ci: cache fixtures

Only generate fixtures if any grammar from any parser or the parser
generation itself has changed.

.github/actions/cache/action.yml

@@ -0,0 +1,25 @@
+name: 'Cache'
+description: "This action caches fixtures"
+outputs:
+  cache-hit:
+    description: 'Cache hit'
+    value: ${{ steps.cache_output.outputs.cache-hit }}
+runs:
+  using: "composite"
+  steps:
+    - uses: actions/cache@v4
+      id: cache_fixtures
+      with:
+        path: |
+          test/fixtures/grammars
+          target/release/tree-sitter-*.wasm
+        key: fixtures-${{ join(matrix.*, '_') }}-${{ hashFiles(
+          '.github/workflows/builds.yml',
+          '.github/workflows/sanitize.yml',
+          'cli/src/generate/**',
+          'script/generate-fixtures*',
+          'test/fixtures/grammars/*/**/src/*.c') }}
+
+    - run: echo "cache-hit=${{ steps.cache_fixtures.outputs.cache-hit }}" >> $GITHUB_OUTPUT
+      shell: bash
+      id: cache_output

.github/workflows/build.yml

@@ -156,16 +156,17 @@ jobs:
     - name: Build CLI
       run: $BUILD_CMD build --release --target=${{ matrix.target }} --features=${CLI_FEATURES}
 
-    - name: Fetch fixtures
-      if: ${{ !matrix.cli-only && inputs.run_test }} # Don't fetch fixtures for only CLI building targets
-      run: script/fetch-fixtures
+    - run: script/fetch-fixtures
+
+    - uses: ./.github/actions/cache
+      id: cache
 
     - name: Generate fixtures
-      if: ${{ !matrix.cli-only && inputs.run_test }} # Can't natively run CLI on Github runner's host
+      if: ${{ !matrix.cli-only && inputs.run_test && steps.cache.outputs.cache-hit != 'true' }} # Can't natively run CLI on Github runner's host
       run: script/generate-fixtures
 
     - name: Generate WASM fixtures
-      if: ${{ !matrix.cli-only && !matrix.use-cross && inputs.run_test }} # See comment for the "Build wasm library" step
+      if: ${{ !matrix.cli-only && !matrix.use-cross && inputs.run_test && steps.cache.outputs.cache-hit != 'true' }} # See comment for the "Build wasm library" step
       run: script/generate-fixtures-wasm
 
     - name: Run main tests

.github/workflows/sanitize.yml

@@ -27,10 +27,12 @@ jobs:
     - name: Build CLI
       run: cargo build --release
 
-    - name: Fetch fixtures
-      run: script/fetch-fixtures
+    - run: script/fetch-fixtures
 
-    - name: Generate fixtures
+    - uses: ./.github/actions/cache
+      id: cache
+
+    - if: ${{ steps.cache.outputs.cache-hit != 'true' }}
       run: script/generate-fixtures
 
     - name: Run main tests with undefined behaviour sanitizer (UBSAN)