Merge impl

src/config/mod.rs

@@ -1361,7 +1361,48 @@ impl Merge for bool {
 
 impl Merge for Syntax {
     fn merge(&mut self, from: &Self) {
-        *self = *from;
+        match (&mut *self, from) {
+            (Syntax::Es(a), Syntax::Es(b)) => {
+                a.merge(b);
+            }
+            (Syntax::Typescript(a), Syntax::Typescript(b)) => {
+                a.merge(b);
+            }
+            _ => {
+                *self = *from;
+            }
+        }
+    }
+}
+
+impl Merge for swc_ecma_parser::EsConfig {
+    fn merge(&mut self, from: &Self) {
+        self.jsx |= from.jsx;
+        self.class_private_props |= from.class_private_props;
+        self.class_private_methods |= from.class_private_methods;
+        self.class_props |= from.class_props;
+        self.fn_bind |= from.fn_bind;
+        self.decorators |= from.decorators;
+        self.decorators_before_export |= from.decorators_before_export;
+        self.export_default_from |= from.export_default_from;
+        self.export_namespace_from |= from.export_namespace_from;
+        self.dynamic_import |= from.dynamic_import;
+        self.nullish_coalescing |= from.nullish_coalescing;
+        self.optional_chaining |= from.optional_chaining;
+        self.import_meta |= from.import_meta;
+        self.top_level_await |= from.top_level_await;
+        self.import_assertions |= from.import_assertions;
+        self.static_blocks |= from.static_blocks;
+        self.private_in_object |= from.private_in_object;
+    }
+}
+
+impl Merge for swc_ecma_parser::TsConfig {
+    fn merge(&mut self, from: &Self) {
+        self.tsx |= from.tsx;
+        self.decorators |= from.decorators;
+        self.dynamic_import |= from.dynamic_import;
+        self.import_assertions |= from.import_assertions;
     }
 }