Bound attribute value types Send and Sync

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

@@ -28,7 +28,11 @@ pub trait Attribute: 'static {
 	/// is the evaluation the value flows in; non-reference values ignore it.
 	/// The value outlives that evaluation, so its `'static` instantiation is
 	/// the one the census registers and layouts stamp their type id from.
-	type Value<'e>: Copy + Default + std::fmt::Debug + 'e;
+	///
+	/// `Send + Sync` because a record's bytes are these values: `RecordValue`
+	/// is `Send + Sync` over whatever the field writes put there, and the write
+	/// path never consults the census, so the bound has to sit here.
+	type Value<'e>: Copy + Default + std::fmt::Debug + Send + Sync + 'e;
 	/// The name-specific default, filled where an item lacks the attribute.
 	/// Producing a value for any `'e` from no inputs, reference defaults can
 	/// only point at `'static` data, which is what lets the census fill them

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

@@ -50,9 +50,10 @@ impl std::fmt::Debug for RecordValue<'_> {
 	}
 }
 
-// SAFETY: `element_write` requires the element `Send + Sync` and attribute payloads
+// SAFETY: `element_write` requires the element `Send + Sync` and every field holds an
-// are `Copy` or arena-backed, so the record bytes behind the pointer are thread-safe;
+// `Attribute::Value`, which the trait bounds `Send + Sync`, so the record bytes behind
-// `'e` ties the pointer's validity to the shared arena and record-stack discipline.
+// the pointer are thread-safe; `'e` ties the pointer's validity to the shared arena and
+// record-stack discipline.
 unsafe impl Send for RecordValue<'_> {}
 // SAFETY: as `Send`.
 unsafe impl Sync for RecordValue<'_> {}