Quickstart Guide to Building and Testing the Rust Compiler

# Quickstart This is a quickstart guide about getting the compiler running. For more information on the individual steps, see the other pages in this chapter. First, clone the repository: ```sh git clone https://github.com/rust-lang/rust.git cd rust ``` When building the compiler, we don't use `cargo` directly, instead we use a wrapper called "x". It is invoked with `./x`. We need to create a configuration for the build. Use `./x setup` to create a good default. ```sh ./x setup ``` Then, we can build the compiler. Use `./x build` to build the compiler, standard library and a few tools. You can also `./x check` to just check it. All these commands can take specific components/paths as arguments, for example `./x check compiler` to just check the compiler. ```sh ./x build ``` > When doing a change to the compiler that does not affect the way it compiles the standard library (so for example, a change to an error message), use `--keep-stage-std 1` to avoid recompiling it. After building the compiler and standard library, you now have a working compiler toolchain. You can use it with rustup by linking it. ```sh rustup toolchain link stage1 build/host/stage1 ``` Now you have a toolchain called `stage1` linked to your build. You can use it to test the compiler. ```sh rustc +stage1 testfile.rs ``` After doing a change, you can run the compiler test suite with `./x test`. `./x test` runs the full test suite, which is slow and rarely what you want. Usually, `./x test tests/ui` is what you want after a compiler change, testing all [UI tests](../tests/ui.md) that invoke the compiler on a specific test file and check the output. ```sh ./x test tests/ui ``` Use `--bless` if you've made a change and want to update the `.stderr` files with the new output. > `./x suggest` can also be helpful for suggesting which tests to run after a > change. Congrats, you are now ready to make a change to the compiler! If you have more questions, [the full chapter](./how-to-build-and-run.md) might contain the answers, and if it doesn't, feel free to ask for help on [Zulip](https://rust-lang.zulipchat.com/#narrow/stream/182449-t-compiler.2Fhelp). If you use VSCode, Vim, Emacs or Helix, `./x setup` will ask you if you want to set up the editor config. For more information, check out [suggested workflows](./suggested.md).

This section provides a quickstart guide on how to set up, build, and test the Rust compiler. It covers cloning the repository, configuring the build using `./x setup`, building the compiler with `./x build`, and linking the compiled toolchain with rustup. It also explains how to run tests, specifically UI tests, and update `.stderr` files using the `--bless` option. Additionally, it mentions using `./x suggest` to find relevant tests and points to more resources for further assistance.