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 source-location &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      ;; Detecting illegal redefinition in the cross-compiler
  22      ;; adds unnecessary complexity, so don't bother.
  23      #-sb-xc-host
  24      (when *type-system-initialized*
  25        (error "illegal to redefine standard type: ~S" name)))
  26     (:instance
  27      (warn "The class ~S is being redefined to be a DEFTYPE." name)
  28      (undeclare-structure (find-classoid name) t)
  29      ;; FIXME: shouldn't this happen only at eval-time?
  30      (setf (classoid-cell-classoid (find-classoid-cell name :create t)) nil)
  31      (clear-info :type :compiler-layout name)
  32      (setf (info :type :kind name) :defined))
  33     (:defined
  34      ;; Note: It would be nice to warn here when a type is being
  35      ;; incompatibly redefined, but it's hard to tell, since type
  36      ;; expanders are often function objects which can't easily be
  37      ;; compared for equivalence. And just warning on redefinition
  38      ;; isn't good, since DEFTYPE necessarily does its thing once at
  39      ;; compile time and again at load time, so that it's very common
  40      ;; and normal for types to be defined twice. So since there
  41      ;; doesn't seem to be anything simple and obvious to do, and
  42      ;; since mistakenly redefining a type isn't a common error
  43      ;; anyway, we just don't worry about trying to warn about it.
  44      )
  45     ((nil :forthcoming-defclass-type)
  46      (setf (info :type :kind name) :defined)))
  47   (setf (info :type :expander name) expander)
  48   (when source-location
  49     (setf (info :type :source-location name) source-location))
  50   (when doc
  51     (setf (fdocumentation name 'type) doc))
  52   (sb!c::%note-type-defined name)
  53   name)
  54
  55 (/show0 "compiler-deftype.lisp end of file")