Avoid assert fault when using --trace-type-checks

runtime/vm/object.cc

Index: runtime/vm/object.cc
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index 62844ac892779b7ad81664024b61fa86d0e9c57b..45320b5eeb7de108d60b244d9b478641cf2061fe 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -3757,7 +3757,7 @@ RawType* Class::canonical_type() const {
 
 
 void Class::set_canonical_type(const Type& value) const {
-  ASSERT(!value.IsNull());
+  ASSERT(!value.IsNull() && value.IsCanonical() && value.IsOld());
   StorePointer(&raw_ptr()->canonical_type_, value.raw());
 }
 
@@ -17522,13 +17522,12 @@ RawAbstractType* Type::Canonicalize(TrailPtr trail) const {
     return Object::dynamic_type().raw();
   }
 
-  AbstractType& type = Type::Handle(zone);
   const Class& cls = Class::Handle(zone, type_class());
 
   // Fast canonical lookup/registry for simple types.
   if (!cls.IsGeneric() && !cls.IsClosureClass() && !cls.IsTypedefClass()) {
     ASSERT(!IsFunctionType());
-    type = cls.CanonicalType();
+    Type& type = Type::Handle(zone, cls.CanonicalType());
     if (type.IsNull()) {
       ASSERT(!cls.raw()->IsVMHeapObject() || (isolate == Dart::vm_isolate()));
       // Canonicalize the type arguments of the supertype, if any.
@@ -17546,18 +17545,26 @@ RawAbstractType* Type::Canonicalize(TrailPtr trail) const {
         // Recheck if type exists.
         type = cls.CanonicalType();
         if (type.IsNull()) {
-          ComputeHash();
-          SetCanonical();
-          cls.set_canonical_type(*this);
-          return this->raw();
+          if (this->IsNew()) {
+            type ^= Object::Clone(*this, Heap::kOld);
+          } else {
+            type ^= this->raw();
+          }
+          ASSERT(type.IsOld());
+          type.ComputeHash();
+          type.SetCanonical();
+          cls.set_canonical_type(type);
+          return type.raw();
         }
       }
     }
     ASSERT(this->Equals(type));
     ASSERT(type.IsCanonical());
+    ASSERT(type.IsOld());
     return type.raw();
   }
 
+  AbstractType& type = Type::Handle(zone);
   ObjectStore* object_store = isolate->object_store();
   {
     SafepointMutexLocker ml(isolate->type_canonicalization_mutex());