fix unexpected cfg on nightly

.github/workflows/ci.yml

@@ -165,6 +165,17 @@ jobs:
       run: rustup component add rust-src
     - name: Run tests with sanitizer
       run: make test_sanitizer SAN=${{ matrix.sanitizer }}
+  UnexpectedCfgs:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@nightly
+      - uses: Swatinem/rust-cache@v2
+      - run: cargo check --all-features
+        env:
+          RUSTFLAGS: >-
+            -D unexpected_cfgs
+            --cfg internal_check_unexpected_cfgs
   # Single job required to merge the pr.
   Passed:
     runs-on: ubuntu-latest
@@ -179,5 +190,6 @@ jobs:
       - Rustfmt
       - CheckTargets
       - CheckTier3Targets
+      - UnexpectedCfgs
     steps:
       - run: exit 0

src/lib.rs

@@ -5,6 +5,7 @@
     unused_imports,
     dead_code
 )]
+#![cfg_attr(internal_check_unexpected_cfgs, allow(unexpected_cfgs))]
 #![cfg_attr(docsrs, feature(doc_cfg))]
 // Disallow warnings when running tests.
 #![cfg_attr(test, deny(warnings))]