Remove hashbrown dependency

Replace the usage of `HashMap` and `HashSet` with `BTreeMap` and
`BTreeSet` and remove the `hashbrown` dependency

This is an API breaking change because the `KeyMap` type is public.

Author: tcharding

Cargo.toml

@@ -13,7 +13,7 @@ edition = "2018"
 [features]
 default = ["std"]
 std = ["bitcoin/std", "bitcoin/secp-recovery"]
-no-std = ["hashbrown", "bitcoin/no-std"]
+no-std = ["bitcoin/no-std"]
 compiler = []
 trace = []
 
@@ -23,7 +23,6 @@ base64 = ["bitcoin/base64"]
 
 [dependencies]
 bitcoin = { version = "0.30.0", default-features = false }
-hashbrown = { version = "0.11", optional = true }
 internals = { package = "bitcoin-private", version = "0.1.0", default_features = false }
 
 # Do NOT use this as a feature! Use the `serde` feature instead.

src/descriptor/mod.rs

@@ -57,7 +57,7 @@ pub use self::key::{
 /// [`Descriptor::parse_descriptor`], since the descriptor will always only contain
 /// public keys. This map allows looking up the corresponding secret key given a
 /// public key from the descriptor.
-pub type KeyMap = HashMap<DescriptorPublicKey, DescriptorSecretKey>;
+pub type KeyMap = BTreeMap<DescriptorPublicKey, DescriptorSecretKey>;
 
 /// Script descriptor
 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
@@ -656,7 +656,7 @@ impl Descriptor<DescriptorPublicKey> {
             Ok(public_key)
         }
 
-        let mut keymap_pk = KeyMapWrapper(HashMap::new(), secp);
+        let mut keymap_pk = KeyMapWrapper(BTreeMap::new(), secp);
 
         struct KeyMapWrapper<'a, C: secp256k1::Signing>(KeyMap, &'a secp256k1::Secp256k1<C>);
 
@@ -1501,7 +1501,7 @@ mod tests {
             witness: Witness::default(),
         };
         let satisfier = {
-            let mut satisfier = HashMap::with_capacity(2);
+            let mut satisfier = BTreeMap::new();
 
             satisfier.insert(
                 a,

src/lib.rs

@@ -100,9 +100,6 @@ pub use bitcoin;
 #[macro_use]
 extern crate alloc;
 
-#[cfg(not(feature = "std"))]
-extern crate hashbrown;
-
 #[cfg(any(feature = "std", test))]
 extern crate core;
 
@@ -961,9 +958,6 @@ mod prelude {
         vec::Vec,
     };
 
-    #[cfg(all(not(feature = "std"), not(test)))]
-    pub use hashbrown::{HashMap, HashSet};
-
     #[cfg(all(not(feature = "std"), not(test)))]
     pub use self::mutex::Mutex;
 }

src/miniscript/analyzable.rs

@@ -213,7 +213,7 @@ impl<Pk: MiniscriptKey, Ctx: ScriptContext> Miniscript<Pk, Ctx> {
         // to have an iterator
         let all_pkhs_len = self.iter_pk().count();
 
-        let unique_pkhs_len = self.iter_pk().collect::<HashSet<_>>().len();
+        let unique_pkhs_len = self.iter_pk().collect::<BTreeSet<_>>().len();
 
         unique_pkhs_len != all_pkhs_len
     }

src/policy/concrete.rs

@@ -327,7 +327,7 @@ impl<Pk: MiniscriptKey> Policy<Pk> {
             let mut prob = 0.;
             let semantic_policy = self.lift()?;
             let concrete_keys = self.keys();
-            let key_prob_map: HashMap<_, _> = self
+            let key_prob_map: BTreeMap<_, _> = self
                 .to_tapleaf_prob_vec(1.0)
                 .into_iter()
                 .filter(|(_, ref pol)| matches!(*pol, Concrete::Key(..)))
@@ -563,7 +563,7 @@ impl<Pk: MiniscriptKey> PolicyArc<Pk> {
         // owing to the current [policy element enumeration algorithm][`Policy::enumerate_pol`],
         // two passes of the algorithm might result in same sub-policy showing up. Currently, we
         // merge the nodes by adding up the corresponding probabilities for the same policy.
-        let mut pol_prob_map = HashMap::<Arc<Self>, OrdF64>::new();
+        let mut pol_prob_map = BTreeMap::<Arc<Self>, OrdF64>::new();
 
         let arc_self = Arc::new(self);
         tapleaf_prob_vec.insert((Reverse(OrdF64(prob)), Arc::clone(&arc_self)));
@@ -791,7 +791,7 @@ impl<Pk: MiniscriptKey> Policy<Pk> {
     pub fn check_duplicate_keys(&self) -> Result<(), PolicyError> {
         let pks = self.keys();
         let pks_len = pks.len();
-        let unique_pks_len = pks.into_iter().collect::<HashSet<_>>().len();
+        let unique_pks_len = pks.into_iter().collect::<BTreeSet<_>>().len();
 
         if pks_len > unique_pks_len {
             Err(PolicyError::DuplicatePubKeys)