This repository is the compiler toolchain for the Carbon Language, an experimental successor to C++ focused on performance, C++ interoperability, and memory safety. The codebase implements a full compilation pipeline from lexing and parsing through semantic analysis (SemIR) to LLVM IR code generation, along with a language server (LSP), a formatting tool, and C++ interop via Clang integration. The architecture follows a phased compiler design with distinct modules for lex, parse, check, sem_ir, lower, and driver, all orchestrated through a Bazel build system. Key entry points include the main driver binary (`toolchain/driver/`) with subcommands like `compile`, `link`, `build`, `format`, and `language-server`, and the semantic checker (`toolchain/check/`) which handles type checking, generics, and impl resolution. The toolchain also features a robust diagnostics system, a custom high-performance hashtable, and an extensive file-based testing framework with automatic CHECK-line updates. The codebase is actively developed with frequent commits, extensive test coverage, and fuzz testing, though it remains experimental and subject to breaking changes.