Use RootedTraceableBox for unions.

2 files changed, 7 insertions, 1 deletions

diff --git a/components/script/dom/bindings/codegen/CodegenRust.py b/components/script/dom/bindings/codegen/CodegenRust.py
index e4448ff834c..4a9e7a8cc32 100644
--- a/components/script/dom/bindings/codegen/CodegenRust.py
+++ b/components/script/dom/bindings/codegen/CodegenRust.py
@@ -722,6 +722,9 @@ def getJSToNativeConversionInfo(type, descriptorProvider, failureCode=None,
         if type.nullable():
             declType = CGWrapper(declType, pre="Option<", post=" >")
 
+        if isMember != "Dictionary" and type_needs_tracing(type):
+            declType = CGTemplatedType("RootedTraceableBox", declType)
+
         templateBody = ("match FromJSValConvertible::from_jsval(cx, ${val}, ()) {\n"
                         "    Ok(ConversionResult::Success(value)) => value,\n"
                         "    Ok(ConversionResult::Failure(error)) => {\n"
@@ -6190,6 +6193,9 @@ def type_needs_tracing(t):
         if t.isSequence():
             return type_needs_tracing(t.inner)
 
+        if t.isUnion():
+            return any(type_needs_tracing(member) for member in t.flatMemberTypes)
+
         return False
 
     if t.isDictionary():
diff --git a/components/script/dom/testbinding.rs b/components/script/dom/testbinding.rs
index 1582647ca33..3be8597ed41 100644
--- a/components/script/dom/testbinding.rs
+++ b/components/script/dom/testbinding.rs
@@ -435,7 +435,7 @@ impl TestBindingMethods for TestBinding {
     fn PassUnion6(&self, _: UnsignedLongOrBoolean) {}
     fn PassUnion7(&self, _: StringSequenceOrUnsignedLong) {}
     fn PassUnion8(&self, _: ByteStringSequenceOrLong) {}
-    fn PassUnion9(&self, _: UnionTypes::TestDictionaryOrLong) {}
+    fn PassUnion9(&self, _: RootedTraceableBox<UnionTypes::TestDictionaryOrLong>) {}
     fn PassUnionWithTypedef(&self, _: DocumentOrTestTypedef) {}
     fn PassUnionWithTypedef2(&self, _: LongSequenceOrTestTypedef) {}
     #[allow(unsafe_code)]