experiment with sccache

.github/workflows/build_test.yml

@@ -8,6 +8,10 @@ on:
     branches:
       - main
 
+env:
+  SCCACHE_GHA_ENABLED: true
+  RUSTC_WRAPPER: sccache
+
 jobs:
   build_all:
     name: Rust project - latest
@@ -30,14 +34,18 @@ jobs:
           # avoid the default "-D warnings" which thrashes cache
           rustflags: ""
 
+      - name: Run sccache-cache
+        uses: mozilla-actions/sccache-action@v0.0.3
+
+
       # https://github.com/actions/cache/blob/main/examples.md#rust---cargo
       - uses: actions/cache@v3
         with:
           path: |
             ~/.cargo/bin/
-            ~/.cargo/registry/index/
-            ~/.cargo/registry/cache/
-            ~/.cargo/git/db/
+#            ~/.cargo/registry/index/
+#            ~/.cargo/registry/cache/
+#            ~/.cargo/git/db/
             target/
           key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}