From 8aa893ebd0364c3dac4ff8f7319a373f4dcea837 Mon Sep 17 00:00:00 2001
From: "Tobin C. Harding" <me@tobin.cc>
Date: Tue, 11 Jun 2024 13:59:55 +1000
Subject: [PATCH] Remove repetition from sha256t_hash_newtype macro

The `sha256t_hash_newtype` macro is hard to reason about because we
allow repetition so which tag goes with which type is slightly obscure.

Remove repetition and call the macro three times.

Internal change in `bitcoin`, API change in `hashes`.
---
 bitcoin/src/taproot/mod.rs | 4 ++++
 hashes/src/sha256t.rs      | 4 +---
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/bitcoin/src/taproot/mod.rs b/bitcoin/src/taproot/mod.rs
index dc3de6e73..138c391ce 100644
--- a/bitcoin/src/taproot/mod.rs
+++ b/bitcoin/src/taproot/mod.rs
@@ -36,14 +36,18 @@ sha256t_hash_newtype! {
     ///
     /// This is used for computing tapscript script spend hash.
     pub struct TapLeafHash(_);
+}
 
+sha256t_hash_newtype! {
     pub struct TapBranchTag = hash_str("TapBranch");
 
     /// Tagged hash used in taproot trees.
     ///
     /// See BIP-340 for tagging rules.
     pub struct TapNodeHash(_);
+}
 
+sha256t_hash_newtype! {
     pub struct TapTweakTag = hash_str("TapTweak");
 
     /// Taproot-tagged hash with tag \"TapTweak\".
diff --git a/hashes/src/sha256t.rs b/hashes/src/sha256t.rs
index 0560bd3db..00df121fb 100644
--- a/hashes/src/sha256t.rs
+++ b/hashes/src/sha256t.rs
@@ -112,8 +112,7 @@ fn from_engine<T: Tag>(e: sha256::HashEngine) -> Hash<T> {
 /// [`hash_newtype`]: crate::hash_newtype
 #[macro_export]
 macro_rules! sha256t_hash_newtype {
-    ($($(#[$($tag_attr:tt)*])* $tag_vis:vis struct $tag:ident = $constructor:tt($($tag_value:tt)+); $(#[$($hash_attr:tt)*])* $hash_vis:vis struct $hash_name:ident($(#[$($field_attr:tt)*])* _);)+) => {
-        $(
+    ($(#[$($tag_attr:tt)*])* $tag_vis:vis struct $tag:ident = $constructor:tt($($tag_value:tt)+); $(#[$($hash_attr:tt)*])* $hash_vis:vis struct $hash_name:ident($(#[$($field_attr:tt)*])* _);) => {
         $crate::sha256t_hash_newtype_tag!($tag_vis, $tag, stringify!($hash_name), $(#[$($tag_attr)*])*);
 
         impl $crate::sha256t::Tag for $tag {
@@ -130,7 +129,6 @@ macro_rules! sha256t_hash_newtype {
             $(#[$($hash_attr)*])*
             $hash_vis struct $hash_name($(#[$($field_attr)*])* $crate::sha256t::Hash<$tag>);
         }
-        )+
     }
 }