3 files changed, 10 insertions, 2 deletions
diff --git a/src/libcore/iter/adapters/mod.rs b/src/libcore/iter/adapters/mod.rs
index 6eb837ed0fe..5787b9174ed 100644
--- a/src/libcore/iter/adapters/mod.rs
+++ b/src/libcore/iter/adapters/mod.rs
@@ -1815,8 +1815,14 @@ where
     }
 
     #[inline]
-    fn count(self) -> usize {
-        self.iter.count().saturating_sub(self.n)
+    fn count(mut self) -> usize {
+        if self.n > 0 {
+            // nth(n) skips n+1
+            if self.iter.nth(self.n - 1).is_none() {
+                return 0;
+            }
+        }
+        self.iter.count()
     }
 
     #[inline]
diff --git a/src/libcore/option.rs b/src/libcore/option.rs
index a471b174534..cb4247d9874 100644
--- a/src/libcore/option.rs
+++ b/src/libcore/option.rs
@@ -151,6 +151,7 @@ use crate::{
 
 /// The `Option` type. See [the module level documentation](index.html) for more.
 #[derive(Copy, PartialEq, PartialOrd, Eq, Ord, Debug, Hash)]
+#[rustc_diagnostic_item = "option_type"]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub enum Option<T> {
     /// No value
diff --git a/src/libcore/result.rs b/src/libcore/result.rs
index c657ce33f60..bc70dbd62eb 100644
--- a/src/libcore/result.rs
+++ b/src/libcore/result.rs
@@ -242,6 +242,7 @@ use crate::ops::{self, Deref, DerefMut};
 /// [`Err`]: enum.Result.html#variant.Err
 #[derive(Copy, PartialEq, PartialOrd, Eq, Ord, Debug, Hash)]
 #[must_use = "this `Result` may be an `Err` variant, which should be handled"]
+#[rustc_diagnostic_item = "result_type"]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub enum Result<T, E> {
     /// Contains the success value