test that align_of handles alignment properly for the mid part

1 files changed, 14 insertions, 0 deletions

diff --git a/src/libcore/tests/slice.rs b/src/libcore/tests/slice.rs
index 7968521f7b4..b087ec81f59 100644
--- a/src/libcore/tests/slice.rs
+++ b/src/libcore/tests/slice.rs
@@ -986,3 +986,17 @@ fn test_align_to_non_trivial() {
     assert_eq!(aligned.len(), 4);
     assert_eq!(prefix.len() + suffix.len(), 2);
 }
+
+#[test]
+fn test_align_to_empty_mid() {
+    use core::mem;
+
+    // Make sure that we do not create empty unaligned slices for the mid part, even when the
+    // overall slice is too short to contain an aligned address.
+    let bytes = [1, 2, 3, 4, 5, 6, 7];
+    type Chunk = u32;
+    for offset in 0..4 {
+        let (_, mid, _) = unsafe { bytes[offset..offset+1].align_to::<Chunk>() };
+        assert_eq!(mid.as_ptr() as usize % mem::align_of::<Chunk>(), 0);
+    }
+}