Test the size_hint of empty ranges too

Author: cuviper

src/libcore/tests/iter.rs

@@ -1804,20 +1804,24 @@ fn test_range_inclusive_folds() {
 #[test]
 fn test_range_size_hint() {
     use core::usize::MAX as UMAX;
+    assert_eq!((0..0usize).size_hint(), (0, Some(0)));
     assert_eq!((0..100usize).size_hint(), (100, Some(100)));
     assert_eq!((0..UMAX).size_hint(), (UMAX, Some(UMAX)));
 
     let umax = u128::try_from(UMAX).unwrap();
+    assert_eq!((0..0u128).size_hint(), (0, Some(0)));
     assert_eq!((0..100u128).size_hint(), (100, Some(100)));
     assert_eq!((0..umax).size_hint(), (UMAX, Some(UMAX)));
     assert_eq!((0..umax + 1).size_hint(), (UMAX, None));
 
     use core::isize::{MAX as IMAX, MIN as IMIN};
+    assert_eq!((0..0isize).size_hint(), (0, Some(0)));
     assert_eq!((-100..100isize).size_hint(), (200, Some(200)));
     assert_eq!((IMIN..IMAX).size_hint(), (UMAX, Some(UMAX)));
 
     let imin = i128::try_from(IMIN).unwrap();
     let imax = i128::try_from(IMAX).unwrap();
+    assert_eq!((0..0i128).size_hint(), (0, Some(0)));
     assert_eq!((-100..100i128).size_hint(), (200, Some(200)));
     assert_eq!((imin..imax).size_hint(), (UMAX, Some(UMAX)));
     assert_eq!((imin..imax + 1).size_hint(), (UMAX, None));
@@ -1826,23 +1830,31 @@ fn test_range_size_hint() {
 #[test]
 fn test_range_inclusive_size_hint() {
     use core::usize::MAX as UMAX;
+    assert_eq!((1..=0usize).size_hint(), (0, Some(0)));
+    assert_eq!((0..=0usize).size_hint(), (1, Some(1)));
     assert_eq!((0..=100usize).size_hint(), (101, Some(101)));
     assert_eq!((0..=UMAX - 1).size_hint(), (UMAX, Some(UMAX)));
     assert_eq!((0..=UMAX).size_hint(), (UMAX, None));
 
     let umax = u128::try_from(UMAX).unwrap();
+    assert_eq!((1..=0u128).size_hint(), (0, Some(0)));
+    assert_eq!((0..=0u128).size_hint(), (1, Some(1)));
     assert_eq!((0..=100u128).size_hint(), (101, Some(101)));
     assert_eq!((0..=umax - 1).size_hint(), (UMAX, Some(UMAX)));
     assert_eq!((0..=umax).size_hint(), (UMAX, None));
     assert_eq!((0..=umax + 1).size_hint(), (UMAX, None));
 
     use core::isize::{MAX as IMAX, MIN as IMIN};
+    assert_eq!((0..=-1isize).size_hint(), (0, Some(0)));
+    assert_eq!((0..=0isize).size_hint(), (1, Some(1)));
     assert_eq!((-100..=100isize).size_hint(), (201, Some(201)));
     assert_eq!((IMIN..=IMAX - 1).size_hint(), (UMAX, Some(UMAX)));
     assert_eq!((IMIN..=IMAX).size_hint(), (UMAX, None));
 
     let imin = i128::try_from(IMIN).unwrap();
     let imax = i128::try_from(IMAX).unwrap();
+    assert_eq!((0..=-1i128).size_hint(), (0, Some(0)));
+    assert_eq!((0..=0i128).size_hint(), (1, Some(1)));
     assert_eq!((-100..=100i128).size_hint(), (201, Some(201)));
     assert_eq!((imin..=imax - 1).size_hint(), (UMAX, Some(UMAX)));
     assert_eq!((imin..=imax).size_hint(), (UMAX, None));