script: Make layout DOM wrappers not generic on layout data (#31994)

Remove the type parameter from the layout DOM wrappers. This is possible
now that style and layout data are separate and the `Any` nature of the
layout data is exposed in the wrappers.

Removing the phantom data member of the wrappers also allows using the
default `derive` implementations for things like `Clone`, `Copy`, and
`PartialEq`.

components/script/layout_dom/document.rs

@@ -2,9 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
-use std::marker::PhantomData;
-
-use script_layout_interface::wrapper_traits::LayoutDataTrait;
 use selectors::matching::QuirksMode;
 use style::dom::{TDocument, TNode};
 use style::shared_lock::{
@@ -18,25 +15,14 @@ use crate::dom::node::{LayoutNodeHelpers, Node, NodeFlags};
 use crate::layout_dom::{ServoLayoutElement, ServoLayoutNode, ServoShadowRoot};
 
 // A wrapper around documents that ensures ayout can only ever access safe properties.
-pub struct ServoLayoutDocument<'dom, LayoutDataType: LayoutDataTrait> {
+#[derive(Clone, Copy)]
+pub struct ServoLayoutDocument<'dom> {
     /// The wrapped private DOM Document
     document: LayoutDom<'dom, Document>,
-
-    /// A PhantomData that is used to track the type of the stored layout data.
-    phantom: PhantomData<LayoutDataType>,
 }
 
-impl<'dom, LayoutDataType: LayoutDataTrait> Clone for ServoLayoutDocument<'dom, LayoutDataType> {
-    fn clone(&self) -> Self {
-        *self
-    }
-}
-impl<'dom, LayoutDataType: LayoutDataTrait> Copy for ServoLayoutDocument<'dom, LayoutDataType> {}
-
-impl<'ld, LayoutDataType: LayoutDataTrait> ::style::dom::TDocument
-    for ServoLayoutDocument<'ld, LayoutDataType>
-{
-    type ConcreteNode = ServoLayoutNode<'ld, LayoutDataType>;
+impl<'ld> ::style::dom::TDocument for ServoLayoutDocument<'ld> {
+    type ConcreteNode = ServoLayoutNode<'ld>;
 
     fn as_node(&self) -> Self::ConcreteNode {
         ServoLayoutNode::from_layout_js(self.document.upcast())
@@ -55,8 +41,8 @@ impl<'ld, LayoutDataType: LayoutDataTrait> ::style::dom::TDocument
     }
 }
 
-impl<'ld, LayoutDataType: LayoutDataTrait> ServoLayoutDocument<'ld, LayoutDataType> {
-    pub fn root_element(&self) -> Option<ServoLayoutElement<'ld, LayoutDataType>> {
+impl<'ld> ServoLayoutDocument<'ld> {
+    pub fn root_element(&self) -> Option<ServoLayoutElement<'ld>> {
         self.as_node()
             .dom_children()
             .flat_map(|n| n.as_element())
@@ -75,7 +61,7 @@ impl<'ld, LayoutDataType: LayoutDataTrait> ServoLayoutDocument<'ld, LayoutDataTy
         self.document.style_shared_lock()
     }
 
-    pub fn shadow_roots(&self) -> Vec<ServoShadowRoot<LayoutDataType>> {
+    pub fn shadow_roots(&self) -> Vec<ServoShadowRoot> {
         unsafe {
             self.document
                 .shadow_roots()
@@ -104,10 +90,7 @@ impl<'ld, LayoutDataType: LayoutDataTrait> ServoLayoutDocument<'ld, LayoutDataTy
         }
     }
 
-    pub fn from_layout_js(doc: LayoutDom<'ld, Document>) -> Self {
-        ServoLayoutDocument {
-            document: doc,
-            phantom: PhantomData,
-        }
+    pub fn from_layout_js(document: LayoutDom<'ld, Document>) -> Self {
+        ServoLayoutDocument { document }
     }
 }

components/script/layout_dom/element.rs

@@ -3,14 +3,13 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 use std::fmt;
-use std::hash::{Hash, Hasher};
-use std::marker::PhantomData;
+use std::hash::Hash;
 use std::sync::atomic::Ordering;
 
 use atomic_refcell::{AtomicRef, AtomicRefMut};
 use html5ever::{local_name, namespace_url, ns, LocalName, Namespace};
 use script_layout_interface::wrapper_traits::{
-    LayoutDataTrait, LayoutNode, PseudoElementType, ThreadSafeLayoutElement, ThreadSafeLayoutNode,
+    LayoutNode, PseudoElementType, ThreadSafeLayoutElement, ThreadSafeLayoutNode,
 };
 use script_layout_interface::{LayoutNodeType, StyleData};
 use selectors::attr::{AttrSelectorOperation, CaseSensitivity, NamespaceConstraint};
@@ -49,39 +48,13 @@ use crate::dom::node::{LayoutNodeHelpers, NodeFlags};
 use crate::layout_dom::{ServoLayoutNode, ServoShadowRoot, ServoThreadSafeLayoutNode};
 
 /// A wrapper around elements that ensures layout can only ever access safe properties.
-pub struct ServoLayoutElement<'dom, LayoutDataType: LayoutDataTrait> {
+#[derive(Clone, Copy, Eq, Hash, PartialEq)]
+pub struct ServoLayoutElement<'dom> {
     /// The wrapped private DOM Element.
     element: LayoutDom<'dom, Element>,
-
-    /// A PhantomData that is used to track the type of the stored layout data.
-    phantom: PhantomData<LayoutDataType>,
 }
 
-// These impls are required because `derive` has trouble with PhantomData.
-// See https://github.com/rust-lang/rust/issues/52079
-impl<'dom, LayoutDataType: LayoutDataTrait> Clone for ServoLayoutElement<'dom, LayoutDataType> {
-    fn clone(&self) -> Self {
-        *self
-    }
-}
-impl<'dom, LayoutDataType: LayoutDataTrait> Copy for ServoLayoutElement<'dom, LayoutDataType> {}
-impl<'dom, LayoutDataType: LayoutDataTrait> PartialEq for ServoLayoutElement<'dom, LayoutDataType> {
-    #[inline]
-    fn eq(&self, other: &Self) -> bool {
-        self.as_node() == other.as_node()
-    }
-}
-
-// `Hash` + `Eq` + `Debug` are required by ::style::dom::TElement.
-impl<'dom, LayoutDataType: LayoutDataTrait> Eq for ServoLayoutElement<'dom, LayoutDataType> {}
-impl<'dom, LayoutDataType: LayoutDataTrait> Hash for ServoLayoutElement<'dom, LayoutDataType> {
-    fn hash<H: Hasher>(&self, state: &mut H) {
-        self.element.hash(state);
-    }
-}
-impl<'dom, LayoutDataType: LayoutDataTrait> fmt::Debug
-    for ServoLayoutElement<'dom, LayoutDataType>
-{
+impl<'dom> fmt::Debug for ServoLayoutElement<'dom> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         write!(f, "<{}", self.element.local_name())?;
         if let Some(id) = self.id() {
@@ -91,12 +64,9 @@ impl<'dom, LayoutDataType: LayoutDataTrait> fmt::Debug
     }
 }
 
-impl<'dom, LayoutDataType: LayoutDataTrait> ServoLayoutElement<'dom, LayoutDataType> {
+impl<'dom> ServoLayoutElement<'dom> {
     pub(super) fn from_layout_js(el: LayoutDom<'dom, Element>) -> Self {
-        ServoLayoutElement {
-            element: el,
-            phantom: PhantomData,
-        }
+        ServoLayoutElement { element: el }
     }
 
     #[inline]
@@ -152,13 +122,11 @@ impl<'dom, LayoutDataType: LayoutDataTrait> ServoLayoutElement<'dom, LayoutDataT
     }
 }
 
-impl<'dom, LayoutDataType: LayoutDataTrait> style::dom::TElement
-    for ServoLayoutElement<'dom, LayoutDataType>
-{
-    type ConcreteNode = ServoLayoutNode<'dom, LayoutDataType>;
+impl<'dom> style::dom::TElement for ServoLayoutElement<'dom> {
+    type ConcreteNode = ServoLayoutNode<'dom>;
     type TraversalChildrenIterator = DomChildren<Self::ConcreteNode>;
 
-    fn as_node(&self) -> ServoLayoutNode<'dom, LayoutDataType> {
+    fn as_node(&self) -> ServoLayoutNode<'dom> {
         ServoLayoutNode::from_layout_js(self.element.upcast())
     }
 
@@ -413,14 +381,14 @@ impl<'dom, LayoutDataType: LayoutDataTrait> style::dom::TElement
     }
 
     /// The shadow root this element is a host of.
-    fn shadow_root(&self) -> Option<ServoShadowRoot<'dom, LayoutDataType>> {
+    fn shadow_root(&self) -> Option<ServoShadowRoot<'dom>> {
         self.element
             .get_shadow_root_for_layout()
             .map(ServoShadowRoot::from_layout_js)
     }
 
     /// The shadow root which roots the subtree this element is contained in.
-    fn containing_shadow(&self) -> Option<ServoShadowRoot<'dom, LayoutDataType>> {
+    fn containing_shadow(&self) -> Option<ServoShadowRoot<'dom>> {
         self.element
             .upcast()
             .containing_shadow_root_for_layout()
@@ -458,9 +426,7 @@ impl<'dom, LayoutDataType: LayoutDataTrait> style::dom::TElement
     }
 }
 
-impl<'dom, LayoutDataType: LayoutDataTrait> ::selectors::Element
-    for ServoLayoutElement<'dom, LayoutDataType>
-{
+impl<'dom> ::selectors::Element for ServoLayoutElement<'dom> {
     type Impl = SelectorImpl;
 
     fn opaque(&self) -> ::selectors::OpaqueElement {
@@ -496,7 +462,7 @@ impl<'dom, LayoutDataType: LayoutDataTrait> ::selectors::Element
         None
     }
 
-    fn next_sibling_element(&self) -> Option<ServoLayoutElement<'dom, LayoutDataType>> {
+    fn next_sibling_element(&self) -> Option<ServoLayoutElement<'dom>> {
         let mut node = self.as_node();
         while let Some(sibling) = node.next_sibling() {
             if let Some(element) = sibling.as_element() {
@@ -689,42 +655,20 @@ impl<'dom, LayoutDataType: LayoutDataTrait> ::selectors::Element
 
 /// A wrapper around elements that ensures layout can only
 /// ever access safe properties and cannot race on elements.
-pub struct ServoThreadSafeLayoutElement<'dom, LayoutDataType: LayoutDataTrait> {
-    pub(super) element: ServoLayoutElement<'dom, LayoutDataType>,
+#[derive(Clone, Copy, Debug)]
+pub struct ServoThreadSafeLayoutElement<'dom> {
+    pub(super) element: ServoLayoutElement<'dom>,
 
     /// The pseudo-element type, with (optionally)
     /// a specified display value to override the stylesheet.
     pub(super) pseudo: PseudoElementType,
 }
 
-// These impls are required because `derive` has trouble with PhantomData.
-// See https://github.com/rust-lang/rust/issues/52079
-impl<'dom, LayoutDataType: LayoutDataTrait> Clone
-    for ServoThreadSafeLayoutElement<'dom, LayoutDataType>
-{
-    fn clone(&self) -> Self {
-        *self
-    }
-}
-impl<'dom, LayoutDataType: LayoutDataTrait> Copy
-    for ServoThreadSafeLayoutElement<'dom, LayoutDataType>
-{
-}
-impl<'dom, LayoutDataType: LayoutDataTrait> fmt::Debug
-    for ServoThreadSafeLayoutElement<'dom, LayoutDataType>
-{
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        self.element.fmt(f)
-    }
-}
+impl<'dom> ThreadSafeLayoutElement<'dom> for ServoThreadSafeLayoutElement<'dom> {
+    type ConcreteThreadSafeLayoutNode = ServoThreadSafeLayoutNode<'dom>;
+    type ConcreteElement = ServoLayoutElement<'dom>;
 
-impl<'dom, LayoutDataType: LayoutDataTrait> ThreadSafeLayoutElement<'dom>
-    for ServoThreadSafeLayoutElement<'dom, LayoutDataType>
-{
-    type ConcreteThreadSafeLayoutNode = ServoThreadSafeLayoutNode<'dom, LayoutDataType>;
-    type ConcreteElement = ServoLayoutElement<'dom, LayoutDataType>;
-
-    fn as_node(&self) -> ServoThreadSafeLayoutNode<'dom, LayoutDataType> {
+    fn as_node(&self) -> ServoThreadSafeLayoutNode<'dom> {
         ServoThreadSafeLayoutNode {
             node: self.element.as_node(),
             pseudo: self.pseudo,
@@ -746,7 +690,7 @@ impl<'dom, LayoutDataType: LayoutDataTrait> ThreadSafeLayoutElement<'dom>
         self.as_node().type_id()
     }
 
-    fn unsafe_get(self) -> ServoLayoutElement<'dom, LayoutDataType> {
+    fn unsafe_get(self) -> ServoLayoutElement<'dom> {
         self.element
     }
 
@@ -787,9 +731,7 @@ impl<'dom, LayoutDataType: LayoutDataTrait> ThreadSafeLayoutElement<'dom>
 ///
 /// Note that the element implementation is needed only for selector matching,
 /// not for inheritance (styles are inherited appropriately).
-impl<'dom, LayoutDataType: LayoutDataTrait> ::selectors::Element
-    for ServoThreadSafeLayoutElement<'dom, LayoutDataType>
-{
+impl<'dom> ::selectors::Element for ServoThreadSafeLayoutElement<'dom> {
     type Impl = SelectorImpl;
 
     fn opaque(&self) -> ::selectors::OpaqueElement {

components/script/layout_dom/node.rs

@@ -6,7 +6,6 @@
 
 use std::borrow::Cow;
 use std::fmt;
-use std::marker::PhantomData;
 use std::sync::Arc as StdArc;
 
 use gfx_traits::ByteIndex;
@@ -44,12 +43,10 @@ use crate::dom::text::Text;
 /// several style and selectors traits for use during layout. This version
 /// should only be used on a single thread. If you need to use nodes across
 /// threads use ServoThreadSafeLayoutNode.
-pub struct ServoLayoutNode<'dom, LayoutDataType: LayoutDataTrait> {
+#[derive(Clone, Copy, PartialEq)]
+pub struct ServoLayoutNode<'dom> {
     /// The wrapped private DOM node.
     pub(super) node: LayoutDom<'dom, Node>,
-
-    /// A PhantomData that is used to track the type of the stored layout data.
-    pub(super) phantom: PhantomData<LayoutDataType>,
 }
 
 /// Those are supposed to be sound, but they aren't because the entire system
@@ -58,25 +55,10 @@ pub struct ServoLayoutNode<'dom, LayoutDataType: LayoutDataTrait> {
 ///
 /// FIXME(mrobinson): These are required because Layout 2020 sends non-threadsafe
 /// nodes to different threads. This should be adressed in a comprehensive way.
-unsafe impl<LayoutDataType: LayoutDataTrait> Send for ServoLayoutNode<'_, LayoutDataType> {}
-unsafe impl<LayoutDataType: LayoutDataTrait> Sync for ServoLayoutNode<'_, LayoutDataType> {}
+unsafe impl Send for ServoLayoutNode<'_> {}
+unsafe impl Sync for ServoLayoutNode<'_> {}
 
-// These impls are required because `derive` has trouble with PhantomData.
-// See https://github.com/rust-lang/rust/issues/52079
-impl<'dom, LayoutDataType: LayoutDataTrait> Clone for ServoLayoutNode<'dom, LayoutDataType> {
-    fn clone(&self) -> Self {
-        *self
-    }
-}
-impl<'dom, LayoutDataType: LayoutDataTrait> Copy for ServoLayoutNode<'dom, LayoutDataType> {}
-impl<'a, LayoutDataType: LayoutDataTrait> PartialEq for ServoLayoutNode<'a, LayoutDataType> {
-    #[inline]
-    fn eq(&self, other: &Self) -> bool {
-        self.node == other.node
-    }
-}
-
-impl<'dom, LayoutDataType: LayoutDataTrait> fmt::Debug for ServoLayoutNode<'dom, LayoutDataType> {
+impl<'dom> fmt::Debug for ServoLayoutNode<'dom> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         if let Some(el) = self.as_element() {
             el.fmt(f)
@@ -88,12 +70,9 @@ impl<'dom, LayoutDataType: LayoutDataTrait> fmt::Debug for ServoLayoutNode<'dom,
     }
 }
 
-impl<'dom, LayoutDataType: LayoutDataTrait> ServoLayoutNode<'dom, LayoutDataType> {
+impl<'dom> ServoLayoutNode<'dom> {
     pub(super) fn from_layout_js(n: LayoutDom<'dom, Node>) -> Self {
-        ServoLayoutNode {
-            node: n,
-            phantom: PhantomData,
-        }
+        ServoLayoutNode { node: n }
     }
 
     pub unsafe fn new(address: &TrustedNodeAddress) -> Self {
@@ -110,9 +89,7 @@ impl<'dom, LayoutDataType: LayoutDataTrait> ServoLayoutNode<'dom, LayoutDataType
     }
 }
 
-impl<'dom, LayoutDataType: LayoutDataTrait> style::dom::NodeInfo
-    for ServoLayoutNode<'dom, LayoutDataType>
-{
+impl<'dom> style::dom::NodeInfo for ServoLayoutNode<'dom> {
     fn is_element(&self) -> bool {
         self.node.is_element_for_layout()
     }
@@ -123,12 +100,10 @@ impl<'dom, LayoutDataType: LayoutDataTrait> style::dom::NodeInfo
     }
 }
 
-impl<'dom, LayoutDataType: LayoutDataTrait> style::dom::TNode
-    for ServoLayoutNode<'dom, LayoutDataType>
-{
-    type ConcreteDocument = ServoLayoutDocument<'dom, LayoutDataType>;
-    type ConcreteElement = ServoLayoutElement<'dom, LayoutDataType>;
-    type ConcreteShadowRoot = ServoShadowRoot<'dom, LayoutDataType>;
+impl<'dom> style::dom::TNode for ServoLayoutNode<'dom> {
+    type ConcreteDocument = ServoLayoutDocument<'dom>;
+    type ConcreteElement = ServoLayoutElement<'dom>;
+    type ConcreteShadowRoot = ServoShadowRoot<'dom>;
 
     fn parent_node(&self) -> Option<Self> {
         self.node
@@ -156,7 +131,7 @@ impl<'dom, LayoutDataType: LayoutDataTrait> style::dom::TNode
         ServoLayoutDocument::from_layout_js(self.node.owner_doc_for_layout())
     }
 
-    fn traversal_parent(&self) -> Option<ServoLayoutElement<'dom, LayoutDataType>> {
+    fn traversal_parent(&self) -> Option<ServoLayoutElement<'dom>> {
         let parent = self.parent_node()?;
         if let Some(shadow) = parent.as_shadow_root() {
             return Some(shadow.host());
@@ -172,17 +147,17 @@ impl<'dom, LayoutDataType: LayoutDataTrait> style::dom::TNode
         self.opaque().0
     }
 
-    fn as_element(&self) -> Option<ServoLayoutElement<'dom, LayoutDataType>> {
+    fn as_element(&self) -> Option<ServoLayoutElement<'dom>> {
         self.node.downcast().map(ServoLayoutElement::from_layout_js)
     }
 
-    fn as_document(&self) -> Option<ServoLayoutDocument<'dom, LayoutDataType>> {
+    fn as_document(&self) -> Option<ServoLayoutDocument<'dom>> {
         self.node
             .downcast()
             .map(ServoLayoutDocument::from_layout_js)
     }
 
-    fn as_shadow_root(&self) -> Option<ServoShadowRoot<'dom, LayoutDataType>> {
+    fn as_shadow_root(&self) -> Option<ServoShadowRoot<'dom>> {
         self.node.downcast().map(ServoShadowRoot::from_layout_js)
     }
 
@@ -191,10 +166,8 @@ impl<'dom, LayoutDataType: LayoutDataTrait> style::dom::TNode
     }
 }
 
-impl<'dom, LayoutDataType: LayoutDataTrait> LayoutNode<'dom>
-    for ServoLayoutNode<'dom, LayoutDataType>
-{
-    type ConcreteThreadSafeLayoutNode = ServoThreadSafeLayoutNode<'dom, LayoutDataType>;
+impl<'dom> LayoutNode<'dom> for ServoLayoutNode<'dom> {
+    type ConcreteThreadSafeLayoutNode = ServoThreadSafeLayoutNode<'dom>;
 
     fn to_threadsafe(&self) -> Self::ConcreteThreadSafeLayoutNode {
         ServoThreadSafeLayoutNode::new(*self)
@@ -239,48 +212,19 @@ impl<'dom, LayoutDataType: LayoutDataTrait> LayoutNode<'dom>
 /// A wrapper around a `ServoLayoutNode` that can be used safely on different threads.
 /// It's very important that this never mutate anything except this wrapped node and
 /// never access any other node apart from its parent.
-pub struct ServoThreadSafeLayoutNode<'dom, LayoutDataType: LayoutDataTrait> {
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct ServoThreadSafeLayoutNode<'dom> {
     /// The wrapped `ServoLayoutNode`.
-    pub(super) node: ServoLayoutNode<'dom, LayoutDataType>,
+    pub(super) node: ServoLayoutNode<'dom>,
 
     /// The pseudo-element type, with (optionally)
     /// a specified display value to override the stylesheet.
     pub(super) pseudo: PseudoElementType,
 }
 
-// These impls are required because `derive` has trouble with PhantomData.
-// See https://github.com/rust-lang/rust/issues/52079
-impl<'dom, LayoutDataType: LayoutDataTrait> Clone
-    for ServoThreadSafeLayoutNode<'dom, LayoutDataType>
-{
-    fn clone(&self) -> Self {
-        *self
-    }
-}
-impl<'dom, LayoutDataType: LayoutDataTrait> Copy
-    for ServoThreadSafeLayoutNode<'dom, LayoutDataType>
-{
-}
-impl<'a, LayoutDataType: LayoutDataTrait> PartialEq
-    for ServoThreadSafeLayoutNode<'a, LayoutDataType>
-{
-    #[inline]
-    fn eq(&self, other: &Self) -> bool {
-        self.node == other.node
-    }
-}
-
-impl<'lr, LayoutDataType: LayoutDataTrait> fmt::Debug
-    for ServoThreadSafeLayoutNode<'lr, LayoutDataType>
-{
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        self.node.fmt(f)
-    }
-}
-
-impl<'dom, LayoutDataType: LayoutDataTrait> ServoThreadSafeLayoutNode<'dom, LayoutDataType> {
+impl<'dom> ServoThreadSafeLayoutNode<'dom> {
     /// Creates a new `ServoThreadSafeLayoutNode` from the given `ServoLayoutNode`.
-    pub fn new(node: ServoLayoutNode<'dom, LayoutDataType>) -> Self {
+    pub fn new(node: ServoLayoutNode<'dom>) -> Self {
         ServoThreadSafeLayoutNode {
             node,
             pseudo: PseudoElementType::Normal,
@@ -312,9 +256,7 @@ impl<'dom, LayoutDataType: LayoutDataTrait> ServoThreadSafeLayoutNode<'dom, Layo
     }
 }
 
-impl<'dom, LayoutDataType: LayoutDataTrait> style::dom::NodeInfo
-    for ServoThreadSafeLayoutNode<'dom, LayoutDataType>
-{
+impl<'dom> style::dom::NodeInfo for ServoThreadSafeLayoutNode<'dom> {
     fn is_element(&self) -> bool {
         self.node.is_element()
     }
@@ -324,13 +266,11 @@ impl<'dom, LayoutDataType: LayoutDataTrait> style::dom::NodeInfo
     }
 }
 
-impl<'dom, LayoutDataType: LayoutDataTrait> ThreadSafeLayoutNode<'dom>
-    for ServoThreadSafeLayoutNode<'dom, LayoutDataType>
-{
-    type ConcreteNode = ServoLayoutNode<'dom, LayoutDataType>;
-    type ConcreteThreadSafeLayoutElement = ServoThreadSafeLayoutElement<'dom, LayoutDataType>;
-    type ConcreteElement = ServoLayoutElement<'dom, LayoutDataType>;
-    type ChildrenIterator = ServoThreadSafeLayoutNodeChildrenIterator<'dom, LayoutDataType>;
+impl<'dom> ThreadSafeLayoutNode<'dom> for ServoThreadSafeLayoutNode<'dom> {
+    type ConcreteNode = ServoLayoutNode<'dom>;
+    type ConcreteThreadSafeLayoutElement = ServoThreadSafeLayoutElement<'dom>;
+    type ConcreteElement = ServoLayoutElement<'dom>;
+    type ChildrenIterator = ServoThreadSafeLayoutNodeChildrenIterator<'dom>;
 
     fn opaque(&self) -> style::dom::OpaqueNode {
         unsafe { self.get_jsmanaged().opaque() }
@@ -363,7 +303,7 @@ impl<'dom, LayoutDataType: LayoutDataTrait> ThreadSafeLayoutNode<'dom>
         style::dom::LayoutIterator(ServoThreadSafeLayoutNodeChildrenIterator::new(*self))
     }
 
-    fn as_element(&self) -> Option<ServoThreadSafeLayoutElement<'dom, LayoutDataType>> {
+    fn as_element(&self) -> Option<ServoThreadSafeLayoutElement<'dom>> {
         self.node
             .as_element()
             .map(|el| ServoThreadSafeLayoutElement {
@@ -494,15 +434,13 @@ impl<'dom, LayoutDataType: LayoutDataTrait> ThreadSafeLayoutNode<'dom>
     }
 }
 
-pub struct ServoThreadSafeLayoutNodeChildrenIterator<'dom, LayoutDataType: LayoutDataTrait> {
-    current_node: Option<ServoThreadSafeLayoutNode<'dom, LayoutDataType>>,
-    parent_node: ServoThreadSafeLayoutNode<'dom, LayoutDataType>,
+pub struct ServoThreadSafeLayoutNodeChildrenIterator<'dom> {
+    current_node: Option<ServoThreadSafeLayoutNode<'dom>>,
+    parent_node: ServoThreadSafeLayoutNode<'dom>,
 }
 
-impl<'dom, LayoutDataType: LayoutDataTrait>
-    ServoThreadSafeLayoutNodeChildrenIterator<'dom, LayoutDataType>
-{
-    pub fn new(parent: ServoThreadSafeLayoutNode<'dom, LayoutDataType>) -> Self {
+impl<'dom> ServoThreadSafeLayoutNodeChildrenIterator<'dom> {
+    pub fn new(parent: ServoThreadSafeLayoutNode<'dom>) -> Self {
         let first_child = match parent.get_pseudo_element_type() {
             PseudoElementType::Normal => parent
                 .get_before_pseudo()
@@ -520,11 +458,9 @@ impl<'dom, LayoutDataType: LayoutDataTrait>
     }
 }
 
-impl<'dom, LayoutDataType: LayoutDataTrait> Iterator
-    for ServoThreadSafeLayoutNodeChildrenIterator<'dom, LayoutDataType>
-{
-    type Item = ServoThreadSafeLayoutNode<'dom, LayoutDataType>;
-    fn next(&mut self) -> Option<ServoThreadSafeLayoutNode<'dom, LayoutDataType>> {
+impl<'dom> Iterator for ServoThreadSafeLayoutNodeChildrenIterator<'dom> {
+    type Item = ServoThreadSafeLayoutNode<'dom>;
+    fn next(&mut self) -> Option<ServoThreadSafeLayoutNode<'dom>> {
         use selectors::Element;
         match self.parent_node.get_pseudo_element_type() {
             PseudoElementType::Before | PseudoElementType::After => None,

components/script/layout_dom/shadow_root.rs

@@ -3,9 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 use std::fmt;
-use std::marker::PhantomData;
 
-use script_layout_interface::wrapper_traits::LayoutDataTrait;
 use style::dom::TShadowRoot;
 use style::shared_lock::SharedRwLockReadGuard as StyleSharedRwLockReadGuard;
 use style::stylist::{CascadeData, Stylist};
@@ -14,44 +12,26 @@ use crate::dom::bindings::root::LayoutDom;
 use crate::dom::shadowroot::{LayoutShadowRootHelpers, ShadowRoot};
 use crate::layout_dom::{ServoLayoutElement, ServoLayoutNode};
 
-pub struct ServoShadowRoot<'dom, LayoutDataType: LayoutDataTrait> {
+#[derive(Clone, Copy, PartialEq)]
+pub struct ServoShadowRoot<'dom> {
     /// The wrapped private DOM ShadowRoot.
     shadow_root: LayoutDom<'dom, ShadowRoot>,
-
-    /// A PhantomData that is used to track the type of the stored layout data.
-    phantom: PhantomData<LayoutDataType>,
 }
 
-impl<'dom, LayoutDataType: LayoutDataTrait> Clone for ServoShadowRoot<'dom, LayoutDataType> {
-    fn clone(&self) -> Self {
-        *self
-    }
-}
-impl<'dom, LayoutDataType: LayoutDataTrait> Copy for ServoShadowRoot<'dom, LayoutDataType> {}
-
-impl<'a, LayoutDataType: LayoutDataTrait> PartialEq for ServoShadowRoot<'a, LayoutDataType> {
-    #[inline]
-    fn eq(&self, other: &Self) -> bool {
-        self.shadow_root == other.shadow_root
-    }
-}
-
-impl<'dom, LayoutDataType: LayoutDataTrait> fmt::Debug for ServoShadowRoot<'dom, LayoutDataType> {
+impl<'dom> fmt::Debug for ServoShadowRoot<'dom> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         self.as_node().fmt(f)
     }
 }
 
-impl<'dom, LayoutDataType: LayoutDataTrait> ::style::dom::TShadowRoot
-    for ServoShadowRoot<'dom, LayoutDataType>
-{
-    type ConcreteNode = ServoLayoutNode<'dom, LayoutDataType>;
+impl<'dom> TShadowRoot for ServoShadowRoot<'dom> {
+    type ConcreteNode = ServoLayoutNode<'dom>;
 
     fn as_node(&self) -> Self::ConcreteNode {
         ServoLayoutNode::from_layout_js(self.shadow_root.upcast())
     }
 
-    fn host(&self) -> ServoLayoutElement<'dom, LayoutDataType> {
+    fn host(&self) -> ServoLayoutElement<'dom> {
         ServoLayoutElement::from_layout_js(self.shadow_root.get_host_for_layout())
     }
 
@@ -63,12 +43,9 @@ impl<'dom, LayoutDataType: LayoutDataTrait> ::style::dom::TShadowRoot
     }
 }
 
-impl<'dom, LayoutDataType: LayoutDataTrait> ServoShadowRoot<'dom, LayoutDataType> {
+impl<'dom> ServoShadowRoot<'dom> {
     pub(super) fn from_layout_js(shadow_root: LayoutDom<'dom, ShadowRoot>) -> Self {
-        ServoShadowRoot {
-            shadow_root,
-            phantom: PhantomData,
-        }
+        ServoShadowRoot { shadow_root }
     }
 
     pub unsafe fn flush_stylesheets(
@@ -77,6 +54,6 @@ impl<'dom, LayoutDataType: LayoutDataTrait> ServoShadowRoot<'dom, LayoutDataType
         guard: &StyleSharedRwLockReadGuard,
     ) {
         self.shadow_root
-            .flush_stylesheets::<ServoLayoutElement<LayoutDataType>>(stylist, guard)
+            .flush_stylesheets::<ServoLayoutElement>(stylist, guard)
     }
 }