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.
diff --git a/src/window.c b/src/window.c
index abdbd50..a1cda83 100644
--- a/src/window.c
+++ b/src/window.c
@@ -2438,6 +2438,9 @@
int help_window = FALSE;
tabpage_T *prev_curtab = curtab;
frame_T *win_frame = win->w_frame->fr_parent;
+#ifdef FEAT_DIFF
+ int had_diffmode = win->w_p_diff;
+#endif
if (ERROR_IF_POPUP_WINDOW)
return FAIL;
@@ -2625,6 +2628,23 @@
if (help_window)
restore_snapshot(SNAP_HELP_IDX, close_curwin);
+#ifdef FEAT_DIFF
+ // 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;
+ win_T *dwin;
+
+ FOR_ALL_WINDOWS(dwin)
+ if (dwin->w_p_diff)
+ ++diffcount;
+ if (diffcount == 1)
+ do_cmdline_cmd((char_u *)"diffoff!");
+ }
+#endif
+
#if defined(FEAT_GUI)
/* When 'guioptions' includes 'L' or 'R' may have to remove scrollbars. */
if (gui.in_use && !win_hasvertsplit())