ci: Try to enable merge queue.

Author: emilio

.github/workflows/bindgen.yml

@@ -7,6 +7,9 @@ on:
   pull_request:
     branches:
       - main
+  merge_group:
+    branches:
+      - main
 
 jobs:
   rustfmt-clippy:
@@ -254,3 +257,19 @@ jobs:
           curl -L https://github.com/rust-lang/mdBook/releases/download/v0.4.5/mdbook-v0.4.5-x86_64-unknown-linux-gnu.tar.gz | tar xz
           ./mdbook build book
           ./mdbook test book
+
+  # 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: [rustfmt-clippy, msrv, minimal, docs, quickchecking, test-expectations, test, check-cfg, test-book]
+    # 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:
+      # 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) }}'