toolchain/README.md

# `rustup toolchain` Action

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This GitHub Action installs [Rust toolchain](https://github.com/rust-lang/rustup.rs#toolchain-specification).

Optionally it can set installed toolchain as a default and as an override for current directory.

## Example workflow

```yaml
on: [push]

name: build

jobs:
  check:
    name: Rust project
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@master
      - name: Install nightly
        uses: actions-rs/toolchain@v1
        with:
            toolchain: nightly
            override: true
```

## Inputs

* `toolchain` (*required*): Toolchain name, see [rustup page](https://github.com/rust-lang/rustup.rs#toolchain-specification) for details.\
  Examples: `stable`, `nightly`, `nightly-2019-04-20`
* `target`: Additionally install specific target for this toolchain (ex. `x86_64-apple-darwin`)
* `default`: Set installed toolchain as default (executes `rustup toolchain default {TOOLCHAIN}`)
* `override`: Set installed toolchain as an override for current directory

## Components

If you are going to install `clippy`, `rustfmt` or any other [rustup component](https://rust-lang.github.io/rustup-components-history/),
it might not be available in latest `nightly` build;
check out the [`actions-rs/components-nightly`](https://github.com/actions-rs/components-nightly) Action,
which makes this process much easier.

## Notes

As `rustup` is not installed by default for [macOS environments](https://help.github.com/en/articles/virtual-environments-for-github-actions)
at the moment (2019-09-13), this Action will try its best to install it before any other operations.