Update class_ir.py

Author: BobTheBuidler

mypyc/ir/class_ir.py

@@ -333,7 +333,7 @@ def has_method_decl(self, name: str) -> bool:
         return any(name in ir.method_decls for ir in self.mro)
 
     def has_no_subclasses(self) -> bool:
-        return self.children == [] and not self.allow_interpreted_subclasses
+        return self.children == [] and not self.allow_interpreted_subclasses and (self.is_ext_class or self.is_final_class)
 
     def subclasses(self) -> set[ClassIR] | None:
         """Return all subclasses of this class, both direct and indirect.