Merge pull request #309 from cuviper/ci

More CI updates

.github/workflows/ci.yml

@@ -38,6 +38,11 @@ jobs:
 
     steps:
       - uses: actions/checkout@v4
+      - uses: actions/cache@v4
+        if: matrix.rust == '1.63.0'
+        with:
+          path: ~/.cargo/registry/index
+          key: cargo-git-index
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: ${{ matrix.rust }}
@@ -67,6 +72,11 @@ jobs:
 
     steps:
       - uses: actions/checkout@v4
+      - uses: actions/cache@v4
+        if: matrix.rust == '1.63.0'
+        with:
+          path: ~/.cargo/registry/index
+          key: cargo-git-index
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: ${{ matrix.rust }}
@@ -99,29 +109,30 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - uses: dtolnay/rust-toolchain@master
-        with:
-          toolchain: nightly
-      - uses: dtolnay/rust-toolchain@master
+      - uses: actions/cache@v4
         with:
-          toolchain: 1.63.0 # MSRV
+          path: ~/.cargo/registry/index
+          key: cargo-git-index
+      - uses: dtolnay/rust-toolchain@nightly
+      - uses: dtolnay/[email protected] # MSRV
       - uses: taiki-e/install-action@v2
         with:
           tool: cargo-hack
       - run: cargo +nightly hack generate-lockfile --remove-dev-deps -Z direct-minimal-versions
       - name: Build
         run: cargo build --verbose --all-features
 
-  ci-success:
-    name: Complete
-    runs-on: ubuntu-latest
-    needs: [tests, nostd_build, clippy, miri, minimal-versions]
-    steps:
-      - run: exit 0
-  ci-failed:
-    name: Complete
+  # One job that "summarizes" the success state of this pipeline. This can then be added to branch
+  # protection, rather than having to add each job separately.
+  success:
+    name: Success
     runs-on: ubuntu-latest
     needs: [tests, nostd_build, clippy, miri, minimal-versions]
-    if: failure()
+    # Github branch protection is exceedingly silly and treats "jobs skipped because a dependency
+    # failed" as success. So we have to do some contortions to ensure the job fails if any of its
+    # dependencies fails.
+    if: always() # make sure this is never "skipped"
     steps:
-      - run: exit 1
+      # Manually check the status of all dependencies. `if: failure()` does not work.
+      - name: check if any dependency failed
+        run: jq --exit-status 'all(.result == "success")' <<< '${{ toJson(needs) }}'