Revert "Prevent name clashes between CL structures and builtin types"

This reverts commit 151496a4b9.
That commit breaks bootstrap builds due to a cyclic dependency.

etc/NEWS

@@ -190,10 +190,6 @@ calling 'eldoc-message' directly.
 ** Old-style backquotes now generate an error.  They have been
 generating warnings for a decade.
 
-** Defining a Common Lisp structure using 'cl-defstruct' or
-'cl-struct-define' whose name clashes with a builtin type (e.g.,
-'integer' or 'hash-table') now signals an error.
-
 
 * Lisp Changes in Emacs 27.1
 

lisp/emacs-lisp/cl-macs.el

@@ -43,7 +43,6 @@
 
 ;;; Code:
 
-(require 'cl-generic)
 (require 'cl-lib)
 (require 'macroexp)
 ;; `gv' is required here because cl-macs can be loaded before loaddefs.el.
@@ -2664,9 +2663,6 @@ non-nil value, that slot cannot be set via `setf'.
 	 (forms nil)
          (docstring (if (stringp (car descs)) (pop descs)))
 	 pred-form pred-check)
-    ;; Can't use `cl-check-type' yet.
-    (unless (cl--struct-name-p name)
-      (signal 'wrong-type-argument (list 'cl-struct-name-p name 'name)))
     (setq descs (cons '(cl-tag-slot)
 		      (mapcar (function (lambda (x) (if (consp x) x (list x))))
 			      descs)))

lisp/emacs-lisp/cl-preloaded.el

@@ -36,7 +36,6 @@
 
 ;;; Code:
 
-(eval-when-compile (require 'cl-generic))
 (eval-when-compile (require 'cl-lib))
 (eval-when-compile (require 'cl-macs))  ;For cl--struct-class.
 
@@ -51,12 +50,6 @@
         (apply #'error string (append sargs args))
       (signal 'cl-assertion-failed `(,form ,@sargs)))))
 
-(defun cl--struct-name-p (name)
-  "Return t if NAME is a valid structure name for `cl-defstruct'."
-  (and name (symbolp name) (not (keywordp name))
-       (not (memq name (eval-when-compile cl--generic-all-builtin-types)))
-       t))
-
 ;; When we load this (compiled) file during pre-loading, the cl--struct-class
 ;; code below will need to access the `cl-struct' info, since it's considered
 ;; already as its parent (because `cl-struct' was defined while the file was
@@ -117,7 +110,6 @@
 ;;;###autoload
 (defun cl-struct-define (name docstring parent type named slots children-sym
                               tag print)
-  (cl-check-type name cl--struct-name)
   (unless type
     ;; Legacy defstruct, using tagged vectors.  Enable backward compatibility.
     (cl-old-struct-compat-mode 1))

test/lisp/emacs-lisp/cl-macs-tests.el

@@ -497,13 +497,4 @@ collection clause."
                           vconcat (vector (1+ x)))
                  [2 3 4 5 6])))
 
-
-(ert-deftest cl-defstruct/builtin-type ()
-  (should-error
-   (macroexpand '(cl-defstruct hash-table))
-   :type 'wrong-type-argument)
-  (should-error
-   (macroexpand '(cl-defstruct (hash-table (:predicate hash-table-p))))
-   :type 'wrong-type-argument))
-
 ;;; cl-macs-tests.el ends here

test/lisp/emacs-lisp/cl-preloaded-tests.el

@@ -1,33 +0,0 @@
-;;; cl-preloaded-tests.el --- unit tests for cl-preloaded.el  -*- lexical-binding: t; -*-
-
-;; Copyright (C) 2017 Free Software Foundation, Inc.
-;; Author: Philipp Stephani <phst@google.com>
-
-;; This file is part of GNU Emacs.
-
-;; This program 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.
-
-;; This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
-
-;;; Commentary:
-
-;; Unit tests for lisp/emacs-lisp/cl-preloaded.el.
-
-;;; Code:
-
-(ert-deftest cl-struct-define/builtin-type ()
-  (should-error
-   (cl-struct-define 'hash-table nil nil 'record nil nil
-                     'cl-preloaded-tests-tag 'cl-preloaded-tests nil)
-   :type 'wrong-type-argument))
-
-;;; cl-preloaded-tests.el ends here