1 files changed, 10 insertions, 13 deletions

diff --git a/lisp/emacs-lisp/bytecomp.el b/lisp/emacs-lisp/bytecomp.el
index d7140ad9e63..ee530f95d09 100644
--- a/lisp/emacs-lisp/bytecomp.el
+++ b/lisp/emacs-lisp/bytecomp.el
@@ -4943,8 +4943,6 @@ binding slots have been popped."
     (push (nth 1 (nth 1 form)) byte-compile-global-not-obsolete-vars))
   (byte-compile-normal-call form))
 
-(defconst byte-compile-tmp-var (make-symbol "def-tmp-var"))
-
 (defun byte-compile-defvar (form)
   ;; This is not used for file-level defvar/consts.
   (when (and (symbolp (nth 1 form))
@@ -4977,18 +4975,17 @@ binding slots have been popped."
        string
        "third arg to `%s %s' is not a string: %s"
        fun var string))
+    ;; Delegate the actual work to the function version of the
+    ;; special form, named with a "-1" suffix.
     (byte-compile-form-do-effect
-     (if (cddr form)  ; `value' provided
-         ;; Quote with `quote' to prevent byte-compiling the body,
-         ;; which would lead to an inf-loop.
-         `(funcall '(lambda (,byte-compile-tmp-var)
-                      (,fun ,var ,byte-compile-tmp-var ,@(nthcdr 3 form)))
-                   ,value)
-        (if (eq fun 'defconst)
-            ;; This will signal an appropriate error at runtime.
-            `(eval ',form)
-          ;; A simple (defvar foo) just returns foo.
-          `',var)))))
+     (cond
+      ((eq fun 'defconst) `(defconst-1 ',var ,@(nthcdr 2 form)))
+      ((not (cddr form)) `',var) ; A simple (defvar foo) just returns foo.
+      (t `(defvar-1 ',var
+                    ;; Don't eval `value' if `defvar' wouldn't eval it either.
+                    ,(if (macroexp-const-p value) value
+                       `(if (boundp ',var) nil ,value))
+                    ,@(nthcdr 3 form)))))))
 
 (defun byte-compile-autoload (form)
   (and (macroexp-const-p (nth 1 form))