Merge remote-tracking branch 'upstream/master'

.editorconfig

@@ -0,0 +1,11 @@
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+max_line_length = 80
+indent_size =  4
+
+[*.yml]
+indent_size = 2

.eslintrc.json

@@ -0,0 +1,19 @@
+{
+  "parser": "@typescript-eslint/parser",
+  "parserOptions": {
+    "project": "./tsconfig.eslint.json"
+  },
+  "plugins": ["@typescript-eslint"],
+  "extends": [
+    "eslint:recommended",
+    "plugin:@typescript-eslint/eslint-recommended",
+    "plugin:@typescript-eslint/recommended-requiring-type-checking",
+    "plugin:@typescript-eslint/recommended",
+    "plugin:prettier/recommended",
+    "prettier",
+    "prettier/@typescript-eslint"
+  ],
+  "rules": {
+    "@typescript-eslint/ban-ts-ignore": "off"
+  }
+}

.githooks/pre-commit

@@ -0,0 +1,15 @@
+#!/bin/bash
+
+# This commit hook checks whether we ran `npm run build` when committed TypeScript files.
+# For GitHub actions to work, we need to check the compiled JavaScript into VCS.
+#
+# This script can yield false positives in cases where you only make stylistic changes to the TypeScript code that don't result in changes to the compiled JavaScript code.
+# It is your responsibility as a developer to then commit the changes with `git commit --no-verify` and simply skip this commit hook.
+
+TS_FILES=$(git diff --staged --name-only | grep -c '.ts')
+DIST_MODIFIED=$(git diff --staged --name-only | grep -c dist/index.js)
+
+if [ $TS_FILES -gt 0 ] && [ $DIST_MODIFIED -eq 0 ] ; then
+    echo "You modified TypeScript files but apparently did not run 'npm run build'".
+    exit 1;
+fi

.github/workflows/ci.yml

@@ -0,0 +1,72 @@
+name: Continuous integration
+
+on: [push, pull_request]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Create npm configuration
+        run: echo "//npm.pkg.github.com/:_authToken=${token}" >> ~/.npmrc
+        env:
+          token: ${{ secrets.GITHUB_TOKEN }}
+
+      - uses: actions/checkout@v1
+      - run: npm ci
+      - run: npm run lint
+      - run: npm run build
+      - run: npm run test
+
+  install_stable:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os:
+          - ubuntu-latest
+          - macOS-latest
+          - windows-latest
+    steps:
+      - uses: actions/checkout@v1
+      - id: toolchain
+        uses: ./
+        with:
+          toolchain: stable
+      - name: Test toolchain outputs
+        env:
+          RUSTC: ${{ steps.toolchain.outputs.rustc }}
+          RUSTC_HASH: ${{ steps.toolchain.outputs.rustc_hash }}
+          CARGO: ${{ steps.toolchain.outputs.cargo }}
+          RUSTUP: ${{ steps.toolchain.outputs.rustup }}
+        run: |
+          echo $RUSTC
+          echo $RUSTC_HASH
+          echo $CARGO
+          echo $RUSTUP
+
+  install_nightly:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v1
+      - uses: ./
+        with:
+          profile: minimal
+          toolchain: nightly
+          components: rustfmt, clippy
+
+  install_stable_in_docker:
+    runs-on: ubuntu-latest
+    container: ubuntu:latest  # Docker image, not the GitHub Actions VM
+    steps:
+      # `rustup` will need `curl` or `wget` later
+      - run: apt-get update && apt-get install -y curl
+      - uses: actions/checkout@v1
+      - uses: ./
+        with:
+          toolchain: stable
+
+  install_stable_through_rust_toolchain_file:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v1
+      - run: echo "stable" > ./rust-toolchain
+      - uses: ./

.gitignore

@@ -0,0 +1,94 @@
+__tests__/runner/*
+
+# Rest pulled from https://github.com/github/gitignore/blob/master/Node.gitignore
+# Logs
+logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+lerna-debug.log*
+
+# Diagnostic reports (https://nodejs.org/api/report.html)
+report.[0-9]*.[0-9]*.[0-9]*.[0-9]*.json
+
+# Runtime data
+pids
+*.pid
+*.seed
+*.pid.lock
+
+# Directory for instrumented libs generated by jscoverage/JSCover
+lib-cov
+
+# Coverage directory used by tools like istanbul
+coverage
+*.lcov
+
+# nyc test coverage
+.nyc_output
+
+# Grunt intermediate storage (https://gruntjs.com/creating-plugins#storing-task-files)
+.grunt
+
+# Bower dependency directory (https://bower.io/)
+bower_components
+
+# node-waf configuration
+.lock-wscript
+
+# Compiled binary addons (https://nodejs.org/api/addons.html)
+build/Release
+
+# Dependency directories
+node_modules/
+jspm_packages/
+
+# TypeScript v1 declaration files
+typings/
+
+# TypeScript cache
+*.tsbuildinfo
+
+# Optional npm cache directory
+.npm
+
+# Optional eslint cache
+.eslintcache
+
+# Optional REPL history
+.node_repl_history
+
+# Output of 'npm pack'
+*.tgz
+
+# Yarn Integrity file
+.yarn-integrity
+
+# dotenv environment variables file
+.env
+.env.test
+
+# parcel-bundler cache (https://parceljs.org/)
+.cache
+
+# next.js build output
+.next
+
+# nuxt.js build output
+.nuxt
+
+# vuepress build output
+.vuepress/dist
+
+# Serverless directories
+.serverless/
+
+# FuseBox cache
+.fusebox/
+
+# DynamoDB Local files
+.dynamodb/
+
+# IntelliJ IDEs
+.idea

.npmrc

@@ -0,0 +1 @@
+@actions-rs:registry=https://npm.pkg.github.com

CHANGELOG.md

@@ -0,0 +1,49 @@
+# Changelog
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [1.0.6] - 2020-03-24
+
+### Added
+
+- Pass `allow-downgrade` flag to `rustup` if `nightly` toolchain with components requested
+
+## [1.0.5] - 2020-01-26
+
+### Fixed
+
+- `rustup` version parser does not fail Action execution on `macOS-latest` VM images anymore
+
+## [1.0.4] - 2020-01-26
+
+### Added
+
+- Support for the `rust-toolchain` file: If the toolchain input is not given, we will try and install the version specified in the `rust-toolchain` file.
+- Action outputs with `rustc`, `cargo` and `rustup` versions installed
+
+## [1.0.3] - 2019-10-19
+
+### Added
+
+- Support for `rustup set profile` command
+- Support for `--component` flag for the `rustup toolchain install` command
+
+## [1.0.2] - 2019-10-14
+
+### Changed
+
+- Missing `rustup` executable will not raise an annotating warning before the installation anymore (#13)
+
+## [1.0.1] - 2019-10-05
+
+### Changed
+
+- `target` input is not used as a `--default-target` argument for `rustup` anymore (#8)
+
+## [1.0.0] - 2019-09-15
+
+### Added
+
+- First public version

LICENSE

@@ -0,0 +1,22 @@
+
+The MIT License (MIT)
+
+Copyright (c) 2019 actions-rs team and contributors
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

README.md

@@ -0,0 +1,169 @@
+# `rust-toolchain` Action
+
+[![Sponsoring](https://img.shields.io/badge/Support%20it-Say%20%22Thank%20you!%22-blue)](https://actions-rs.github.io/#sponsoring)
+![MIT licensed](https://img.shields.io/badge/license-MIT-blue.svg)
+[![Gitter](https://badges.gitter.im/actions-rs/community.svg)](https://gitter.im/actions-rs/community)
+![Continuous integration](https://github.com/actions-rs/toolchain/workflows/Continuous%20integration/badge.svg)
+![Dependabot enabled](https://api.dependabot.com/badges/status?host=github&repo=actions-rs/toolchain)
+
+This GitHub Action installs [Rust toolchain](https://github.com/rust-lang/rustup.rs#toolchain-specification)
+with [rustup](https://github.com/rust-lang/rustup) help.
+
+It supports additional targets, components and profiles and handles all
+these small papercuts for you.
+
+**Table of Contents**
+
+* [Example workflow](#example-workflow)
+* [Inputs](#inputs)
+* [Outputs](#outputs)
+* [Profiles](#profiles)
+* [Components](#components)
+* [The toolchain file](#the-toolchain-file)
+* [License](#license)
+* [Contribute and support](#contribute-and-support)
+
+## Example workflow
+
+```yaml
+on: [push]
+
+name: build
+
+jobs:
+  check:
+    name: Rust project
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Install latest nightly
+        uses: actions-rs/toolchain@v1
+        with:
+            toolchain: nightly
+            override: true
+            components: rustfmt, clippy
+
+      # `cargo check` command here will use installed `nightly`
+      # as it is set as an "override" for current directory
+
+      - name: Run cargo check
+        uses: actions-rs/cargo@v1
+        with:
+          command: check
+```
+
+See [additional recipes here](https://github.com/actions-rs/meta).
+
+## Inputs
+
+| Name         | Required | Description                                                                                                                                         | Type   | Default |
+| ------------ | :------: | ----------------------------------------------------------------------------------------------------------------------------------------------------| ------ | --------|
+| `toolchain`  |          | [Toolchain](https://github.com/rust-lang/rustup.rs#toolchain-specification) name to use, ex. `stable`, `nightly`, `nightly-2019-04-20`, or `1.32.0` | string |         |
+| `target`     |          | Additionally install specified target for this toolchain, ex. `x86_64-apple-darwin`                                                                 | string |         |
+| `default`    |          | Set installed toolchain as a default toolchain                                                                                                      | bool   | false   |
+| `override`   |          | Set installed toolchain as an override for the current directory                                                                                    | bool   | false   |
+| `profile`    |          | Execute `rustup set profile {value}` before installing the toolchain, ex. `minimal`                                                                 | string |         |
+| `components` |          | Comma-separated list of the additional components to install, ex. `clippy, rustfmt`                                                                 | string |         |
+
+Note: since `v1.0.4` version, `toolchain` input is not marked as required
+in order to support toolchain files. See the details [below](#the-toolchain-file).
+
+## Outputs
+
+Installed `rustc`, `cargo` and `rustup` versions can be fetched from the Action outputs:
+
+| Name         | Description           | Example                         |
+| ------------ | --------------------- | ------------------------------- |
+| `rustc`      | Rustc version         | `1.40.0 (73528e339 2019-12-16)` |
+| `rustc_hash` | Rustc version hash    | `73528e339`                     |
+| `cargo`      | Cargo version         | `1.40.0 (bc8e4c8be 2019-11-22)` |
+| `rustup`     | rustup version        | `1.21.1 (7832b2ebe 2019-12-20)` |
+
+Note: `rustc-hash` output value can be used with [actions/cache](https://github.com/actions/cache) Action
+to store cache for different Rust versions, as it is unique across different Rust versions and builds (including `nightly`).
+
+## Profiles
+
+This Action supports rustup [profiles](https://blog.rust-lang.org/2019/10/15/Rustup-1.20.0.html#profiles),
+which are can be used to speed up the workflow execution by installing the
+minimally required set of components, for example:
+
+```yaml
+- name: Install minimal nightly
+  uses: actions-rs/toolchain@v1
+  with:
+    profile: minimal
+    toolchain: nightly
+```
+
+This Action will automatically run `rustup self update` if `profile` input is set
+and the installed `rustup` version does not supports them.
+
+In order to provide backwards compatibility for `v1` version,
+there is no value for `profile` input set by default,
+which means that the `default` profile is used by `rustup`
+(and that includes `rust-docs`, `clippy` and `rustfmt`).\
+You may want to consider using `profile: minimal` to speed up toolchain installation.
+
+## Components
+
+This Action supports rustup [components](https://blog.rust-lang.org/2019/10/15/Rustup-1.20.0.html#installing-the-latest-compatible-nightly) too,
+and in combination with the [profiles](#profiles) input it allows to install only the needed components:
+
+```yaml
+- name: Install minimal stable with clippy and rustfmt
+  uses: actions-rs/toolchain@v1
+  with:
+    profile: minimal
+    toolchain: stable
+    components: rustfmt, clippy
+```
+
+As an extra perk, `rustup >= 1.20.0` is able to find the most recent `nightly` toolchain
+with the requested components available; next example is utilizing this feature
+to install the minimal set of `nightly` toolchain components with the `rustfmt` and `clippy` extras:
+
+```yaml
+- name: Install minimal nightly with clippy and rustfmt
+  uses: actions-rs/toolchain@v1
+  with:
+    profile: minimal
+    toolchain: nightly
+    components: rustfmt, clippy
+```
+
+In case if `nightly` toolchain is requested and one of the components is missing in
+latest `nightly` release, this Action will attempt the downgrade till it find
+the most recent `nightly` with all components needed.\
+Note that this behavior will work only if the following two conditions apply:
+
+ 1. `toolchain` input is `nightly` exactly.
+ 2. At least one component is provided in `components` input.
+
+Same to the `profile` input, if installed `rustup` does not supports "components",
+it will be automatically upgraded by this Action.
+
+## The toolchain file
+
+This Action supports [toolchain files](https://github.com/rust-lang/rustup#the-toolchain-file),
+so it is not necessary to use `toolchain` input anymore.
+
+Input has higher priority, so if you are want to use toolchain file,
+you need to remove the input from the workflow file.
+
+If neither `toolchain` input or `rust-toolchain` file are provided,
+Action execution will fail.
+
+## License
+
+This Action is distributed under the terms of the MIT license, see [LICENSE](https://github.com/actions-rs/toolchain/blob/master/LICENSE) for details.
+
+## Contribute and support
+
+Any contributions are welcomed!
+
+If you want to report a bug or have a feature request,
+check the [Contributing guide](https://github.com/actions-rs/.github/blob/master/CONTRIBUTING.md).
+
+You can also support author by funding the ongoing project work,
+see [Sponsoring](https://actions-rs.github.io/#sponsoring).

__tests__/args.test.ts

@@ -0,0 +1,74 @@
+import { getToolchainArgs } from "../src/args";
+import { morph } from "mock-env";
+import { sync as tempWriteSync } from "temp-write";
+
+describe("actions-rs/toolchain", () => {
+    it("Parses action input into toolchain options", () => {
+        const args = morph(
+            () => {
+                return getToolchainArgs("./rust-toolchain");
+            },
+            {
+                INPUT_TOOLCHAIN: "nightly-2019-04-20",
+                INPUT_DEFAULT: "false",
+                INPUT_OVERRIDE: "true",
+            }
+        );
+
+        expect(args.name).toBe("nightly-2019-04-20");
+        expect(args.default).toBe(false);
+        expect(args.override).toBe(true);
+    });
+
+    it("uses input variable if rust-toolchain file does not exist", function () {
+        const args = morph(
+            () => {
+                return getToolchainArgs("./rust-toolchain");
+            },
+            {
+                INPUT_TOOLCHAIN: "nightly",
+            }
+        );
+
+        expect(args.name).toBe("nightly");
+    });
+
+    it("toolchain input is required if rust-toolchain does not exist", function () {
+        expect(() => getToolchainArgs("./rust-toolchain")).toThrowError();
+    });
+
+    it("prioritizes rust-toolchain file over input variable", function () {
+        const rustToolchainFile = tempWriteSync("1.39.0");
+
+        const args = morph(
+            () => {
+                return getToolchainArgs(rustToolchainFile);
+            },
+            {
+                INPUT_TOOLCHAIN: "nightly",
+            }
+        );
+
+        expect(args.name).toBe("nightly");
+    });
+
+    it("uses rust-toolchain file if input does not exist", function () {
+        const rustToolchainFile = tempWriteSync("1.39.0");
+
+        const args = morph(() => {
+            return getToolchainArgs(rustToolchainFile);
+        }, {});
+
+        expect(args.name).toBe("1.39.0");
+    });
+
+    it("trims content of the override file", function () {
+        const rustToolchainFile = tempWriteSync("\n     1.39.0\n\n\n\n");
+
+        const args = morph(() => {
+            return getToolchainArgs(rustToolchainFile);
+        }, {});
+
+        expect(args.name).toBe("1.39.0");
+    });
+});

action.yml

@@ -0,0 +1,44 @@
+name: 'rust-toolchain'
+description: 'Install the Rust toolchain'
+author: 'actions-rs team'
+branding:
+  icon: play-circle
+  color: black
+inputs:
+  toolchain:
+    description: |
+      Rust toolchain name.
+
+      See https://github.com/rust-lang/rustup.rs#toolchain-specification
+
+      If this is not given, the action will try and install the version specified in the `rust-toolchain` file.
+    required: false
+  target:
+    description: Target triple to install for this toolchain
+    required: false
+  default:
+    description: Set installed toolchain as default
+    default: false
+  override:
+    description: Set installed toolchain as an override for a directory
+    default: false
+  profile:
+    description: Name of the group of components to be installed for a new toolchain
+    required: false
+  components:
+    description: Comma-separated list of components to be additionally installed for a new toolchain
+    required: false
+
+outputs:
+  rustc:
+    description: Installed Rustc version
+  rustc_hash:
+    description: Installed Rustc version hash, can be used for caching purposes
+  cargo:
+    description: Installed Cargo version
+  rustup:
+    description: Installed rustup version
+
+runs:
+  using: 'node12'
+  main: 'dist/index.js'

jest.config.json

@@ -0,0 +1,11 @@
+{
+  "clearMocks": true,
+  "moduleFileExtensions": ["js", "ts"],
+  "testEnvironment": "node",
+  "testMatch": ["**/*.test.ts"],
+  "testRunner": "jest-circus/runner",
+  "transform": {
+    "^.+\\.ts$": "ts-jest"
+  },
+  "verbose": true
+}

package.json

@@ -0,0 +1,58 @@
+{
+    "name": "rust-toolchain",
+    "version": "1.0.6",
+    "private": false,
+    "description": "Install the Rust toolchain",
+    "main": "lib/main.js",
+    "directories": {
+        "lib": "lib",
+        "test": "__tests__"
+    },
+    "scripts": {
+        "build": "rm -rf ./dist/* && ncc build src/main.ts --minify",
+        "format": "prettier --write 'src/**/*.ts' '__tests__/**/*.ts'",
+        "lint": "tsc --noEmit && eslint 'src/**/*.ts' '__tests__/**/*.ts'",
+        "watch": "rm -rf ./dist/* && ncc build src/main.ts --watch",
+        "test": "jest -c jest.config.json",
+        "pretest": "git config core.hooksPath .githooks"
+    },
+    "repository": {
+        "type": "git",
+        "url": "git+https://github.com/actions-rs/toolchain.git"
+    },
+    "keywords": [
+        "actions",
+        "rust",
+        "rustup",
+        "toolchain"
+    ],
+    "author": "actions-rs",
+    "license": "MIT",
+    "bugs": {
+        "url": "https://github.com/actions-rs/toolchain/issues"
+    },
+    "dependencies": {
+        "@actions-rs/core": "^0.0.9",
+        "@actions/core": "^1.2.3",
+        "@actions/exec": "^1.0.3",
+        "@actions/io": "^1.0.2"
+    },
+    "devDependencies": {
+        "@types/jest": "^25.1.4",
+        "@types/node": "^13.9.3",
+        "@typescript-eslint/eslint-plugin": "^2.25.0",
+        "@typescript-eslint/parser": "^2.25.0",
+        "@zeit/ncc": "^0.22.0",
+        "eslint": "^6.8.0",
+        "eslint-config-prettier": "^6.10.1",
+        "eslint-plugin-prettier": "^3.1.2",
+        "jest": "^25.1.0",
+        "jest-circus": "^25.1.0",
+        "mock-env": "^0.2.0",
+        "npm-check-updates": "^4.0.5",
+        "prettier": "^2.0.2",
+        "temp-write": "^4.0.0",
+        "ts-jest": "^25.2.1",
+        "typescript": "^3.8.3"
+    }
+}

src/args.ts

@@ -0,0 +1,52 @@
+import { input } from "@actions-rs/core";
+import { debug } from "@actions/core";
+import { existsSync, readFileSync } from "fs";
+
+export interface ToolchainOptions {
+    name: string;
+    target: string | undefined;
+    default: boolean;
+    override: boolean;
+    profile: string | undefined;
+    components: string[] | undefined;
+}
+
+function determineToolchain(overrideFile: string): string {
+    const toolchainInput = input.getInput("toolchain", { required: false });
+
+    if (toolchainInput) {
+        debug(`using toolchain from input: ${toolchainInput}`);
+        return toolchainInput;
+    }
+
+    if (!existsSync(overrideFile)) {
+        throw new Error(
+            "toolchain input was not given and repository does not have a rust-toolchain file"
+        );
+    }
+
+    const rustToolchainFile = readFileSync(overrideFile, {
+        encoding: "utf-8",
+        flag: "r",
+    }).trim();
+
+    debug(`using toolchain from rust-toolchain file: ${rustToolchainFile}`);
+
+    return rustToolchainFile;
+}
+
+export function getToolchainArgs(overrideFile: string): ToolchainOptions {
+    let components: string[] | undefined = input.getInputList("components");
+    if (components && components.length === 0) {
+        components = undefined;
+    }
+
+    return {
+        name: determineToolchain(overrideFile),
+        target: input.getInput("target") || undefined,
+        default: input.getInputBool("default"),
+        override: input.getInputBool("override"),
+        profile: input.getInput("profile") || undefined,
+        components: components,
+    };
+}

src/main.ts

@@ -0,0 +1,97 @@
+import * as core from "@actions/core";
+import path from "path";
+
+import * as args from "./args";
+import * as versions from "./versions";
+import { RustUp, ToolchainOptions } from "@actions-rs/core";
+
+async function run(): Promise<void> {
+    // we use path.join to make sure this works on Windows, Linux and MacOS
+    const toolchainOverridePath = path.join(process.cwd(), "rust-toolchain");
+
+    const opts = args.getToolchainArgs(toolchainOverridePath);
+    const rustup = await RustUp.getOrInstall();
+    await rustup.call(["show"]);
+
+    let shouldSelfUpdate = false;
+    if (opts.profile && !(await rustup.supportProfiles())) {
+        shouldSelfUpdate = true;
+    }
+    if (opts.components && !(await rustup.supportComponents())) {
+        shouldSelfUpdate = true;
+    }
+    if (shouldSelfUpdate) {
+        core.startGroup("Updating rustup");
+        try {
+            await rustup.selfUpdate();
+        } finally {
+            core.endGroup();
+        }
+    }
+
+    if (opts.profile) {
+        // @ts-ignore: TS2345
+        await rustup.setProfile(opts.profile);
+    }
+
+    const installOptions: ToolchainOptions = {
+        default: opts.default,
+        override: opts.override,
+    };
+    if (opts.components) {
+        installOptions.components = opts.components;
+    }
+    // We already did it just now, there is no reason to do that again,
+    // so it would skip few network calls.
+    if (shouldSelfUpdate) {
+        installOptions.noSelfUpdate = true;
+    }
+
+    // Extra funny case.
+    // Due to `rustup` issue (https://github.com/rust-lang/rustup/issues/2146)
+    // right now installing `nightly` toolchain with extra components might fail
+    // if that specific `nightly` version does not have this component
+    // available.
+    //
+    // See https://github.com/actions-rs/toolchain/issues/53 also.
+    //
+    // By default `rustup` does not downgrade, as it does when you are
+    // updating already installed `nightly`, so we need to pass the
+    // corresponding flag manually.
+    //
+    // We are doing it only if both following conditions apply:
+    //
+    //   1. Requested toolchain is `"nightly"` (exact string match).
+    //   2. At least one component is requested.
+    //
+    // All other cases are not triggering automatic downgrade,
+    // for example, installing specific nightly version
+    // as in `"nightly-2020-03-20"` or `"stable"`.
+    //
+    // Motivation is that users probably want the latest one nightly
+    // with rustfmt and clippy (miri, etc) and they don't really care
+    // about what exact nightly it is.
+    // In case if it's not the nightly at all or it is a some specific
+    // nightly version, they know what they are doing.
+    if (opts.name == "nightly" && opts.components) {
+        installOptions.allowDowngrade = true;
+    }
+
+    await rustup.installToolchain(opts.name, installOptions);
+
+    if (opts.target) {
+        await rustup.addTarget(opts.target, opts.name);
+    }
+
+    await versions.gatherInstalledVersions();
+}
+
+async function main(): Promise<void> {
+    try {
+        await run();
+    } catch (error) {
+        core.setFailed(error.message);
+    }
+}
+
+main();

src/versions.ts

@@ -0,0 +1,114 @@
+import * as exec from "@actions/exec";
+import * as core from "@actions/core";
+
+interface Version {
+    long: string;
+    hash: string;
+}
+
+/**
+ * Try to parse the version parts and return them.
+ *
+ * It is important to note that some components are not providing
+ * all the expected information, ex. `rustup` on `macOS-latest` VM image
+ * does not has the hash in the version string,
+ * so this function might throw an error.
+ *
+ * As a fallback, `parseShort` function can be used.
+ */
+function parseFull(stdout: string): Version {
+    const regex = /\S+\s((\S+)\s\((\S+)\s(\S+)\))/m;
+    stdout = stdout.trim();
+    const matches = regex.exec(stdout);
+    if (matches == null) {
+        throw new Error(`Unable to parse version from the "${stdout}" string`);
+    }
+
+    return {
+        long: matches[1],
+        hash: matches[3],
+    };
+}
+
+function parseShort(stdout: string): string {
+    const regex = /\S+\s(.+)/m;
+    stdout = stdout.trim();
+    const matches = regex.exec(stdout);
+    if (matches == null) {
+        core.warning(`Unable to determine version from the "${stdout}" string`);
+        return "";
+    } else {
+        return matches[1];
+    }
+}
+
+async function getStdout(
+    exe: string,
+    args: string[],
+    options?: {}
+): Promise<string> {
+    let stdout = "";
+    const resOptions = Object.assign({}, options, {
+        listeners: {
+            stdout: (buffer: Buffer): void => {
+                stdout += buffer.toString();
+            },
+        },
+    });
+
+    await exec.exec(exe, args, resOptions);
+
+    return stdout;
+}
+
+/**
+ * Fetch currently used `rustc` version
+ */
+async function rustc(): Promise<void> {
+    const stdout = await getStdout("rustc", ["-V"]);
+    try {
+        const version = parseFull(stdout);
+
+        core.setOutput("rustc", version.long);
+        core.setOutput("rustc_hash", version.hash);
+    } catch (e) {
+        core.warning(e);
+        core.setOutput("rustc", parseShort(stdout));
+    }
+}
+
+/**
+ * Fetch currently used `cargo` version
+ */
+async function cargo(): Promise<void> {
+    const stdout = await getStdout("cargo", ["-V"]);
+    try {
+        const version = parseFull(stdout);
+
+        core.setOutput("cargo", version.long);
+    } catch (e) {
+        core.setOutput("cargo", parseShort(stdout));
+    }
+}
+
+async function rustup(): Promise<void> {
+    const stdout = await getStdout("rustup", ["-V"]);
+    try {
+        const version = parseFull(stdout);
+        core.setOutput("rustup", version.long);
+    } catch (e) {
+        core.setOutput("rustup", parseShort(stdout));
+    }
+}
+
+export async function gatherInstalledVersions(): Promise<void> {
+    try {
+        core.startGroup("Gathering installed versions");
+
+        await rustc();
+        await cargo();
+        await rustup();
+    } finally {
+        core.endGroup();
+    }
+}

tsconfig.eslint.json

@@ -0,0 +1,7 @@
+{
+    "extends": "./tsconfig.json",
+    "include": [
+        "src/**/*.ts",
+        "__tests__/**/*.ts"
+    ]
+}

tsconfig.json

@@ -0,0 +1,32 @@
+{
+    "compilerOptions": {
+        "allowJs": false,
+        "checkJs": false,
+        "esModuleInterop": true,
+        "forceConsistentCasingInFileNames": true,
+        "module": "commonjs",
+        "moduleResolution": "node",
+        "newLine": "LF",
+        "noEmitOnError": true,
+        "noErrorTruncation": true,
+        "noFallthroughCasesInSwitch": true,
+        "noImplicitAny": true,
+        "noImplicitReturns": true,
+        "noImplicitThis": true,
+        "noUnusedLocals": true,
+        "noUnusedParameters": true,
+        "outDir": "dist",
+        "pretty": true,
+        "removeComments": true,
+        "resolveJsonModule": true,
+        "strict": true,
+        "suppressImplicitAnyIndexErrors": false,
+        "target": "es2018",
+        "declaration": false,
+        "sourceMap": false,
+        "typeRoots": ["./types", "./node_modules/@types"]
+    },
+    "include": [
+        "src/**/*.ts"
+    ]
+}

types/mock-env/index.d.ts

@@ -0,0 +1,7 @@
+declare module "mock-env" {
+    function morph<T>(
+        callback: () => T,
+        vars: object,
+        toRemove?: string[]
+    ): any;
+}