Obsolete unused variable in debug.el

* lisp/emacs-lisp/debug.el (debugger-previous-backtrace): Make
unused variable obsolete.

1 files changed, 4 insertions, 4 deletions

diff --git a/lisp/emacs-lisp/debug.el b/lisp/emacs-lisp/debug.el
index 460057b3afd..f78d44cf98e 100644
--- a/lisp/emacs-lisp/debug.el
+++ b/lisp/emacs-lisp/debug.el
@@ -110,10 +110,6 @@ The value used here is passed to `quit-restore-window'."
 (defvar debugger-previous-window-height nil
   "The last recorded height of `debugger-previous-window'.")
 
-(defvar debugger-previous-backtrace nil
-  "The contents of the previous backtrace (including text properties).
-This is to optimize `debugger-make-xrefs'.")
-
 (defvar debugger-outer-match-data)
 (defvar debugger-will-be-back nil
   "Non-nil if we expect to get back in the debugger soon.")
@@ -836,6 +832,10 @@ To specify a nil argument interactively, exit with an empty minibuffer."
 ;;;###autoload
 (defalias 'cancel-debug-watch #'cancel-debug-on-variable-change)
 
+(make-obsolete-variable 'debugger-previous-backtrace
+                        "no longer used." "29.1")
+(defvar debugger-previous-backtrace nil)
+
 (provide 'debug)
 
 ;;; debug.el ends here