2 files changed, 9 insertions, 0 deletions
diff --git a/library/std/src/error.rs b/library/std/src/error.rs
index c3cb71a5dee..4fb94908c80 100644
--- a/library/std/src/error.rs
+++ b/library/std/src/error.rs
@@ -516,6 +516,14 @@ impl<T: Error> Error for Box<T> {
     }
 }
 
+#[unstable(feature = "thin_box", issue = "92791")]
+impl<T: ?Sized + crate::error::Error> crate::error::Error for crate::boxed::ThinBox<T> {
+    fn source(&self) -> Option<&(dyn crate::error::Error + 'static)> {
+        use core::ops::Deref;
+        self.deref().source()
+    }
+}
+
 #[stable(feature = "error_by_ref", since = "1.51.0")]
 impl<'a, T: Error + ?Sized> Error for &'a T {
     #[allow(deprecated, deprecated_in_future)]
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index 5ade65ad9c6..60e7c2af8e4 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -290,6 +290,7 @@
 #![feature(get_mut_unchecked)]
 #![feature(map_try_insert)]
 #![feature(new_uninit)]
+#![feature(thin_box)]
 #![feature(toowned_clone_into)]
 #![feature(try_reserve_kind)]
 #![feature(vec_into_raw_parts)]