add workspaces input field to support non-root projects

Author: gruebel

README.md

@@ -48,14 +48,15 @@ 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          |
-| `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`        | 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`                                          |               |
+| `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" |
 
 ### RUSTFLAGS
 

action.yml

@@ -25,6 +25,9 @@ inputs:
     description: "Automatically configure Rust cache"
     required: false
     default: "true"
+  cache-workspaces:
+    description: "Paths to multiple Cargo workspaces and their target directories, separated by newlines."
+    required: false
   matcher:
     description: "Enable the Rust problem matcher"
     required: false
@@ -171,3 +174,5 @@ runs:
     - name: Setup Rust Caching
       if: inputs.cache == 'true'
       uses: Swatinem/rust-cache@v2
+      with:
+        workspaces: ${{inputs.cache-workspaces}}