Bring back range optimisation, fixed for boundary case.

JonHanna · JonHanna · commit ded3bd5e97db · 2015-08-17T23:36:24.000+01:00
31599c5 introduced a boundary error, and was hence reverted in b75ffa4. This reintroduces the idea of 31599c5, but fixed for the boundary case.
diff --git a/src/System.Linq/src/System/Linq/Enumerable.cs b/src/System.Linq/src/System/Linq/Enumerable.cs
@@ -1472,7 +1472,7 @@ public static IEnumerable<int> Range(int start, int count)
 
         private static IEnumerable<int> RangeIterator(int start, int count)
         {
-            for (int i = 0; i < count; i++) yield return start + i;
+            for (int end = start + count; start != end; start++) yield return start;
         }
 
         public static IEnumerable<TResult> Repeat<TResult>(TResult element, int count)

Original file line number	Diff line number	Diff line change
`@@ -1472,7 +1472,7 @@ public static IEnumerable<int> Range(int start, int count)`
`1472`	`1472`
`1473`	`1473`	`private static IEnumerable<int> RangeIterator(int start, int count)`
`1474`	`1474`	`{`
`1475`		`- for (int i = 0; i < count; i++) yield return start + i;`
	`1475`	`+ for (int end = start + count; start != end; start++) yield return start;`
`1476`	`1476`	`}`
`1477`	`1477`
`1478`	`1478`	`public static IEnumerable<TResult> Repeat<TResult>(TResult element, int count)`