Worked on the swiftlang/swift repository to enhance compiler stability and diagnostic clarity for key path operations involving protocol metatypes. Addressed a critical bug by preventing compiler crashes when static key path members were referenced on protocol metatypes, introducing targeted error messages and robust type handling during key path evaluation. Improved constraint solving to reject invalid static member references early, ensuring such cases do not propagate to later compilation stages. Focused on consistent treatment of metatype bases as AnyMetatypeType during type checking and SILGen. Utilized Swift, C++, and static analysis techniques to deliver safer, more predictable compiler behavior for downstream users.