clean up default constructor in derived classes - fixes #1748

src/babel/transformation/templates/class-derived-default-constructor.js

@@ -0,0 +1,3 @@
+(function () {
+  super(...arguments);
+})

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

@@ -1,3 +0,0 @@
-if (SUPER_NAME != null) {
-  SUPER_NAME.apply(this, arguments);
-}

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

@@ -1,3 +0,0 @@
-if (SUPER_NAME != null) {
-  SUPER_NAME.apply(this, arguments);
-}

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

@@ -1,5 +0,0 @@
-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

@@ -251,20 +251,43 @@ class ClassTransformer {
     }
   }
 
+  /**
+   * https://www.youtube.com/watch?v=fWNaR-rxAic
+   */
+
+  constructorMeMaybe() {
+    if (!this.hasSuper) return;
+
+    var hasConstructor = false;
+    var paths = this.path.get("body.body");
+
+    for (var path of (paths: Array)) {
+      hasConstructor = path.equals("kind", "constructor");
+      if (hasConstructor) break;
+    }
+
+    if (!hasConstructor) {
+      this.path.get("body").unshiftContainer("body", t.methodDefinition(
+        t.identifier("constructor"),
+        util.template("class-derived-default-constructor"),
+        "constructor"
+      ));
+    }
+  }
+
   /**
    * Description
    */
 
   buildBody() {
+    this.constructorMeMaybe();
+
     var constructorBody = this.constructorBody;
-    var classBody       = this.node.body.body;
+    var classBodyPaths  = this.path.get("body.body");
     var body            = this.body;
 
-    var classBodyPaths = this.path.get("body").get("body");
-
-    for (var i = 0; i < classBody.length; i++) {
-      var node = classBody[i];
-      var path = classBodyPaths[i];
+    for (var path of (classBodyPaths: Array)) {
+      var node = path.node;
 
       if (node.decorators) {
         memoiseDecorators(node.decorators, this.scope);
@@ -297,16 +320,6 @@ class ClassTransformer {
       }
     }
 
-    // we have no constructor, but we're a derived class
-    if (!this.hasConstructor && this.hasSuper) {
-      var helperName = "class-super-constructor-call";
-      if (this.isLoose) helperName += "-loose";
-      constructorBody.body.push(util.template(helperName, {
-        CLASS_NAME: this.classRef,
-        SUPER_NAME: this.superName
-      }, true));
-    }
-
     //
     this.placePropertyInitializers();
 

src/babel/traversal/path/modification.js

@@ -16,7 +16,7 @@ export function insertBefore(nodes) {
   } else if (this.isNodeType("Expression") || (this.parentPath.isForStatement() && this.key === "init")) {
     if (this.node) nodes.push(this.node);
     this.replaceExpressionWithStatements(nodes);
-  } else if (this.isNodeType("Statement") || !this.type) {
+  } else {
     this._maybePopFromStatements(nodes);
     if (Array.isArray(this.container)) {
       return this._containerInsertBefore(nodes);
@@ -26,8 +26,6 @@ export function insertBefore(nodes) {
     } else {
       throw new Error("We don't know what to do with this node type. We were previously a Statement but we can't fit in here?");
     }
-  } else {
-    throw new Error("No clue what to do with this node type.");
   }
 
   return [this];
@@ -94,7 +92,7 @@ export function insertAfter(nodes) {
       nodes.push(t.expressionStatement(temp));
     }
     this.replaceExpressionWithStatements(nodes);
-  } else if (this.isNodeType("Statement") || !this.type) {
+  } else {
     this._maybePopFromStatements(nodes);
     if (Array.isArray(this.container)) {
       return this._containerInsertAfter(nodes);
@@ -104,8 +102,6 @@ export function insertAfter(nodes) {
     } else {
       throw new Error("We don't know what to do with this node type. We were previously a Statement but we can't fit in here?");
     }
-  } else {
-    throw new Error("No clue what to do with this node type.");
   }
 
   return [this];