---

yaml
---
r: 275630
b: refs/heads/master
c: 7b33d39
h: refs/heads/master

Author: ranma42

[refs]

@@ -1,5 +1,5 @@
 ---
-refs/heads/master: 2fd2670ea0a55b7f7481c5ce2a95c5c5033941d5
+refs/heads/master: 7b33d39da93a9873fa002c6875c934fd13ec7d4a
 refs/heads/snap-stage3: 235d77457d80b549dad3ac36d94f235208a1eafb
 refs/heads/try: 49312a405e14a449b98fe0056b12a40ac128be4a
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105

trunk/src/libcore/char.rs

@@ -299,14 +299,16 @@ impl CharExt for char {
 
     #[inline]
     fn escape_unicode(self) -> EscapeUnicode {
-        let mut n = 0;
-        while (self as u32) >> (4 * (n + 1)) != 0 {
-            n += 1;
-        }
+        let c = self as u32;
+        // or-ing 1 ensures that for c==0 the code computes that one
+        // digit should be printed and (which is the same) avoids the
+        // (31 - 32) underflow
+        let msb = 31 - (c | 1).leading_zeros();
+        let msdigit = msb / 4;
         EscapeUnicode {
             c: self,
             state: EscapeUnicodeState::Backslash,
-            offset: n,
+            offset: msdigit as usize,
         }
     }