| # Bootstrapping the compiler |
| |
| [*Bootstrapping*][boot] is the process of using a compiler to compile itself. |
| More accurately, it means using an older compiler to compile a newer version |
| of the same compiler. |
| |
| This raises a chicken-and-egg paradox: where did the first compiler come from? |
| It must have been written in a different language. In Rust's case it was |
| [written in OCaml][ocaml-compiler]. However, it was abandoned long ago, and the |
| only way to build a modern version of rustc is with a slightly less modern |
| version. |
| |
| This is exactly how `x.py` works: it downloads the current beta release of |
| rustc, then uses it to compile the new compiler. |
| |
| In this section, we give a high-level overview of |
| [what Bootstrap does](./what-bootstrapping-does.md), followed by a high-level |
| introduction to [how Bootstrap does it](./how-bootstrap-does-it.md). |
| |
| Additionally, see [debugging bootstrap](./debugging-bootstrap.md) to learn |
| about debugging methods. |
| |
| [boot]: https://en.wikipedia.org/wiki/Bootstrapping_(compilers) |
| [ocaml-compiler]: https://github.com/rust-lang/rust/tree/ef75860a0a72f79f97216f8aaa5b388d98da6480/src/boot |
