Tighten up the tagcode used for eieio and cl-struct objects

* lisp/emacs-lisp/eieio-core.el (eieio-defclass-internal): Set the function
slot of the tag symbol to :quick-object-witness-check.
(eieio-object-p): Use :quick-object-witness-check.
(eieio--generic-tagcode): Use cl--generic-struct-tag.
* lisp/emacs-lisp/cl-preloaded.el: New file.
* lisp/emacs-lisp/cl-macs.el (cl--bind-inits): Remove, unused.
(cl--transform-lambda, cl-destructuring-bind): Remove cl--bind-inits.
(cl--make-usage-args): Strip away &aux args.
(cl-case, cl-typecase, cl--parse-loop-clause): Use macroexp-let2.
(cl-the, cl-check-type): Use macroexp-let2 and cl-typep.
(cl-defstruct): Use `declare' and cl-struct-define.
* lisp/emacs-lisp/cl-generic.el (cl--generic-struct-tag): New function.
(cl--generic-struct-tagcode): Use it to tighten the tagcode.
* lisp/loadup.el: Load cl-preloaded.
* src/lisp.mk (lisp): Add cl-preloaded.

1 files changed, 48 insertions, 0 deletions

diff --git a/lisp/emacs-lisp/cl-preloaded.el b/lisp/emacs-lisp/cl-preloaded.el
new file mode 100644
index 00000000000..c9867b412a1
--- /dev/null
+++ b/lisp/emacs-lisp/cl-preloaded.el
@@ -0,0 +1,48 @@
+;;; cl-preloaded.el --- Preloaded part of the CL library  -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2015  Free Software Foundation, Inc
+
+;; Author: Stefan Monnier <monnier@iro.umontreal.ca>
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; The expectation is that structs defined with cl-defstruct do not
+;; need cl-lib at run-time, but we'd like to hide the details of the
+;; cl-struct metadata behind the cl-struct-define function, so we put
+;; it in this pre-loaded file.
+
+;;; Code:
+
+(defun cl-struct-define (name docstring parent type named slots children-sym
+                              tag print-auto)
+  (if (boundp children-sym)
+      (add-to-list children-sym tag)
+    (set children-sym (list tag)))
+  ;; If the cl-generic support, we need to be able to check
+  ;; if a vector is a cl-struct object, without knowing its particular type.
+  ;; So we use the (otherwise) unused function slots of the tag symbol
+  ;; to put a special witness value, to make the check easy and reliable.
+  (unless named (fset tag :quick-object-witness-check))
+  (put name 'cl-struct-slots slots)
+  (put name 'cl-struct-type (list type named))
+  (if parent (put name 'cl-struct-include parent))
+  (if print-auto (put name 'cl-struct-print print-auto))
+  (if docstring (put name 'structure-documentation docstring)))
+
+(provide 'cl-preloaded)
+;;; cl-preloaded.el ends here