From f0558e8eb9743381a2ef3b83de1fb894dfdc8ff8 Mon Sep 17 00:00:00 2001
From: "Tobin C. Harding" <me@tobin.cc>
Date: Wed, 28 Feb 2024 09:47:21 +1100
Subject: [PATCH] Use fmt_hex_exact

Currently we have two functions for displaying forwards and backwards and
we also have `fmt_hex_exact`. I do not know why we added the functions.

In the latest version of hex we do not have the ability to construct a
`DisplayArray` type so we have to use `fmt_hex_exact`.

Make the change now, separate from the `hex` upgrade, to assist review.
---
 hashes/src/internal_macros.rs | 16 ----------------
 hashes/src/util.rs            | 16 ++++++++--------
 2 files changed, 8 insertions(+), 24 deletions(-)

diff --git a/hashes/src/internal_macros.rs b/hashes/src/internal_macros.rs
index 9352cde5..5534f697 100644
--- a/hashes/src/internal_macros.rs
+++ b/hashes/src/internal_macros.rs
@@ -71,22 +71,6 @@ pub(crate) use arr_newtype_fmt_impl;
 macro_rules! hash_trait_impls {
     ($bits:expr, $reverse:expr $(, $gen:ident: $gent:ident)*) => {
         impl<$($gen: $gent),*> Hash<$($gen),*> {
-            /// Displays hex forwards, regardless of how this type would display it naturally.
-            ///
-            /// This is mainly intended as an internal method and you shouldn't need it unless
-            /// you're doing something special.
-            pub fn forward_hex(&self) -> impl '_ + core::fmt::LowerHex + core::fmt::UpperHex {
-                $crate::hex::DisplayHex::as_hex(&self.0)
-            }
-
-            /// Displays hex backwards, regardless of how this type would display it naturally.
-            ///
-            /// This is mainly intended as an internal method and you shouldn't need it unless
-            /// you're doing something special.
-            pub fn backward_hex(&self) -> impl '_ + core::fmt::LowerHex + core::fmt::UpperHex {
-                $crate::hex::display::DisplayArray::<_, [u8; $bits / 8 * 2]>::new(self.0.iter().rev())
-            }
-
             /// Zero cost conversion between a fixed length byte array shared reference and
             /// a shared reference to this Hash type.
             pub fn from_bytes_ref(bytes: &[u8; $bits / 8]) -> &Self {
diff --git a/hashes/src/util.rs b/hashes/src/util.rs
index 92fd4855..fcb1b173 100644
--- a/hashes/src/util.rs
+++ b/hashes/src/util.rs
@@ -3,17 +3,17 @@
 #[macro_export]
 /// Adds hexadecimal formatting implementation of a trait `$imp` to a given type `$ty`.
 macro_rules! hex_fmt_impl(
-    ($reverse:expr, $ty:ident) => (
-        $crate::hex_fmt_impl!($reverse, $ty, );
+    ($reverse:expr, $len:expr, $ty:ident) => (
+        $crate::hex_fmt_impl!($reverse, $len, $ty, );
     );
-    ($reverse:expr, $ty:ident, $($gen:ident: $gent:ident),*) => (
+    ($reverse:expr, $len:expr, $ty:ident, $($gen:ident: $gent:ident),*) => (
         impl<$($gen: $gent),*> $crate::_export::_core::fmt::LowerHex for $ty<$($gen),*> {
             #[inline]
             fn fmt(&self, f: &mut $crate::_export::_core::fmt::Formatter) -> $crate::_export::_core::fmt::Result {
                 if $reverse {
-                    $crate::_export::_core::fmt::LowerHex::fmt(&self.0.backward_hex(), f)
+                    $crate::hex::fmt_hex_exact!(f, $len, <Self as $crate::Hash>::as_byte_array(&self).iter().rev(), $crate::hex::Case::Lower)
                 } else {
-                    $crate::_export::_core::fmt::LowerHex::fmt(&self.0.forward_hex(), f)
+                    $crate::hex::fmt_hex_exact!(f, $len, <Self as $crate::Hash>::as_byte_array(&self), $crate::hex::Case::Lower)
                 }
             }
         }
@@ -22,9 +22,9 @@ macro_rules! hex_fmt_impl(
             #[inline]
             fn fmt(&self, f: &mut $crate::_export::_core::fmt::Formatter) -> $crate::_export::_core::fmt::Result {
                 if $reverse {
-                    $crate::_export::_core::fmt::UpperHex::fmt(&self.0.backward_hex(), f)
+                    $crate::hex::fmt_hex_exact!(f, $len, <Self as $crate::Hash>::as_byte_array(&self).iter().rev(), $crate::hex::Case::Upper)
                 } else {
-                    $crate::_export::_core::fmt::UpperHex::fmt(&self.0.forward_hex(), f)
+                    $crate::hex::fmt_hex_exact!(f, $len, <Self as $crate::Hash>::as_byte_array(&self), $crate::hex::Case::Upper)
                 }
             }
         }
@@ -188,7 +188,7 @@ macro_rules! hash_newtype {
             $({ $($type_attrs)* })*
         }
 
-        $crate::hex_fmt_impl!(<$newtype as $crate::Hash>::DISPLAY_BACKWARD, $newtype);
+        $crate::hex_fmt_impl!(<$newtype as $crate::Hash>::DISPLAY_BACKWARD, <$newtype as $crate::Hash>::LEN, $newtype);
         $crate::serde_impl!($newtype, <$newtype as $crate::Hash>::LEN);
         $crate::borrow_slice_impl!($newtype);