fix(server): cfg-gate accept-backoff TEST libc errnos for Windows

CHANGELOG.md

@@ -13,7 +13,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   on Windows, breaking the main-push Windows check (PRs never caught it —
   Windows CI is skipped on PRs). Now cfg-split: unix keeps the errno match,
   Windows matches WSAEMFILE (10024) / WSAENOBUFS (10055) /
-  `ErrorKind::OutOfMemory`.
+  `ErrorKind::OutOfMemory`. Follow-up: the module's unit test
+  (`resource_exhaustion_classification`) also referenced `libc` errnos —
+  now cfg-split the same way (unix errnos vs WSA codes).
 
 ### Changed — AOF writer coalesces each group-commit batch into one write (PR #TBD)
 

src/server/accept_backoff.rs

@@ -136,13 +136,26 @@ mod tests {
 
     #[test]
     fn resource_exhaustion_classification() {
-        let emfile = std::io::Error::from_raw_os_error(libc::EMFILE);
-        let enfile = std::io::Error::from_raw_os_error(libc::ENFILE);
+        // Platform-native fd-exhaustion errnos: unix EMFILE/ENFILE,
+        // Windows WSAEMFILE/WSAENOBUFS (libc is not linked on Windows).
+        #[cfg(unix)]
+        let (emfile, enfile) = (
+            std::io::Error::from_raw_os_error(libc::EMFILE),
+            std::io::Error::from_raw_os_error(libc::ENFILE),
+        );
+        #[cfg(not(unix))]
+        let (emfile, enfile) = (
+            std::io::Error::from_raw_os_error(10024), // WSAEMFILE
+            std::io::Error::from_raw_os_error(10055), // WSAENOBUFS
+        );
         assert!(is_resource_exhaustion(&emfile));
         assert!(is_resource_exhaustion(&enfile));
 
         // A reset-by-peer during accept is transient, not exhaustion.
+        #[cfg(unix)]
         let aborted = std::io::Error::from_raw_os_error(libc::ECONNABORTED);
+        #[cfg(not(unix))]
+        let aborted = std::io::Error::from_raw_os_error(10053); // WSAECONNABORTED
         assert!(!is_resource_exhaustion(&aborted));
         // A non-OS error (e.g. synthesized) is not classified as exhaustion.
         let other = std::io::Error::new(std::io::ErrorKind::Other, "synthetic");