Set and keep parent function of signature functions.

runtime/vm/class_finalizer.cc

 // 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.
 
 #include "vm/class_finalizer.h"
 
 #include "vm/flags.h"
 #include "vm/hash_table.h"
 #include "vm/heap.h"
 #include "vm/isolate.h"
@@ skipping 573 matching lines @@
         ResolveSignature(scope_class, signature);
       } else {
         ASSERT(scope_class.IsClosureClass());
         ResolveSignature(cls, signature);
         ASSERT(type.arguments() == TypeArguments::null());
         if (signature.IsSignatureFunction()) {
           // Drop fields that are not necessary anymore after resolution.
           // The parent function, owner, and token position of a shared
           // canonical function type are meaningless, since the canonical
           // representent is picked arbitrarily.
-          signature.set_parent_function(Function::Handle());
+          // The parent function is however still required to finalize function
+          // type parameters when the function has a generic parent.
+          if (!signature.HasGenericParent()) {
+            signature.set_parent_function(Function::Handle());
+          }
           // TODO(regis): As long as we support metadata in typedef signatures,
           // we cannot reset these fields used to reparse a typedef.
           // Note that the scope class of a typedef function type is always
           // preserved as the typedef class (not reset to _Closure class),
           // thereby preventing sharing of canonical function types between
           // typedefs. Not being shared, these fields are therefore always
           // meaningful for typedefs.
           if (!scope_class.IsTypedefClass()) {
             signature.set_owner(Object::Handle());
             signature.set_token_pos(TokenPosition::kNoSource);
@@ skipping 3195 matching lines @@
   ProgramVisitor::VisitFunctions(&function_visitor);
 
   class ClearCodeClassVisitor : public ClassVisitor {
     void Visit(const Class& cls) { cls.DisableAllocationStub(); }
   };
   ClearCodeClassVisitor class_visitor;
   ProgramVisitor::VisitClasses(&class_visitor);
 }
 
 }  // namespace dart