Delete deprecated sha256t_hash_newtype macro

This macro is a maintenance burden. We would like to put a tag on the
hash engine but doing so would require breaking this macro anyway so
lets just delete it.

hashes/src/sha256t/mod.rs

@@ -140,105 +140,6 @@ where
     Hash::from_byte_array(sha256::Hash::from_engine(e).to_byte_array())
 }
 
-/// Macro used to define a newtype tagged hash.
-///
-/// This macro creates two types:
-///
-/// * a tag struct
-/// * a hash wrapper
-///
-/// The syntax is:
-///
-/// ```
-/// # #[allow(deprecated)] {
-/// # use bitcoin_hashes::sha256t_hash_newtype;
-/// sha256t_hash_newtype! {
-///     /// Optional documentation details here.
-///     /// Summary is always generated.
-///     pub struct FooTag = hash_str("foo");
-///
-///     /// A foo hash.
-///     // Direction works just like the hash_newtype! macro.
-///     #[hash_newtype(backward)]
-///     pub struct FooHash(_);
-/// }
-/// # }
-/// ```
-///
-/// The structs must be defined in this order - tag first, then hash type. `hash_str` marker
-/// says the midstate should be generated by hashing the supplied string in a way described in
-/// BIP-341. Alternatively, you can supply `hash_bytes` to hash raw bytes. If you have the midstate
-/// already pre-computed and prefer **compiler** performance to readability you may use
-/// `raw(MIDSTATE_BYTES, HASHED_BYTES_LENGTH)` instead.
-///
-/// Both visibility modifiers and attributes are optional and passed to inner structs (excluding
-/// `#[hash_newtype(...)]`). The attributes suffer same compiler performance limitations as in
-/// [`hash_newtype`] macro.
-///
-/// [`hash_newtype`]: crate::hash_newtype
-#[macro_export]
-#[deprecated(since = "0.15.0", note = "use `sha256_tag!` combined with `hash_newtype!` instead")]
-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)*])* _);) => {
-        $crate::sha256t_tag_struct!($tag_vis, $tag, stringify!($hash_name), $(#[$($tag_attr)*])*);
-
-        impl $crate::sha256t::Tag for $tag {
-            #[inline]
-            fn engine() -> $crate::sha256::HashEngine {
-                const MIDSTATE: $crate::sha256::Midstate = $crate::sha256t_tag_constructor!($constructor, $($tag_value)+);
-                $crate::sha256::HashEngine::from_midstate(MIDSTATE)
-            }
-        }
-
-        $crate::hash_newtype! {
-            $(#[$($hash_attr)*])*
-            $hash_vis struct $hash_name($(#[$($field_attr)*])* $crate::sha256t::Hash<$tag>);
-        }
-
-        impl $hash_name {
-            /// Constructs a new engine.
-            #[allow(unused)] // the user of macro may not need this
-            pub fn engine() -> <$hash_name as $crate::GeneralHash>::Engine {
-                <$hash_name as $crate::GeneralHash>::engine()
-            }
-
-            /// Produces a hash from the current state of a given engine.
-            #[allow(unused)] // the user of macro may not need this
-            pub fn from_engine(e: <$hash_name as $crate::GeneralHash>::Engine) -> Self {
-                <$hash_name as $crate::GeneralHash>::from_engine(e)
-            }
-
-            /// Hashes some bytes.
-            #[allow(unused)] // the user of macro may not need this
-            pub fn hash(data: &[u8]) -> Self {
-                <$hash_name as $crate::GeneralHash>::hash(data)
-            }
-
-            /// Hashes all the byte slices retrieved from the iterator together.
-            #[allow(unused)] // the user of macro may not need this
-            pub fn hash_byte_chunks<B, I>(byte_slices: I) -> Self
-            where
-                B: AsRef<[u8]>,
-                I: IntoIterator<Item = B>,
-            {
-                <$hash_name as $crate::GeneralHash>::hash_byte_chunks(byte_slices)
-            }
-        }
-
-        impl $crate::GeneralHash for $hash_name {
-            type Engine = <$crate::sha256t::Hash<$tag> as $crate::GeneralHash>::Engine;
-
-            fn engine() -> Self::Engine {
-                <$crate::sha256t::Hash<$tag> as $crate::GeneralHash>::engine()
-            }
-
-            fn from_engine(e: Self::Engine) -> $hash_name {
-                Self::from(<$crate::sha256t::Hash<$tag> as $crate::GeneralHash>::from_engine(e))
-            }
-        }
-    }
-}
-
 // Workaround macros being unavailable in attributes.
 #[doc(hidden)]
 #[macro_export]