2 files changed, 3 insertions, 1 deletions
diff --git a/library/std/src/sync/rwlock.rs b/library/std/src/sync/rwlock.rs
index 6e4a2cfc8..9ab781561 100644
--- a/library/std/src/sync/rwlock.rs
+++ b/library/std/src/sync/rwlock.rs
@@ -101,6 +101,7 @@ unsafe impl<T: ?Sized + Send + Sync> Sync for RwLock<T> {}
                       and cause Futures to not implement `Send`"]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[clippy::has_significant_drop]
+#[cfg_attr(not(test), rustc_diagnostic_item = "RwLockReadGuard")]
 pub struct RwLockReadGuard<'a, T: ?Sized + 'a> {
     // NB: we use a pointer instead of `&'a T` to avoid `noalias` violations, because a
     // `Ref` argument doesn't hold immutability for its whole scope, only until it drops.
@@ -130,6 +131,7 @@ unsafe impl<T: ?Sized + Sync> Sync for RwLockReadGuard<'_, T> {}
                       and cause Future's to not implement `Send`"]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[clippy::has_significant_drop]
+#[cfg_attr(not(test), rustc_diagnostic_item = "RwLockWriteGuard")]
 pub struct RwLockWriteGuard<'a, T: ?Sized + 'a> {
     lock: &'a RwLock<T>,
     poison: poison::Guard,
diff --git a/library/std/src/sync/rwlock/tests.rs b/library/std/src/sync/rwlock/tests.rs
index 08255c985..b5b3ad989 100644
--- a/library/std/src/sync/rwlock/tests.rs
+++ b/library/std/src/sync/rwlock/tests.rs
@@ -19,7 +19,7 @@ fn smoke() {
 #[test]
 fn frob() {
     const N: u32 = 10;
-    const M: usize = 1000;
+    const M: usize = if cfg!(miri) { 100 } else { 1000 };
 
     let r = Arc::new(RwLock::new(()));