Add override input parameter that controls the `rustup override` behavior

.pre-commit-config.yaml

@@ -0,0 +1,18 @@
+repos:
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v4.6.0
+    hooks:
+      - id: check-case-conflict
+      - id: check-executables-have-shebangs
+      - id: check-merge-conflict
+      - id: check-json
+      - id: check-yaml
+      - id: end-of-file-fixer
+      - id: trailing-whitespace
+        args: [--markdown-linebreak-ext=md]
+  - repo: https://github.com/python-jsonschema/check-jsonschema
+    rev: 0.29.2
+    hooks:
+      - id: check-dependabot
+      - id: check-github-actions
+      - id: check-github-workflows

CHANGELOG.md

@@ -10,6 +10,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * Add new parameter `cache-directories` that is propagated to `Swatinem/rust-cache` (#44 by @pranc1ngpegasus)
 * Add new parameter `cache-key` that is propagated to `Swatinem/rust-cache` as `key` (#41 by @iainlane)
 * Make rustup toolchain installation more robust in light of planned changes https://github.com/rust-lang/rustup/issues/3635 and https://github.com/rust-lang/rustup/pull/3985
+* Allow installing multiple Rust toolchains by specifying multiple versions in the `toolchain` input parameter.
+* Configure the `rustup override` behavior via the new `override` input. (#38)
 
 ## [1.9.0] - 2024-06-08
 

README.md

@@ -48,18 +48,19 @@ If no `toolchain` value or toolchain file is present, it will default to `stable
 First, all items specified in the toolchain file are installed.
 Afterward, the `components` and `target` specified via inputs are installed in addition to the items from the toolchain file.
 
-| Name                | Description                                                                            | Default       |
-| ------------------- | -------------------------------------------------------------------------------------- | ------------- |
-| `toolchain`         | Rustup toolchain specifier e.g. `stable`, `nightly`, `1.42.0`.                         | stable        |
-| `target`            | Additional target support to install e.g. `wasm32-unknown-unknown`                     |               |
-| `components`        | Comma-separated string of additional components to install e.g. `clippy, rustfmt`      |               |
-| `cache`             | Automatically configure Rust cache (using [`Swatinem/rust-cache`])                     | true          |
-| `cache-directories` | Propagates the value to [`Swatinem/rust-cache`]                                        |               |
-| `cache-workspaces`  | Propagates the value to [`Swatinem/rust-cache`]                                        |               |
-| `cache-on-failure`  | Propagates the value to [`Swatinem/rust-cache`]                                        | true          |
-| `cache-key`         | Propagates the value to [`Swatinem/rust-cache`] as `key`                               |               |
-| `matcher`           | Enable problem matcher to surface build messages and formatting issues                 | true          |
-| `rustflags`         | Set the value of `RUSTFLAGS` (set to empty string to avoid overwriting existing flags) | "-D warnings" |
+| Name                | Description                                                                                                              | Default       |
+| ------------------- | ------------------------------------------------------------------------------------------------------------------------ | ------------- |
+| `toolchain`         | Comma-separated list of Rustup toolchain specifier e.g. `stable`, `nightly`, `1.42.0`.  The last version is the default. | stable        |
+| `target`            | Additional target support to install e.g. `wasm32-unknown-unknown`                                                       |               |
+| `components`        | Comma-separated string of additional components to install e.g. `clippy, rustfmt`                                        |               |
+| `cache`             | Automatically configure Rust cache (using [`Swatinem/rust-cache`])                                                       | true          |
+| `cache-directories` | Propagates the value to [`Swatinem/rust-cache`]                                                                          |               |
+| `cache-workspaces`  | Propagates the value to [`Swatinem/rust-cache`]                                                                          |               |
+| `cache-on-failure`  | Propagates the value to [`Swatinem/rust-cache`]                                                                          | true          |
+| `cache-key`         | Propagates the value to [`Swatinem/rust-cache`] as `key`                                                                 |               |
+| `matcher`           | Enable problem matcher to surface build messages and formatting issues                                                   | true          |
+| `rustflags`         | Set the value of `RUSTFLAGS` (set to empty string to avoid overwriting existing flags)                                   | "-D warnings" |
+| `override`          | Setup the last installed toolchain as the default via `rustup override`                                                  | true          |
 
 [`Swatinem/rust-cache`]: https://github.com/Swatinem/rust-cache
 

action.yml

@@ -13,7 +13,7 @@ branding:
 # The action is heavily inspired by https://github.com/dtolnay/rust-toolchain
 inputs:
   toolchain:
-    description: "Rust toolchain specification -- see https://rust-lang.github.io/rustup/concepts/toolchains.html#toolchain-specification"
+    description: "Comma-separated list of Rust toolchain specifications. Last version becomes the default. -- see https://rust-lang.github.io/rustup/concepts/toolchains.html#toolchain-specification"
     required: false
   target:
     description: "Target triple to install for this toolchain"
@@ -46,6 +46,10 @@ inputs:
     description: "set RUSTFLAGS environment variable, set to empty string to avoid overwriting build.rustflags"
     required: false
     default: "-D warnings"
+  override:
+    description: "Setup the last installed toolchain as the default via `rustup override`"
+    required: false
+    default: "true"
 
 outputs:
   rustc-version:
@@ -80,7 +84,7 @@ runs:
         : construct rustup command line
         echo "targets=$(for t in ${targets//,/ }; do echo -n ' --target' $t; done)" >> $GITHUB_OUTPUT
         echo "components=$(for c in ${components//,/ }; do echo -n ' --component' $c; done)" >> $GITHUB_OUTPUT
-        echo "downgrade=${{inputs.toolchain == 'nightly' && inputs.components && ' --allow-downgrade' || ''}}" >> $GITHUB_OUTPUT
+        echo "downgrade=${{contains(inputs.toolchain, 'nightly') && inputs.components && ' --allow-downgrade' || ''}}" >> $GITHUB_OUTPUT
 
     # The environment variables always need to be set before the caching action
     - name: Setting Environment Variables
@@ -132,6 +136,7 @@ runs:
         toolchain: ${{inputs.toolchain}}
         targets: ${{inputs.target}}
         components: ${{inputs.components}}
+        override: ${{inputs.override}}
       shell: bash
       run: |
         if [[ -z "$toolchain" && ( -f "rust-toolchain" || -f "rust-toolchain.toml" ) ]]
@@ -152,8 +157,12 @@ runs:
           then
             toolchain=stable
           fi
-          rustup toolchain install $toolchain${{steps.flags.outputs.targets}}${{steps.flags.outputs.components}} --profile minimal${{steps.flags.outputs.downgrade}} --no-self-update
-          rustup override set $toolchain
+          rustup toolchain install ${toolchain//,/ } ${{steps.flags.outputs.targets}}${{steps.flags.outputs.components}} --profile minimal${{steps.flags.outputs.downgrade}} --no-self-update
+          # Take the last element from the list
+          if [[ "$override" == "true" ]]
+          then
+            rustup override set ${toolchain//*,/ }
+          fi
         fi
 
     - id: versions