src/compiler/compiler-deftype.lisp

   1 ;;;; that part of DEFTYPE which runs within the compiler itself
   2
   3 ;;;; This software is part of the SBCL system. See the README file for
   4 ;;;; more information.
   5 ;;;;
   6 ;;;; This software is derived from the CMU CL system, which was
   7 ;;;; written at Carnegie Mellon University and released into the
   8 ;;;; public domain. The software is in the public domain and is
   9 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
  10 ;;;; files for more information.
  11
  12 (in-package "SB!IMPL")
  13
  14 (/show0 "compiler-deftype.lisp 14")
  15
  16 (defun %compiler-deftype (name expander &optional doc)
  17   (ecase (info :type :kind name)
  18     (:primitive
  19      (when *type-system-initialized*
  20        (error "illegal to redefine standard type: ~S" name)))
  21     (:instance
  22      (warn "The class ~S is being redefined to be a DEFTYPE." name)
  23      (undefine-structure (layout-info (class-layout (sb!xc:find-class name))))
  24      (setf (class-cell-class (find-class-cell name)) nil)
  25      (setf (info :type :compiler-layout name) nil)
  26      (setf (info :type :kind name) :defined))
  27     (:defined
  28      ;; Note: It would be nice to warn here when a type is being
  29      ;; incompatibly redefined, but it's hard to tell, since type
  30      ;; expanders are often function objects which can't easily be
  31      ;; compared for equivalence. And just warning on redefinition
  32      ;; isn't good, since DEFTYPE necessarily does its thing once at
  33      ;; compile time and again at load time, so that it's very common
  34      ;; and normal for types to be defined twice. So since there
  35      ;; doesn't seem to be anything simple and obvious to do, and
  36      ;; since mistakenly redefining a type isn't a common error
  37      ;; anyway, we just don't worry about trying to warn about it.
  38      )
  39     ((nil :forthcoming-defclass-type)
  40      (setf (info :type :kind name) :defined)))
  41   (setf (info :type :expander name) expander)
  42   (when doc
  43     (setf (fdocumentation name 'type) doc))
  44   ;; ### Bootstrap hack -- we need to define types before %NOTE-TYPE-DEFINED
  45   ;; is defined. (FIXME: Do we still need to do this? -- WHN 19990310)
  46   (if (fboundp 'sb!c::%note-type-defined)
  47     (sb!c::%note-type-defined name)
  48     (warn "defining type before %NOTE-TYPE-DEFINED is defined"))
  49   name)
  50
  51 (/show0 "compiler-deftype.lisp end of file")