Implement implicit interfaces

runtime/vm/class_finalizer.cc

 // 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.
 
 #include "vm/class_finalizer.h"
 
 #include "vm/flags.h"
 #include "vm/heap.h"
 #include "vm/isolate.h"
 #include "vm/longjump.h"
@@ skipping 1132 matching lines @@
   for (intptr_t i = 0; i < super_interfaces.Length(); i++) {
     interface ^= super_interfaces.At(i);
     ResolveType(cls, interface, kFinalizeWellFormed);
     if (interface.IsTypeParameter()) {
       const Script& script = Script::Handle(cls.script());
       ReportError(script, cls.token_index(),
                   "type parameter '%s' cannot be used as interface",
                   String::Handle(interface.Name()).ToCString());
     }
     interface_class = interface.type_class();
-    if (!interface_class.is_interface()) {
+    if (interface_class.IsSignatureClass()) {
       const Script& script = Script::Handle(cls.script());
       ReportError(script, cls.token_index(),
-                  "class '%s' is used where an interface is expected",
+                  "'%s' is used where an interface or class name is expected",
                   String::Handle(interface_class.Name()).ToCString());
     }
     // Verify that unless cls belongs to core lib, it cannot extend or implement
     // any of bool, num, int, double, String, Function, Dynamic.
     // The exception is signature classes, which are compiler generated and
     // represent a function type, therefore implementing the Function interface.
     if (!cls_belongs_to_core_lib) {
       if (interface.IsBoolInterface() ||
           interface.IsNumberInterface() ||
           interface.IsIntInterface() ||
@@ skipping 155 matching lines @@
 void ClassFinalizer::ReportError(const char* format, ...) {
   va_list args;
   va_start(args, format);
   const Error& error = Error::Handle(
       Parser::FormatError(Script::Handle(), -1, "Error", format, args));
   va_end(args);
   ReportError(error);
 }
 
 }  // namespace dart