In May 2025, Pietrek contributed to the rust-lang/gcc repository by developing a new configuration option that allows explicit selection of GNAT LLVM toolchains within GPR project files. This feature enables Ada projects to be built with different GNAT versions, supporting greater flexibility and reproducibility in build environments. Pietrek implemented the change using Ada and updated the documentation in reStructuredText and Texinfo to clearly explain the new option’s usage and implications. The work focused on build systems and compiler configuration, providing a targeted solution for multi-version toolchain experimentation. The contribution was delivered as a single, well-documented commit.