Add rust-toolchain.toml awareness

README.md

@@ -17,16 +17,19 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
-      - uses: dtolnay/rust-toolchain@stable
+      - uses: IronCoreLabs/rust-toolchain@stable
       - run: cargo test --all-features
 ```
 
 The selection of Rust toolchain is made based on the particular @rev of this
-Action being requested. For example "dtolnay/rust-toolchain@nightly" pulls in
-the nightly Rust toolchain, while "dtolnay/rust-toolchain@1.42.0" pulls in
+Action being requested. For example "IronCoreLabs/rust-toolchain@nightly" pulls in
+the nightly Rust toolchain, while "IronCoreLabs/rust-toolchain@1.42.0" pulls in
 1.42.0.
 
-<br>
+## Toolchain File
+
+The [Rust toolchain file](https://rust-lang.github.io/rustup/overrides.html#the-toolchain-file) is supported.
+If present it will be used to populate `toolchain`, `components` and `targets` parameters. If those parameters are explicitly set as inputs to the action, they will take precedence over the values in the toolchain file. To use only the toolchain file for parameters, pass no inputs and set the @rev to @master.
 
 ## Inputs
 
@@ -42,7 +45,7 @@ All inputs are optional.
   <td>
     Rustup toolchain specifier e.g. <code>stable</code>, <code>nightly</code>, <code>1.42.0</code>, <code>nightly-2022-01-01</code>.
     <b>Important: the default is to match the @rev as described above.</b>
-    When passing an explicit <code>toolchain</code> as an input instead of @rev, you'll want to use "dtolnay/rust-toolchain@master" as the revision of the action.
+    When passing an explicit <code>toolchain</code> as an input instead of @rev, you'll want to use "IronCoreLabs/rust-toolchain@master" as the revision of the action.
   </td>
 </tr>
 <tr>
@@ -57,6 +60,27 @@ All inputs are optional.
 
 <br>
 
+## Outputs
+
+<table>
+<tr>
+  <th>Name</th>
+  <th>Description</th>
+</tr>
+<tr>
+  <td><code>toolchain</code></td>
+  <td>
+    The parsed toolchain that was installed by this action.
+  </td>
+</tr>
+<tr>
+  <td><code>cachekey</code></td>
+  <td>A short hash of the rustc version, appropriate for use as a cache key. ex "20220627a831"</td>
+</tr>
+</table>
+
+<br>
+
 ## Toolchain expressions
 
 The following forms are available for projects that use a sliding window of
@@ -65,7 +89,7 @@ compiler support.
 ```yaml
      # Installs the most recent stable toolchain as of the specified time
      # offset, which may be written in years, months, weeks, or days.
-  - uses: dtolnay/rust-toolchain@master
+  - uses: IronCoreLabs/rust-toolchain@master
     with:
       toolchain: stable 18 months ago
 ```
@@ -73,7 +97,7 @@ compiler support.
 ```yaml
      # Installs the stable toolchain which preceded the most recent one by
      # the specified number of minor versions.
-  - uses: dtolnay/rust-toolchain@master
+  - uses: IronCoreLabs/rust-toolchain@master
     with:
       toolchain: stable minus 8 releases
 ```