ci: rewrite the success job

.github/workflows/ci.yml

@@ -1,8 +1,7 @@
 on:
   push:
-    branches: [ master ]
+    branches: [ main ]
   pull_request:
-    branches: [ master ]
   merge_group:
 
 name: CI
@@ -26,6 +25,13 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v3
 
+      - name: Cache the registry
+        uses: actions/cache@v4
+        if: startsWith(matrix.rust, '1')
+        with:
+          path: ~/.cargo/registry/index
+          key: cargo-${{ matrix.rust }}-git-index
+
       - name: Set up Rust
         uses: dtolnay/rust-toolchain@master
         with:
@@ -70,9 +76,17 @@ jobs:
       - name: Clippy
         run: cargo clippy  # -- -D warnings
 
-  done:
-    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: [ci, clippy]
+    # 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 0
+      # 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) }}'

README.rst

@@ -16,7 +16,7 @@ __ https://docs.rs/either/
 
 |build_status|_ |crates|_
 
-.. |build_status| image:: https://github.com/rayon-rs/either/workflows/CI/badge.svg?branch=master
+.. |build_status| image:: https://github.com/rayon-rs/either/workflows/CI/badge.svg?branch=main
 .. _build_status: https://github.com/rayon-rs/either/actions
 
 .. |crates| image:: https://img.shields.io/crates/v/either.svg