RNA: Validate scene/view-layer combination for statistics query

Users may input an invalid scene/view-layer combination via Python. We
can easily detect that and fail gracefully.

Besides checking input parameters in RNA, also assert the
scene/view-layer combination is valid in lower level Depsgraph lookup
function (called by statistics query).

source/blender/blenkernel/BKE_scene.h

@@ -110,6 +110,8 @@ void BKE_toolsettings_free(struct ToolSettings *toolsettings);
 struct Scene *BKE_scene_duplicate(struct Main *bmain, struct Scene *sce, eSceneCopyMethod type);
 void BKE_scene_groups_relink(struct Scene *sce);
 
+struct Scene *BKE_scene_find_from_view_layer(const struct Main *bmain,
+                                             const struct ViewLayer *layer);
 struct Scene *BKE_scene_find_from_collection(const struct Main *bmain,
                                              const struct Collection *collection);
 

source/blender/blenkernel/intern/scene.c

@@ -1129,6 +1129,17 @@ int BKE_scene_base_iter_next(
   return iter->phase;
 }
 
+Scene *BKE_scene_find_from_view_layer(const Main *bmain, const ViewLayer *layer)
+{
+  for (Scene *scene = bmain->scenes.first; scene; scene = scene->id.next) {
+    if (BLI_findindex(&scene->view_layers, layer) != -1) {
+      return scene;
+    }
+  }
+
+  return NULL;
+}
+
 Scene *BKE_scene_find_from_collection(const Main *bmain, const Collection *collection)
 {
   for (Scene *scene = bmain->scenes.first; scene; scene = scene->id.next) {
@@ -2246,6 +2257,7 @@ static Depsgraph **scene_get_depsgraph_p(Main *bmain,
 {
   BLI_assert(scene != NULL);
   BLI_assert(view_layer != NULL);
+  BLI_assert(BKE_scene_find_from_view_layer(bmain, view_layer) == scene);
   /* Make sure hash itself exists. */
   if (allocate_ghash_entry) {
     BKE_scene_ensure_depsgraph_hash(scene);

source/blender/makesrna/intern/rna_scene.c

@@ -926,8 +926,18 @@ static void rna_Scene_volume_update(Main *UNUSED(bmain), Scene *UNUSED(scene), P
 
 static const char *rna_Scene_statistics_string_get(Scene *scene,
                                                    Main *bmain,
+                                                   ReportList *reports,
                                                    ViewLayer *view_layer)
 {
+  if (BKE_scene_find_from_view_layer(bmain, view_layer) != scene) {
+    BKE_reportf(reports,
+                RPT_ERROR,
+                "View Layer '%s' not found in scene '%s'",
+                view_layer->name,
+                scene->id.name + 2);
+    return "";
+  }
+
   return ED_info_statistics_string(bmain, scene, view_layer);
 }
 
@@ -7680,7 +7690,7 @@ void RNA_def_scene(BlenderRNA *brna)
 
   /* Statistics */
   func = RNA_def_function(srna, "statistics", "rna_Scene_statistics_string_get");
-  RNA_def_function_flag(func, FUNC_USE_MAIN);
+  RNA_def_function_flag(func, FUNC_USE_MAIN | FUNC_USE_REPORTS);
   parm = RNA_def_pointer(func, "view_layer", "ViewLayer", "View Layer", "");
   RNA_def_parameter_flags(parm, PROP_NEVER_NULL, PARM_REQUIRED);
   parm = RNA_def_string(func, "statistics", NULL, 0, "Statistics", "");