Worked on the rust-lang/gcc repository to deliver a new configuration option that allows explicit selection of GNAT LLVM toolchains within GPR project files, enabling Ada builds with different GNAT versions. This feature was implemented using Ada and involved updates to both build system logic and project documentation, written in reStructuredText and Texinfo. The approach focused on enhancing build configurability and reproducibility, making it easier for users to experiment with multiple GNAT LLVM versions. Documentation was expanded to clarify usage and implications, ensuring that the new option integrates smoothly into existing workflows and supports more flexible compiler configuration for Ada projects.