add support for inheriting from statically inlined native constructors - closes #1172

src/babel/transformation/templates/.babelrc

@@ -1,4 +1,4 @@
 {
-  "blacklist": ["useStrict", "es6.blockScoping", "regenerator"],
+  "blacklist": ["useStrict", "es6.blockScoping", "regenerator", "es6.spread"],
   "loose": ["es6.modules"]
 }

src/babel/transformation/templates/class-super-native-constructor-call.js

@@ -0,0 +1,5 @@
+if (SUPER_NAME != null) {
+  var NATIVE_REF = new SUPER_NAME(...arguments);
+  NATIVE_REF.__proto__ = CLASS_NAME.prototype;
+  return NATIVE_REF;
+}

src/babel/transformation/transformers/es6/classes.js

@@ -79,6 +79,10 @@ var verifyConstructorVisitor = traverse.explode({
       if (state.hasSuper && !state.hasBareSuper) {
         throw this.errorWithNode("'this' is not allowed before super()");
       }
+
+      if (state.isNativeSuper) {
+        return state.nativeSuperRef;
+      }
     }
   }
 });
@@ -133,6 +137,15 @@ class ClassTransformer {
 
     //
 
+    var superClass = this.node.superClass;
+    this.isNativeSuper = superClass && t.isIdentifier(superClass) && t.NATIVE_TYPE_NAMES.indexOf(superClass.name) >= 0;
+
+    if (this.isNativeSuper) {
+      this.nativeSuperRef = this.scope.generateUidIdentifier("this");
+    }
+
+    //
+
     var body = this.body;
 
     //
@@ -203,6 +216,10 @@ class ClassTransformer {
       }
     }
 
+    if (this.isNativeSuper) {
+      constructorBody.body.push(t.returnStatement(this.nativeSuperRef));
+    }
+
     if (this.className) {
       // named class with only a constructor
       if (body.length === 1) return t.toExpression(body[0]);
@@ -303,7 +320,9 @@ class ClassTransformer {
     if (!this.hasConstructor && this.hasSuper) {
       var helperName = "class-super-constructor-call";
       if (this.isLoose) helperName += "-loose";
+      if (this.isNativeSuper) helperName = "class-super-native-constructor-call";
       constructorBody.body.push(util.template(helperName, {
+        NATIVE_REF: this.nativeSuperRef,
         CLASS_NAME: className,
         SUPER_NAME: this.superName
       }, true));
@@ -432,10 +451,12 @@ class ClassTransformer {
 
    verifyConstructor(path: TraversalPath) {
     var state = {
-      hasBareSuper: false,
-      bareSuper:    null,
-      hasSuper:     this.hasSuper,
-      file:         this.file
+      nativeSuperRef: this.nativeSuperRef,
+      isNativeSuper:  this.isNativeSuper,
+      hasBareSuper:   false,
+      bareSuper:      null,
+      hasSuper:       this.hasSuper,
+      file:           this.file
     };
 
     path.get("value").traverse(verifyConstructorVisitor, state);
@@ -445,6 +466,21 @@ class ClassTransformer {
     if (!state.hasBareSuper && this.hasSuper) {
       throw path.errorWithNode("Derived constructor must call super()");
     }
+
+    if (this.isNativeSuper && this.bareSuper) {
+      this.bareSuper.replaceWithMultiple([
+        t.variableDeclaration("var", [
+          t.variableDeclarator(this.nativeSuperRef, t.newExpression(this.superName, this.bareSuper.node.arguments))
+        ]),
+
+        t.expressionStatement(t.assignmentExpression(
+          "=",
+          t.memberExpression(this.nativeSuperRef, t.identifier("__proto__")),
+          t.memberExpression(this.classRef, t.identifier("prototype"))
+        )),
+        t.expressionStatement(this.nativeSuperRef)
+      ]);
+    }
    }
 
   /**