name
                     :initargs ',(initargs)
                     :readers ',(readers)
                     :writers ',(writers)
                     :initform-p ',initform-p
                     :documentation ',documentation
                     :initform
                     ,(if (sb!xc:constantp initform)
                          `',(constant-form-value initform)
                          `#'(lambda () ,initform)))))))

      (dolist (option options)
        (unless (consp option)
          (error "bad option:~%  ~S" option))
        (case (first option)
          (:documentation (setq documentation (second option)))
          (:report
           (let ((arg (second option)))
             (setq report
                   (if (stringp arg)
                       `#'(lambda (condition stream)
                          (declare (ignore condition))
                          (write-string ,arg stream))
                       `#'(lambda (condition stream)
                          (funcall #',arg condition stream))))))
          (:default-initargs
           (do ((initargs (rest option) (cddr initargs)))
               ((endp initargs))
             (let ((val (second initargs)))
               (setq default-initargs
                     (list* `',(first initargs)
                            (if (sb!xc:constantp val)
                                `',(constant-form-value val)
                                `#'(lambda () ,val))
                            default-initargs)))))
          (t
           (error "unknown option: ~S" (first option)))))

      `(progn
         (eval-when (:compile-toplevel)
           (%compiler-define-condition ',name ',parent-types ',layout
                                       ',(all-readers) ',(all-writers)))
         (eval-when (:load-toplevel :execute)
           (%define-condition ',name
                              ',parent-types
                              ',layout
                              (list ,@(slots))
                              ,documentation
                              ,report
                              (list ,@default-initargs)
                              ',(all-readers)
                              ',(all-writers)
                              (sb!c:source-location)))))))

;;;; various CONDITIONs specified by ANSI

(define-condition serious-condition (condition) ())

(define-condition error (serious-condition) ())

(define-condition warning (condition) ())
(define-condition style-warning (warning) ())

(defun simple-condition-printer (condition stream)
  (let ((control (simple-condition-format-control condition)))
    (if control
        (apply #'format stream
               control
               (simple-condition-format-arguments condition))
        (error "No format-control for ~S" condition))))

(define-condition simple-condition ()
  ((format-control :reader simple-condition-format-control
                   :initarg :format-control
                   :initform nil
                   :type format-control)
   (format-arguments :reader simple-condition-format-arguments
                     :initarg :format-arguments
                     :initform nil
                     :type list))
  (:report simple-condition-printer))

(define-condition simple-warning (simple-condition warning) ())

(define-condition simple-error (simple-condition error) ())

(define-condition storage-condition (serious-condition) ())

(define-condition type-error (error)
  ((datum :reader type-error-datum :initarg :datum)
   (expected-type :reader type-error-expected-type :initarg :expected-type))
  (:report
   (lambda (condition stream)
     (format stream
             "~@<The value ~2I~:_~S ~I~_is not of type ~2I~_~S.~:>"
             (type-error-datum condition)
             (type-error-expected-type condition)))))

(def!method print-object ((condition type-error) stream)
  (if *print-escape*
      (flet ((maybe-string (thing)
               (ignore-errors
                 (write-to-string thing :lines 1 :readably nil :array nil :pretty t))))
        (let ((type (maybe-string (type-error-expected-type condition)))
              (datum (maybe-string (type-error-datum condition))))
          (if (and type datum)
              (print-unreadable-object (condition stream :type t)
                (format stream "~@<expected-type: ~A ~_datum: ~A~:@>" type datum))
              (call-next-method))))
      (call-next-method)))

;;; not specified by ANSI, but too useful not to have around.
(define-condition simple-style-warning (simple-condition style-warning) ())
(define-condition simple-type-error (simple-condition type-error) ())

;; Can't have a function called SIMPLE-TYPE-ERROR or TYPE-ERROR...
(declaim (ftype (sfunction (t t t &rest t) nil) bad-type))
(defun bad-type (datum type control &rest arguments)
  (error 'simple-type-error
         :datum datum
         :expected-type type
         :format-control control
         :format-arguments arguments))

(define-condition program-error (error) ())
(define-condition parse-error   (error) ())
(define-condition control-error (error) ())
(define-condition stream-error  (error)
  ((stream :reader stream-error-stream :initarg :stream)))

(define-condition end-of-file (stream-error) ()
  (:report
   (lambda (condition stream)
     (format stream
             "end of file on ~S"
             (stream-error-stream condition)))))

(define-condition closed-stream-error (stream-error) ()
  (:report
   (lambda (condition stream)
     (format stream "~S is closed" (stream-error-stream condition)))))

(define-condition file-error (error)
  ((pathname :reader file-error-pathname :initarg :pathname))
  (:report
   (lambda (condition stream)
     (format stream "error on file ~S" (file-error-pathname condition)))))

(define-condition package-error (error)
  ((package :reader package-error-package :initarg :package)))

(define-condition cell-error (error)
  ((name :reader cell-error-name :initarg :name)))

(def!method print-object ((condition cell-error) stream)
  (if (and *print-escape* (slot-boundp condition 'name))
      (print-unreadable-object (condition stream :type t :identity t)
        (princ (cell-error-name condition) stream))
      (call-next-method)))

(define-condition unbound-variable (cell-error) ()
  (:report
   (lambda (condition stream)
     (format stream
             "The variable ~S is unbound."
             (cell-error-name condition)))))

(define-condition undefined-function (cell-error) ()
  (:report
   (lambda (condition stream)
     (format stream
             "The function ~/sb-impl::print-symbol-with-prefix/ is undefined."
             (cell-error-name condition)))))

(define-condition special-form-function (undefined-function) ()
  (:report
   (lambda (condition stream)
     (format stream
             "Cannot FUNCALL the SYMBOL-FUNCTION of special operator ~S."
             (cell-error-name condition)))))

(define-condition arithmetic-error (error)
  ((operation :reader arithmetic-error-operation
              :initarg :operation
              :initform nil)
   (operands :reader arithmetic-error-operands
             :initarg :operands))
  (:report (lambda (condition stream)
             (format stream
                     "arithmetic error ~S signalled"
                     (type-of condition))
             (when (arithmetic-error-operation condition)
               (format stream
                       "~%Operation was ~S, operands ~S."
                       (arithmetic-error-operation condition)
                       (arithmetic-error-operands condition))))))

(define-condition division-by-zero         (arithmetic-error) ())
(define-condition floating-point-overflow  (arithmetic-error) ())
(define-condition floating-point-underflow (arithmetic-error) ())
(define-condition floating-point-inexact   (arithmetic-error) ())
(define-condition floating-point-invalid-operation (arithmetic-error) ())

(define-condition print-not-readable (error)
  ((object :reader print-not-readable-object :initarg :object))
  (:report
   (lambda (condition stream)
     (let ((obj (print-not-readable-object condition))
           (*print-array* nil))
       (format stream "~S cannot be printed readably." obj)))))

(define-condition reader-error (parse-error stream-error) ()
  (:report (lambda (condition stream)
             (%report-reader-error condition stream))))

;;; a READER-ERROR whose REPORTing is controlled by FORMAT-CONTROL and
;;; FORMAT-ARGS (the usual case for READER-ERRORs signalled from
;;; within SBCL itself)
;;;
;;; (Inheriting CL:SIMPLE-CONDITION here isn't quite consistent with
;;; the letter of the ANSI spec: this is not a condition signalled by
;;; SIGNAL when a format-control is supplied by the function's first
;;; argument. It seems to me (WHN) to be basically in the spirit of
;;; the spec, but if not, it'd be straightforward to do our own
;;; DEFINE-CONDITION SB-INT:SIMPLISTIC-CONDITION with
;;; FORMAT-CONTROL and FORMAT-ARGS slots, and use that condition in
;;; place of CL:SIMPLE-CONDITION here.)
(define-condition simple-reader-error (reader-error simple-condition)
  ()
  (:report (lambda (condition stream)
             (%report-reader-error condition stream :simple t))))

;;; base REPORTing of a READER-ERROR
;;;
;;; When SIMPLE, we expect and use SIMPLE-CONDITION-ish FORMAT-CONTROL
;;; and FORMAT-ARGS slots.
(defun %report-reader-error (condition stream &key simple)
  (let* ((error-stream (stream-error-stream condition))
         (pos (file-position-or-nil-for-error error-stream)))
    (when (and pos (plusp pos))
      ;; FILE-POSITION is the next character -- error is at the previous one.
      (decf pos))
    (let (lineno colno)
      (when (and pos
                 (< pos sb!xc:array-dimension-limit)
                 ;; KLUDGE: lseek() (which is what FILE-POSITION
                 ;; reduces to on file-streams) is undefined on
                 ;; "some devices", which in practice means that it
                 ;; can claim to succeed on /dev/stdin on Darwin
                 ;; and Solaris.  This is obviously bad news,
                 ;; because the READ-SEQUENCE below will then
                 ;; block, not complete, and the report will never
                 ;; be printed.  As a workaround, we exclude
                 ;; interactive streams from this attempt to report
                 ;; positions.  -- CSR, 2003-08-21
                 (not (interactive-stream-p error-stream))
                 (file-position error-stream :start))
        (let ((string
               (make-string pos
                            :element-type (stream-element-type
                                           error-stream))))
          (when (= pos (read-sequence string error-stream))
            ;; Lines count from 1, columns from 0. It's stupid and traditional.
            (setq lineno (1+ (count #\Newline string))
                  colno (- pos (or (position #\Newline string :from-end t) 0)))))
        (file-position-or-nil-for-error error-stream pos))
      (pprint-logical-block (stream nil)
        (if simple
            (apply #'format stream
                   (simple-condition-format-control condition)
                   (simple-condition-format-arguments condition))
            (prin1 (class-name (class-of condition)) stream))
        (format stream "~2I~@[~_~_~:{~:(~A~): ~S~:^, ~:_~}~]~_~_Stream: ~S"
                (remove-if-not #'second
                               (list (list :line lineno)
                                     (list :column colno)
                                     (list :file-position pos)))
                error-stream)))))

;;;; special SBCL extension conditions

;;; an error apparently caused by a bug in SBCL itself
;;;
;;; Note that we don't make any serious effort to use this condition
;;; for *all* errors in SBCL itself. E.g. type errors and array
;;; indexing errors can occur in functions called from SBCL code, and
;;; will just end up as ordinary TYPE-ERROR or invalid index error,
;;; because the signalling code has no good way to know that the
;;; underlying problem is a bug in SBCL. But in the fairly common case
;;; that the signalling code does know that it's found a bug in SBCL,
;;; this condition is appropriate, reusing boilerplate and helping
;;; users to recognize it as an SBCL bug.
(define-condition bug (simple-error)
  ()
  (:report
   (lambda (condition stream)
     (format stream
             "~@<  ~? ~:@_~?~:>"
             (simple-condition-format-control condition)
             (simple-condition-format-arguments condition)
             "~@<This is probably a bug in SBCL itself. (Alternatively, ~
              SBCL might have been corrupted by bad user code, e.g. by an ~
              undefined Lisp operation like ~S, or by stray pointers from ~
              alien code or from unsafe Lisp code; or there might be a bug ~
              in the OS or hardware that SBCL is running on.) If it seems to ~
              be a bug in SBCL itself, the maintainers would like to know ~
              about it. Bug reports are welcome on the SBCL ~
              mailing lists, which you can find at ~
              <http://sbcl.sourceforge.net/>.~:@>"
             '((fmakunbound 'compile))))))

(define-condition simple-storage-condition (storage-condition simple-condition)
  ())

;;; a condition for use in stubs for operations which aren't supported
;;; on some platforms
;;;
;;; E.g. in sbcl-0.7.0.5, it might be appropriate to do something like
;;;   #-(or freebsd linux)
;;;   (defun load-foreign (&rest rest)
;;;     (error 'unsupported-operator :name 'load-foreign))
;;;   #+(or freebsd linux)
;;;   (defun load-foreign ... actual definition ...)
;;; By signalling a standard condition in this case, we make it
;;; possible for test code to distinguish between (1) intentionally
;;; unimplemented and (2) unintentionally just screwed up somehow.
;;; (Before this condition was defined, test code tried to deal with
;;; this by checking for FBOUNDP, but that didn't work reliably. In
;;; sbcl-0.7.0, a package screwup left the definition of
;;; LOAD-FOREIGN in the wrong package, so it was unFBOUNDP even on
;;; architectures where it was supposed to be supported, and the
;;; regression tests cheerfully passed because they assumed that
;;; unFBOUNDPness meant they were running on an system which didn't
;;; support the extension.)
(define-condition unsupported-operator (simple-error) ())

;;; (:ansi-cl :function remove)
;;; (:ansi-cl :section (a b c))
;;; (:ansi-cl :glossary "similar")
;;;
;;; (:sbcl :node "...")
;;; (:sbcl :variable *ed-functions*)
;;;
;;; FIXME: this is not the right place for this.
(defun print-reference (reference stream)
  (ecase (car reference)
    (:amop
     (format stream "AMOP")
     (format stream ", ")
     (destructuring-bind (type data) (cdr reference)
       (ecase type
         (:readers "Readers for ~:(~A~) Metaobjects"
                   (substitute #\  #\- (symbol-name data)))
         (:initialization
          (format stream "Initialization of ~:(~A~) Metaobjects"
                  (substitute #\  #\- (symbol-name data))))
         (:generic-function (format stream "Generic Function ~S" data))
         (:function (format stream "Function ~S" data))
         (:section (format stream "Section ~{~D~^.~}" data)))))
    (:ansi-cl
     (format stream "The ANSI Standard")
     (format stream ", ")
     (destructuring-bind (type data) (cdr reference)
       (ecase type
         (:function (format stream "Function ~S" data))
         (:special-operator (format stream "Special Operator ~S" data))
         (:macro (format stream "Macro ~S" data))
         (:section (format stream "Section ~{~D~^.~}" data))
         (:glossary (format stream "Glossary entry for ~S" data))
         (:issue (format stream "writeup for Issue ~A" data)))))
    (:sbcl
     (format stream "The SBCL Manual")
     (format stream ", ")
     (destructuring-bind (type data) (cdr reference)
       (ecase type
         (:node (format stream "Node ~S" data))
         (:variable (format stream "Variable ~S" data))
         (:function (format stream "Function ~S" data)))))
    ;; FIXME: other documents (e.g. CLIM, Franz documentation :-)
    ))
(define-condition reference-condition ()
  ((references :initarg :references :reader reference-condition-references)))
(defvar *print-condition-references* t)
(def!method print-object :around ((o reference-condition) s)
  (call-next-method)
  (unless (or *print-escape* *print-readably*)
    (when (and *print-condition-references*
               (reference-condition-references o))
      (format s "~&See also:~%")
      (pprint-logical-block (s nil :per-line-prefix "  ")
        (do* ((rs (reference-condition-references o) (cdr rs))
              (r (car rs) (car rs)))
             ((null rs))
          (print-reference r s)
          (unless (null (cdr rs))
            (terpri s)))))))

(define-condition simple-reference-error (reference-condition simple-error)
  ())

(define-condition simple-reference-warning (reference-condition simple-warning)
  ())

(define-condition arguments-out-of-domain-error
    (arithmetic-error reference-condition)
  ())

(define-condition duplicate-definition (reference-condition warning)
  ((name :initarg :name :reader duplicate-definition-name))
  (:report (lambda (c s)
             (format s "~@<Duplicate definition for ~S found in ~
                        one file.~@:>"
                     (duplicate-definition-name c))))
  (:default-initargs :references (list '(:ansi-cl :section (3 2 2 3)))))

(define-condition constant-modified (reference-condition warning)
  ((fun-name :initarg :fun-name :reader constant-modified-fun-name))
  (:report (lambda (c s)
             (format s "~@<Destructive function ~S called on ~
                        constant data.~@:>"
                     (constant-modified-fun-name c))))
  (:default-initargs :references (list '(:ansi-cl :special-operator quote)
                                       '(:ansi-cl :section (3 2 2 3)))))

(define-condition package-at-variance (reference-condition simple-warning)
  ()
  (:default-initargs :references (list '(:ansi-cl :macro defpackage))))

(define-condition defconstant-uneql (reference-condition error)
  ((name :initarg :name :reader defconstant-uneql-name)
   (old-value :initarg :old-value :reader defconstant-uneql-old-value)
   (new-value :initarg :new-value :reader defconstant-uneql-new-value))
  (:report
   (lambda (condition stream)
     (format stream
             "~@<The constant ~S is being redefined (from ~S to ~S)~@:>"
             (defconstant-uneql-name condition)
             (defconstant-uneql-old-value condition)
             (defconstant-uneql-new-value condition))))
  (:default-initargs :references (list '(:ansi-cl :macro defconstant)
                                       '(:sbcl :node "Idiosyncrasies"))))

(define-condition array-initial-element-mismatch
    (reference-condition simple-warning)
  ()
  (:default-initargs
      :references (list
                   '(:ansi-cl :function make-array)
                   '(:ansi-cl :function sb!xc:upgraded-array-element-type))))

(define-condition type-warning (reference-condition simple-warning)
  ()
  (:default-initargs :references (list '(:sbcl :node "Handling of Types"))))
(define-condition type-style-warning (reference-condition simple-style-warning)
  ()
  (:default-initargs :references (list '(:sbcl :node "Handling of Types"))))

(define-condition local-argument-mismatch (reference-condition simple-warning)
  ()
  (:default-initargs :references (list '(:ansi-cl :section (3 2 2 3)))))

(define-condition format-args-mismatch (reference-condition)
  ()
  (:default-initargs :references (list '(:ansi-cl :section (22 3 10 2)))))

(define-condition format-too-few-args-warning
    (format-args-mismatch simple-warning)
  ())
(define-condition format-too-many-args-warning
    (format-args-mismatch simple-style-warning)
  ())

(define-condition implicit-generic-function-warning (style-warning)
  ((name :initarg :name :reader implicit-generic-function-name))
  (:report
   (lambda (condition stream)
     (format stream "~@<Implicitly creating new generic function ~S.~:@>"
             (implicit-generic-function-name condition)))))

(define-condition extension-failure (reference-condition simple-error)
  ())

(define-condition structure-initarg-not-keyword
    (reference-condition simple-style-warning)
  ()
  (:default-initargs :references (list '(:ansi-cl :section (2 4 8 13)))))

#!+sb-package-locks
(progn

(define-condition package-lock-violation (package-error
                                          reference-condition
                                          simple-condition)
  ((current-package :initform *package*
                    :reader package-lock-violation-in-package))
  (:report
   (lambda (condition stream)
     (let ((control (simple-condition-format-control condition))
           (error-package (package-name (package-error-package condition)))
           (current-package (package-name (package-lock-violation-in-package condition))))
       (if control
           (apply #'format stream
                  (format nil "~~@<Lock on package ~A violated when ~A while in package ~A.~~:@>"
                          error-package
                          control
                          current-package)
                  (simple-condition-format-arguments condition))
           (format stream "~@<Lock on package ~A violated while in package ~A.~:@>"
                   error-package
                   current-package)))))
  ;; no :default-initargs -- reference-stuff provided by the
  ;; signalling form in target-package.lisp
  #!+sb-doc
  (:documentation
   "Subtype of CL:PACKAGE-ERROR. A subtype of this error is signalled
when a package-lock is violated."))

(define-condition package-locked-error (package-lock-violation) ()
  #!+sb-doc
  (:documentation
   "Subtype of SB-EXT:PACKAGE-LOCK-VIOLATION. An error of this type is
signalled when an operation on a package violates a package lock."))

(define-condition symbol-package-locked-error (package-lock-violation)
  ((symbol :initarg :symbol :reader package-locked-error-symbol))
  #!+sb-doc
  (:documentation
   "Subtype of SB-EXT:PACKAGE-LOCK-VIOLATION. An error of this type is
signalled when an operation on a symbol violates a package lock. The
symbol that caused the violation is accessed by the function
SB-EXT:PACKAGE-LOCKED-ERROR-SYMBOL."))

) ; progn

(define-condition undefined-alien-error (cell-error) ()
  (:report
   (lambda (condition stream)
     (if (slot-boundp condition 'name)
         (format stream "Undefined alien: ~S" (cell-error-name condition))
         (format stream "Undefined alien symbol.")))))

(define-condition undefined-alien-variable-error (undefined-alien-error) ()
  (:report
   (lambda (condition stream)
     (declare (ignore condition))
     (format stream "Attempt to access an undefined alien variable."))))

(define-condition undefined-alien-function-error (undefined-alien-error) ()
  (:report
   (lambda (condition stream)
     (declare (ignore condition))
     (format stream "Attempt to call an undefined alien function."))))


;;;; various other (not specified by ANSI) CONDITIONs
;;;;
;;;; These might logically belong in other files; they're here, after
;;;; setup of CONDITION machinery, only because that makes it easier to
;;;; get cold init to work.

;;; OAOOM warning: see cross-condition.lisp
(define-condition encapsulated-condition (condition)
  ((condition :initarg :condition :reader encapsulated-condition)))

;;; KLUDGE: a condition for floating point errors when we can't or
;;; won't figure out what type they are. (In FreeBSD and OpenBSD we
;;; don't know how, at least as of sbcl-0.6.7; in Linux we probably
;;; know how but the old code was broken by the conversion to POSIX
;;; signal handling and hasn't been fixed as of sbcl-0.6.7.)
;;;
;;; FIXME: Perhaps this should also be a base class for all
;;; floating point exceptions?
(define-condition floating-point-exception (arithmetic-error)
  ((flags :initarg :traps
          :initform nil
          :reader floating-point-exception-traps))
  (:report (lambda (condition stream)
             (format stream
                     "An arithmetic error ~S was signalled.~%"
                     (type-of condition))
             (let ((traps (floating-point-exception-traps condition)))
               (if traps
                   (format stream
                           "Trapping conditions are: ~%~{ ~S~^~}~%"
                           traps)
                   (write-line
                    "No traps are enabled? How can this be?"
                    stream))))))

(define-condition unhandled-exception (error)
  ((name :initarg :name :reader unhandled-exception-name)
   (code :initarg :code :reader unhandled-exception-code)
   (pc   :initarg :pc   :reader unhandled-exception-pc))
  (:report (lambda (exception stream)
             (format stream
                     "Unhandled exception ~X ~@[(~A)~] at ~X"
                     (unhandled-exception-code exception)
                     (unhandled-exception-name exception)
                     (unhandled-exception-pc exception)))))

(define-condition invalid-array-index-error (type-error)
  ((array :initarg :array :reader invalid-array-index-error-array)
   (axis :initarg :axis :reader invalid-array-index-error-axis))
  (:report
   (lambda (condition stream)
     (let ((array (invalid-array-index-error-array condition)))
       (format stream "Index ~W out of bounds for ~@[axis ~W of ~]~S, ~
                       should be nonnegative and <~W."
               (type-error-datum condition)
               (when (> (array-rank array) 1)
                 (invalid-array-index-error-axis condition))
               (type-of array)
               ;; Extract the bound from (INTEGER 0 (BOUND))
               (caaddr (type-error-expected-type condition)))))))

(define-condition invalid-array-error (reference-condition type-error) ()
  (:report
   (lambda (condition stream)
     (let ((*print-array* nil))
       (format stream
               "~@<Displaced array originally of type ~S has been invalidated ~
                due its displaced-to array ~S having become too small to hold ~
                it: the displaced array's dimensions have all been set to zero ~
                to trap accesses to it.~:@>"
               (type-error-expected-type condition)
               (array-displacement (type-error-datum condition))))))
  (:default-initargs
      :references
      (list '(:ansi-cl :function adjust-array))))

(define-condition index-too-large-error (type-error)
  ()
  (:report
   (lambda (condition stream)
     (format stream
             "The index ~S is too large."
             (type-error-datum condition)))))

(define-condition bounding-indices-bad-error (reference-condition type-error)
  ((object :reader bounding-indices-bad-object :initarg :object))
  (:report
   (lambda (condition stream)
     (let* ((datum (type-error-datum condition))
            (start (car datum))
            (end (cdr datum))
            (object (bounding-indices-bad-object condition)))
       (etypecase object
         (sequence
          (format stream
                  "The bounding indices ~S and ~S are bad ~
                   for a sequence of length ~S."
                  start end (length object)))
         (array
          ;; from WITH-ARRAY-DATA
          (format stream
                  "The START and END parameters ~S and ~S are ~
                   bad for an array of total size ~S."
                  start end (array-total-size object)))))))
  (:default-initargs
      :references
      (list '(:ansi-cl :glossary "bounding index designator")
            '(:ansi-cl :issue "SUBSEQ-OUT-OF-BOUNDS:IS-AN-ERROR"))))

(define-condition nil-array-accessed-error (reference-condition type-error)
  ()
  (:report (lambda (condition stream)
             (declare (ignore condition))
             (format stream
                     "An attempt to access an array of element-type ~
                      NIL was made.  Congratulations!")))
  (:default-initargs
      :references (list '(:ansi-cl :function sb!xc:upgraded-array-element-type)
                        '(:ansi-cl :section (15 1 2 1))
                        '(:ansi-cl :section (15 1 2 2)))))

(define-condition namestring-parse-error (parse-error)
  ((complaint :reader namestring-parse-error-complaint :initarg :complaint)
   (args :reader namestring-parse-error-args :initarg :args :initform nil)
   (namestring :reader namestring-parse-error-namestring :initarg :namestring)
   (offset :reader namestring-parse-error-offset :initarg :offset))
  (:report
   (lambda (condition stream)
     (format stream
             "parse error in namestring: ~?~%  ~A~%  ~V@T^"
             (namestring-parse-error-complaint condition)
             (namestring-parse-error-args condition)
             (namestring-parse-error-namestring condition)
             (namestring-parse-error-offset condition)))))

(define-condition simple-package-error (simple-condition package-error) ())

(define-condition simple-reader-package-error (simple-reader-error) ())

(define-condition reader-eof-error (end-of-file)
  ((context :reader reader-eof-error-context :initarg :context))
  (:report
   (lambda (condition stream)
     (format stream
             "unexpected end of file on ~S ~A"
             (stream-error-stream condition)
             (reader-eof-error-context condition)))))

(define-condition reader-impossible-number-error (simple-reader-error)
  ((error :reader reader-impossible-number-error-error :initarg :error))
  (:report
   (lambda (condition stream)
     (let ((error-stream (stream-error-stream condition)))
       (format stream
               "READER-ERROR ~@[at ~W ~]on ~S:~%~?~%Original error: ~A"
               (file-position-or-nil-for-error error-stream) error-stream
               (simple-condition-format-control condition)
               (simple-condition-format-arguments condition)
               (reader-impossible-number-error-error condition))))))

(define-condition standard-readtable-modified-error (reference-condition error)
  ((operation :initarg :operation :reader standard-readtable-modified-operation))
  (:report (lambda (condition stream)
             (format stream "~S would modify the standard readtable."
                     (standard-readtable-modified-operation condition))))
  (:default-initargs :references `((:ansi-cl :section (2 1 1 2))
                                   (:ansi-cl :glossary "standard readtable"))))

(define-condition standard-pprint-dispatch-table-modified-error
    (reference-condition error)
  ((operation :initarg :operation
              :reader standard-pprint-dispatch-table-modified-operation))
  (:report (lambda (condition stream)
             (format stream "~S would modify the standard pprint dispatch table."
                     (standard-pprint-dispatch-table-modified-operation
                      condition))))
  (:default-initargs
      :references `((:ansi-cl :glossary "standard pprint dispatch table"))))

(define-condition timeout (serious-condition)
  ((seconds :initarg :seconds :initform nil :reader timeout-seconds))
  (:report (lambda (condition stream)
             (format stream "Timeout occurred~@[ after ~A seconds~]."
                     (timeout-seconds condition)))))

(define-condition io-timeout (stream-error timeout)
  ((direction :reader io-timeout-direction :initarg :direction))
  (:report
   (lambda (condition stream)
     (declare (type stream stream))
     (format stream
             "I/O timeout while doing ~(~A~) on ~S."
             (io-timeout-direction condition)
             (stream-error-stream condition)))))

(define-condition deadline-timeout (timeout) ()
  (:report (lambda (condition stream)
             (format stream "A deadline was reached after ~A seconds."
                     (timeout-seconds condition)))))

(define-condition declaration-type-conflict-error (reference-condition
                                                   simple-error)
  ()
  (:default-initargs
      :format-control "symbol ~S cannot be both the name of a type and the name of a declaration"
    :references (list '(:ansi-cl :section (3 8 21)))))

;;; Single stepping conditions

(define-condition step-condition ()
  ((form :initarg :form :reader step-condition-form))

  #!+sb-doc
  (:documentation "Common base class of single-stepping conditions.
STEP-CONDITION-FORM holds a string representation of the form being
stepped."))

#!+sb-doc
(setf (fdocumentation 'step-condition-form 'function)
      "Form associated with the STEP-CONDITION.")

(define-condition step-form-condition (step-condition)
  ((args :initarg :args :reader step-condition-args))
  (:report
   (lambda (condition stream)
     (let ((*print-circle* t)
           (*print-pretty* t)
           (*print-readably* nil))
       (format stream
                 "Evaluating call:~%~<  ~@;~A~:>~%~
                  ~:[With arguments:~%~{  ~S~%~}~;With unknown arguments~]~%"
               (list (step-condition-form condition))
               (eq (step-condition-args condition) :unknown)
               (step-condition-args condition)))))
  #!+sb-doc
  (:documentation "Condition signalled by code compiled with
single-stepping information when about to execute a form.
STEP-CONDITION-FORM holds the form, STEP-CONDITION-PATHNAME holds the
pathname of the original file or NIL, and STEP-CONDITION-SOURCE-PATH
holds the source-path to the original form within that file or NIL.
Associated with this condition are always the restarts STEP-INTO,
STEP-NEXT, and STEP-CONTINUE."))

(define-condition step-result-condition (step-condition)
  ((result :initarg :result :reader step-condition-result)))

#!+sb-doc
(setf (fdocumentation 'step-condition-result 'function)
      "Return values associated with STEP-VALUES-CONDITION as a list,
or the variable value associated with STEP-VARIABLE-CONDITION.")

(define-condition step-values-condition (step-result-condition)
  ()
  #!+sb-doc
  (:documentation "Condition signalled by code compiled with
single-stepping information after executing a form.
STEP-CONDITION-FORM holds the form, and STEP-CONDITION-RESULT holds
the values returned by the form as a list. No associated restarts."))

(define-condition step-finished-condition (step-condition)
  ()
  (:report
   (lambda (condition stream)
     (declare (ignore condition))
     (format stream "Returning from STEP")))
  #!+sb-doc
  (:documentation "Condition signaled when STEP returns."))

;;; A knob for muffling warnings, mostly for use while loading files.
(defvar *muffled-warnings* 'uninteresting-redefinition
  "A type that ought to specify a subtype of WARNING.  Whenever a
warning is signaled, if the warning if of this type and is not
handled by any other handler, it will be muffled.")

;;; Various STYLE-WARNING signaled in the system.
;; For the moment, we're only getting into the details for function
;; redefinitions, but other redefinitions could be done later
;; (e.g. methods).
(define-condition redefinition-warning (style-warning)
  ((name
    :initarg :name
    :reader redefinition-warning-name)
   (new-location
    :initarg :new-location
    :reader redefinition-warning-new-location)))

(define-condition function-redefinition-warning (redefinition-warning)
  ((new-function
    :initarg :new-function
    :reader function-redefinition-warning-new-function)))

(define-condition redefinition-with-defun (function-redefinition-warning)
  ()
  (:report (lambda (warning stream)
             (format stream "redefining ~/sb-impl::print-symbol-with-prefix/ ~
                             in DEFUN"
                     (redefinition-warning-name warning)))))

(define-condition redefinition-with-defmacro (function-redefinition-warning)
  ()
  (:report (lambda (warning stream)
             (format stream "redefining ~/sb-impl::print-symbol-with-prefix/ ~
                             in DEFMACRO"
                     (redefinition-warning-name warning)))))

(define-condition redefinition-with-defgeneric (redefinition-warning)
  ()
  (:report (lambda (warning stream)
             (format stream "redefining ~/sb-impl::print-symbol-with-prefix/ ~
                             in DEFGENERIC"
                     (redefinition-warning-name warning)))))

(define-condition redefinition-with-defmethod (redefinition-warning)
  ((qualifiers :initarg :qualifiers
               :reader redefinition-with-defmethod-qualifiers)
   (specializers :initarg :specializers
                 :reader redefinition-with-defmethod-specializers)
   (new-location :initarg :new-location
                 :reader redefinition-with-defmethod-new-location)
   (old-method :initarg :old-method
               :reader redefinition-with-defmethod-old-method))
  (:report (lambda (warning stream)
             (format stream "redefining ~S~{ ~S~} ~S in DEFMETHOD"
                     (redefinition-warning-name warning)
                     (redefinition-with-defmethod-qualifiers warning)
                     (redefinition-with-defmethod-specializers warning)))))

;;;; Deciding which redefinitions are "interesting".

(defun function-file-namestring (function)
  #!+sb-eval
  (when (typep function 'sb!eval:interpreted-function)
    (return-from function-file-namestring
      (sb!c:definition-source-location-namestring
          (sb!eval:interpreted-function-source-location function))))
  (let* ((fun (sb!kernel:%fun-fun function))
         (code (sb!kernel:fun-code-header fun))
         (debug-info (sb!kernel:%code-debug-info code))
         (debug-source (when debug-info
                         (sb!c::debug-info-source debug-info)))
         (namestring (when debug-source
                       (sb!c::debug-source-namestring debug-source))))
    namestring))

(defun interesting-function-redefinition-warning-p (warning old)
  (let ((new (function-redefinition-warning-new-function warning))
        (source-location (redefinition-warning-new-location warning)))
    (or
     ;; Compiled->Interpreted is interesting.
     (and (typep old 'compiled-function)
          (typep new '(not compiled-function)))
     ;; FIN->Regular is interesting.
     (and (typep old 'funcallable-instance)
          (typep new '(not funcallable-instance)))
     ;; Different file or unknown location is interesting.
     (let* ((old-namestring (function-file-namestring old))
            (new-namestring
             (or (function-file-namestring new)
                 (when source-location
                   (sb!c::definition-source-location-namestring source-location)))))
       (and (or (not old-namestring)
                (not new-namestring)
                (not (string= old-namestring new-namestring))))))))

(defun uninteresting-ordinary-function-redefinition-p (warning)
  (and
   ;; There's garbage in various places when the first DEFUN runs in
   ;; cold-init.
   sb!kernel::*cold-init-complete-p*
   (typep warning 'redefinition-with-defun)
   ;; Shared logic.
   (let ((name (redefinition-warning-name warning)))
     (not (interesting-function-redefinition-warning-p
           warning (or (fdefinition name) (macro-function name)))))))

(defun uninteresting-macro-redefinition-p (warning)
  (and
   (typep warning 'redefinition-with-defmacro)
   ;; Shared logic.
   (let ((name (redefinition-warning-name warning)))
     (not (interesting-function-redefinition-warning-p
           warning (or (macro-function name) (fdefinition name)))))))

(defun uninteresting-generic-function-redefinition-p (warning)
  (and
   (typep warning 'redefinition-with-defgeneric)
   ;; Can't use the shared logic above, since GF's don't get a "new"
   ;; definition -- rather the FIN-FUNCTION is set.
   (let* ((name (redefinition-warning-name warning))
          (old (fdefinition name))
          (old-location (when (typep old 'generic-function)
                          (sb!pcl::definition-source old)))
          (old-namestring (when old-location
                            (sb!c:definition-source-location-namestring old-location)))
          (new-location (redefinition-warning-new-location warning))
          (new-namestring (when new-location
                           (sb!c:definition-source-location-namestring new-location))))
     (and old-namestring
          new-namestring
          (string= old-namestring new-namestring)))))

(defun uninteresting-method-redefinition-p (warning)
  (and
   (typep warning 'redefinition-with-defmethod)
   ;; Can't use the shared logic above, since GF's don't get a "new"
   ;; definition -- rather the FIN-FUNCTION is set.
   (let* ((old-method (redefinition-with-defmethod-old-method warning))
          (old-location (sb!pcl::definition-source old-method))
          (old-namestring (when old-location
                            (sb!c:definition-source-location-namestring old-location)))
          (new-location (redefinition-warning-new-location warning))
          (new-namestring (when new-location
                            (sb!c:definition-source-location-namestring new-location))))
         (and new-namestring
              old-namestring
              (string= new-namestring old-namestring)))))

(deftype uninteresting-redefinition ()
  '(or (satisfies uninteresting-ordinary-function-redefinition-p)
       (satisfies uninteresting-macro-redefinition-p)
       (satisfies uninteresting-generic-function-redefinition-p)
       (satisfies uninteresting-method-redefinition-p)))

(define-condition redefinition-with-deftransform (redefinition-warning)
  ((transform :initarg :transform
              :reader redefinition-with-deftransform-transform))
  (:report (lambda (warning stream)
             (format stream "Overwriting ~S"
                     (redefinition-with-deftransform-transform warning)))))

;;; Various other STYLE-WARNINGS
(define-condition dubious-asterisks-around-variable-name
    (style-warning simple-condition)
  ()
  (:report (lambda (warning stream)
             (format stream "~@?, even though the name follows~@
the usual naming convention (names like *FOO*) for special variables"
                     (simple-condition-format-control warning)
                     (simple-condition-format-arguments warning)))))

(define-condition asterisks-around-lexical-variable-name
    (dubious-asterisks-around-variable-name)
  ())

(define-condition asterisks-around-constant-variable-name
    (dubious-asterisks-around-variable-name)
  ())

;; We call this UNDEFINED-ALIEN-STYLE-WARNING because there are some
;; subclasses of ERROR above having to do with undefined aliens.
(define-condition undefined-alien-style-warning (style-warning)
  ((symbol :initarg :symbol :reader undefined-alien-symbol))
  (:report (lambda (warning stream)
             (format stream "Undefined alien: ~S"
                     (undefined-alien-symbol warning)))))

#!+sb-eval
(define-condition lexical-environment-too-complex (style-warning)
  ((form :initarg :form :reader lexical-environment-too-complex-form)
   (lexenv :initarg :lexenv :reader lexical-environment-too-complex-lexenv))
  (:report (lambda (warning stream)
             (format stream
                     "~@<Native lexical environment too complex for ~
                         SB-EVAL to evaluate ~S, falling back to ~
                         SIMPLE-EVAL-IN-LEXENV.  Lexenv: ~S~:@>"
                     (lexical-environment-too-complex-form warning)
                     (lexical-environment-too-complex-lexenv warning)))))

;; Although this has -ERROR- in the name, it's just a STYLE-WARNING.
(define-condition character-decoding-error-in-comment (style-warning)
  ((stream :initarg :stream :reader decoding-error-in-comment-stream)
   (position :initarg :position :reader decoding-error-in-comment-position))
  (:report (lambda (warning stream)
             (format stream
                      "Character decoding error in a ~A-comment at ~
                      position ~A reading source stream ~A, ~
                      resyncing."
                      (decoding-error-in-comment-macro warning)
                      (decoding-error-in-comment-position warning)
                      (decoding-error-in-comment-stream warning)))))

(define-condition character-decoding-error-in-macro-char-comment
    (character-decoding-error-in-comment)
  ((char :initform #\; :initarg :char
         :reader character-decoding-error-in-macro-char-comment-char)))

(define-condition character-decoding-error-in-dispatch-macro-char-comment
    (character-decoding-error-in-comment)
  ;; ANSI doesn't give a way for a reader function invoked by a
  ;; dispatch macro character to determine which dispatch character
  ;; was used, so if a user wants to signal one of these from a custom
  ;; comment reader, he'll have to supply the :DISP-CHAR himself.
  ((disp-char :initform #\# :initarg :disp-char
              :reader character-decoding-error-in-macro-char-comment-disp-char)
   (sub-char :initarg :sub-char
             :reader character-decoding-error-in-macro-char-comment-sub-char)))

(defun decoding-error-in-comment-macro (warning)
  (etypecase warning
    (character-decoding-error-in-macro-char-comment
     (character-decoding-error-in-macro-char-comment-char warning))
    (character-decoding-error-in-dispatch-macro-char-comment
     (format
      nil "~C~C"
      (character-decoding-error-in-macro-char-comment-disp-char warning)
      (character-decoding-error-in-macro-char-comment-sub-char warning)))))

(define-condition deprecated-eval-when-situations (style-warning)
  ((situations :initarg :situations
               :reader deprecated-eval-when-situations-situations))
  (:report (lambda (warning stream)
             (format stream "using deprecated EVAL-WHEN situation names~{ ~S~}"
                     (deprecated-eval-when-situations-situations warning)))))

(define-condition proclamation-mismatch (style-warning)
  ((name :initarg :name :reader proclamation-mismatch-name)
   (old :initarg :old :reader proclamation-mismatch-old)
   (new :initarg :new :reader proclamation-mismatch-new)))

(define-condition type-proclamation-mismatch (proclamation-mismatch)
  ()
  (:report (lambda (warning stream)
             (format stream
                     "The new TYPE proclamation~% ~S for ~S does not ~
                     match the old TYPE proclamation ~S"
                     (proclamation-mismatch-new warning)
                     (proclamation-mismatch-name warning)
                     (proclamation-mismatch-old warning)))))

(define-condition ftype-proclamation-mismatch (proclamation-mismatch)
  ()
  (:report (lambda (warning stream)
             (format stream
                     "The new FTYPE proclamation~% ~S for ~S does not ~
                     match the old FTYPE proclamation ~S"
                     (proclamation-mismatch-new warning)
                     (proclamation-mismatch-name warning)
                     (proclamation-mismatch-old warning)))))

;;;; deprecation conditions

(define-condition deprecation-condition ()
  ((name :initarg :name :reader deprecated-name)
   (replacement :initarg :replacement :reader deprecated-name-replacement)
   (since :initarg :since :reader deprecated-since)
   (runtime-error :initarg :runtime-error :reader deprecated-name-runtime-error)))

(def!method print-object ((condition deprecation-condition) stream)
  (let ((*package* (find-package :keyword)))
    (if *print-escape*
        (print-unreadable-object (condition stream :type t)
          (format stream "~S is deprecated~@[, use ~S~]"
                  (deprecated-name condition)
                  (deprecated-name-replacement condition)))
        (format stream "~@<~S has been deprecated as of SBCL ~A~
                        ~@[, use ~S instead~].~:@>"
                (deprecated-name condition)
                (deprecated-since condition)
                (deprecated-name-replacement condition)))))

(define-condition early-deprecation-warning (style-warning deprecation-condition)
  ())

(def!method print-object :after ((warning early-deprecation-warning) stream)
  (unless *print-escape*
    (let ((*package* (find-package :keyword)))
      (format stream "~%~@<~:@_In future SBCL versions ~S will signal a full warning ~
                      at compile-time.~:@>"
              (deprecated-name warning)))))

(define-condition late-deprecation-warning (warning deprecation-condition)
  ())

(def!method print-object :after ((warning late-deprecation-warning) stream)
  (unless *print-escape*
    (when (deprecated-name-runtime-error warning)
      (let ((*package* (find-package :keyword)))
        (format stream "~%~@<~:@_In future SBCL versions ~S will signal a runtime error.~:@>"
                (deprecated-name warning))))))

(define-condition final-deprecation-warning (warning deprecation-condition)
  ())

(def!method print-object :after ((warning final-deprecation-warning) stream)
  (unless *print-escape*
    (when (deprecated-name-runtime-error warning)
      (let ((*package* (find-package :keyword)))
        (format stream "~%~@<~:@_An error will be signaled at runtime for ~S.~:@>"
                (deprecated-name warning))))))

(define-condition deprecation-error (error deprecation-condition)
  ())

;;;; restart definitions

(define-condition abort-failure (control-error) ()
  (:report
   "An ABORT restart was found that failed to transfer control dynamically."))

(defun abort (&optional condition)
  #!+sb-doc
  "Transfer control to a restart named ABORT, signalling a CONTROL-ERROR if
   none exists."
  (invoke-restart (find-restart-or-control-error 'abort condition))
  ;; ABORT signals an error in case there was a restart named ABORT
  ;; that did not transfer control dynamically. This could happen with
  ;; RESTART-BIND.
  (error 'abort-failure))

(defun muffle-warning (&optional condition)
  #!+sb-doc
  "Transfer control to a restart named MUFFLE-WARNING, signalling a
   CONTROL-ERROR if none exists."
  (invoke-restart (find-restart-or-control-error 'muffle-warning condition)))

(defun try-restart (name condition &rest arguments)
  (let ((restart (find-restart name condition)))
    (when restart
      (apply #'invoke-restart restart arguments))))

(macrolet ((define-nil-returning-restart (name args doc)
             #!-sb-doc (declare (ignore doc))
             `(defun ,name (,@args &optional condition)
                #!+sb-doc ,doc
                (try-restart ',name condition ,@args))))
  (define-nil-returning-restart continue ()
    "Transfer control to a restart named CONTINUE, or return NIL if none exists.")
  (define-nil-returning-restart store-value (value)
    "Transfer control and VALUE to a restart named STORE-VALUE, or return NIL if
   none exists.")
  (define-nil-returning-restart use-value (value)
    "Transfer control and VALUE to a restart named USE-VALUE, or return NIL if
   none exists."))

;;; single-stepping restarts

(macrolet ((def (name doc)
               #!-sb-doc (declare (ignore doc))
               `(defun ,name (condition)
                 #!+sb-doc ,doc
                 (invoke-restart (find-restart-or-control-error ',name condition)))))
  (def step-continue
      "Transfers control to the STEP-CONTINUE restart associated with
the condition, continuing execution without stepping. Signals a
CONTROL-ERROR if the restart does not exist.")
  (def step-next
      "Transfers control to the STEP-NEXT restart associated with the
condition, executing the current form without stepping and continuing
stepping with the next form. Signals CONTROL-ERROR is the restart does
not exists.")
  (def step-into
      "Transfers control to the STEP-INTO restart associated with the
condition, stepping into the current form. Signals a CONTROL-ERROR is
the restart does not exist."))

(/show0 "condition.lisp end of file")