From: Samuel Neves <sneves@dei.uc.pt>
Date: Wed, 2 Jul 2014 03:58:23 +0000 (+0100)
Subject: Fix rotate_{left, right} for multiple of bitsize rotation amounts
X-Git-Url: https://git.lizzy.rs/?a=commitdiff_plain;h=c0248c0839cfdf5b7030f4191ea7aed0981b9e4e;p=rust.git

Fix rotate_{left, right} for multiple of bitsize rotation amounts

Add additional rotation tests
---

diff --git a/src/libcore/num/mod.rs b/src/libcore/num/mod.rs
index b32e4167da1..1fae362471d 100644
--- a/src/libcore/num/mod.rs
+++ b/src/libcore/num/mod.rs
@@ -586,14 +586,14 @@ fn trailing_zeros(self) -> $T { unsafe { $cttz(self) } }
             fn rotate_left(self, n: uint) -> $T {
                 // Protect against undefined behaviour for over-long bit shifts
                 let n = n % $BITS;
-                (self << n) | (self >> ($BITS - n))
+                (self << n) | (self >> (($BITS - n) % $BITS))
             }
 
             #[inline]
             fn rotate_right(self, n: uint) -> $T {
                 // Protect against undefined behaviour for over-long bit shifts
                 let n = n % $BITS;
-                (self >> n) | (self << ($BITS - n))
+                (self >> n) | (self << (($BITS - n) % $BITS))
             }
 
             #[inline]
diff --git a/src/libcoretest/num/int_macros.rs b/src/libcoretest/num/int_macros.rs
index 940b036ca90..d078b514085 100644
--- a/src/libcoretest/num/int_macros.rs
+++ b/src/libcoretest/num/int_macros.rs
@@ -114,6 +114,15 @@ fn test_rotate() {
         assert_eq!(_1.rotate_left(124), _1);
         assert_eq!(_0.rotate_right(124), _0);
         assert_eq!(_1.rotate_right(124), _1);
+
+        // Rotating by 0 should have no effect
+        assert_eq!(A.rotate_left(0), A);
+        assert_eq!(B.rotate_left(0), B);
+        assert_eq!(C.rotate_left(0), C);
+        // Rotating by a multiple of word size should also have no effect
+        assert_eq!(A.rotate_left(64), A);
+        assert_eq!(B.rotate_left(64), B);
+        assert_eq!(C.rotate_left(64), C);
     }
 
     #[test]
diff --git a/src/libcoretest/num/uint_macros.rs b/src/libcoretest/num/uint_macros.rs
index 2272af67daf..aefaa90520e 100644
--- a/src/libcoretest/num/uint_macros.rs
+++ b/src/libcoretest/num/uint_macros.rs
@@ -74,6 +74,15 @@ fn test_rotate() {
         assert_eq!(_1.rotate_left(124), _1);
         assert_eq!(_0.rotate_right(124), _0);
         assert_eq!(_1.rotate_right(124), _1);
+
+        // Rotating by 0 should have no effect
+        assert_eq!(A.rotate_left(0), A);
+        assert_eq!(B.rotate_left(0), B);
+        assert_eq!(C.rotate_left(0), C);
+        // Rotating by a multiple of word size should also have no effect
+        assert_eq!(A.rotate_left(64), A);
+        assert_eq!(B.rotate_left(64), B);
+        assert_eq!(C.rotate_left(64), C);
     }
 
     #[test]