Move the block hash types to primitives

Move the `BlockHash` and `WitnessCommitment` hash types over to
`primitives`.

bitcoin/src/blockdata/block.rs

@@ -23,18 +23,11 @@ use crate::script::{self, ScriptExt as _};
 use crate::transaction::{Transaction, Wtxid};
 use crate::VarInt;
 
-hashes::hash_newtype! {
-    /// A bitcoin block hash.
-    pub struct BlockHash(sha256d::Hash);
-    /// A hash corresponding to the witness structure commitment in the coinbase transaction.
-    pub struct WitnessCommitment(sha256d::Hash);
-}
-impl_hashencode!(BlockHash);
+#[rustfmt::skip]                // Keep public re-exports separate.
+#[doc(inline)]
+pub use primitives::block::*;
 
-impl BlockHash {
-    /// Dummy hash used as the previous blockhash of the genesis block.
-    pub const GENESIS_PREVIOUS_BLOCK_HASH: Self = Self::from_byte_array([0; 32]);
-}
+impl_hashencode!(BlockHash);
 
 /// Bitcoin block header.
 ///
@@ -74,7 +67,7 @@ impl Header {
     pub fn block_hash(&self) -> BlockHash {
         let mut engine = sha256d::Hash::engine();
         self.consensus_encode(&mut engine).expect("engines don't error");
-        BlockHash(sha256d::Hash::from_engine(engine))
+        BlockHash::from_byte_array(sha256d::Hash::from_engine(engine).to_byte_array())
     }
 
     /// Computes the target (range [0, T] inclusive) that a blockhash must land in to be valid.
@@ -296,7 +289,7 @@ impl Block {
         let mut encoder = sha256d::Hash::engine();
         witness_root.consensus_encode(&mut encoder).expect("engines don't error");
         encoder.input(witness_reserved_value);
-        WitnessCommitment(sha256d::Hash::from_engine(encoder))
+        WitnessCommitment::from_byte_array(sha256d::Hash::from_engine(encoder).to_byte_array())
     }
 
     /// Computes the Merkle root of transactions hashed for witness.

primitives/src/block.rs

@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: CC0-1.0
+
+//! Bitcoin blocks.
+//!
+//! A block is a bundle of transactions with a proof-of-work attached,
+//! which commits to an earlier block to form the blockchain. This
+//! module describes structures and functions needed to describe
+//! these blocks and the blockchain.
+
+use hashes::sha256d;
+
+hashes::hash_newtype! {
+    /// A bitcoin block hash.
+    pub struct BlockHash(sha256d::Hash);
+    /// A hash corresponding to the witness structure commitment in the coinbase transaction.
+    pub struct WitnessCommitment(sha256d::Hash);
+}
+
+impl BlockHash {
+    /// Dummy hash used as the previous blockhash of the genesis block.
+    pub const GENESIS_PREVIOUS_BLOCK_HASH: Self = Self::from_byte_array([0; 32]);
+}

primitives/src/lib.rs

@@ -29,6 +29,7 @@ extern crate std;
 #[macro_use]
 extern crate serde;
 
+pub mod block;
 #[cfg(feature = "alloc")]
 pub mod locktime;
 pub mod opcodes;
@@ -44,6 +45,7 @@ pub use units::*;
 pub use self::locktime::{absolute, relative};
 #[doc(inline)]
 pub use self::{
+    block::{BlockHash, WitnessCommitment},
     pow::CompactTarget,
     sequence::Sequence,
     transaction::{Txid, Wtxid},