From 22789a827571009b836fa20801961bedeea9f7ae Mon Sep 17 00:00:00 2001
From: Reimer Behrends <behrends@gmail.com>
Date: Fri, 14 Aug 2015 14:32:30 +0200
Subject: [PATCH] Fix exponentiation operation to avoid overflow.

The exponentation implementation unnecessarily multiplied the
result with itself at the end if the exponent was an even number.
This led to overflow if result*result > high(int).
---
 lib/pure/math.nim | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/pure/math.nim b/lib/pure/math.nim
index 821ab738b..8d95ea9c0 100644
--- a/lib/pure/math.nim
+++ b/lib/pure/math.nim
@@ -427,10 +427,12 @@ proc `^`*[T](x, y: T): T =
   var (x, y) = (x, y)
   result = 1
 
-  while y != 0:
+  while true:
     if (y and 1) != 0:
       result *= x
     y = y shr 1
+    if y == 0:
+      break
     x *= x
 
 proc gcd*[T](x, y: T): T =