Disallow explicit parameter default values in redirecting factory (issue 13662).

tests/language/redirecting_factory_default_values_test.dart

Index: tests/language/redirecting_factory_default_values_test.dart
===================================================================
--- tests/language/redirecting_factory_default_values_test.dart	(revision 0)
+++ tests/language/redirecting_factory_default_values_test.dart	(revision 0)
@@ -0,0 +1,27 @@
+// Copyright (c) 2013, 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.
+
+// Test that parameter default values are disallowed in a redirecting factory.
+
+import "package:expect/expect.dart";
+
+class A {
+  A(this.a, [this.b = 0]);
+  factory A.f(a) = A;
+  factory A.g(a, [b = 0]) = A;  /// 01: compile-time error
+  factory A.h(a, {b: 0}) = A;  /// 02: compile-time error
+
+ int a;
+ int b;
+}
+
+main() {
+  var x = new A.f(42);
+  Expect.equals(x.a, 42);
+  Expect.equals(x.b, 0);
+
+  var y = new A.f(42, 43);
+  Expect.equals(y.a, 42);
+  Expect.equals(y.b, 43);
+}