vim-patch:8.1.2289: after :diffsplit closing the window does not disable diff

Problem:    After :diffsplit closing the window does not disable diff.
Solution:   Add "closeoff" to 'diffopt' and add it to the default.
https://github.com/vim/vim/commit/c8234779790dd873acb88331c50988adf94cc383

1 files changed, 17 insertions, 0 deletions

diff --git a/src/nvim/window.c b/src/nvim/window.c
index 0531ad1938..2a7578e33c 100644
--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@@ -2418,6 +2418,7 @@ int win_close(win_T *win, bool free_buf)
   bool help_window = false;
   tabpage_T   *prev_curtab = curtab;
   frame_T *win_frame = win->w_floating ? NULL : win->w_frame->fr_parent;
+  const bool had_diffmode = win->w_p_diff;
 
   if (last_window() && !win->w_floating) {
     EMSG(_("E444: Cannot close last window"));
@@ -2642,6 +2643,22 @@ int win_close(win_T *win, bool free_buf)
   if (help_window)
     restore_snapshot(SNAP_HELP_IDX, close_curwin);
 
+  // If the window had 'diff' set and now there is only one window left in
+  // the tab page with 'diff' set, and "closeoff" is in 'diffopt', then
+  // execute ":diffoff!".
+  if (diffopt_closeoff() && had_diffmode && curtab == prev_curtab) {
+    int diffcount = 0;
+
+    FOR_ALL_WINDOWS_IN_TAB(dwin, curtab) {
+      if (dwin->w_p_diff) {
+        diffcount++;
+      }
+    }
+    if (diffcount == 1) {
+      do_cmdline_cmd("diffoff!");
+    }
+  }
+
   curwin->w_pos_changed = true;
   redraw_all_later(NOT_VALID);
   return OK;