Fix analyzer's treatment of mixin constructors.

pkg/analyzer/lib/src/generated/error.dart

Index: pkg/analyzer/lib/src/generated/error.dart
diff --git a/pkg/analyzer/lib/src/generated/error.dart b/pkg/analyzer/lib/src/generated/error.dart
index f88d40a76327ad9f8e6c7148b0c0d4d6496d7c03..9b763efce47e064c64ba1487765bc2350ecf2799 100644
--- a/pkg/analyzer/lib/src/generated/error.dart
+++ b/pkg/analyzer/lib/src/generated/error.dart
@@ -1422,6 +1422,19 @@ class CompileTimeErrorCode extends ErrorCode {
   static const CompileTimeErrorCode MIXIN_DEFERRED_CLASS = const CompileTimeErrorCode('MIXIN_DEFERRED_CLASS', "This class cannot mixin the deferred class '{0}'");
 
   /**
+   * Not yet in the spec, but consistent with VM behavior.  It is a
+   * compile-time error if all of the constructors of a mixin's base class have
+   * at least one optional parameter (since only constructors that lack
+   * optional parameters can be forwarded to the mixin).  See
+   * https://code.google.com/p/dart/issues/detail?id=15101#c4
+   */
+  static const CompileTimeErrorCode MIXIN_HAS_NO_CONSTRUCTORS =
+      const CompileTimeErrorCode('MIXIN_HAS_NO_CONSTRUCTORS',
+          "No constructors could be created for this class, since all the "
+          "constructors in the base class have at least one optional "
+          "parameter.");

[Brian Wilkerson, 2014/11/07 16:59:32]

I find this message to be confusing and think that users will too. The "this
class" refers to the class containing the mixins, but we're not creating
constructors for that class, we're creating constructors for the implicit
superclass of that class.

[Paul Berry, 2014/11/07 17:31:01]

Good point.  I've changed it to "This mixin application is invalid because all
of the constructors in the base class '{0}' have optional parameters."

+
+  /**
    * 9 Mixins: It is a compile-time error if a mixin is derived from a class
    * whose superclass is not Object.
    *