From 5a909a6a62fedb897c152d90a339c0a58b3685da Mon Sep 17 00:00:00 2001
From: Andre Bogus <bogusandre@gmail.com>
Date: Mon, 5 Feb 2018 23:11:15 +0100
Subject: [PATCH 1/2] optimize Range[Inclusive].count()

---
 src/libcore/iter/range.rs | 49 +++++++++++++++++++++++++++++++++++++++
 src/libcore/tests/iter.rs |  7 ++++++
 2 files changed, 56 insertions(+)

diff --git a/src/libcore/iter/range.rs b/src/libcore/iter/range.rs
index 3b034efcce14c..2b052db21e2fa 100644
--- a/src/libcore/iter/range.rs
+++ b/src/libcore/iter/range.rs
@@ -268,6 +268,31 @@ impl<A: Step> Iterator for ops::Range<A> {
     }
 }
 
+macro_rules! impl_range_count {
+    ($t:ty) => {
+        #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
+        impl Iterator for ops::Range<$t> {
+            #[inline]
+            fn count(self) -> usize {
+                self.end.wrapping_sub(self.start) as usize
+            }
+        }
+    };
+}
+
+impl_range_count!(u8);
+impl_range_count!(u16);
+impl_range_count!(u32);
+impl_range_count!(u64);
+impl_range_count!(usize);
+
+impl_range_count!(i8);
+impl_range_count!(i16);
+impl_range_count!(i32);
+impl_range_count!(i64);
+impl_range_count!(isize);
+
+
 // These macros generate `ExactSizeIterator` impls for various range types.
 // Range<{u,i}64> and RangeInclusive<{u,i}{32,64,size}> are excluded
 // because they cannot guarantee having a length <= usize::MAX, which is
@@ -421,6 +446,30 @@ impl<A: Step> Iterator for ops::RangeInclusive<A> {
     }
 }
 
+macro_rules! impl_inclusive_range_count {
+    ($t:ty) => {
+        #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
+        impl Iterator for ops::RangeInclusive<$t> {
+            #[inline]
+            fn count(self) -> usize {
+                (self.end.wrapping_sub(self.start) as usize).wrapping_add(1)
+            }
+        }
+    };
+}
+
+impl_inclusive_range_count!(u8);
+impl_inclusive_range_count!(u16);
+impl_inclusive_range_count!(u32);
+impl_inclusive_range_count!(u64);
+impl_inclusive_range_count!(usize);
+
+impl_inclusive_range_count!(i8);
+impl_inclusive_range_count!(i16);
+impl_inclusive_range_count!(i32);
+impl_inclusive_range_count!(i64);
+impl_inclusive_range_count!(isize);
+
 #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
 impl<A: Step> DoubleEndedIterator for ops::RangeInclusive<A> {
     #[inline]
diff --git a/src/libcore/tests/iter.rs b/src/libcore/tests/iter.rs
index dc866d180bfa0..8e9140595dce8 100644
--- a/src/libcore/tests/iter.rs
+++ b/src/libcore/tests/iter.rs
@@ -1391,6 +1391,13 @@ fn test_range_inclusive_nth() {
     assert_eq!(r, 1..=0);  // We may not want to document/promise this detail
 }
 
+#[test]
+fn test_range_inclusive_count() {
+    assert_eq!((1..=1).count(), 1);
+    assert_eq!((0..=10).count(), 11);
+    assert_eq!((5..=7).count(), 3);
+}
+
 #[test]
 fn test_range_step() {
     #![allow(deprecated)]

From 9ac41601a4631a333390534ef5767e612ad0d88d Mon Sep 17 00:00:00 2001
From: Andre Bogus <bogusandre@gmail.com>
Date: Tue, 6 Feb 2018 21:34:11 +0100
Subject: [PATCH 2/2] remove Range specialization, simplify RangeInclusive code

---
 src/libcore/iter/range.rs | 28 +++++-----------------------
 1 file changed, 5 insertions(+), 23 deletions(-)

diff --git a/src/libcore/iter/range.rs b/src/libcore/iter/range.rs
index 2b052db21e2fa..0248c782910db 100644
--- a/src/libcore/iter/range.rs
+++ b/src/libcore/iter/range.rs
@@ -444,32 +444,14 @@ impl<A: Step> Iterator for ops::RangeInclusive<A> {
         }
         Try::from_ok(accum)
     }
-}
 
-macro_rules! impl_inclusive_range_count {
-    ($t:ty) => {
-        #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
-        impl Iterator for ops::RangeInclusive<$t> {
-            #[inline]
-            fn count(self) -> usize {
-                (self.end.wrapping_sub(self.start) as usize).wrapping_add(1)
-            }
-        }
-    };
+    #[inline]
+    fn count(self) -> usize {
+        <A as Step>::steps_between(&self.start, &self.end)
+            .expect("Overflow on `RangeInclusive::count()`") + 1
+    }
 }
 
-impl_inclusive_range_count!(u8);
-impl_inclusive_range_count!(u16);
-impl_inclusive_range_count!(u32);
-impl_inclusive_range_count!(u64);
-impl_inclusive_range_count!(usize);
-
-impl_inclusive_range_count!(i8);
-impl_inclusive_range_count!(i16);
-impl_inclusive_range_count!(i32);
-impl_inclusive_range_count!(i64);
-impl_inclusive_range_count!(isize);
-
 #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
 impl<A: Step> DoubleEndedIterator for ops::RangeInclusive<A> {
     #[inline]