From 3931fba140bfbc85b4c66d2298d8935839925f03 Mon Sep 17 00:00:00 2001
From: Paul Dicker <pitdicker@gmail.com>
Date: Thu, 7 Dec 2017 20:35:58 +0100
Subject: [PATCH] Use a sign test for bools

---
 src/distributions/uniform.rs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/distributions/uniform.rs b/src/distributions/uniform.rs
index 5dc9fc54cfb..fce3b6c9746 100644
--- a/src/distributions/uniform.rs
+++ b/src/distributions/uniform.rs
@@ -184,7 +184,11 @@ impl Distribution<u128> for Uniform {
 impl Distribution<bool> for Uniform {
     #[inline]
     fn sample<R: Rng+?Sized>(&self, rng: &mut R) -> bool {
-        rng.next_u32() & 1 == 1
+        // We can compare against an arbitrary bit of an u32 to get a bool.
+        // Because the least significant bits of a lower quality RNG can have
+        // simple patterns, we compare against the most significant bit. This is
+        // easiest done using a sign test.
+        (rng.next_u32() as i32) < 0
     }
 }