* lisp/emacs-lisp/cl.el: Use lexical-binding. Fix flet.

(cl--symbol-function): New macro.
(cl--letf, cl--letf*): Use it.

Fixes: debbugs:11780

1 files changed, 17 insertions, 4 deletions

diff --git a/lisp/emacs-lisp/cl.el b/lisp/emacs-lisp/cl.el
index b17d6f4e671..7996af4e02d 100644
--- a/lisp/emacs-lisp/cl.el
+++ b/lisp/emacs-lisp/cl.el
@@ -1,4 +1,4 @@
-;;; cl.el --- Compatibility aliases for the old CL library.
+;;; cl.el --- Compatibility aliases for the old CL library.  -*- lexical-binding: t -*-
 
 ;; Copyright (C) 2012  Free Software Foundation, Inc.
 
@@ -235,7 +235,6 @@
                multiple-value-bind
                symbol-macrolet
                macrolet
-               flet
                progv
                psetq
                do-all-symbols
@@ -450,6 +449,16 @@ Common Lisp.
       (setq body (list `(lexical-let (,(pop bindings)) ,@body))))
     (car body)))
 
+(defmacro cl--symbol-function (symbol)
+  "Like `symbol-function' but return `cl--unbound' if not bound."
+  ;; (declare (gv-setter (lambda (store)
+  ;;                       `(if (eq ,store 'cl--unbound)
+  ;;                            (fmakunbound ,symbol) (fset ,symbol ,store)))))
+  `(if (fboundp ,symbol) (symbol-function ,symbol) 'cl--unbound))
+(gv-define-setter cl--symbol-function (store symbol)
+  `(if (eq ,store 'cl--unbound) (fmakunbound ,symbol) (fset ,symbol ,store)))
+
+
 ;; This should really have some way to shadow 'byte-compile properties, etc.
 (defmacro flet (bindings &rest body)
   "Make temporary function definitions.
@@ -543,6 +552,8 @@ Unlike `flet', this macro is fully compliant with the Common Lisp standard.
                                 (funcall setter vold)))
                        binds))))
     (let ((binding (car bindings)))
+      (if (eq (car-safe (car binding)) 'symbol-function)
+          (setcar (car binding) 'cl--symbol-function))
       (gv-letplace (getter setter) (car binding)
         (macroexp-let2 nil vnew (cadr binding)
           (if (symbolp (car binding))
@@ -579,7 +590,9 @@ the PLACE is not modified before executing BODY.
           ;; Special-case for simple variables.
           (macroexp-let* (list (if (cdr binding) binding
                                 (list (car binding) (car binding))))
-                        (cl--letf* (cdr bindings) body))
+                         (cl--letf* (cdr bindings) body))
+        (if (eq (car-safe (car binding)) 'symbol-function)
+            (setcar (car binding) 'cl--symbol-function))
         (gv-letplace (getter setter) (car binding)
           (macroexp-let2 macroexp-copyable-p vnew (cadr binding)
             (macroexp-let2 nil vold getter
@@ -736,7 +749,7 @@ from ARGLIST using FUNC: (define-modify-macro incf (&optional (n 1)) +)"
 ;; This is just kept for compatibility with code byte-compiled by Emacs-20.
 
 ;; No idea if this might still be needed.
-(defun cl-not-hash-table (x &optional y &rest z)
+(defun cl-not-hash-table (x &optional y &rest _z)
   (declare (obsolete nil "24.2"))
   (signal 'wrong-type-argument (list 'cl-hash-table-p (or y x))))