Check for a passed-in type argument vector in the prolog of generic functions.

runtime/lib/object_patch.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.
 
 @patch
 class Object {
   // The VM has its own implementation of equals.
   @patch
   bool operator ==(other) native "Object_equals";
 
@@ skipping 39 matching lines @@
         invocation._type,
         invocation.positionalArguments,
         _symbolMapToStringMap(invocation.namedArguments));
   }
 
   @patch
   Type get runtimeType native "Object_runtimeType";
 
   static bool _haveSameRuntimeType(a, b) native "Object_haveSameRuntimeType";
 
+  // Prepend the parent type arguments (maybe null) to the function type
+  // arguments (may be null). The result is null if both input vectors are null
+  // or is a newly allocated and canonicalized vector of length 'len'.
+  static _prependTypeArguments(functionTypeArguments, parentTypeArguments, len)

[Vyacheslav Egorov (Google), 2017/06/15 14:05:44]

Is it possible to put this into dart:_internal instead of placing it on Object?
I find it a bit confusing that we put a lot of helpers on Object.

[regis, 2017/06/15 21:38:26]

Yes, definitely. I did not know of the existence of internal_patch.dart.

+      native "Object_prependTypeArguments";
+
   // Call this function instead of inlining instanceof, thus collecting
   // type feedback and reducing code size of unoptimized code.
-  bool _instanceOf(instantiator_type_arguments, function_type_arguments, type)
+  bool _instanceOf(instantiatorTypeArguments, functionTypeArguments, type)
       native "Object_instanceOf";
 
   // Group of functions for implementing fast simple instance of.
   bool _simpleInstanceOf(type) native "Object_simpleInstanceOf";
   bool _simpleInstanceOfTrue(type) => true;
   bool _simpleInstanceOfFalse(type) => false;
 
   // Call this function instead of inlining 'as', thus collecting type
   // feedback. Returns receiver.
-  _as(instantiator_type_arguments, function_type_arguments, type)
+  _as(instantiatorTypeArguments, functionTypeArguments, type)
       native "Object_as";
 
   static _symbolMapToStringMap(Map<Symbol, dynamic> map) {
     var result = new Map<String, dynamic>();
     map.forEach((Symbol key, value) {
       result[internal.Symbol.getName(key)] = value;
     });
     return result;
   }
 }