From 61d1a9b030d01d9b8320688951f42d18507c5535 Mon Sep 17 00:00:00 2001
From: Taylor Cramer <cramertaylorj@gmail.com>
Date: Wed, 13 Jul 2016 09:55:16 -0700
Subject: [PATCH] Check for comparison of -0.0 and 0.0 in PartialOrd for
 Constant

---
 clippy_lints/src/consts.rs | 6 +++++-
 tests/consts.rs            | 6 ++++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/clippy_lints/src/consts.rs b/clippy_lints/src/consts.rs
index 9ed37e70a01..aac9aa3e8ef 100644
--- a/clippy_lints/src/consts.rs
+++ b/clippy_lints/src/consts.rs
@@ -162,7 +162,11 @@ fn partial_cmp(&self, other: &Constant) -> Option<Ordering> {
             (&Constant::Int(l), &Constant::Int(r)) => Some(l.cmp(&r)),
             (&Constant::Float(ref ls, _), &Constant::Float(ref rs, _)) => {
                 match (ls.parse::<f64>(), rs.parse::<f64>()) {
-                    (Ok(ref l), Ok(ref r)) => l.partial_cmp(r),
+                    (Ok(ref l), Ok(ref r)) => match (l.partial_cmp(r), l.is_sign_positive() == r.is_sign_positive()) {
+                        // Check for comparison of -0.0 and 0.0
+                        (Some(Ordering::Equal), false) => None,
+                        (x, _) => x
+                    },
                     _ => None,
                 }
             }
diff --git a/tests/consts.rs b/tests/consts.rs
index 773b889ebff..5f5f4cb47d0 100644
--- a/tests/consts.rs
+++ b/tests/consts.rs
@@ -82,6 +82,12 @@ fn test_ops() {
     let half_any = Constant::Float("0.5".into(), FloatWidth::Any);
     let half32 = Constant::Float("0.5".into(), FloatWidth::F32);
     let half64 = Constant::Float("0.5".into(), FloatWidth::F64);
+    let pos_zero = Constant::Float("0.0".into(), FloatWidth::F64);
+    let neg_zero = Constant::Float("-0.0".into(), FloatWidth::F64);
+
+    assert_eq!(pos_zero, pos_zero);
+    assert_eq!(neg_zero, neg_zero);
+    assert_eq!(None, pos_zero.partial_cmp(&neg_zero));
 
     assert_eq!(half_any, half32);
     assert_eq!(half_any, half64);