Fix: Run the version detection steps in the selected rust-src-dir directory.

This should enable the version selection even without a default
toolchain installed.

Fixes #74.

.github/dependabot.yml

@@ -8,4 +8,4 @@ updates:
   - package-ecosystem: "github-actions"
     directory: "/"
     schedule:
-      interval: "monthly"
+      interval: "weekly"

.github/workflows/autotag-releases.yml

@@ -15,7 +15,7 @@ jobs:
     permissions:
       contents: write
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - name: Get version from tag
         id: tag_name
         run: |

.github/workflows/ci.yml

@@ -32,7 +32,7 @@ jobs:
           - "beta"
           - "stable"
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
       # Test toolchain file support
       - name: Write rust-toolchain.toml
@@ -93,7 +93,7 @@ jobs:
     name: Cache
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
       - name: Install Rust
         uses: ./

.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

@@ -7,6 +7,58 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [1.15.2] - 2025-10-04
+
+* Fix: Run the version detection steps in the selected `rust-src-dir` directory.
+    This should enable the version selection even without a default toolchain installed.
+    Fixes #74.
+
+## [1.15.1] - 2025-09-23
+
+* Update `Swatinem/rust-cache` to v2.8.1
+
+## [1.15.0] - 2025-09-14
+
+* Add support for non-root source directory.
+    Accept source code and `rust-toolchain.toml` file in subdirectories of the repository.
+    Adds a new parameter `rust-src-dir` that controls the lookup for toolchain files and sets a default value for the `cache-workspace` input. (#69 by @Kubaryt)
+
+## [1.14.1] - 2025-08-28
+
+* Pin `Swatinem/rust-cache` action to a full commit SHA (#68 by @JohnTitor)
+
+## [1.14.0] - 2025-08-23
+
+* Add new parameters `cache-all-crates` and `cache-workspace-crates` that are propagated to `Swatinem/rust-cache` as `cache-all-crates` and `cache-workspace-crates`
+
+## [1.13.0] - 2025-06-16
+
+* Add new parameter `cache-provider` that is propagated to `Swatinem/rust-cache` as `cache-provider` (#65 by @mindrunner)
+
+## [1.12.0] - 2025-04-23
+
+* Add support for installing rustup on Windows (#58 by @maennchen)
+    This adds support for using Rust on the GitHub provided Windows ARM runners.
+
+## [1.11.0] - 2025-02-24
+
+* Add new parameter `cache-bin` that is propagated to `Swatinem/rust-cache` as `cache-bin` (#51 by @enkhjile)
+* Add new parameter `cache-shared-key` that is propagated to `Swatinem/rust-cache` as `shared-key` (#52 by @skanehira)
+
+## [1.10.1] - 2024-10-01
+
+* Fix problem matcher for rustfmt output.
+    The format has changed since https://github.com/rust-lang/rustfmt/pull/5971 and now follows the form "filename:line".
+    Thanks to @0xcypher02 for pointing out the problem.
+
+## [1.10.0] - 2024-09-23
+
+* 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
 
 * Add extra argument `cache-on-failure` and forward it to `Swatinem/rust-cache`. (#39 by @samuelhnrq)  

README.md

@@ -6,7 +6,7 @@ Caching for Rust tools and build artifacts is enabled.
 Environment variables are set to optimize the cache hits.
 [Problem Matchers] are provided for build messages (cargo, clippy) and formatting (rustfmt).
 
-The action is heavily inspired by *dtolnay*'s <https://github.com/dtolnay/rust-toolchain> and extends it with further features.
+The action is heavily inspired by _dtolnay_'s <https://github.com/dtolnay/rust-toolchain> and extends it with further features.
 
 ## Example workflow
 
@@ -21,7 +21,7 @@ jobs:
     name: cargo test
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - uses: actions-rust-lang/setup-rust-toolchain@v1
       - run: cargo test --all-features
 
@@ -30,7 +30,7 @@ jobs:
     name: cargo fmt
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       # Ensure rustfmt is installed and setup problem matcher
       - uses: actions-rust-lang/setup-rust-toolchain@v1
         with:
@@ -48,16 +48,25 @@ 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-workspaces` | Propagates the value to [`Swatinem/rust-cache`]                                        |               |
-| `cache-on-failure` | Propagates the value to [`Swatinem/rust-cache`]                                        | true          |
-| `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`]. Influenced by the value of `rust-src-dir`.                                                                                        |               |
+| `cache-on-failure`       | Propagates the value to [`Swatinem/rust-cache`]                                                                                                                                    | true          |
+| `cache-key`              | Propagates the value to [`Swatinem/rust-cache`] as `key`                                                                                                                           |               |
+| `cache-shared-key`       | Propagates the value to [`Swatinem/rust-cache`] as `shared-key`                                                                                                                    |               |
+| `cache-bin`              | Propagates the value to [`Swatinem/rust-cache`] as `cache-bin`                                                                                                                     | true          |
+| `cache-provider`         | Propagates the value to [`Swatinem/rust-cache`] as `cache-provider`                                                                                                                | 'github'      |
+| `cache-all-crates`       | Propagates the value to [`Swatinem/rust-cache`] as `cache-all-crates`                                                                                                              | false         |
+| `cache-workspace-crates` | Propagates the value to [`Swatinem/rust-cache`] as `cache-workspace-crates`                                                                                                        | false         |
+| `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          |
+| `rust-src-dir`           | Path from root directory to directory with the Rust source directory (if its not in the root of the repository). Sets a default value for `cache-workspaces` that enables caching. |               |
 
 [`Swatinem/rust-cache`]: https://github.com/Swatinem/rust-cache
 
@@ -66,10 +75,10 @@ Afterward, the `components` and `target` specified via inputs are installed in a
 By default, this action sets the `RUSTFLAGS` environment variable to `-D warnings`.
 However, rustflags sources are mutually exclusive, so setting this environment variable omits any configuration through `target.*.rustflags` or `build.rustflags`.
 
-* If `RUSTFLAGS` is already set, no modifications of the variable are made and the original value remains.
-* If `RUSTFLAGS` is unset and the `rustflags` input is empty (i.e., the empty string), then it will remain unset.
-    Use this, if you want to prevent the value from being set because you make use of `target.*.rustflags` or `build.rustflags`.
-* Otherwise, the environment variable `RUSTFLAGS` is set to the content of `rustflags`.
+- If `RUSTFLAGS` is already set, no modifications of the variable are made and the original value remains.
+- If `RUSTFLAGS` is unset and the `rustflags` input is empty (i.e., the empty string), then it will remain unset.
+  Use this, if you want to prevent the value from being set because you make use of `target.*.rustflags` or `build.rustflags`.
+- Otherwise, the environment variable `RUSTFLAGS` is set to the content of `rustflags`.
 
 To prevent this from happening, set the `rustflags` input to an empty string, which will
 prevent the action from setting `RUSTFLAGS` at all, keeping any existing preferences.
@@ -85,6 +94,16 @@ You can read more rustflags, and their load order, in the [Cargo reference].
 | `rustup-version` | Version as reported by `rustup --version`   |
 | `cachekey`       | A short hash of the installed rustc version |
 
+## Dependencies
+
+The action works best on the GitHub-hosted runners, but can work on self-hosted ones too, provided the necessary dependencies are available.
+PRs to add support for more environments are welcome.
+
+- bash 5
+- brew (macOS only)
+- rustup or curl
+- using other node actions
+
 ## License
 
 The scripts and documentation in this project are released under the [MIT

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"
@@ -28,10 +28,35 @@ inputs:
   cache-workspaces:
     description: "Paths to multiple Cargo workspaces and their target directories, separated by newlines."
     required: false
+  cache-directories:
+    description: "Additional non workspace directories to be cached, separated by newlines."
+    required: false
   cache-on-failure:
-    description: "Also cache on workflow failures"
+    description: "Cache even if the build fails."
     default: "true"
     required: false
+  cache-key:
+    description: "An additional cache key that is added alongside the automatic `job`-based cache key and can be used to further differentiate jobs."
+    required: false
+  cache-shared-key:
+    description: "A cache key that is used instead of the automatic `job`-based key, and is stable over multiple jobs."
+    required: false
+  cache-bin:
+    description: "Determines whether to cache ${CARGO_HOME}/bin."
+    required: false
+    default: "true"
+  cache-provider:
+    description: "Determines which provider to use for caching. Options are github, buildjet, or warpbuild. Defaults to github."
+    required: false
+    default: "github"
+  cache-all-crates:
+    description: "Determines which crates are cached. If `true` all crates will be cached, otherwise only dependent crates will be cached."
+    required: false
+    default: "false"
+  cache-workspace-crates:
+    description: "Determines which crates are cached. If `true` all crates will be cached, otherwise only dependent crates will be cached."
+    required: false
+    default: "false"
   matcher:
     description: "Enable the Rust problem matcher"
     required: false
@@ -40,6 +65,13 @@ 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"
+  rust-src-dir:
+    description: "Specify path from root directory to the Rust source directory. By default root directory will be used."
+    required: false
 
 outputs:
   rustc-version:
@@ -74,7 +106,7 @@ 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
@@ -113,26 +145,50 @@ runs:
       run: echo "::add-matcher::${{ github.action_path }}/rust.json"
 
     - name: Install rustup, if needed
-      if: runner.os != 'Windows'
       shell: bash
       run: |
         if ! command -v rustup &> /dev/null ; then
           curl --proto '=https' --tlsv1.2 --retry 10 --retry-connrefused -fsSL "https://sh.rustup.rs" | sh -s -- --default-toolchain none -y
-          echo "${CARGO_HOME:-$HOME/.cargo}/bin" >> $GITHUB_PATH
+
+          # Resolve the correct CARGO_HOME path depending on OS
+          if [[ "$RUNNER_OS" == "Windows" ]]; then
+            echo "${CARGO_HOME:-$USERPROFILE/.cargo}/bin" | sed 's|/|\\|g' >> $GITHUB_PATH
+          else
+            echo "${CARGO_HOME:-$HOME/.cargo}/bin" >> $GITHUB_PATH
+          fi
         fi
+      env:
+        RUNNER_OS: "${{ runner.os }}"
 
     - name: rustup toolchain install ${{inputs.toolchain || 'stable'}}
       env:
         toolchain: ${{inputs.toolchain}}
         targets: ${{inputs.target}}
         components: ${{inputs.components}}
+        override: ${{inputs.override}}
+        rust_src_dir: ${{inputs.rust-src-dir}}
       shell: bash
       run: |
-        if [[ -z "$toolchain" && ( -f "rust-toolchain" || -f "rust-toolchain.toml" ) ]]
+        # Check if value is set
+        if [[ -n "$rust_src_dir" ]]
+        then
+          # If value is set the directory must exist
+          if [[ -d "$rust_src_dir" ]]
+          then
+            cd "$rust_src_dir"
+          else
+            echo "'rust-src-dir' does not point to an existing directory" >&2
+            echo "The value of 'rust-src-dir' is: ${rust_src_dir}" >&2
+            exit 1
+          fi
+        fi
+        if [[ -z "$toolchain" && ( -f "rust-toolchain" || -f "rust-toolchain.toml") ]]
         then
           # Install the toolchain as specified in the file
-          # Might break at some point: https://github.com/rust-lang/rustup/issues/1397
-          rustup show
+          # rustup show is the old way that implicitly installed a toolchain
+          # rustup toolchain install is the new explicit way
+          # https://github.com/rust-lang/rustup/issues/3635#issuecomment-2343511297
+          rustup show active-toolchain || rustup toolchain install
           if [[ -n $components ]]; then
             rustup component add ${components//,/ }
           fi
@@ -144,13 +200,19 @@ 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
       name: Print installed versions
       shell: bash
+      # Switch to the Rust sub-directory
+      working-directory: ${{inputs.rust-src-dir || '.'}}
       run: |
         echo "rustc-version=$(rustc --version)" >> $GITHUB_OUTPUT
         rustc --version --verbose
@@ -177,7 +239,14 @@ runs:
 
     - name: Setup Rust Caching
       if: inputs.cache == 'true'
-      uses: Swatinem/rust-cache@v2
+      uses: Swatinem/rust-cache@f13886b937689c021905a6b90929199931d60db1 # v2.8.1
       with:
-        workspaces: ${{inputs.cache-workspaces}}
+        workspaces: ${{ inputs.cache-workspaces || inputs.rust-src-dir }}
+        cache-directories: ${{inputs.cache-directories}}
         cache-on-failure: ${{inputs.cache-on-failure}}
+        cache-bin: ${{inputs.cache-bin}}
+        cache-provider: ${{inputs.cache-provider}}
+        cache-all-crates: ${{inputs.cache-all-crates}}
+        cache-workspace-crates: ${{inputs.cache-workspace-crates}}
+        key: ${{inputs.cache-key}}
+        shared-key: ${{inputs.cache-shared-key}}

rust.json

@@ -5,7 +5,7 @@
             "severity": "warning",
             "pattern": [
                 {
-                    "regexp": "^(Diff in (.+)) at line (\\d+):$",
+                    "regexp": "^(Diff in (.+))(?: at line |:)(\\d+):$",
                     "message": 1,
                     "file": 2,
                     "line": 3