Emit a compile-time error when returning a value from a constructor.

sdk/lib/_internal/compiler/implementation/resolution/members.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of resolution;
 
 abstract class TreeElements {
   Element get currentElement;
   Set<Node> get superUses;
 
@@ skipping 2505 matching lines @@
   visitRethrow(Rethrow node) {
     if (!inCatchBlock) {
       error(node, MessageKind.THROW_WITHOUT_EXPRESSION);
     }
   }
 
   visitReturn(Return node) {
     if (node.isRedirectingFactoryBody) {
       handleRedirectingFactoryBody(node);
     } else {
+      Node expression = node.expression;
+      if (expression != null &&
+          enclosingElement.isGenerativeConstructor()) {
+        // It is a compile-time error if a return statement of the form
+        // `return e;` appears in a generative constructor.  (Dart Language
+        // Specification 13.12.)
+        compiler.reportError(expression,
+                             MessageKind.CANNOT_RETURN_FROM_CONSTRUCTOR);
+      }
       visit(node.expression);
     }
   }
 
   void handleRedirectingFactoryBody(Return node) {
     final isSymbolConstructor = enclosingElement == compiler.symbolConstructor;
     if (!enclosingElement.isFactoryConstructor()) {
       compiler.reportError(
           node, MessageKind.FACTORY_REDIRECTION_IN_NON_FACTORY);
       compiler.reportHint(
@@ skipping 1569 matching lines @@
     return e;
   }
 
   /// Assumed to be called by [resolveRedirectingFactory].
   Element visitReturn(Return node) {
     Node expression = node.expression;
     return finishConstructorReference(visit(expression),
                                       expression, expression);
   }
 }