uint: make const matching work again

uint/CHANGELOG.md

@@ -6,6 +6,9 @@ The format is based on [Keep a Changelog].
 
 ## [Unreleased]
 
+## [0.8.5] - 2020-08-12
+- Make const matching work again. [#421](https://github.com/paritytech/parity-common/pull/421)
+
 ## [0.8.4] - 2020-08-03
 - Added a manual impl of `Eq` and `Hash`. [#390](https://github.com/paritytech/parity-common/pull/390)
 - Removed some unsafe code and added big-endian support. [#407](https://github.com/paritytech/parity-common/pull/407)

uint/Cargo.toml

@@ -4,7 +4,7 @@ homepage = "http://parity.io"
 repository = "https://github.com/paritytech/parity-common"
 license = "MIT OR Apache-2.0"
 name = "uint"
-version = "0.8.4"
+version = "0.8.5"
 authors = ["Parity Technologies <admin@parity.io>"]
 readme = "README.md"
 edition = "2018"

uint/src/uint.rs

@@ -135,7 +135,7 @@ macro_rules! uint_overflowing_binop {
 		}
 
 		($name(ret), carry > 0)
-		}};
+	}};
 }
 
 #[macro_export]
@@ -244,7 +244,7 @@ macro_rules! panic_on_overflow {
 	($name: expr) => {
 		if $name {
 			panic!("arithmetic operation overflow")
-			}
+		}
 	};
 }
 
@@ -445,7 +445,7 @@ macro_rules! construct_uint {
 		/// Little-endian large integer type
 		#[repr(C)]
 		$(#[$attr])*
-		#[derive(Copy, Clone)]
+		#[derive(Copy, Clone, Eq, PartialEq, Hash)]
 		$visibility struct $name (pub [u64; $n_words]);
 
 		/// Get a reference to the underlying little-endian words.
@@ -1475,26 +1475,9 @@ macro_rules! construct_uint {
 			}
 		}
 
-		// We implement `Eq` and `Hash` manually to workaround
-		// https://github.com/rust-lang/rust/issues/61415
-		impl $crate::core_::cmp::PartialEq for $name {
-			fn eq(&self, other: &$name) -> bool {
-				self.as_ref() == other.as_ref()
-			}
-		}
-
-		impl $crate::core_::cmp::Eq for $name {}
-
-		impl $crate::core_::hash::Hash for $name {
-			fn hash<H: $crate::core_::hash::Hasher>(&self, state: &mut H) {
-				// use the impl as slice &[u64]
-				self.as_ref().hash(state);
-			}
-		}
-
 		impl $crate::core_::cmp::Ord for $name {
 			fn cmp(&self, other: &$name) -> $crate::core_::cmp::Ordering {
-                self.as_ref().iter().rev().cmp(other.as_ref().iter().rev())
+				self.as_ref().iter().rev().cmp(other.as_ref().iter().rev())
 			}
 		}
 

uint/tests/uint_tests.rs

@@ -40,6 +40,16 @@ fn hash_impl_is_the_same_as_for_a_slice() {
 	assert_eq!(uint_hash, slice_hash);
 }
 
+// https://github.com/paritytech/parity-common/issues/420
+#[test]
+fn const_matching_works() {
+	const ONE: U256 = U256([1, 0, 0, 0]);
+	match U256::zero() {
+		ONE => unreachable!(),
+		_ => {}
+	}
+}
+
 #[test]
 fn u128_conversions() {
 	let mut a = U256::from(u128::max_value());