From 3ef4ee84fa3f658c2df802569dc89023d98e9947 Mon Sep 17 00:00:00 2001
From: Daniel Colascione
Date: Tue, 8 Nov 2016 15:26:43 -0800
Subject: Avoid infloop in python

Fix bug#24905

* lisp/progmodes/python.el (python-info-docstring-p): Improve
infloop avoidance: replace (bobp) with generic test for
forward progress.
* test/lisp/progmodes/python-tests.el (python-bob-infloop-avoid): Add
test for bug#24905
---
 lisp/progmodes/python.el | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

(limited to 'lisp/progmodes/python.el')

diff --git a/lisp/progmodes/python.el b/lisp/progmodes/python.el
index 9091289b62e..d0d4a7f766e 100644
--- a/lisp/progmodes/python.el
+++ b/lisp/progmodes/python.el
@@ -4865,12 +4865,19 @@ point's current `syntax-ppss'."
              ;; Allow up to two consecutive docstrings only.
              (>=
               2
-              (progn
+              (let (last-backward-sexp-point)
                 (while (save-excursion
                          (python-nav-backward-sexp)
                          (setq backward-sexp-point (point))
                          (and (= indentation (current-indentation))
-                              (not (bobp)) ; Prevent infloop.
+                              ;; Make sure we're always moving point.
+                              ;; If we get stuck in the same position
+                              ;; on consecutive loop iterations,
+                              ;; bail out.
+                              (prog1 (not (eql last-backward-sexp-point
+                                               backward-sexp-point))
+                                (setq last-backward-sexp-point
+                                      backward-sexp-point))
                               (looking-at-p
                                (concat "[uU]?[rR]?"
                                        (python-rx string-delimiter)))))
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