From cb368e1bffe110a8b73b3c13e3780f2d587bbde2 Mon Sep 17 00:00:00 2001
From: Jan Edmund Lazo <jan.lazo@mail.utoronto.ca>
Date: Thu, 10 Jun 2021 08:27:18 -0400
Subject: vim-patch:8.2.1702: crash when using undo after deleting folded lines

Problem:    Crash when using undo after deleting folded lines.
Solution:   Check for NULL pointer. (closes vim/vim#6968)
https://github.com/vim/vim/commit/da697645d5917eb3d4168c06c3442bef9fb746bf
---
 src/nvim/fold.c                |  5 +++--
 src/nvim/testdir/test_fold.vim | 20 ++++++++++++++++++++
 2 files changed, 23 insertions(+), 2 deletions(-)

(limited to 'src')

diff --git a/src/nvim/fold.c b/src/nvim/fold.c
index 5032646d7e..ad8418034a 100644
--- a/src/nvim/fold.c
+++ b/src/nvim/fold.c
@@ -2227,8 +2227,9 @@ static linenr_T foldUpdateIEMSRecurse(
   if (getlevel == foldlevelMarker && flp->start <= flp->lvl - level
       && flp->lvl > 0) {
     (void)foldFind(gap, startlnum - 1, &fp);
-    if (fp >= ((fold_T *)gap->ga_data) + gap->ga_len
-        || fp->fd_top >= startlnum) {
+    if (fp != NULL
+        && (fp >= ((fold_T *)gap->ga_data) + gap->ga_len
+            || fp->fd_top >= startlnum)) {
       fp = NULL;
     }
   }
diff --git a/src/nvim/testdir/test_fold.vim b/src/nvim/testdir/test_fold.vim
index fcdf888b96..2cc5b47cb0 100644
--- a/src/nvim/testdir/test_fold.vim
+++ b/src/nvim/testdir/test_fold.vim
@@ -796,6 +796,26 @@ func Test_fold_delete_first_line()
   set foldmethod&
 endfunc
 
+func Test_undo_fold_deletion()
+  new
+  set fdm=marker
+  let lines =<< trim END
+      " {{{
+      " }}}1
+      " {{{
+  END
+  call setline(1, lines)
+  3d
+  g/"/d
+  undo
+  redo
+  " eval getline(1, '$')->assert_equal([''])
+  eval assert_equal(getline(1, '$'), [''])
+
+  set fdm&vim
+  bwipe!
+endfunc
+
 " this was crashing
 func Test_move_no_folds()
   new
-- 
cgit