Make bdk and bdk_chain work under 1.57.0

- rewrite some parts of the code to deal with older borrow checker
- downgraded hashbrown

crates/chain/src/keychain/persist.rs

@@ -23,7 +23,7 @@ pub struct Persist<K, P, B> {
     stage: keychain::KeychainChangeSet<K, P>,
 }
 
-impl<K, P, B: PersistBackend<K, P>> Persist<K, P, B> {
+impl<K, P, B> Persist<K, P, B> {
     /// Create a new `Persist` from a [`PersistBackend`].
     pub fn new(backend: B) -> Self {
         Self {
@@ -51,7 +51,10 @@ impl<K, P, B: PersistBackend<K, P>> Persist<K, P, B> {
     /// Commit the staged changes to the underlying persistence backend.
     ///
     /// Retuns a backend defined error if this fails
-    pub fn commit(&mut self) -> Result<(), B::WriteError> {
+    pub fn commit(&mut self) -> Result<(), B::WriteError>
+    where
+        B: PersistBackend<K, P>,
+    {
         self.backend.append_changeset(&self.stage)?;
         self.stage = Default::default();
         Ok(())

crates/chain/src/keychain/tracker.rs

@@ -125,7 +125,7 @@ where
     pub fn full_txouts(&self) -> impl Iterator<Item = (&(K, u32), FullTxOut<P>)> + '_ {
         self.txout_index
             .txouts()
-            .filter_map(|(spk_i, op, _)| Some((spk_i, self.chain_graph.full_txout(op)?)))
+            .filter_map(move |(spk_i, op, _)| Some((spk_i, self.chain_graph.full_txout(op)?)))
     }
 
     /// Iterates through [`FullTxOut`]s that are unspent outputs.

crates/chain/src/keychain/txout_index.rs

@@ -423,7 +423,7 @@ impl<K: Clone + Ord + Debug> KeychainTxOutIndex<K> {
                         Cow::Owned(descriptor.clone()),
                         next_reveal_index..index + 1,
                     ),
-                    DerivationAdditions([(keychain.clone(), index)].into()),
+                    DerivationAdditions(core::iter::once((keychain.clone(), index)).collect()),
                 )
             }
             None => (
@@ -575,11 +575,17 @@ where
         .take_while(move |&index| has_wildcard || index == 0)
         // we can only iterate over non-hardened indices
         .take_while(|&index| index <= BIP32_MAX_INDEX)
-        // take until failure
-        .map_while(move |index| {
-            descriptor
-                .derived_descriptor(&secp, index)
-                .map(|desc| (index, desc.script_pubkey()))
-                .ok()
-        })
+        .map(
+            move |index| -> Result<_, miniscript::descriptor::ConversionError> {
+                Ok((
+                    index,
+                    descriptor
+                        .at_derivation_index(index)
+                        .derived_descriptor(&secp)?
+                        .script_pubkey(),
+                ))
+            },
+        )
+        .take_while(Result::is_ok)
+        .map(Result::unwrap)
 }