1 files changed, 23 insertions, 0 deletions
diff --git a/library/core/src/iter/mod.rs b/library/core/src/iter/mod.rs
index 9514466bd..ef0f39782 100644
--- a/library/core/src/iter/mod.rs
+++ b/library/core/src/iter/mod.rs
@@ -352,6 +352,29 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
+// This needs to be up here in order to be usable in the child modules
+macro_rules! impl_fold_via_try_fold {
+    (fold -> try_fold) => {
+        impl_fold_via_try_fold! { @internal fold -> try_fold }
+    };
+    (rfold -> try_rfold) => {
+        impl_fold_via_try_fold! { @internal rfold -> try_rfold }
+    };
+    (@internal $fold:ident -> $try_fold:ident) => {
+        #[inline]
+        fn $fold<AAA, FFF>(mut self, init: AAA, mut fold: FFF) -> AAA
+        where
+            FFF: FnMut(AAA, Self::Item) -> AAA,
+        {
+            use crate::const_closure::ConstFnMutClosure;
+            use crate::ops::NeverShortCircuit;
+
+            let fold = ConstFnMutClosure::new(&mut fold, NeverShortCircuit::wrap_mut_2_imp);
+            self.$try_fold(init, fold).0
+        }
+    };
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use self::traits::Iterator;