Remove extern crate bitcoin_hashes

Now we have edition 2018 we do not need to use `macro_use` or `extern
crate`; `pub use` works with macros.

Remove the extern crate statement and replace it with a pub use
statement. Requires fixing up various imports statements and also
requires importing `sha256t_hash_newtype` macro directly instead of
using a qualified path to it.

src/blockdata/script.rs

@@ -998,7 +998,7 @@ impl<'de> serde::Deserialize<'de> for Script {
         D: serde::Deserializer<'de>,
     {
         use core::fmt::Formatter;
-        use hashes::hex::FromHex;
+        use crate::hashes::hex::FromHex;
 
         if deserializer.is_human_readable() {
 

src/blockdata/witness.rs

@@ -281,7 +281,7 @@ impl serde::Serialize for Witness {
     where
         S: serde::Serializer,
     {
-        use hashes::hex::ToHex;
+        use crate::hashes::hex::ToHex;
         use serde::ser::SerializeSeq;
 
         let human_readable = serializer.is_human_readable();
@@ -315,8 +315,8 @@ impl<'de> serde::Deserialize<'de> for Witness {
 
             fn visit_seq<A: serde::de::SeqAccess<'de>>(self, mut a: A) -> Result<Self::Value, A::Error>
             {
-                use hashes::hex::FromHex;
+                use crate::hashes::hex::FromHex;
-                use hashes::hex::Error::*;
+                use crate::hashes::hex::Error::*;
                 use serde::de::{self, Unexpected};
 
                 let mut ret = match a.size_hint() {

src/lib.rs

@@ -63,8 +63,7 @@ extern crate alloc;
 extern crate core2;
 
 // Re-exported dependencies.
-#[macro_use]
+pub use bitcoin_hashes as hashes;
-pub extern crate bitcoin_hashes as hashes;
 pub extern crate bech32;
 pub extern crate secp256k1;
 

src/serde_utils.rs

@@ -235,7 +235,7 @@ pub mod hex_bytes {
     //! Module for serialization of byte arrays as hex strings.
     #![allow(missing_docs)]
 
-    use hashes::hex::{FromHex, ToHex};
+    use crate::hashes::hex::{FromHex, ToHex};
     use serde;
 
     pub fn serialize<T, S>(bytes: &T, s: S) -> Result<S::Ok, S::Error>

src/util/psbt/mod.rs

@@ -492,7 +492,7 @@ mod tests {
     #[test]
     fn test_serde_psbt() {
         //! Create a full PSBT value with various fields filled and make sure it can be JSONized.
-        use hashes::sha256d;
+        use crate::hashes::sha256d;
         use crate::util::psbt::map::Input;
         use crate::EcdsaSighashType;
 

src/util/taproot.rs

@@ -13,7 +13,7 @@ use core::convert::TryFrom;
 use core::fmt;
 use core::cmp::Reverse;
 
-use crate::hashes::{sha256, Hash, HashEngine};
+use crate::hashes::{sha256, sha256t_hash_newtype, Hash, HashEngine};
 use crate::schnorr::{TweakedPublicKey, UntweakedPublicKey, TapTweak};
 use crate::util::key::XOnlyPublicKey;
 use crate::Script;
@@ -49,16 +49,16 @@ const MIDSTATE_TAPSIGHASH: [u8; 32] = [
 // f504a425d7f8783b1363868ae3e556586eee945dbc7888dd02a6e2c31873fe9f
 
 // Taproot test vectors from BIP-341 state the hashes without any reversing
-hashes::sha256t_hash_newtype!(TapLeafHash, TapLeafTag, MIDSTATE_TAPLEAF, 64,
+sha256t_hash_newtype!(TapLeafHash, TapLeafTag, MIDSTATE_TAPLEAF, 64,
     doc="Taproot-tagged hash for tapscript Merkle tree leafs", false
 );
-hashes::sha256t_hash_newtype!(TapBranchHash, TapBranchTag, MIDSTATE_TAPBRANCH, 64,
+sha256t_hash_newtype!(TapBranchHash, TapBranchTag, MIDSTATE_TAPBRANCH, 64,
     doc="Taproot-tagged hash for tapscript Merkle tree branches", false
 );
-hashes::sha256t_hash_newtype!(TapTweakHash, TapTweakTag, MIDSTATE_TAPTWEAK, 64,
+sha256t_hash_newtype!(TapTweakHash, TapTweakTag, MIDSTATE_TAPTWEAK, 64,
     doc="Taproot-tagged hash for public key tweaks", false
 );
-hashes::sha256t_hash_newtype!(TapSighashHash, TapSighashTag, MIDSTATE_TAPSIGHASH, 64,
+sha256t_hash_newtype!(TapSighashHash, TapSighashTag, MIDSTATE_TAPSIGHASH, 64,
     doc="Taproot-tagged hash for the taproot signature hash", false
 );