chore: add tokio_no_atomic_u64 cfg (#5226)

.github/workflows/ci.yml

@@ -44,6 +44,7 @@ jobs:
       - asan
       - cross-check
       - cross-test
+      - no-atomic-u64
       - features
       - minrust
       - minimal-versions
@@ -288,6 +289,26 @@ jobs:
         env:
           RUSTFLAGS: --cfg tokio_unstable -Dwarnings --cfg tokio_no_ipv6
 
+  # See https://github.com/tokio-rs/tokio/issues/5187
+  no-atomic-u64:
+    name: Test i686-unknown-linux-gnu without AtomicU64
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - name: Install Rust ${{ env.rust_nightly }}
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: ${{ env.rust_nightly }}
+          components: rust-src
+          override: true
+      # Install linker and libraries for i686-unknown-linux-gnu
+      - uses: taiki-e/setup-cross-toolchain-action@v1
+        with:
+          target: i686-unknown-linux-gnu
+      - run: cargo test -Zbuild-std --target target-specs/i686-unknown-linux-gnu.json -p tokio --all-features
+        env:
+          RUSTFLAGS: --cfg tokio_unstable -Dwarnings --cfg tokio_no_atomic_u64
+
   features:
     name: features
     runs-on: ubuntu-latest