Do not share type arguments of mixin types, but clone them to avoid finalization

runtime/vm/object.h

 // 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.
 
 #ifndef VM_OBJECT_H_
 #define VM_OBJECT_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 1121 matching lines @@
   FINAL_HEAP_OBJECT_IMPLEMENTATION(UnresolvedClass, Object);
   friend class Class;
 };
 
 
 // AbstractTypeArguments is an abstract superclass.
 // Subclasses of AbstractTypeArguments are TypeArguments and
 // InstantiatedTypeArguments.
 class AbstractTypeArguments : public Object {
  public:
+  // Returns true if all types of this vector are finalized.
+  virtual bool IsFinalized() const { return true; }
+
   // Returns true if both arguments represent vectors of equal types.
   static bool AreEqual(const AbstractTypeArguments& arguments,
                        const AbstractTypeArguments& other_arguments);
 
   // Return 'this' if this type argument vector is instantiated, i.e. if it does
   // not refer to type parameters. Otherwise, return a new type argument vector
   // where each reference to a type parameter is replaced with the corresponding
   // type of the instantiator type argument vector.
   // If bound_error is not NULL, it may be set to reflect a bound error.
   virtual RawAbstractTypeArguments* InstantiateFrom(
       const AbstractTypeArguments& instantiator_type_arguments,
       Error* bound_error) const;
 
-  // Do not canonicalize InstantiatedTypeArguments or NULL objects
+  // Do not clone InstantiatedTypeArguments or null vectors, since they are
+  // considered finalized.
+  virtual RawAbstractTypeArguments* CloneUnfinalized() const {
+    return this->raw();
+  }
+
+  // Do not canonicalize InstantiatedTypeArguments or null vectors.
   virtual RawAbstractTypeArguments* Canonicalize() const { return this->raw(); }
 
   // The name of this type argument vector, e.g. "<T, dynamic, List<T>, Smi>".
   virtual RawString* Name() const {
     return SubvectorName(0, Length(), kInternalName);
   }
 
   // The name of this type argument vector, e.g. "<T, dynamic, List<T>, int>".
   // Names of internal classes are mapped to their public interfaces.
   virtual RawString* UserVisibleName() const {
@@ skipping 78 matching lines @@
   virtual RawAbstractType* TypeAt(intptr_t index) const;
   static intptr_t type_at_offset(intptr_t index) {
     return OFFSET_OF(RawTypeArguments, types_) + index * kWordSize;
   }
   virtual void SetTypeAt(intptr_t index, const AbstractType& value) const;
   virtual bool IsResolved() const;
   virtual bool IsInstantiated() const;
   virtual bool IsUninstantiatedIdentity() const;
   virtual bool CanShareInstantiatorTypeArguments(
       const Class& instantiator_class) const;
+  virtual bool IsFinalized() const;
   virtual bool IsBounded() const;
+  virtual RawAbstractTypeArguments* CloneUnfinalized() const;
   // Canonicalize only if instantiated, otherwise returns 'this'.
   virtual RawAbstractTypeArguments* Canonicalize() const;
 
   virtual RawAbstractTypeArguments* InstantiateFrom(
       const AbstractTypeArguments& instantiator_type_arguments,
       Error* bound_error) const;
 
   static const intptr_t kBytesPerElement = kWordSize;
   static const intptr_t kMaxElements = kSmiMax / kBytesPerElement;
 
@@ skipping 2595 matching lines @@
   virtual bool IsInstantiated() const;
   virtual bool Equals(const Instance& other) const;
 
   // Instantiate this type using the given type argument vector.
   // Return a new type, or return 'this' if it is already instantiated.
   // If bound_error is not NULL, it may be set to reflect a bound error.
   virtual RawAbstractType* InstantiateFrom(
       const AbstractTypeArguments& instantiator_type_arguments,
       Error* bound_error) const;
 
+  // Return a clone of this unfinalized type or the type itself if it is
+  // already finalized. Apply recursively to type arguments, i.e. finalized
+  // type arguments of an unfinalized type are not cloned, but shared.
+  virtual RawAbstractType* CloneUnfinalized() const;
+
   virtual RawInstance* CheckAndCanonicalize(const char** error_str) const {
     return Canonicalize();
   }
 
   // Return the canonical version of this type.
   virtual RawAbstractType* Canonicalize() const;
 
   // The name of this type, including the names of its type arguments, if any.
   virtual RawString* Name() const {
     return BuildName(kInternalName);
@@ skipping 117 matching lines @@
   virtual RawUnresolvedClass* unresolved_class() const;
   RawString* TypeClassName() const;
   virtual RawAbstractTypeArguments* arguments() const;
   void set_arguments(const AbstractTypeArguments& value) const;
   virtual intptr_t token_pos() const { return raw_ptr()->token_pos_; }
   virtual bool IsInstantiated() const;
   virtual bool Equals(const Instance& other) const;
   virtual RawAbstractType* InstantiateFrom(
       const AbstractTypeArguments& instantiator_type_arguments,
       Error* malformed_error) const;
+  virtual RawAbstractType* CloneUnfinalized() const;
   virtual RawAbstractType* Canonicalize() const;
 
   virtual intptr_t Hash() const;
 
   static intptr_t InstanceSize() {
     return RoundedAllocationSize(sizeof(RawType));
   }
 
   // The type of the literal 'null'.
   static RawType* NullType();
@@ skipping 94 matching lines @@
   // and set bound_error if not NULL.
   bool CheckBound(const AbstractType& bounded_type,
                   const AbstractType& upper_bound,
                   Error* bound_error) const;
   virtual intptr_t token_pos() const { return raw_ptr()->token_pos_; }
   virtual bool IsInstantiated() const { return false; }
   virtual bool Equals(const Instance& other) const;
   virtual RawAbstractType* InstantiateFrom(
       const AbstractTypeArguments& instantiator_type_arguments,
       Error* bound_error) const;
+  virtual RawAbstractType* CloneUnfinalized() const;
   virtual RawAbstractType* Canonicalize() const { return raw(); }
 
   virtual intptr_t Hash() const;
 
   static intptr_t InstanceSize() {
     return RoundedAllocationSize(sizeof(RawTypeParameter));
   }
 
   static RawTypeParameter* New(const Class& parameterized_class,
                                intptr_t index,
@@ skipping 52 matching lines @@
   virtual intptr_t token_pos() const {
     return AbstractType::Handle(type()).token_pos();
   }
   virtual bool IsInstantiated() const {
     return AbstractType::Handle(type()).IsInstantiated();
   }
   virtual bool Equals(const Instance& other) const;
   virtual RawAbstractType* InstantiateFrom(
       const AbstractTypeArguments& instantiator_type_arguments,
       Error* bound_error) const;
+  virtual RawAbstractType* CloneUnfinalized() const;
   virtual RawAbstractType* Canonicalize() const { return raw(); }
 
   virtual intptr_t Hash() const;
 
   static intptr_t InstanceSize() {
     return RoundedAllocationSize(sizeof(RawBoundedType));
   }
 
   static RawBoundedType* New(const AbstractType& type,
                              const AbstractType& bound,
@@ skipping 2021 matching lines @@
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_