feat: &OrderedFloat <op> &OrderedFloat impl workaround

Author: Greg Echelberger

src/lib.rs

@@ -454,6 +454,16 @@ macro_rules! impl_ordered_float_binop {
             }
         }
 
+        // Work around for: https://github.com/reem/rust-ordered-float/issues/91
+        impl<'a, T: $imp + Copy> $imp<Self> for &'a OrderedFloat<T> {
+            type Output = OrderedFloat<T::Output>;
+
+            #[inline]
+            fn $method(self, other: Self) -> Self::Output {
+                OrderedFloat((self.0).$method(other.0))
+            }
+        }
+
         impl<T: $imp> $imp<T> for OrderedFloat<T> {
             type Output = OrderedFloat<T::Output>;
 

tests/test.rs

@@ -659,6 +659,7 @@ fn add() {
     assert_eq!(OrderedFloat(0.0) + OrderedFloat(0.0), 0.0);
     assert_eq!(OrderedFloat(0.0) + &OrderedFloat(0.0), 0.0);
     assert_eq!(&OrderedFloat(0.0) + OrderedFloat(0.0), 0.0);
+    assert_eq!(&OrderedFloat(0.0) + &OrderedFloat(0.0), 0.0);
     assert_eq!(OrderedFloat(0.0) + 0.0, 0.0);
     assert_eq!(OrderedFloat(0.0) + &0.0, 0.0);
     assert_eq!(&OrderedFloat(0.0) + 0.0, 0.0);
@@ -858,6 +859,36 @@ fn test_pow_fails_on_nan() {
     a.pow(b);
 }
 
+
+#[test]
+fn test_ref_ref_binop_regression() {
+    // repro from: 
+    // https://github.com/reem/rust-ordered-float/issues/91
+    //
+    // impl<'a, T> $imp<Self> for &'a OrderedFloat<T>
+    // where 
+    //     &'a T: $imp
+    // {
+    //     type Output = OrderedFloat<<&'a T as $imp>::Output>;
+    //     #[inline]
+    //     fn $method(self, other: Self) -> Self::Output {
+    //         OrderedFloat((self.0).$method(&other.0))
+    //     }
+    // }
+    fn regression<T>(p: T) -> T
+    where
+        for<'a> &'a T: std::ops::Sub<&'a T, Output = T>,
+    {
+        &p - &p
+    }
+
+    assert_eq!(regression(0.0_f64), 0.0);
+
+    let x = OrderedFloat(50.0);
+    let y = OrderedFloat(40.0);
+    assert_eq!(&x - &y, OrderedFloat(10.0));
+}
+
 #[cfg(feature = "arbitrary")]
 mod arbitrary_test {
     use super::{NotNan, OrderedFloat};