Worked on the elixir-lang/elixir repository to enhance developer guidance around deprecations, specifically targeting the handling of single-quoted charlists. Focused on compiler development and language design using Erlang, the work clarified that warnings for single-quoted charlists represent actual deprecations rather than stylistic preferences. The technical approach included updating warning messages and introducing an automated migration path through the mix format --migrate tool, enabling developers to update affected code efficiently. This change reduced confusion and streamlined the migration process, ensuring better alignment with Elixir’s deprecation policy and improving the overall developer experience for those maintaining or upgrading Elixir codebases.