1 files changed, 13 insertions, 1 deletions
diff --git a/library/core/src/iter/sources/once_with.rs b/library/core/src/iter/sources/once_with.rs
index d79f85c25..9309a06c8 100644
--- a/library/core/src/iter/sources/once_with.rs
+++ b/library/core/src/iter/sources/once_with.rs
@@ -1,3 +1,4 @@
+use crate::fmt;
 use crate::iter::{FusedIterator, TrustedLen};
 
 /// Creates an iterator that lazily generates a value exactly once by invoking
@@ -66,12 +67,23 @@ pub fn once_with<A, F: FnOnce() -> A>(gen: F) -> OnceWith<F> {
 ///
 /// This `struct` is created by the [`once_with()`] function.
 /// See its documentation for more.
-#[derive(Clone, Debug)]
+#[derive(Clone)]
 #[stable(feature = "iter_once_with", since = "1.43.0")]
 pub struct OnceWith<F> {
     gen: Option<F>,
 }
 
+#[stable(feature = "iter_once_with_debug", since = "1.68.0")]
+impl<F> fmt::Debug for OnceWith<F> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        if self.gen.is_some() {
+            f.write_str("OnceWith(Some(_))")
+        } else {
+            f.write_str("OnceWith(None)")
+        }
+    }
+}
+
 #[stable(feature = "iter_once_with", since = "1.43.0")]
 impl<A, F: FnOnce() -> A> Iterator for OnceWith<F> {
     type Item = A;