from review: add a comment why try_fold was chosen instead of fold

Author: the8472

library/core/src/array/iter.rs

@@ -129,6 +129,11 @@ impl<T, const N: usize> Iterator for IntoIter<T, N> {
         Fold: FnMut(Acc, Self::Item) -> Acc,
     {
         let data = &mut self.data;
+        // FIXME: This uses try_fold(&mut iter) instead of fold(iter) because the latter
+        //  would go through the blanket `impl Iterator for &mut I` implementation
+        //  which lacks inline annotations on its methods and adding those would be a larger
+        //  perturbation than using try_fold here.
+        //  Whether it would be beneficial to add those annotations should be investigated separately.
         (&mut self.alive)
             .try_fold::<_, _, Result<_, !>>(init, |acc, idx| {
                 // SAFETY: idx is obtained by folding over the `alive` range, which implies the