Better and more verbose version printing and cachekey version.

CHANGELOG.md

@@ -11,6 +11,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 * Install rustup if not available in the CI environment. (Linux only)
     The code is taken from this issue: <https://github.com/dtolnay/rust-toolchain/pull/8>
+* Add rustc version output suitable as a cache key.
+    This is based on <https://github.com/dtolnay/rust-toolchain/pull/20> and <https://github.com/dtolnay/rust-toolchain/pull/17>.
 
 ## [1.0.1] - 2022-04-20
 

action.yml

@@ -33,6 +33,9 @@ outputs:
   rustup-version:
     description: "Version as reported by `rustup --version`"
     value: ${{steps.versions.outputs.rustup-version}}
+  cachekey:
+    description: A short hash of the rustc version, appropriate for use as a cache key. "20220627a831"
+    value: ${{steps.versions.outputs.cachekey}}
 
 runs:
   using: composite
@@ -60,15 +63,20 @@ runs:
         rustup toolchain install ${{inputs.toolchain}}${{steps.flags.outputs.targets}}${{steps.flags.outputs.components}} --profile minimal${{steps.flags.outputs.downgrade}} --no-self-update
         rustup default ${{inputs.toolchain}}
       shell: bash
+
     - name: Print installed versions
       id: versions
       run: |
-        echo "::set-output name=rustc-version::$(rustc --version)"
-        rustc --version
-        echo "::set-output name=cargo-version::$(cargo --version)"
-        cargo --version
-        echo "::set-output name=rustup-version::$(rustup --version)"
-        rustup --version
+        echo "::set-output name=rustc-version::$(rustc +${{inputs.toolchain}} --version)"
+        rustc +${{inputs.toolchain}} --version --verbose
+        echo "::set-output name=cargo-version::$(cargo +${{inputs.toolchain}} --version)"
+        cargo +${{inputs.toolchain}} --version --verbose
+        echo "::set-output name=rustup-version::$(rustup +${{inputs.toolchain}} --version)"
+        rustup +${{inputs.toolchain}} --version
+
+        DATE=$(rustc +${{inputs.toolchain}} --version --verbose | sed -ne 's/^commit-date: \(20[0-9][0-9]\)-\([01][0-9]\)-\([0-3][0-9]\)$/\1\2\3/p')
+        HASH=$(rustc +${{inputs.toolchain}} --version --verbose | sed -ne 's/^commit-hash: //p')
+        echo "::set-output name=cachekey::$(echo $DATE$HASH | head -c12)"
       shell: bash
 
     - name: "Setup Rust Caching"