;;;; miscellaneous functions which use INFO
;;;;
;;;; (In CMU CL, these were in globaldb.lisp. They've been moved here
;;;; because references to INFO can't be compiled correctly until
;;;; globaldb initialization is complete, and the SBCL technique for
;;;; initializing the global database in the cross-compiler isn't
;;;; completed until load time.)

;;;; 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-C")

;;;; internal utilities defined in terms of INFO

(defun check-variable-name (name &key
                                   (context "local variable")
                                   (signal-via #'compiler-error))
  (unless (legal-variable-name-p name)
    (funcall signal-via "~@<~S~[~; is a keyword and~; is not a symbol and~
                         ~] cannot be used as a ~A.~@:>"
             name
             (typecase name
               (null    0)
               (keyword 1)
               (t       2))
             context))
  name)

;;; Check that NAME is a valid function name, returning the name if
;;; OK, and signalling an error if not. In addition to checking for
;;; basic well-formedness, we also check that symbol names are not NIL
;;; or the name of a special form.
(defun check-fun-name (name)
  (typecase name
    (list
     (unless (legal-fun-name-p name)
       (compiler-error "~@<Illegal function name: ~S.~@:>" name)))
    (symbol
     (when (eq (info :function :kind name) :special-form)
       (compiler-error "~@<Special form is an illegal function name: ~S.~@:>"
                       name)))
    (t
     (compiler-error "~@<Illegal function name: ~S.~@:>" name)))
  name)

;;; Record a new function definition, and check its legality.
(defun proclaim-as-fun-name (name)

  ;; legal name?
  (check-fun-name name)

  ;; KLUDGE: This can happen when eg. compiling a NAMED-LAMBDA, and isn't
  ;; guarded against elsewhere -- so we want to assert package locks here. The
  ;; reason we do it only when stomping on existing stuff is because we want
  ;; to keep
  ;;   (WITHOUT-PACKAGE-LOCKS (DEFUN LOCKED:FOO ...))
  ;; viable, which requires no compile-time violations in the harmless cases.
  (with-single-package-locked-error ()
    (flet ((assert-it ()
             (assert-symbol-home-package-unlocked name "proclaiming ~S as a function")))

      (let ((kind (info :function :kind name)))
        ;; scrubbing old data I: possible collision with a macro
        (when (and (fboundp name) (eq :macro kind))
          (assert-it)
          (compiler-style-warn "~S was previously defined as a macro." name)
          (setf (info :function :where-from name) :assumed)
          (clear-info :function :macro-function name))

        (unless (eq :function kind)
          (assert-it)
          (setf (info :function :kind name) :function)))))

  ;; scrubbing old data II: dangling forward references
  ;;
  ;; (This could happen if someone executes PROCLAIM FTYPE at
  ;; macroexpansion time, which is bad style, or at compile time, e.g.
  ;; in EVAL-WHEN (:COMPILE) inside something like DEFSTRUCT, in which
  ;; case it's reasonable style. Either way, NAME is no longer a free
  ;; function.)
  (when (boundp '*free-funs*)       ; when compiling
    (remhash name *free-funs*))

  (values))

;;; This is called to do something about SETF functions that overlap
;;; with SETF macros. Perhaps we should interact with the user to see
;;; whether the macro should be blown away, but for now just give a
;;; warning. Due to the weak semantics of the (SETF FUNCTION) name, we
;;; can't assume that they aren't just naming a function (SETF FOO)
;;; for the heck of it. NAME is already known to be well-formed.
(defun warn-if-setf-macro (name)
  ;; Never warn about this situation when running the cross-compiler.
  ;; SBCL provides expanders/inverses *and* functions for most SETFable things
  ;; even when CLHS does not specifically state that #'(SETF x) exists.
  #+sb-xc-host (declare (ignore name))
  #-sb-xc-host
  (let ((stem (second name)))
    (when (info :setf :expander stem)
      (compiler-style-warn
         "defining function ~S when ~S already has a SETF macro"
         name stem)))
  (values))

;;; Make NAME no longer be a function name: clear everything back to
;;; the default.
(defun undefine-fun-name (name)
  (when name
    (macrolet ((frob (&rest types)
                 `(clear-info-values
                   name ',(mapcar (lambda (x)
                                    (meta-info-number (meta-info :function x)))
                                  types))))
      ;; Note that this does not clear the :DEFINITION.
      ;; That's correct, because if we lose the association between a
      ;; symbol and its #<fdefn> object, it could lead to creation of
      ;; a non-unique #<fdefn> for a name.
      (frob :info
            :type ; Hmm. What if it was proclaimed- shouldn't it stay?
            :where-from ; Ditto.
            :inlinep
            :kind
            :macro-function
            :inlining-data
            :source-transform
            :assumed-type)))
  (values))

;;; part of what happens with DEFUN, also with some PCL stuff: Make
;;; NAME known to be a function definition.
(defun become-defined-fun-name (name)
  (proclaim-as-fun-name name)
  (when (eq (info :function :where-from name) :assumed)
    (setf (info :function :where-from name) :defined)
    (if (info :function :assumed-type name)
        (clear-info :function :assumed-type name))))

;;; Trivially wrap (INFO :FUNCTION :INLINING-DATA FUN-NAME)
;;; to extract an inlineable lambda.
;;; Secondary value is T only if an explicit expansion was stored, and NOT
;;; an implicit expansion of a auto-defined product of DEFSTRUCT.
(declaim (ftype (function ((or symbol cons)) (values list boolean))
                fun-name-inline-expansion))
(defun fun-name-inline-expansion (fun-name)
  (multiple-value-bind (answer winp) (info :function :inlining-data fun-name)
    (typecase answer
      ;; an INLINING-DATA is a DXABLE-ARGS, so test it first
      (inlining-data (setq answer (inlining-data-expansion answer)))
      (dxable-args   (setq answer nil winp nil)))
    (when (and (not winp) (symbolp fun-name))
      (let ((info (info :function :type fun-name)))
        (when (typep info 'defstruct-description)
          (let ((spec (assq fun-name (dd-constructors info))))
            (aver spec)
            (setq answer `(lambda ,@(structure-ctor-lambda-parts
                                     info (cdr spec))))))))
    (values answer winp)))
(defun fun-name-dx-args (fun-name)
  (let ((answer (info :function :inlining-data fun-name)))
    (when (typep answer 'dxable-args)
      (dxable-args-list answer))))

;;;; ANSI Common Lisp functions which are defined in terms of the info
;;;; database

(defun sb-xc:macro-function (symbol &optional env)
  "If SYMBOL names a macro in ENV, returns the expansion function,
else returns NIL. If ENV is unspecified or NIL, use the global environment
only."
  ;; local function definitions (ordinary) can shadow a global macro
  (typecase env
    #!+(and sb-fasteval (host-feature sb-xc))
    (sb-interpreter:basic-env
     (multiple-value-bind (kind def)
         (sb-interpreter:find-lexical-fun env symbol)
       (when def
         (return-from sb-xc:macro-function (when (eq kind :macro) def)))))
    (lexenv
     (let ((def (cdr (assoc symbol (lexenv-funs env)))))
       (when def
         (return-from sb-xc:macro-function
           (when (typep def '(cons (eql macro))) (cdr def)))))))
  (values (info :function :macro-function symbol)))

(defun (setf sb-xc:macro-function) (function symbol &optional environment)
  (declare (symbol symbol) (type function function))
  (when environment
    ;; Note: Technically there could be an ENV optional argument to SETF
    ;; MACRO-FUNCTION, but since ANSI says that the consequences of
    ;; supplying a non-nil one are undefined, we don't allow it.
    ;; (Thus our implementation of this unspecified behavior is to
    ;; complain. SInce the behavior is unspecified, this is conforming.:-)
    (error "Non-NIL environment argument in SETF of MACRO-FUNCTION ~S: ~S"
           symbol environment))
  (when (eq (info :function :kind symbol) :special-form)
    (error "~S names a special form." symbol))
  (with-single-package-locked-error (:symbol symbol "setting the macro-function of ~S")
    (clear-info :function :type symbol)
    (setf (info :function :kind symbol) :macro)
    (setf (info :function :macro-function symbol) function)
    #-sb-xc-host (install-guard-function symbol `(:macro ,symbol)))
  function)

(defun sb-xc:compiler-macro-function (name &optional env)
  "If NAME names a compiler-macro in ENV, return the expansion function, else
return NIL. Can be set with SETF when ENV is NIL."
  (legal-fun-name-or-type-error name)
  ;; CLHS 3.2.2.1: Creating a lexical binding for the function name
  ;; not only creates a new local function or macro definition, but
  ;; also shadows[2] the compiler macro.
  (unless (fun-locally-defined-p name env)
    ;; Note: CMU CL used to return NIL here when a NOTINLINE
    ;; declaration was in force. That's fairly logical, given the
    ;; specified effect of NOTINLINE declarations on compiler-macro
    ;; expansion. However, (1) it doesn't seem to be consistent with
    ;; the ANSI spec for COMPILER-MACRO-FUNCTION, and (2) it would
    ;; give surprising behavior for (SETF (COMPILER-MACRO-FUNCTION
    ;; FOO) ...) in the presence of a (PROCLAIM '(NOTINLINE FOO)). So
    ;; we don't do it.
    (values (info :function :compiler-macro-function name))))

;;; FIXME: we don't generate redefinition warnings for these.
(defun (setf sb-xc:compiler-macro-function) (function name &optional env)
  (declare (type (or symbol list) name)
           (type (or function null) function))
  (when env
    ;; ANSI says this operation is undefined.
    (error "can't SETF COMPILER-MACRO-FUNCTION when ENV is non-NIL"))
  (when (eq (info :function :kind name) :special-form)
    (error "~S names a special form." name))
  (with-single-package-locked-error
      (:symbol name "setting the compiler-macro-function of ~A")
    (setf (info :function :compiler-macro-function name) function)
    function))

;;;; a subset of DOCUMENTATION functionality for bootstrapping

;; Return the number of calls to NAME that IR2 emitted as full calls,
;; not counting calls via #'F that went untracked.
;; Return 0 if the answer is nonzero but a warning was already signaled
;; about any full calls were emitted. This return convention satisfies the
;; intended use of this statistic - to decide whether to generate a warning
;; about failure to inline NAME, which is shown at most once per name
;; to avoid unleashing a flood of identical warnings.
(defun emitted-full-call-count (name)
  (let ((status (car (info :function :emitted-full-calls name))))
     (and (integerp status)
          ;; Bit 0 tells whether any call was NOT in the presence of
          ;; a 'notinline' declaration, thus eligible to be inline.
          ;; Bit 1 tells whether any warning was emitted yet.
          (= (logand status 3) #b01)
          (ash status -2)))) ; the call count as tracked by IR2
