chore: checkpoint before Python removal

vendor/async-trait/tests/ui/arg-implementation-detail.rs

@@ -0,0 +1,22 @@
+use async_trait::async_trait;
+
+pub struct Struct;
+
+#[async_trait]
+pub trait Trait {
+    async fn f((_a, _b): (Struct, Struct)) {
+        // Expands to something like:
+        //
+        //    fn f(__arg0: (Struct, Struct)) -> … {
+        //        Box::pin(async move {
+        //            let (_a, _b) = __arg0;
+        //            …
+        //        })
+        //    }
+        //
+        // but user's code must not be allowed to name that temporary argument:
+        let _ = __arg0;
+    }
+}
+
+fn main() {}