Worked on the rust-lang/rust repository to enhance documentation and improve type layout reliability within the compiler. Focused on clarifying the niche encoding mechanisms and variant representations for the TagEncoding and FakeBorrowKind enums, the developer strengthened documentation to support better onboarding and reduce misinterpretation. Addressed a layout correctness issue by refactoring the discriminant check logic, moving it into the layout_sanity_check to ensure proper alignment between discriminants and variant indices for niche-encoded tags. Leveraged expertise in Rust, compiler design, and system programming to deliver targeted improvements that contribute to safer type layouts and a more accessible codebase for future contributors.