RNA: Cleanup PointerRNA struct

The old layout of `PointerRNA` was confusing for historic reasons:
```
typedef struct PointerRNA {
  struct {
    void *data;
  } id;

  struct StructRNA *type;
  void *data;
} PointerRNA;
```

This patch updates it to:
```
typedef struct PointerRNA {
  struct ID *owner_id;
  struct StructRNA *type;
  void *data;
} PointerRNA;
```

Throughout the code base `id.data` was replaced with `owner_id`.
Furthermore, many explicit pointer type casts were added which
were implicit before. Some type casts to `ID *` were removed.

Reviewers: brecht, campbellbarton

Differential Revision: https://developer.blender.org/D5558

3 files changed, 4 insertions, 4 deletions

diff --git a/source/blender/editors/space_outliner/outliner_edit.c b/source/blender/editors/space_outliner/outliner_edit.c
index 318d90d0dca..943993cb810 100644
--- a/source/blender/editors/space_outliner/outliner_edit.c
+++ b/source/blender/editors/space_outliner/outliner_edit.c
@@ -1780,7 +1780,7 @@ static void tree_element_to_path(TreeElement *te,
       /* no ID, so check if entry is RNA-struct,
        * and if that RNA-struct is an ID datablock to extract info from. */
       if (tse->type == TSE_RNA_STRUCT) {
-        /* ptr->data not ptr->id.data seems to be the one we want,
+        /* ptr->data not ptr->owner_id seems to be the one we want,
          * since ptr->data is sometimes the owner of this ID? */
         if (RNA_struct_is_ID(ptr->type)) {
           *id = (ID *)ptr->data;
diff --git a/source/blender/editors/space_outliner/outliner_tools.c b/source/blender/editors/space_outliner/outliner_tools.c
index 49f6189c17c..2c4a648da65 100644
--- a/source/blender/editors/space_outliner/outliner_tools.c
+++ b/source/blender/editors/space_outliner/outliner_tools.c
@@ -778,7 +778,7 @@ static void singleuser_action_cb(bContext *C,
 
   if (id) {
     IdAdtTemplate *iat = (IdAdtTemplate *)tsep->id;
-    PointerRNA ptr = {{NULL}};
+    PointerRNA ptr = {NULL};
     PropertyRNA *prop;
 
     RNA_pointer_create(&iat->id, &RNA_AnimData, iat->adt, &ptr);
@@ -801,7 +801,7 @@ static void singleuser_world_cb(bContext *C,
   /* need to use parent scene not just scene, otherwise may end up getting wrong one */
   if (id) {
     Scene *parscene = (Scene *)tsep->id;
-    PointerRNA ptr = {{NULL}};
+    PointerRNA ptr = {NULL};
     PropertyRNA *prop;
 
     RNA_id_pointer_create(&parscene->id, &ptr);
diff --git a/source/blender/editors/space_outliner/outliner_tree.c b/source/blender/editors/space_outliner/outliner_tree.c
index 3c693cc5e2b..c3168a7a532 100644
--- a/source/blender/editors/space_outliner/outliner_tree.c
+++ b/source/blender/editors/space_outliner/outliner_tree.c
@@ -766,7 +766,7 @@ static TreeElement *outliner_add_element(
   ID *id = idv;
 
   if (ELEM(type, TSE_RNA_STRUCT, TSE_RNA_PROPERTY, TSE_RNA_ARRAY_ELEM)) {
-    id = ((PointerRNA *)idv)->id.data;
+    id = ((PointerRNA *)idv)->owner_id;
     if (!id) {
       id = ((PointerRNA *)idv)->data;
     }