Fix T81818: Outliner mode column crashes with shared object data

For objects with shared data, it makes sense to show the mode icon for
every object sharing the same data if one of them is in edit mode.

This also disables the "extend" functionality in this case, because
being in edit mode for multiple objects with the same data isn't
supported.

Differential Revision: https://developer.blender.org/D9273

1 files changed, 12 insertions, 2 deletions

diff --git a/source/blender/editors/space_outliner/outliner_draw.c b/source/blender/editors/space_outliner/outliner_draw.c
index 3045529747d..5a789ee0b01 100644
--- a/source/blender/editors/space_outliner/outliner_draw.c
+++ b/source/blender/editors/space_outliner/outliner_draw.c
@@ -1935,8 +1935,14 @@ static void outliner_mode_toggle_fn(bContext *C, void *tselem_poin, void *UNUSED
     return;
   }
 
+  /* Check that the the item is actually an object. */
+  BLI_assert(tselem->id != NULL && GS(tselem->id->name) == ID_OB);
+
+  Object *ob = (Object *)tselem->id;
+  const bool object_data_shared = (ob->data == tvc.obact->data);
+
   wmWindow *win = CTX_wm_window(C);
-  const bool do_extend = win->eventstate->ctrl != 0;
+  const bool do_extend = win->eventstate->ctrl != 0 && !object_data_shared;
   outliner_item_mode_toggle(C, &tvc, te, do_extend);
 }
 
@@ -1974,11 +1980,15 @@ static void outliner_draw_mode_column_toggle(uiBlock *block,
     draw_active_icon = false;
   }
 
+  const bool object_data_shared = (ob->data == ob_active->data);
+  draw_active_icon = draw_active_icon || object_data_shared;
+
   int icon;
   const char *tip;
   if (draw_active_icon) {
     icon = UI_icon_from_object_mode(ob_active->mode);
-    tip = TIP_("Remove from the current mode");
+    tip = object_data_shared ? TIP_("Change the object in the current mode") :
+                               TIP_("Remove from the current mode");
   }
   else {
     icon = ICON_DOT;