bug#33476: [PATCH] Fix occur revert with list-matching-lines-jump-to-current-line

[Raimon Grau]

Hello,

I reproduced this bug with Emacs 26.1 and 26.1.90 using -Q option.

When pressing 'g' (revert-buffer) in an *Occur* buffer, in the case of
having `list-matching-lines-jump-to-current-line' set to non-nil, the
function errors as it can't find orig-line.

I'm attaching a patch that adds a guard to the list of guards before
inserting the current line.

Cheers,

Raimon Grau

>From 2f874d70b6d69debd7370da562e768fc3b9b8198 Mon Sep 17 00:00:00 2001
From: Raimon Grau <raimonster@gmail.com>
Date: Fri, 23 Nov 2018 20:37:12 +0000
Subject: [PATCH] Guard occur against an undefined orig-line

* lisp/replace.el (occur-engine): Avoid inserting the current line if
orig-line is nil. This happens, for example, when reverting an occur
buffer with `list-matching-lines-jump-to-current-line' set to t.
---
 lisp/replace.el | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lisp/replace.el b/lisp/replace.el
index 940bf56..4f0cbf4 100644
--- a/lisp/replace.el
+++ b/lisp/replace.el
@@ -1748,6 +1748,7 @@ occur-engine
                           (when (and list-matching-lines-jump-to-current-line
                                      (not multi-occur-p)
                                      (not orig-line-shown-p)
+                                     orig-line
                                      (>= curr-line orig-line))
                             (insert
                              (concat
@@ -1774,7 +1775,8 @@ occur-engine
                   ;; Insert original line if haven't done yet.
                   (when (and list-matching-lines-jump-to-current-line
                              (not multi-occur-p)
-                             (not orig-line-shown-p))
+                             (not orig-line-shown-p)
+                             orig-line)
                     (with-current-buffer out-buf
                       (insert
                        (concat
-- 
2.7.4