Auto merge of #7460 - camsteffen:run-from-source, r=Manishearth

Add instructions to run from source

changelog: none

We often get messages on Zulip asking how to install and run Clippy from source. This adds instructions to the readme. I also added a note explaining that `cargo install --path . --force` is bad, which I just decided after some investigating. I use macOS. It would be nice to get some tests on other platforms to see if this is correct.
This commit is contained in:
bors 2021-07-15 21:53:17 +00:00
commit 78ffcd9959

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@ -14,6 +14,7 @@ the codebase take a look at [Adding Lints] or [Common Tools].
- [lintcheck](#lintcheck)
- [PR](#pr)
- [Common Abbreviations](#common-abbreviations)
- [Install from source](#install-from-source)
## Get the Code
@ -128,4 +129,45 @@ This is a concise list of abbreviations that can come up during Clippy developme
general list can be found in the [rustc-dev-guide glossary][glossary]. Always feel free to ask if
an abbreviation or meaning is unclear to you.
## Install from source
If you are hacking on Clippy and want to install it from source, do the following:
First, take note of the toolchain [override](https://rust-lang.github.io/rustup/overrides.html) in `/rust-toolchain`.
We will use this override to install Clippy into the right toolchain.
> Tip: You can view the active toolchain for the current directory with `rustup show active-toolchain`.
From the Clippy project root, run the following command to build the Clippy binaries and copy them into the
toolchain directory. This will override the currently installed Clippy component.
```terminal
cargo build --release --bin cargo-clippy --bin clippy-driver -Zunstable-options --out-dir "$(rustc --print=sysroot)/bin"
```
Now you may run `cargo clippy` in any project, using the toolchain where you just installed Clippy.
```terminal
cd my-project
cargo +nightly-2021-07-01 clippy
```
...or `clippy-driver`
```terminal
clippy-driver +nightly-2021-07-01 <filename>
```
If you need to restore the default Clippy installation, run the following (from the Clippy project root).
```terminal
rustup component remove clippy
rustup component add clippy
```
> **DO NOT** install using `cargo install --path . --force` since this will overwrite rustup
[proxies](https://rust-lang.github.io/rustup/concepts/proxies.html). That is, `~/.cargo/bin/cargo-clippy` and
`~/.cargo/bin/clippy-driver` should be hard or soft links to `~/.cargo/bin/rustup`. You can repair these by running
`rustup update`.
[glossary]: https://rustc-dev-guide.rust-lang.org/appendix/glossary.html