Overhaul build cache

.github/workflows/ci.yml

@@ -9,6 +9,8 @@ on:
 env:
   RUSTFLAGS: -Dwarnings
   RUST_BACKTRACE: 1
+  CARGO_INCREMENTAL: 0 # makes cache smaller
+  CARGO_PROFILE_DEV_DEBUG: 0
 
 jobs:
   clippy:
@@ -18,39 +20,49 @@ jobs:
       - uses: actions/checkout@v4
         with:
           submodules: 'recursive'
-      - name: Install Rust
-        run: rustup update stable --no-self-update && rustup default stable
-      - name: Install rustfmt
-        run: rustup component add rustfmt
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: clippy, rustfmt
       - name: Check format
         run: cargo fmt -- --check
-      - name: Cache cargo index and registry
+      - name: Cache cargo index
         uses: actions/cache@v4
         with:
           key: immutable # this will always be hit because it's a constant
-          path: |
-            ~/.cargo/registry/cache
-            ~/.cargo/registry/index
-      - name: Create lockfile
-        run: cargo generate-lockfile
-      - name: Fetch dependencies
-        run: cargo fetch
-      - name: Cache target directory
+          path: ~/.cargo/registry/index
+      - name: Cache cargo crates
         uses: actions/cache@v4
         with:
-          path: target
-          key: clippy-target-${{ runner.os }}-${{ steps.rust-version.outputs.version }}-${{ hashFiles('Cargo.lock') }}
+          key: crates-${{ hashFiles('Cargo.toml') }} # don't accumulate .crate files of old versions
+          path: ~/.cargo/registry/cache # target/ dir of clippy is not worth caching
+      - name: Fetch dependencies
+        run: cargo fetch
       - name: Run clippy
         run: cargo clippy --all --all-targets
   test:
     name: Test
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4
-    - name: Install Rust (rustup)
-      run: rustup update stable --no-self-update && rustup default stable
-    - name: Get rust version
-      id: rust-version
-      run: echo "::set-output name=version::$(rustc --version)"
-    - name: Run Rust tests
-      run: scripts/test.sh
+      - uses: actions/checkout@v4
+        with:
+          submodules: 'recursive'
+      - uses: dtolnay/rust-toolchain@stable
+      - name: Cache cargo index and registry
+        uses: actions/cache@v4
+        with:
+          key: immutable
+          path: ~/.cargo/registry/index
+      - name: Cache cargo crates
+        uses: actions/cache@v4
+        with:
+          key: crates-${{ hashFiles('Cargo.toml') }} # don't accumulate .crate files of old versions
+          path: ~/.cargo/registry/cache
+      - name: Fetch dependencies
+        run: cargo fetch
+      - name: Cache target directory
+        uses: actions/cache@v4
+        with:
+          path: target
+          key: target-${{ hashFiles('Cargo.toml') }}
+      - name: Run Rust tests
+        run: scripts/test.sh