Provide generalized variables in core Elisp.

* lisp/emacs-lisp/gv.el: New file.
* lisp/subr.el (push, pop): Extend to generalized variables.
* lisp/loadup.el (macroexp): Unload if preloaded and uncompiled.
* lisp/emacs-lisp/cl-lib.el (cl-pop, cl-push, cl--set-nthcdr): Remove.
* lisp/emacs-lisp/cl-macs.el: Require gv.  Use gv-define-setter,
gv-define-simple-setter, and gv-define-expander.
Remove setf-methods defined in gv.  Rename cl-setf -> setf.
(cl-setf, cl-do-pop, cl-get-setf-method): Remove.
(cl-letf, cl-letf*, cl-define-modify-macro, cl-defsetf)
(cl-define-setf-expander, cl-struct-setf-expander): Move to cl.el.
(cl-remf, cl-shiftf, cl-rotatef, cl-callf, cl-callf2): Rewrite with
gv-letplace.
(cl-defstruct): Don't define setf-method any more.
* lisp/emacs-lisp/cl.el (flet): Don't autoload.
(cl--letf, letf, cl--letf*, letf*, cl--gv-adapt)
(define-setf-expander, defsetf, define-modify-macro)
(cl-struct-setf-expander): Move from cl-lib.el.
* lisp/emacs-lisp/syntax.el:
* lisp/emacs-lisp/ewoc.el:
* lisp/emacs-lisp/smie.el:
* lisp/emacs-lisp/cconv.el:
* lisp/emacs-lisp/timer.el: Rename cl-setf -> setf, cl-push -> push.
(timer--time): Use gv-define-simple-setter.
* lisp/emacs-lisp/macroexp.el (macroexp-let2): Rename from macroexp-let²
to avoid coding-system problems in subr.el.  Adjust all users.
(macroexp--maxsize, macroexp-small-p): New functions.
* lisp/emacs-lisp/bytecomp.el (byte-compile-file): Don't use cl-letf.
* lisp/scroll-bar.el (scroll-bar-mode):
* lisp/simple.el (auto-fill-mode, overwrite-mode, binary-overwrite-mode)
(normal-erase-is-backspace-mode): Don't use the `eq' place.
* lisp/winner.el (winner-configuration, winner-make-point-alist)
(winner-set-conf, winner-get-point, winner-set): Don't abuse letf.
* lisp/files.el (locate-file-completion-table): Avoid list*.

Fixes: debbugs:11657

1 files changed, 28 insertions, 22 deletions

diff --git a/lisp/subr.el b/lisp/subr.el
index ba9b06d495b..5deaf71e78d 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -26,6 +26,9 @@
 
 ;;; Code:
 
+;; Beware: while this file has tag `utf-8', before it's compiled, it gets
+;; loaded as "raw-text", so non-ASCII chars won't work right during bootstrap.
+
 (defvar custom-declare-variable-list nil
   "Record `defcustom' calls made before `custom.el' is loaded to handle them.
 Each element of this list holds the arguments to one call to `defcustom'.")
@@ -144,29 +147,33 @@ was called."
   `(closure (t) (&rest args)
             (apply ',fun ,@(mapcar (lambda (arg) `',arg) args) args)))
 
-(if (null (featurep 'cl))
-    (progn
-  ;; If we reload subr.el after having loaded CL, be careful not to
-  ;; overwrite CL's extended definition of `dolist', `dotimes',
-  ;; `declare', `push' and `pop'.
-(defmacro push (newelt listname)
-  "Add NEWELT to the list stored in the symbol LISTNAME.
-This is equivalent to (setq LISTNAME (cons NEWELT LISTNAME)).
-LISTNAME must be a symbol."
-  (declare (debug (form sexp)))
-  (list 'setq listname
-        (list 'cons newelt listname)))
-
-(defmacro pop (listname)
-  "Return the first element of LISTNAME's value, and remove it from the list.
-LISTNAME must be a symbol whose value is a list.
+(defmacro push (newelt place)
+  "Add NEWELT to the list stored in the generalized variable PLACE.
+This is morally equivalent to (setf PLACE (cons NEWELT PLACE)),
+except that PLACE is only evaluated once (after NEWELT)."
+  (declare (debug (form gv-place)))
+  (if (symbolp place)
+      ;; Important special case, to avoid triggering GV too early in
+      ;; the bootstrap.
+      (list 'setq place
+            (list 'cons newelt place))
+    (require 'macroexp)
+    (macroexp-let2 macroexp-copyable-p v newelt
+      (gv-letplace (getter setter) place
+        (funcall setter `(cons ,v ,getter))))))
+
+(defmacro pop (place)
+  "Return the first element of PLACE's value, and remove it from the list.
+PLACE must be a generalized variable whose value is a list.
 If the value is nil, `pop' returns nil but does not actually
 change the list."
-  (declare (debug (sexp)))
+  (declare (debug (gv-place)))
   (list 'car
-        (list 'prog1 listname
-              (list 'setq listname (list 'cdr listname)))))
-))
+        (if (symbolp place)
+            ;; So we can use `pop' in the bootstrap before `gv' can be used.
+            (list 'prog1 place (list 'setq place (list 'cdr place)))
+          (gv-letplace (getter setter) place
+            `(prog1 ,getter ,(funcall setter `(cdr ,getter)))))))
 
 (defmacro when (cond &rest body)
   "If COND yields non-nil, do BODY, else return nil.
@@ -189,8 +196,7 @@ value of last one, or nil if there are none.
 (if (null (featurep 'cl))
     (progn
   ;; If we reload subr.el after having loaded CL, be careful not to
-  ;; overwrite CL's extended definition of `dolist', `dotimes',
-  ;; `declare', `push' and `pop'.
+  ;; overwrite CL's extended definition of `dolist', `dotimes', `declare'.
 
 (defmacro dolist (spec &rest body)
   "Loop over a list.