Make Node::layout non-optional, defaulting to a shared empty layout

node-graph/libraries/core-types/src/node.rs

@@ -71,12 +71,12 @@ pub trait Node<Input> {
 		None
 	}
 
-	/// The record layout of this node's output; `None` for element-only
-	/// producers. Consumers read their carrier's layout through this at
-	/// wiring, and the wiring layer derives stack sizing from the same
+	/// The record layout of this node's output; the shared empty layout for
+	/// element-only producers. Consumers read their carrier's layout through
+	/// this at wiring, and the wiring layer derives stack sizing from the same
 	/// layouts, in the dynamic executor and exported source alike.
-	fn layout(&self) -> Option<&crate::record::Layout> {
-		None
+	fn layout(&self) -> &crate::record::Layout {
+		crate::record::empty_layout()
 	}
 
 	fn eval_batch<'a>(&self, input: &'a Input, range: Range<u64>, scratch: Option<&'a mut [MaybeUninit<Self::Output>]>) -> BatchStatus<'a, Self::Output>
@@ -141,7 +141,7 @@ where
 		(**self).serialize()
 	}
 
-	fn layout(&self) -> Option<&crate::record::Layout> {
+	fn layout(&self) -> &crate::record::Layout {
 		(**self).layout()
 	}
 
@@ -171,7 +171,7 @@ where
 		(**self).serialize()
 	}
 
-	fn layout(&self) -> Option<&crate::record::Layout> {
+	fn layout(&self) -> &crate::record::Layout {
 		(**self).layout()
 	}
 
@@ -201,6 +201,10 @@ where
 		(**self).serialize()
 	}
 
+	fn layout(&self) -> &crate::record::Layout {
+		(**self).layout()
+	}
+
 	fn eval_batch<'a>(&self, input: &'a Input, range: Range<u64>, scratch: Option<&'a mut [MaybeUninit<Self::Output>]>) -> BatchStatus<'a, Self::Output>
 	where
 		Input: InjectIndex + Copy,

node-graph/libraries/core-types/src/record.rs

@@ -234,6 +234,14 @@ impl Layout {
 #[derive(Clone, Copy, Debug, Default)]
 pub struct ElToken;
 
+/// The shared empty layout: `depth` 0, no element, no fields, so `frame_bytes`
+/// is 0. The `Node::layout` default returns it for element-only and test nodes,
+/// which carry no record.
+pub fn empty_layout() -> &'static Layout {
+	static EMPTY: std::sync::OnceLock<Layout> = std::sync::OnceLock::new();
+	EMPTY.get_or_init(Layout::default)
+}
+
 /// A view of one record: a pointer whose layout is proven at wiring.
 #[derive(Clone, Copy, Debug)]
 pub struct Rec(*const u8);
@@ -1081,8 +1089,8 @@ where
 		lift_poll(self.edge.eval(input), &self.layout, input.arena())
 	}
 
-	fn layout(&self) -> Option<&Layout> {
-		Some(&self.layout)
+	fn layout(&self) -> &Layout {
+		&self.layout
 	}
 }
 
@@ -1139,8 +1147,8 @@ where
 		}
 	}
 
-	fn layout(&self) -> Option<&Layout> {
-		Some(&self.union)
+	fn layout(&self) -> &Layout {
+		&self.union
 	}
 }
 

node-graph/libraries/core-types/src/registry.rs

@@ -158,7 +158,7 @@ where
 		#[cfg(debug_assertions)]
 		debug_assert_eq!(
 			crate::record::stack::sp(),
-			sp_before + self.layout().map_or(0, |layout| layout.frame_bytes()),
+			sp_before + self.layout().frame_bytes(),
 			"{} left the record stack misaligned",
 			std::any::type_name::<N>(),
 		);
@@ -175,7 +175,7 @@ where
 		unsafe { self.ptr.as_ref() }.serialize()
 	}
 
-	fn layout(&self) -> Option<&crate::record::Layout> {
+	fn layout(&self) -> &crate::record::Layout {
 		// SAFETY: as in eval.
 		unsafe { self.ptr.as_ref() }.layout()
 	}
@@ -228,7 +228,7 @@ impl EdgeHandle {
 			node: Box::new(SharedEdge::new(node)),
 			share: |edge| Box::new(edge.downcast_ref::<SharedEdge<N>>().expect("share hook matches the stored edge type").share()),
 			serialize: |edge| Node::<ContextImpl>::serialize(edge.downcast_ref::<SharedEdge<N>>().expect("serialize hook matches the stored edge type")),
-			layout: |edge| Node::<ContextImpl>::layout(edge.downcast_ref::<SharedEdge<N>>().expect("layout hook matches the stored edge type")),
+			layout: |edge| Some(Node::<ContextImpl>::layout(edge.downcast_ref::<SharedEdge<N>>().expect("layout hook matches the stored edge type"))),
 			ty,
 		}
 	}

node-graph/libraries/core-types/src/value.rs

@@ -40,8 +40,8 @@ where
 		crate::record::lift_poll(crate::gpoll::GPoll::Final(self.value.clone()), &self.layout, input.arena())
 	}
 
-	fn layout(&self) -> Option<&crate::record::Layout> {
-		Some(&self.layout)
+	fn layout(&self) -> &crate::record::Layout {
+		&self.layout
 	}
 }