(Re)Using rustc components in gccrs

The gccrs project aims to develop an alternative Rust compiler using components from the official Rust compiler (rustc) to ensure compatibility and performance. The team has begun integrating various rustc components, starting with rustc_parse_format, which parses Rust format strings for proper string formatting and inline assembly. This integration is crucial for maintaining consistent behavior between gccrs and rustc, especially in complex areas like borrow-checking. The next significant component planned for integration is polonius, a next-generation borrow-checker that enhances the current borrow-checking algorithm. The project faces challenges due to the differences in internal representations between gccrs (written in C++) and rustc (written in Rust), which complicates the reuse of components. The team is committed to ensuring that gccrs mirrors rustc's behavior to avoid discrepancies in error handling and runtime behavior. Currently, gccrs relies on rustc and Cargo to compile these components, with plans to fully integrate them once gccrs is more mature. The bootstrapping process involves creating an intermediate compiler to facilitate the integration of Rust components, ultimately leading to a fully functional Rust compiler with enhanced capabilities.

- gccrs is developing an alternative Rust compiler by reusing components from rustc.

- The first integrated component is rustc_parse_format, which handles Rust format strings.

- Future integration includes polonius, a next-generation borrow-checker.

- Differences in internal representations between gccrs and rustc pose challenges for component reuse.

- The project aims to ensure consistent behavior between gccrs and rustc, particularly in error handling.