Ambiguous type references require a compile time error in some special cases

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 820 matching lines @@
   // parsed type arguments.
   AbstractTypeArguments& arguments =
       AbstractTypeArguments::Handle(parameterized_type.arguments());
   if (!arguments.IsNull()) {
     intptr_t num_arguments = arguments.Length();
     AbstractType& type_argument = AbstractType::Handle();
     for (intptr_t i = 0; i < num_arguments; i++) {
       type_argument = arguments.TypeAt(i);
       type_argument = FinalizeType(cls, type_argument, finalization);
       if (type_argument.IsMalformed()) {
-        // Malformed type arguments to a constructor of a generic type are
-        // reported as a compile-time error.
-        if (finalization >= kCanonicalizeForCreation) {
-          const Script& script = Script::Handle(cls.script());
-          const String& type_name =
-              String::Handle(parameterized_type.UserVisibleName());
-          ReportError(script, parameterized_type.token_pos(),
-                      "type '%s' has malformed type argument",
-                      type_name.ToCString());
-        }
         // In production mode, malformed type arguments are mapped to dynamic.
         // In checked mode, a type with malformed type arguments is malformed.
         if (FLAG_enable_type_checks || FLAG_error_on_malformed_type) {
           const Error& error = Error::Handle(type_argument.malformed_error());
           const String& type_name =
               String::Handle(parameterized_type.UserVisibleName());
           FinalizeMalformedType(error, cls, parameterized_type, finalization,
                                 "type '%s' has malformed type argument",
                                 type_name.ToCString());
           return parameterized_type.raw();
         } else {
           type_argument = Type::DynamicType();
         }
       }
       arguments.SetTypeAt(i, type_argument);
     }
   }
 
   // The finalized type argument vector needs num_type_arguments types.
   const intptr_t num_type_arguments = type_class.NumTypeArguments();
   // The type class has num_type_parameters type parameters.
   const intptr_t num_type_parameters = type_class.NumTypeParameters();
 
   // Initialize the type argument vector.
   // Check the number of parsed type arguments, if any.
   // Specifying no type arguments indicates a raw type, which is not an error.
   // However, type parameter bounds are checked below, even for a raw type.
   if (!arguments.IsNull() && (arguments.Length() != num_type_parameters)) {
     // Wrong number of type arguments. The type is malformed.
-    if (finalization >= kCanonicalizeForCreation) {
+    if (finalization >= kCanonicalizeExpression) {
       const Script& script = Script::Handle(cls.script());
       const String& type_name =
           String::Handle(parameterized_type.UserVisibleName());
       ReportError(script, parameterized_type.token_pos(),
                   "wrong number of type arguments in type '%s'",
                   type_name.ToCString());
     }
     FinalizeMalformedType(
         Error::Handle(),  // No previous error.
         cls, parameterized_type, finalization,
@@ skipping 806 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