Improve upper bound finalization in VM and fix #25122.

runtime/vm/object.cc

Index: runtime/vm/object.cc
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index 6863a85cd1f60df78ce0d5e59239e25a748bc799..7dd76e7c29ec1707a965ae8c9a2c84f4498c425e 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -3787,11 +3787,11 @@ bool Class::TypeTestNonRecursive(const Class& cls,
     }
     // Check for reflexivity.
     if (thsi.raw() == other.raw()) {
-      const intptr_t num_type_args = thsi.NumTypeArguments();
-      if (num_type_args == 0) {
+      const intptr_t num_type_params = thsi.NumTypeParameters();
+      if (num_type_params == 0) {
         return true;
       }
-      const intptr_t num_type_params = thsi.NumTypeParameters();
+      const intptr_t num_type_args = thsi.NumTypeArguments();
       const intptr_t from_index = num_type_args - num_type_params;
       // Since we do not truncate the type argument vector of a subclass (see
       // below), we only check a subvector of the proper length.
@@ -15630,8 +15630,8 @@ bool AbstractType::TypeTest(TypeTestKind test_kind,
                             const AbstractType& other,
                             Error* bound_error,
                             Heap::Space space) const {
-  ASSERT(IsResolved());
-  ASSERT(other.IsResolved());
+  ASSERT(IsFinalized());
+  ASSERT(other.IsFinalized());
   if (IsMalformed() || other.IsMalformed()) {
     // Malformed types involved in subtype tests should be handled specially
     // by the caller. Malformed types should only be encountered here in a
@@ -15685,6 +15685,15 @@ bool AbstractType::TypeTest(TypeTestKind test_kind,
       }
     }
     const AbstractType& bound = AbstractType::Handle(type_param.bound());
+    // We may be checking bounds at finalization time and can encounter
+    // a still unfinalized bound.
+    if (!bound.IsFinalized() && !bound.IsBeingFinalized()) {
+      ClassFinalizer::FinalizeType(
+          Class::Handle(type_param.parameterized_class()),
+          bound,
+          ClassFinalizer::kCanonicalize);
+      type_param.set_bound(bound);
+    }
     if (bound.IsMoreSpecificThan(other, bound_error)) {
       return true;
     }