Add workaround for bug in macOS CI cache.

Author: ehuss

.github/workflows/macos-builds-on-all.yaml

@@ -57,8 +57,8 @@ jobs:
         uses: actions/cache@v2
         with:
           path: target
-          key: ${{ github.base_ref }}-${{ github.head_ref }}-${{ matrix.target }}-cargo-target-dir-${{ steps.cargo-target-cache.outputs.rust_hash }}-${{ hashFiles('**/Cargo.lock') }}
-          restore-keys: ${{ github.base_ref }}-${{ matrix.target }}-cargo-target-dir-${{ steps.cargo-target-cache.outputs.rust_hash }}-${{ hashFiles('**/Cargo.lock') }}
+          key: ${{ github.base_ref }}-${{ github.head_ref }}-${{ matrix.target }}-cargo-target-dir-${{ steps.cargo-target-cache.outputs.rust_hash }}-${{ hashFiles('**/Cargo.lock') }}-3
+          restore-keys: ${{ github.base_ref }}-${{ matrix.target }}-cargo-target-dir-${{ steps.cargo-target-cache.outputs.rust_hash }}-${{ hashFiles('**/Cargo.lock') }}-3
       - name: Install Rustup using ./rustup-init.sh
         run: |
           sh ./rustup-init.sh --default-toolchain=none --profile=minimal -y
@@ -92,3 +92,9 @@ jobs:
         run: |
           cargo install cargo-cache --no-default-features --features ci-autoclean
           cargo-cache
+      - name: Flush cache
+        # This is a workaround for a bug with GitHub Actions Cache that causes
+        # corrupt cache entries (particularly in the target directory). See
+        # https://github.com/actions/cache/issues/403 and
+        # https://github.com/rust-lang/cargo/issues/8603.
+        run: sudo /usr/sbin/purge

ci/actions-templates/macos-builds-template.yaml

@@ -57,8 +57,8 @@ jobs:
         uses: actions/cache@v2
         with:
           path: target
-          key: ${{ github.base_ref }}-${{ github.head_ref }}-${{ matrix.target }}-cargo-target-dir-${{ steps.cargo-target-cache.outputs.rust_hash }}-${{ hashFiles('**/Cargo.lock') }}
-          restore-keys: ${{ github.base_ref }}-${{ matrix.target }}-cargo-target-dir-${{ steps.cargo-target-cache.outputs.rust_hash }}-${{ hashFiles('**/Cargo.lock') }}
+          key: ${{ github.base_ref }}-${{ github.head_ref }}-${{ matrix.target }}-cargo-target-dir-${{ steps.cargo-target-cache.outputs.rust_hash }}-${{ hashFiles('**/Cargo.lock') }}-3
+          restore-keys: ${{ github.base_ref }}-${{ matrix.target }}-cargo-target-dir-${{ steps.cargo-target-cache.outputs.rust_hash }}-${{ hashFiles('**/Cargo.lock') }}-3
       - name: Install Rustup using ./rustup-init.sh
         run: |
           sh ./rustup-init.sh --default-toolchain=none --profile=minimal -y
@@ -92,3 +92,9 @@ jobs:
         run: |
           cargo install cargo-cache --no-default-features --features ci-autoclean
           cargo-cache
+      - name: Flush cache
+        # This is a workaround for a bug with GitHub Actions Cache that causes
+        # corrupt cache entries (particularly in the target directory). See
+        # https://github.com/actions/cache/issues/403 and
+        # https://github.com/rust-lang/cargo/issues/8603.
+        run: sudo /usr/sbin/purge