Keep a trail while checking upper bounds in the VM in order to properly handle

runtime/vm/object.h

Index: runtime/vm/object.h
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index eed376be2152b218585740f514db5420dd8771de..6b029709f3c456eec7c624ad6a76f4700ede3fc2 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -901,6 +901,10 @@ class PassiveObject : public Object {
 };
 
 
+typedef ZoneGrowableHandlePtrArray<const AbstractType> Trail;
+typedef ZoneGrowableHandlePtrArray<const AbstractType>* TrailPtr;
+
+
 class Class : public Object {
  public:
   intptr_t instance_size() const {
@@ -1122,12 +1126,14 @@ class Class : public Object {
                    const Class& other,
                    const TypeArguments& other_type_arguments,
                    Error* bound_error,
+                   TrailPtr bound_trail = NULL,
                    Heap::Space space = Heap::kNew) const {
     return TypeTest(kIsSubtypeOf,
                     type_arguments,
                     other,
                     other_type_arguments,
                     bound_error,
+                    bound_trail,
                     space);
   }
 
@@ -1136,12 +1142,14 @@ class Class : public Object {
                           const Class& other,
                           const TypeArguments& other_type_arguments,
                           Error* bound_error,
+                          TrailPtr bound_trail = NULL,
                           Heap::Space space = Heap::kNew) const {
     return TypeTest(kIsMoreSpecificThan,
                     type_arguments,
                     other,
                     other_type_arguments,
                     bound_error,
+                    bound_trail,
                     space);
   }
 
@@ -1464,6 +1472,7 @@ class Class : public Object {
                 const Class& other,
                 const TypeArguments& other_type_arguments,
                 Error* bound_error,
+                TrailPtr bound_trail,
                 Heap::Space space) const;
 
   static bool TypeTestNonRecursive(
@@ -1473,6 +1482,7 @@ class Class : public Object {
       const Class& other,
       const TypeArguments& other_type_arguments,
       Error* bound_error,
+      TrailPtr bound_trail,
       Heap::Space space);
 
   FINAL_HEAP_OBJECT_IMPLEMENTATION(Class, Object);
@@ -1518,9 +1528,6 @@ class UnresolvedClass : public Object {
 };
 
 
-typedef ZoneGrowableHandlePtrArray<const AbstractType> Trail;
-typedef ZoneGrowableHandlePtrArray<const AbstractType>* TrailPtr;
-
 // A TypeArguments is an array of AbstractType.
 class TypeArguments : public Object {
  public:
@@ -1569,8 +1576,10 @@ class TypeArguments : public Object {
                    intptr_t from_index,
                    intptr_t len,
                    Error* bound_error,
+                   TrailPtr bound_trail = NULL,
                    Heap::Space space = Heap::kNew) const {
-    return TypeTest(kIsSubtypeOf, other, from_index, len, bound_error, space);
+    return TypeTest(kIsSubtypeOf, other, from_index, len,
+                    bound_error, bound_trail, space);
   }
 
   // Check the 'more specific' relationship, considering only a subvector of
@@ -1579,9 +1588,10 @@ class TypeArguments : public Object {
                           intptr_t from_index,
                           intptr_t len,
                           Error* bound_error,
+                          TrailPtr bound_trail = NULL,
                           Heap::Space space = Heap::kNew) const {
-    return TypeTest(kIsMoreSpecificThan,
-        other, from_index, len, bound_error, space);
+    return TypeTest(kIsMoreSpecificThan, other, from_index, len,
+                    bound_error, bound_trail, space);
   }
 
   // Check if the vectors are equal (they may be null).
@@ -1637,7 +1647,8 @@ class TypeArguments : public Object {
   RawTypeArguments* InstantiateFrom(
       const TypeArguments& instantiator_type_arguments,
       Error* bound_error,
-      TrailPtr trail = NULL,
+      TrailPtr instantiation_trail = NULL,
+      TrailPtr bound_trail = NULL,
       Heap::Space space = Heap::kNew) const;
 
   // Runtime instantiation with canonicalization. Not to be used during type
@@ -1694,6 +1705,7 @@ class TypeArguments : public Object {
                 intptr_t from_index,
                 intptr_t len,
                 Error* bound_error,
+                TrailPtr bound_trail,
                 Heap::Space space) const;
 
   // Return the internal or public name of a subvector of this type argument
@@ -2498,7 +2510,7 @@ class Function : public Object {
                           const Function& other,
                           const TypeArguments& other_type_arguments,
                           Error* bound_error,
-                   Heap::Space space = Heap::kNew) const {
+                          Heap::Space space = Heap::kNew) const {
     return TypeTest(kIsMoreSpecificThan,
                     type_arguments,
                     other,
@@ -5266,7 +5278,8 @@ class AbstractType : public Instance {
   virtual RawAbstractType* InstantiateFrom(
       const TypeArguments& instantiator_type_arguments,
       Error* bound_error,
-      TrailPtr trail = NULL,
+      TrailPtr instantiation_trail = NULL,
+      TrailPtr bound_trail = NULL,
       Heap::Space space = Heap::kNew) const;
 
   // Return a clone of this unfinalized type or the type itself if it is
@@ -5297,6 +5310,17 @@ class AbstractType : public Instance {
   // the trail. The receiver may only be added once with its only buddy.
   void AddOnlyBuddyToTrail(TrailPtr* trail, const AbstractType& buddy) const;
 
+  // Return true if the receiver is contained in the trail.
+  // Otherwise, if the trail is null, allocate a trail, then add the receiver to
+  // the trail and return false.
+  bool TestAndAddToTrail(TrailPtr* trail) const;
+
+  // Return true if the pair <receiver, buddy> is contained in the trail.
+  // Otherwise, if the trail is null, allocate a trail, add the pair <receiver,
+  // buddy> to the trail and return false.
+  // The receiver may be added several times, each time with a different buddy.
+  bool TestAndAddBuddyToTrail(TrailPtr* trail, const AbstractType& buddy) const;
+
   // The name of this type, including the names of its type arguments, if any.
   virtual RawString* Name() const {
     return BuildName(kInternalName);
@@ -5369,15 +5393,18 @@ class AbstractType : public Instance {
   // Check the subtype relationship.
   bool IsSubtypeOf(const AbstractType& other,
                    Error* bound_error,
+                   TrailPtr bound_trail = NULL,
                    Heap::Space space = Heap::kNew) const {
-    return TypeTest(kIsSubtypeOf, other, bound_error, space);
+    return TypeTest(kIsSubtypeOf, other, bound_error, bound_trail, space);
   }
 
   // Check the 'more specific' relationship.
   bool IsMoreSpecificThan(const AbstractType& other,
                           Error* bound_error,
+                          TrailPtr bound_trail = NULL,
                           Heap::Space space = Heap::kNew) const {
-    return TypeTest(kIsMoreSpecificThan, other, bound_error, space);
+    return TypeTest(kIsMoreSpecificThan, other,
+                    bound_error, bound_trail, space);
   }
 
  private:
@@ -5385,6 +5412,7 @@ class AbstractType : public Instance {
   bool TypeTest(TypeTestKind test_kind,
                 const AbstractType& other,
                 Error* bound_error,
+                TrailPtr bound_trail,
                 Heap::Space space) const;
 
   // Return the internal or public name of this type, including the names of its
@@ -5443,7 +5471,8 @@ class Type : public AbstractType {
   virtual RawAbstractType* InstantiateFrom(
       const TypeArguments& instantiator_type_arguments,
       Error* bound_error,
-      TrailPtr trail = NULL,
+      TrailPtr instantiation_trail = NULL,
+      TrailPtr bound_trail = NULL,
       Heap::Space space = Heap::kNew) const;
   virtual RawAbstractType* CloneUnfinalized() const;
   virtual RawAbstractType* CloneUninstantiated(
@@ -5590,7 +5619,8 @@ class FunctionType : public AbstractType {
   virtual RawAbstractType* InstantiateFrom(
       const TypeArguments& instantiator_type_arguments,
       Error* malformed_error,
-      TrailPtr trail = NULL,
+      TrailPtr instantiation_trail = NULL,
+      TrailPtr bound_trail = NULL,
       Heap::Space space = Heap::kNew) const;
   virtual RawAbstractType* CloneUnfinalized() const;
   virtual RawAbstractType* CloneUninstantiated(
@@ -5666,7 +5696,8 @@ class TypeRef : public AbstractType {
   virtual RawTypeRef* InstantiateFrom(
       const TypeArguments& instantiator_type_arguments,
       Error* bound_error,
-      TrailPtr trail = NULL,
+      TrailPtr instantiation_trail = NULL,
+      TrailPtr bound_trail = NULL,
       Heap::Space space = Heap::kNew) const;
   virtual RawTypeRef* CloneUninstantiated(
       const Class& new_owner,
@@ -5675,17 +5706,6 @@ class TypeRef : public AbstractType {
 
   virtual intptr_t Hash() const;
 
-  // Return true if the receiver is contained in the trail.
-  // Otherwise, if the trail is null, allocate a trail, then add the receiver to
-  // the trail and return false.
-  bool TestAndAddToTrail(TrailPtr* trail) const;
-
-  // Return true if the pair <receiver, buddy> is contained in the trail.
-  // Otherwise, if the trail is null, allocate a trail, add the pair <receiver,
-  // buddy> to the trail and return false.
-  // The receiver may be added several times, each time with a different buddy.
-  bool TestAndAddBuddyToTrail(TrailPtr* trail, const AbstractType& buddy) const;
-
   static intptr_t InstanceSize() {
     return RoundedAllocationSize(sizeof(RawTypeRef));
   }
@@ -5738,6 +5758,7 @@ class TypeParameter : public AbstractType {
   bool CheckBound(const AbstractType& bounded_type,
                   const AbstractType& upper_bound,
                   Error* bound_error,
+                  TrailPtr bound_trail = NULL,
                   Heap::Space space = Heap::kNew) const;
   virtual TokenPosition token_pos() const { return raw_ptr()->token_pos_; }
   virtual bool IsInstantiated(TrailPtr trail = NULL) const {
@@ -5748,7 +5769,8 @@ class TypeParameter : public AbstractType {
   virtual RawAbstractType* InstantiateFrom(
       const TypeArguments& instantiator_type_arguments,
       Error* bound_error,
-      TrailPtr trail = NULL,
+      TrailPtr instantiation_trail = NULL,
+      TrailPtr bound_trail = NULL,
       Heap::Space space = Heap::kNew) const;
   virtual RawAbstractType* CloneUnfinalized() const;
   virtual RawAbstractType* CloneUninstantiated(
@@ -5833,7 +5855,8 @@ class BoundedType : public AbstractType {
   virtual RawAbstractType* InstantiateFrom(
       const TypeArguments& instantiator_type_arguments,
       Error* bound_error,
-      TrailPtr trail = NULL,
+      TrailPtr instantiation_trail = NULL,
+      TrailPtr bound_trail = NULL,
       Heap::Space space = Heap::kNew) const;
   virtual RawAbstractType* CloneUnfinalized() const;
   virtual RawAbstractType* CloneUninstantiated(