Add typed trait requirements and enforce actual capability results

crates/objects/src/native.rs

@@ -375,6 +375,12 @@ impl<'a> NativeContext<'a> {
         if let Some(signature) = &signature {
             signature.check_arguments(store, &name, arguments)?;
         }
+        let trait_returns = if let Some(Value::Object(receiver)) = arguments.first() {
+            store.check_method_contract_call(function, *receiver, false)?;
+            store.method_trait_returns(function, *receiver)?
+        } else {
+            Vec::new()
+        };
         let mut context = Self {
             store,
             roots: Vec::new(),
@@ -386,6 +392,11 @@ impl<'a> NativeContext<'a> {
                 context.protect(&Value::Object(reference))?;
             }
         }
+        for (_, expected) in &trait_returns {
+            for reference in expected.references() {
+                context.protect(&Value::Object(reference))?;
+            }
+        }
         for argument in arguments {
             context.protect(argument)?;
         }
@@ -393,6 +404,11 @@ impl<'a> NativeContext<'a> {
         if let (Some(signature), NativeResult::Return(value)) = (&signature, &result) {
             signature.check_return(context.store(), &name, value)?;
         }
+        if let NativeResult::Return(value) = &result {
+            for (name, expected) in &trait_returns {
+                expected.check(context.store(), name, "return".into(), value)?;
+            }
+        }
         let transferred_from = context.roots.len();
         match &result {
             NativeResult::Return(value) => context.protect(value)?,