- (sb!c::%%defconstant name value doc))
-#+sb-xc-host (sb!xc:proclaim '(ftype function sb!c::%%defconstant)) ; to avoid
- ; undefined function warnings
-(defun sb!c::%%defconstant (name value doc)
+ (unless (symbolp name)
+ (error "constant name not a symbol: ~S" name))
+ (about-to-modify name)
+ (let ((kind (info :variable :kind name)))
+ (case kind
+ (:constant
+ ;; Note: This behavior (discouraging any non-EQL modification)
+ ;; is unpopular, but it is specified by ANSI (i.e. ANSI says a
+ ;; non-EQL change has undefined consequences). If people really
+ ;; want bindings which are constant in some sense other than
+ ;; EQL, I suggest either just using DEFVAR (which is usually
+ ;; appropriate, despite the un-mnemonic name), or defining
+ ;; something like SB-INT:DEFCONSTANT-EQX (which is occasionally
+ ;; more appropriate). -- WHN 2000-11-03
+ (unless (eql value
+ (info :variable :constant-value name))
+ (cerror "Go ahead and change the value."
+ "The constant ~S is being redefined."
+ name)))
+ (:global
+ ;; (This is OK -- undefined variables are of this kind. So we
+ ;; don't warn or error or anything, just fall through.)
+ )
+ (t (warn "redefining ~(~A~) ~S to be a constant" kind name))))