CI lint: consolidate clippy definitions

.github/actions/rust-toolchain/action.yml

@@ -0,0 +1,41 @@
+name: Rust Toolchain
+
+inputs:
+  toolchain_channel:
+    description: Either "stable" or "msrv"
+    required: true
+  targets:
+    description: Comma-separated list of target triples to install for this toolchain
+    required: false
+  components:
+    description: Comma-separated list of components to be additionally installed
+    required: false
+
+permissions:
+  contents: read
+
+runs:
+  using: "composite"
+  steps:
+    - name: Set toolchain
+      env:
+        toolchain_channel: ${{ inputs.toolchain_channel }}
+      shell: bash
+      run: |
+        set -x
+        toolchain=$(
+          case "$toolchain_channel" in
+            (stable) echo 1.90 ;;
+            (msrv)   echo 1.70 ;;
+            (*)
+              printf >&2 "error: unsupported toolchain channel %s" "$toolchain_channel"
+              exit 1
+              ;;
+          esac
+        )
+        printf 'TOOLCHAIN=%s\n' "$toolchain" >>"$GITHUB_ENV"
+    - uses: dtolnay/rust-toolchain@master
+      with:
+        toolchain: ${{ env.TOOLCHAIN }}
+        targets: ${{ inputs.targets }}
+        components: ${{ inputs.components }}

.github/actions/rust-toolchain@oldest-supported/action.yml

@@ -14,7 +14,8 @@ permissions:
 runs:
   using: "composite"
   steps:
-    - uses: dtolnay/rust-toolchain@1.70
+    - uses: ./.github/actions/rust-toolchain
       with:
+        toolchain_channel: "msrv"
         targets: ${{ inputs.targets }}
-        components: ${{ inputs.components}}
+        components: ${{ inputs.components }}

.github/actions/rust-toolchain@stable/action.yml

@@ -14,7 +14,8 @@ permissions:
 runs:
   using: "composite"
   steps:
-    - uses: dtolnay/rust-toolchain@1.90
+    - uses: ./.github/actions/rust-toolchain
       with:
+        toolchain_channel: "stable"
         targets: ${{ inputs.targets }}
         components: ${{ inputs.components }}

.github/workflows/lint.yml

@@ -20,15 +20,22 @@ jobs:
     - name: check format
       run: PATH="target/debug:$PATH" build_tools/style.fish --all --check
 
-  clippy-stable:
+  clippy:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        features: ["", "--no-default-features"]
+        include:
+          - rust_version: "stable"
+            features: ""
+          - rust_version: "stable"
+            features: "--no-default-features"
+          - rust_version: "msrv"
+            features: ""
     steps:
     - uses: actions/checkout@v3
-    - uses: ./.github/actions/rust-toolchain@stable
+    - uses: ./.github/actions/rust-toolchain
       with:
+        toolchain_channel: ${{ matrix.rust_version }}
         components: clippy
     - name: Install deps
       run: |
@@ -36,19 +43,6 @@ jobs:
     - name: cargo clippy
       run: cargo clippy --workspace --all-targets ${{ matrix.features }} -- --deny=warnings
 
-  clippy-msrv:
-    runs-on: ubuntu-latest
-    steps:
-    - uses: actions/checkout@v3
-    - uses: ./.github/actions/rust-toolchain@oldest-supported
-      with:
-        components: clippy
-    - name: Install deps
-      run: |
-        sudo apt install gettext
-    - name: cargo clippy
-      run: cargo clippy --workspace --all-targets -- --deny=warnings
-
   rustdoc:
     runs-on: ubuntu-latest
     steps: