Worked on the bazelbuild/rules_rust repository to address reliability issues related to proc-macro crate handling in Rust projects. Focused on improving the make_rust_binary rule, the developer implemented a fix to ensure proc-macro libraries are correctly placed in proc_macro_deps rather than standard dependencies when building binary targets. This adjustment resolved analysis failures and improved the accuracy of the dependency graph, particularly for projects combining proc-macro libraries and binaries. Automated testing was introduced to validate the new behavior and prevent regressions. The work emphasized software development best practices, robust testing, and maintainability within the Rust and Bazel build system ecosystem.