Worked on improving the reliability of Apple SDK integration within the rust-lang/cc-rs repository by addressing an issue in environment variable handling. Implemented a default case for the env variable in the apple_sdk_name function using Rust, which prevented incorrect target environment resolution and reduced build-time failures for Apple platforms. This change focused on defensive programming techniques common in system programming, ensuring more robust toolchain integration and enhancing CI stability. The contribution did not introduce new features but provided a targeted bug fix that improved the overall build process, demonstrating attention to detail and a methodical approach to platform-specific reliability.