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-rw-r--r--lisp/emacs-lisp/debug.el18
1 files changed, 15 insertions, 3 deletions
diff --git a/lisp/emacs-lisp/debug.el b/lisp/emacs-lisp/debug.el
index 88633eaaa46..28962595ace 100644
--- a/lisp/emacs-lisp/debug.el
+++ b/lisp/emacs-lisp/debug.el
@@ -118,6 +118,10 @@ first will be printed into the backtrace buffer."
(let (debugger-value
(debug-on-error nil)
(debug-on-quit nil)
+ (debugger-previous-state
+ (if (get-buffer "*Backtrace*")
+ (with-current-buffer (get-buffer "*Backtrace*")
+ (list major-mode (buffer-string)))))
(debugger-buffer (get-buffer-create "*Backtrace*"))
(debugger-old-buffer (current-buffer))
(debugger-step-after-exit nil)
@@ -214,8 +218,6 @@ first will be printed into the backtrace buffer."
;; recreate it every time the debugger stops, so instead we'll
;; erase it (and maybe hide it) but keep it alive.
(with-current-buffer debugger-buffer
- (erase-buffer)
- (fundamental-mode)
(with-selected-window (get-buffer-window debugger-buffer 0)
(when (and (window-dedicated-p (selected-window))
(not debugger-will-be-back))
@@ -232,7 +234,17 @@ first will be printed into the backtrace buffer."
;; to be left at the top-level, still working on how
;; best to do that.
(bury-buffer))))
- (kill-buffer debugger-buffer))
+ (unless debugger-previous-state
+ (kill-buffer debugger-buffer)))
+ ;; Restore the previous state of the debugger-buffer, in case we were
+ ;; in a recursive invocation of the debugger.
+ (when (and debugger-previous-state
+ (buffer-live-p debugger-buffer))
+ (with-current-buffer debugger-buffer
+ (let ((inhibit-read-only t))
+ (erase-buffer)
+ (insert (nth 1 debugger-previous-state))
+ (funcall (nth 0 debugger-previous-state)))))
(with-timeout-unsuspend debugger-with-timeout-suspend)
(set-match-data debugger-outer-match-data)))
;; Put into effect the modified values of these variables