secp256k1: Remove custom implementations of Eq, Ord and friends

Now that we have Rust 1.48 as the MSRV we no longer need the custom
implementations of `PartialEq`, `Eq`, `PartialOrd`, `Ord`, and `Hash`.
We can just let users of the `impl_array_newtype` macro derive these
traits if they want them.

Remove the custom implementations and add derives to our two users of
the macro.

Author: tcharding

CHANGELOG.md

@@ -1,6 +1,8 @@
 # Unreleased
 
 * Bump MSRV to 1.48
+* Remove implementations of `PartialEq`, `Eq`, `PartialOrd`, `Ord`, and `Hash` from the
+  `impl_array_newtype` macro. Users will now need to derive these traits if they are wanted.
 
 # 0.27.0 - 2023-03-15
 

src/lib.rs

@@ -232,7 +232,7 @@ impl<T: hashes::sha256t::Tag> ThirtyTwoByteHash for hashes::sha256t::Hash<T> {
 }
 
 /// A (hashed) message input to an ECDSA signature.
-#[derive(Copy, Clone)]
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct Message([u8; constants::MESSAGE_SIZE]);
 impl_array_newtype!(Message, u8, constants::MESSAGE_SIZE);
 impl_pretty_debug!(Message);

src/macros.rs

@@ -17,31 +17,6 @@
 #[macro_export]
 macro_rules! impl_array_newtype {
     ($thing:ident, $ty:ty, $len:expr) => {
-        // We cannot derive these traits because Rust 1.41.1 requires `std::array::LengthAtMost32`.
-
-        impl PartialEq for $thing {
-            #[inline]
-            fn eq(&self, other: &$thing) -> bool { &self[..] == &other[..] }
-        }
-
-        impl Eq for $thing {}
-
-        impl core::hash::Hash for $thing {
-            fn hash<H: core::hash::Hasher>(&self, state: &mut H) { (&self[..]).hash(state) }
-        }
-
-        impl PartialOrd for $thing {
-            #[inline]
-            fn partial_cmp(&self, other: &$thing) -> Option<core::cmp::Ordering> {
-                self[..].partial_cmp(&other[..])
-            }
-        }
-
-        impl Ord for $thing {
-            #[inline]
-            fn cmp(&self, other: &$thing) -> core::cmp::Ordering { self[..].cmp(&other[..]) }
-        }
-
         impl AsRef<[$ty; $len]> for $thing {
             #[inline]
             /// Gets a reference to the underlying array

src/schnorr.rs

@@ -15,7 +15,7 @@ use crate::{
 };
 
 /// Represents a schnorr signature.
-#[derive(Copy, Clone)]
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct Signature([u8; constants::SCHNORR_SIGNATURE_SIZE]);
 impl_array_newtype!(Signature, u8, constants::SCHNORR_SIGNATURE_SIZE);
 impl_pretty_debug!(Signature);