Worked on enhancing code completion in the rust-lang/rust-analyzer repository by implementing support for displaying variadic arguments in function details. This involved introducing a new method to identify variadic functions and updating the parameter display logic to append an ellipsis for such cases, improving the clarity of code suggestions. The solution was developed using Rust and leveraged expertise in IDE development and the Language Server Protocol. Comprehensive tests were added to validate the new behavior and ensure future stability. The work focused on improving developer experience by making function signatures in code completion more informative and accurate for Rust users.