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   (with-single-package-locked-error
  18       (:symbol name "defining ~A as a type specifier"))
  19   (ecase (info :type :kind name)
  20     (:primitive
  21      (when *type-system-initialized*
  22        (error "illegal to redefine standard type: ~S" name)))
  23     (:instance
  24      (warn "The class ~S is being redefined to be a DEFTYPE." name)
  25      (undefine-structure (layout-info (classoid-layout (find-classoid name))))
  26      (setf (classoid-cell-classoid (find-classoid-cell name)) nil)
  27      (setf (info :type :compiler-layout name) nil)
  28      (setf (info :type :kind name) :defined))
  29     (:defined
  30      ;; Note: It would be nice to warn here when a type is being
  31      ;; incompatibly redefined, but it's hard to tell, since type
  32      ;; expanders are often function objects which can't easily be
  33      ;; compared for equivalence. And just warning on redefinition
  34      ;; isn't good, since DEFTYPE necessarily does its thing once at
  35      ;; compile time and again at load time, so that it's very common
  36      ;; and normal for types to be defined twice. So since there
  37      ;; doesn't seem to be anything simple and obvious to do, and
  38      ;; since mistakenly redefining a type isn't a common error
  39      ;; anyway, we just don't worry about trying to warn about it.
  40      )
  41     ((nil :forthcoming-defclass-type)
  42      (setf (info :type :kind name) :defined)))
  43   (setf (info :type :expander name) expander)
  44   (when doc
  45     (setf (fdocumentation name 'type) doc))
  46   ;; ### Bootstrap hack -- we need to define types before %NOTE-TYPE-DEFINED
  47   ;; is defined. (FIXME: Do we still need to do this? -- WHN 19990310)
  48   (if (fboundp 'sb!c::%note-type-defined)
  49     (sb!c::%note-type-defined name)
  50     (warn "defining type before %NOTE-TYPE-DEFINED is defined"))
  51   name)
  52
  53 (/show0 "compiler-deftype.lisp end of file")