Merge rust-bitcoin/rust-secp256k1#335: Implement Hash for schnorrsig::Signature

75b49efb3d10c307631e6005c5f1e7bf233ecfc6 Implement `Hash` for all array newtypes (elsirion)

Pull request description:

  I pondered putting the impl into the array type macro together with `(Partial)Eq`, but that would have meant removing other implementations and potentially implementing it for types where it is not wanted. The drawback of the separate impl is that it is more disconnected from the `(Partial)Eq` impl and could theoretically diverge (although unlikely in case of such a simple type) which would break the trait's contract.

ACKs for top commit:
  apoelstra:
    ACK 75b49efb3d10c307631e6005c5f1e7bf233ecfc6

Tree-SHA512: 44d1bebdd3437dfd86de8b475f12097c4a2f872905c822a9cde624089fdc20f68f59a7734fdcc6f3a17ed233f70f63258dfd204ca269d2baf8002ffc325ddc87

Author: chain-forgexcr45

secp256k1-sys/src/lib.rs

@@ -36,7 +36,7 @@ pub mod types;
 #[cfg(feature = "recovery")]
 pub mod recovery;
 
-use core::{hash, slice, ptr};
+use core::{slice, ptr};
 use types::*;
 
 /// Flag for context to enable no precomputation
@@ -133,12 +133,6 @@ impl PublicKey {
     }
 }
 
-impl hash::Hash for PublicKey {
-    fn hash<H: hash::Hasher>(&self, state: &mut H) {
-        state.write(&self.0)
-    }
-}
-
 /// Library-internal representation of a Secp256k1 signature
 #[repr(C)]
 pub struct Signature([c_uchar; 64]);
@@ -210,12 +204,6 @@ impl XOnlyPublicKey {
     }
 }
 
-impl hash::Hash for XOnlyPublicKey {
-    fn hash<H: hash::Hasher>(&self, state: &mut H) {
-        state.write(&self.0)
-    }
-}
-
 #[repr(C)]
 pub struct KeyPair([c_uchar; 96]);
 impl_array_newtype!(KeyPair, c_uchar, 96);
@@ -251,12 +239,6 @@ impl KeyPair {
     }
 }
 
-impl hash::Hash for KeyPair {
-    fn hash<H: hash::Hasher>(&self, state: &mut H) {
-        state.write(&self.0)
-    }
-}
-
 extern "C" {
     /// Default ECDH hash function
     #[cfg_attr(not(rust_secp_no_symbol_renaming), link_name = "rustsecp256k1_v0_4_1_ecdh_hash_function_default")]

secp256k1-sys/src/macros.rs

@@ -61,6 +61,12 @@ macro_rules! impl_array_newtype {
 
         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> {