Make cl-defstruct use records.

* lisp/emacs-lisp/cl-extra.el (cl--describe-class)
(cl--describe-class-slots): Use the new `type-of'.

* lisp/emacs-lisp/cl-generic.el (cl--generic-struct-tag): Use type-of.
(cl--generic-struct-specializers): Adjust to new tag.

* lisp/emacs-lisp/cl-macs.el (cl-defstruct): When type is nil, use records.
Use the type symbol as the tag.  Use copy-record to copy structs.
(cl--defstruct-predicate): New function.
(cl--pcase-mutually-exclusive-p): Use it.
(cl-struct-sequence-type): Can now return `record'.

* lisp/emacs-lisp/cl-preloaded.el (cl--make-slot-desc): Adjust ad-hoc
code to new format.
(cl--struct-register-child): Work with records.
(cl-struct-define): Don't touch the tag's symbol-value and
symbol-function slots when we use the type as tag.

* lisp/emacs-lisp/cl-print.el (cl-print-object): Adjust to new tag.

* test/lisp/emacs-lisp/cl-lib-tests.el (cl-lib-defstruct-record):
New test.

* doc/lispref/records.texi, doc/misc/cl.texi: Update for records.

1 files changed, 4 insertions, 20 deletions

diff --git a/lisp/emacs-lisp/cl-generic.el b/lisp/emacs-lisp/cl-generic.el
index 8c6d3d5d51f..e15c94242fb 100644
--- a/lisp/emacs-lisp/cl-generic.el
+++ b/lisp/emacs-lisp/cl-generic.el
@@ -1082,24 +1082,8 @@ These match if the argument is `eql' to VAL."
 ;;; Support for cl-defstructs specializers.
 
 (defun cl--generic-struct-tag (name &rest _)
-  ;; It's tempting to use (and (vectorp ,name) (aref ,name 0))
-  ;; but that would suffer from some problems:
-  ;; - the vector may have size 0.
-  ;; - when called on an actual vector (rather than an object), we'd
-  ;;   end up returning an arbitrary value, possibly colliding with
-  ;;   other tagcode's values.
-  ;; - it can also result in returning all kinds of irrelevant
-  ;;   values which would end up filling up the method-cache with
-  ;;   lots of irrelevant/redundant entries.
-  ;; FIXME: We could speed this up by introducing a dedicated
-  ;; vector type at the C level, so we could do something like
-  ;; (and (vector-objectp ,name) (aref ,name 0))
-  `(and (vectorp ,name)
-        (> (length ,name) 0)
-        (let ((tag (aref ,name 0)))
-          (and (symbolp tag)
-               (eq (symbol-function tag) :quick-object-witness-check)
-               tag))))
+  ;; Use exactly the same code as for `typeof'.
+  `(if ,name (type-of ,name) 'null))
 
 (defun cl--generic-class-parents (class)
   (let ((parents ())
@@ -1113,8 +1097,8 @@ These match if the argument is `eql' to VAL."
     (nreverse parents)))
 
 (defun cl--generic-struct-specializers (tag &rest _)
-  (and (symbolp tag) (boundp tag)
-       (let ((class (symbol-value tag)))
+  (and (symbolp tag)
+       (let ((class (get tag 'cl--class)))
          (when (cl-typep class 'cl-structure-class)
            (cl--generic-class-parents class)))))