From aa4181c85d2930b981501b054f7bda78ad8a9df5 Mon Sep 17 00:00:00 2001
From: TheIronBorn <TheIronBorn@users.noreply.github.com>
Date: Tue, 11 Dec 2018 00:17:23 +0000
Subject: [PATCH] fix https://github.com/rust-random/rand/issues/661

---
 src/distributions/uniform.rs | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/distributions/uniform.rs b/src/distributions/uniform.rs
index 5fb89e34053..074dafc88c5 100644
--- a/src/distributions/uniform.rs
+++ b/src/distributions/uniform.rs
@@ -452,8 +452,9 @@ macro_rules! uniform_int_impl {
                         let ints_to_reject = (unsigned_max - range + 1) % range;
                         unsigned_max - ints_to_reject
                     } else {
-                        // conservative but fast approximation
-                       range << range.leading_zeros()
+                        // conservative but fast approximation. `- 1` is necessary to allow the
+                        // same comparison without bias.
+                        (range << range.leading_zeros()).wrapping_sub(1)
                     };
 
                 loop {