While the compilation process itself is quite complex and involves many moving parts, it can be broken down into a handful of discrete phases. These are:

• Lexing and Parsing
• Lowering to HIR
• Analysis (type checking, inference, borrowck, etc)
• Translation to LLVM IR
• Optimisation and code generation (done by LLVM)
• Linking into a single executable (also outsourced, usually to something like ld)

All of these steps are coordinated by the driver which resides in rustc_driver. A lot of this tutorial will be interacting with rustc_driver and the various knobs and hooks it gives us access to.

TODO: Write a bit about each step and where they are located in the rust-lang/rust repo.