Rollup merge of #39936 - djzin:inclusive_rangeargument, r=alexcrichton

impl RangeArgument for RangeInclusive and add appropriate tests

Now that `RangeArgument` returns a `Bound`, the impl for `RangeInclusive` is natural to implement and all that's required are tests around it.

src/libcollections/range.rs

@@ -14,7 +14,7 @@
 
 //! Range syntax.
 
-use core::ops::{RangeFull, Range, RangeTo, RangeFrom};
+use core::ops::{RangeFull, Range, RangeTo, RangeFrom, RangeInclusive, RangeToInclusive};
 use Bound::{self, Excluded, Included, Unbounded};
 
 /// **RangeArgument** is implemented by Rust's built-in range types, produced
@@ -105,6 +105,32 @@ impl<T> RangeArgument<T> for Range<T> {
     }
 }
 
+#[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
+impl<T> RangeArgument<T> for RangeInclusive<T> {
+    fn start(&self) -> Bound<&T> {
+        match *self {
+            RangeInclusive::Empty{ ref at }            => Included(at),
+            RangeInclusive::NonEmpty { ref start, .. } => Included(start),
+        }
+    }
+    fn end(&self) -> Bound<&T> {
+        match *self {
+            RangeInclusive::Empty{ ref at }            => Excluded(at),
+            RangeInclusive::NonEmpty { ref end, .. }   => Included(end),
+        }
+    }
+}
+
+#[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
+impl<T> RangeArgument<T> for RangeToInclusive<T> {
+    fn start(&self) -> Bound<&T> {
+        Unbounded
+    }
+    fn end(&self) -> Bound<&T> {
+        Included(&self.end)
+    }
+}
+
 impl<T> RangeArgument<T> for (Bound<T>, Bound<T>) {
     fn start(&self) -> Bound<&T> {
         match *self {