Make LayoutNodeHelpers::composed_parent_node_ref be safe

For clarity, I introduce <LayoutDom<Element>>::parent_node_ref to contain
the remaining unsafety bits out of composed_parent_node_ref which is more
complex than just a field access.

1 files changed, 12 insertions, 5 deletions

diff --git a/components/script/dom/node.rs b/components/script/dom/node.rs
index a42f2371d3d..7348431d4f3 100644
--- a/components/script/dom/node.rs
+++ b/components/script/dom/node.rs
@@ -1307,7 +1307,7 @@ pub unsafe fn from_untrusted_node_address(
 pub trait LayoutNodeHelpers<'dom> {
     fn type_id_for_layout(self) -> NodeTypeId;
 
-    unsafe fn composed_parent_node_ref(self) -> Option<LayoutDom<'dom, Node>>;
+    fn composed_parent_node_ref(self) -> Option<LayoutDom<'dom, Node>>;
     fn first_child_ref(self) -> Option<LayoutDom<'dom, Node>>;
     fn last_child_ref(self) -> Option<LayoutDom<'dom, Node>>;
     fn prev_sibling_ref(self) -> Option<LayoutDom<'dom, Node>>;
@@ -1339,6 +1339,14 @@ pub trait LayoutNodeHelpers<'dom> {
     fn opaque(self) -> OpaqueNode;
 }
 
+impl<'dom> LayoutDom<'dom, Node> {
+    #[inline]
+    #[allow(unsafe_code)]
+    fn parent_node_ref(self) -> Option<LayoutDom<'dom, Node>> {
+        unsafe { self.unsafe_get().parent_node.get_inner_as_layout() }
+    }
+}
+
 impl<'dom> LayoutNodeHelpers<'dom> for LayoutDom<'dom, Node> {
     #[inline]
     #[allow(unsafe_code)]
@@ -1352,10 +1360,9 @@ impl<'dom> LayoutNodeHelpers<'dom> for LayoutDom<'dom, Node> {
     }
 
     #[inline]
-    #[allow(unsafe_code)]
-    unsafe fn composed_parent_node_ref(self) -> Option<LayoutDom<'dom, Node>> {
-        let parent = (*self.unsafe_get()).parent_node.get_inner_as_layout();
-        if let Some(ref parent) = parent {
+    fn composed_parent_node_ref(self) -> Option<LayoutDom<'dom, Node>> {
+        let parent = self.parent_node_ref();
+        if let Some(parent) = parent {
             if let Some(shadow_root) = parent.downcast::<ShadowRoot>() {
                 return Some(shadow_root.get_host_for_layout().upcast());
             }