From db0fc32ab2d5277655a87200be8f602473ed30d2 Mon Sep 17 00:00:00 2001
From: Jimmi Holst Christensen <jhc@liab.dk>
Date: Wed, 17 Jan 2018 14:00:27 +0100
Subject: [PATCH] fixed xor with zero

---
 src/bigint.cpp      | 6 ++++++
 test/cases/math.zig | 5 +++++
 2 files changed, 11 insertions(+)

diff --git a/src/bigint.cpp b/src/bigint.cpp
index a68dd3a4b8..05c6463aa3 100644
--- a/src/bigint.cpp
+++ b/src/bigint.cpp
@@ -1271,6 +1271,12 @@ void bigint_and(BigInt *dest, const BigInt *op1, const BigInt *op2) {
 }
 
 void bigint_xor(BigInt *dest, const BigInt *op1, const BigInt *op2) {
+    if (op1->digit_count == 0) {
+        return bigint_init_bigint(dest, op2);
+    }
+    if (op2->digit_count == 0) {
+        return bigint_init_bigint(dest, op1);
+    }
     if (op1->is_negative || op2->is_negative) {
         // TODO this code path is untested
         size_t big_bit_count = max(bigint_bits_needed(op1), bigint_bits_needed(op2));
diff --git a/test/cases/math.zig b/test/cases/math.zig
index 090e2b9dfd..7f57838ecb 100644
--- a/test/cases/math.zig
+++ b/test/cases/math.zig
@@ -369,3 +369,8 @@ fn test_f128() {
 fn should_not_be_zero(x: f128) {
     assert(x != 0.0);
 }
+
+test "xor with zero" {
+    assert(0xFF ^ 0x00 == 0xFF);
+    comptime assert(0xFF ^ 0x00 == 0xFF);
+}