From 308290325a416539236d6c0d06234924d0dff10e Mon Sep 17 00:00:00 2001
From: nicoo <nicoo@debian.org>
Date: Sat, 4 Jul 2020 12:58:09 +0200
Subject: [PATCH] factor::miller_rabin::is_prime: Fix bug

Montgomery<_> only works for odd n, so attempting to construct an instance
for an even number results in a panic!

The most obvious solution is to special-case even numbers.
---
 src/uu/factor/src/miller_rabin.rs | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/uu/factor/src/miller_rabin.rs b/src/uu/factor/src/miller_rabin.rs
index 330c8f127..f909f1ec1 100644
--- a/src/uu/factor/src/miller_rabin.rs
+++ b/src/uu/factor/src/miller_rabin.rs
@@ -101,10 +101,14 @@ pub(crate) fn test<A: Arithmetic + Basis>(m: A) -> Result {
     Prime
 }
 
-// Used by build.rs' tests
+// Used by build.rs' tests and debug assertions
 #[allow(dead_code)]
 pub(crate) fn is_prime(n: u64) -> bool {
-    test::<Montgomery<u64>>(Montgomery::new(n)).is_prime()
+    if n % 2 == 0 {
+        n == 2
+    } else {
+        test::<Montgomery<u64>>(Montgomery::new(n)).is_prime()
+    }
 }
 
 #[cfg(test)]