Add better documentation for unsafe block

diff --git a/src/libcore/cmp.rs b/src/libcore/cmp.rs
index e16a428feb64579e5b562455ee90b4e4db9d0237..87a407c5e9f7ba3cc297b64197560df01fa9e861 100644 (file)
--- a/src/libcore/cmp.rs
+++ b/src/libcore/cmp.rs
@@ -1134,7 +1134,7 @@ fn cmp(&self, other: &bool) -> Ordering {
                 -1 => Less,
                 0 => Equal,
                 1 => Greater,
-                // SAFETY: Unreachable code
+                // SAFETY: bool as i8 returns 0 or 1, so the difference can't be anything else
                 _ => unsafe { unreachable_unchecked() },
             }
         }