gccrs is a work-in-progress alternative compiler for Rust being developed as part of the GCC project. GCC is a collection of compilers for various programming languages that all share a common compilation framework. You may have heard about gccgo, gfortran, or g++, which are all binaries within that project, the GNU Compiler Collection. The aim of gccrs is to add support for the Rust programming language to that collection, with the goal of having the exact same behavior as rustc.