From 92ca51cc5e9d30818f5abf60a5a13f08f2ea7e96 Mon Sep 17 00:00:00 2001
From: Stefan Monnier <monnier@iro.umontreal.ca>
Date: Tue, 12 Dec 2017 22:40:27 -0500
Subject: [PATCH] * lisp/subr.el (backtrace--print-frame): Use cl-prin1

* lisp/emacs-lisp/cl-print.el (cl-prin1): Catch errors, since callers
generally don't expect errors.
---
 lisp/emacs-lisp/cl-print.el | 13 +++++++------
 lisp/subr.el                |  6 +++---
 2 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/lisp/emacs-lisp/cl-print.el b/lisp/emacs-lisp/cl-print.el
index 4fc178c29aa..5a26ecf05fe 100644
--- a/lisp/emacs-lisp/cl-print.el
+++ b/lisp/emacs-lisp/cl-print.el
@@ -269,12 +269,13 @@ Output is further controlled by the variables
 `cl-print-readably', `cl-print-compiled', along with output
 variables for the standard printing functions.  See Info
 node `(elisp)Output Variables'."
-  (cond
-   (cl-print-readably (prin1 object stream))
-   ((not print-circle) (cl-print-object object stream))
-   (t
-    (let ((cl-print--number-table (cl-print--preprocess object)))
-      (cl-print-object object stream)))))
+  (if cl-print-readably
+      (prin1 object stream)
+    (with-demoted-errors "cl-prin1: %S"
+      (if (not print-circle)
+          (cl-print-object object stream)
+        (let ((cl-print--number-table (cl-print--preprocess object)))
+          (cl-print-object object stream))))))
 
 ;;;###autoload
 (defun cl-prin1-to-string (object)
diff --git a/lisp/subr.el b/lisp/subr.el
index d6dceb79fa1..eca8dfdb857 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -4536,10 +4536,10 @@ EVALD, FUNC, ARGS, FLAGS are as in `mapbacktrace'."
   (princ (if (plist-get flags :debug-on-exit) "* " "  "))
   (cond
    ((and evald (not debugger-stack-frame-as-list))
-    (prin1 func)
-    (if args (prin1 args) (princ "()")))
+    (cl-prin1 func)
+    (if args (cl-prin1 args) (princ "()")))
    (t
-    (prin1 (cons func args))))
+    (cl-prin1 (cons func args))))
   (princ "\n"))
 
 (defun backtrace ()
-- 
2.11.4.GIT