Remove PkTranslator trait

This is the second commit in a series of two in order to remove the
PkTranslator trait. The triat has a general implementation of Tranlator
like `impl Translator for PkTranslator where P::Sha256 ...`.

However, this blanket implemented has constraints on associated types
and makes it impossible to implement the trait for a generic type
downstream. Rust compiler does not support for trait specialization yet,
and so we should only provide a macro to ease implementation rather than
a blanket implementation that causes duplicate conflicts downstream

Author: sanket1729

src/descriptor/mod.rs

@@ -37,8 +37,8 @@ use self::checksum::verify_checksum;
 use crate::miniscript::{Legacy, Miniscript, Segwitv0};
 use crate::prelude::*;
 use crate::{
-    expression, hash256, miniscript, BareCtx, Error, ForEach, ForEachKey, MiniscriptKey,
-    PkTranslator, Satisfier, ToPublicKey, TranslatePk, Translator,
+    expression, hash256, miniscript, BareCtx, Error, ForEach, ForEachKey, MiniscriptKey, Satisfier,
+    ToPublicKey, TranslatePk, Translator,
 };
 
 mod bare;
@@ -526,14 +526,16 @@ impl Descriptor<DescriptorPublicKey> {
     pub fn derive(&self, index: u32) -> Descriptor<DerivedDescriptorKey> {
         struct Derivator(u32);
 
-        impl PkTranslator<DescriptorPublicKey, DerivedDescriptorKey, ()> for Derivator {
+        impl Translator<DescriptorPublicKey, DerivedDescriptorKey, ()> for Derivator {
             fn pk(&mut self, pk: &DescriptorPublicKey) -> Result<DerivedDescriptorKey, ()> {
                 Ok(pk.clone().derive(self.0))
             }
 
             fn pkh(&mut self, pkh: &DescriptorPublicKey) -> Result<DerivedDescriptorKey, ()> {
                 Ok(pkh.clone().derive(self.0))
             }
+
+            translate_assoc_clone!(DescriptorPublicKey, DescriptorPublicKey, ());
         }
         self.translate_pk(&mut Derivator(index))
             .expect("BIP 32 key index substitution cannot fail")
@@ -571,7 +573,7 @@ impl Descriptor<DescriptorPublicKey> {
         struct Derivator<'a, C: secp256k1::Verification>(&'a secp256k1::Secp256k1<C>);
 
         impl<'a, C: secp256k1::Verification>
-            PkTranslator<DerivedDescriptorKey, bitcoin::PublicKey, ConversionError>
+            Translator<DerivedDescriptorKey, bitcoin::PublicKey, ConversionError>
             for Derivator<'a, C>
         {
             fn pk(
@@ -587,6 +589,8 @@ impl Descriptor<DescriptorPublicKey> {
             ) -> Result<bitcoin::hashes::hash160::Hash, ConversionError> {
                 Ok(pkh.derive_public_key(&self.0)?.to_pubkeyhash())
             }
+
+            translate_assoc_clone!(DerivedDescriptorKey, bitcoin::PublicKey, ConversionError);
         }
 
         let derived = self.derive(index).translate_pk(&mut Derivator(secp))?;

src/interpreter/inner.rs

@@ -20,7 +20,7 @@ use bitcoin::util::taproot::{ControlBlock, TAPROOT_ANNEX_PREFIX};
 use super::{stack, BitcoinKey, Error, Stack, TypedHash160};
 use crate::miniscript::context::{NoChecks, ScriptContext};
 use crate::prelude::*;
-use crate::{BareCtx, Legacy, Miniscript, MiniscriptKey, PkTranslator, Segwitv0, Tap};
+use crate::{BareCtx, Legacy, Miniscript, MiniscriptKey, Segwitv0, Tap, Translator};
 
 /// Attempts to parse a slice as a Bitcoin public key, checking compressedness
 /// if asked to, but otherwise dropping it
@@ -377,14 +377,16 @@ impl<Ctx: ScriptContext> ToNoChecks for Miniscript<bitcoin::PublicKey, Ctx> {
     fn to_no_checks_ms(&self) -> Miniscript<BitcoinKey, NoChecks> {
         struct TranslateFullPk;
 
-        impl PkTranslator<bitcoin::PublicKey, BitcoinKey, ()> for TranslateFullPk {
+        impl Translator<bitcoin::PublicKey, BitcoinKey, ()> for TranslateFullPk {
             fn pk(&mut self, pk: &bitcoin::PublicKey) -> Result<BitcoinKey, ()> {
                 Ok(BitcoinKey::Fullkey(*pk))
             }
 
             fn pkh(&mut self, pkh: &hash160::Hash) -> Result<TypedHash160, ()> {
                 Ok(TypedHash160::FullKey(*pkh))
             }
+
+            translate_assoc_clone!(bitcoin::PublicKey, BitcoinKey, ());
         }
 
         self.real_translate_pk(&mut TranslateFullPk)
@@ -397,14 +399,15 @@ impl<Ctx: ScriptContext> ToNoChecks for Miniscript<bitcoin::XOnlyPublicKey, Ctx>
         // specify the () error type as this cannot error
         struct TranslateXOnlyPk;
 
-        impl PkTranslator<bitcoin::XOnlyPublicKey, BitcoinKey, ()> for TranslateXOnlyPk {
+        impl Translator<bitcoin::XOnlyPublicKey, BitcoinKey, ()> for TranslateXOnlyPk {
             fn pk(&mut self, pk: &bitcoin::XOnlyPublicKey) -> Result<BitcoinKey, ()> {
                 Ok(BitcoinKey::XOnlyPublicKey(*pk))
             }
 
             fn pkh(&mut self, pkh: &hash160::Hash) -> Result<TypedHash160, ()> {
                 Ok(TypedHash160::XonlyKey(*pkh))
             }
+            translate_assoc_clone!(bitcoin::XOnlyPublicKey, BitcoinKey, ());
         }
         self.real_translate_pk(&mut TranslateXOnlyPk)
             .expect("Translation should succeed")

src/lib.rs

@@ -465,44 +465,6 @@ where
     fn hash256(&mut self, hash256: &P::Hash256) -> Result<Q::Hash256, E>;
 }
 
-/// Provides the conversion information required in [`TranslatePk`].
-/// Same as [`Translator`], but useful when all the associated types apart
-/// from Pk/Pkh don't change in translation
-pub trait PkTranslator<P, Q, E>
-where
-    P: MiniscriptKey,
-    Q: MiniscriptKey<Sha256 = P::Sha256>,
-{
-    /// Provides the translation public keys P -> Q
-    fn pk(&mut self, pk: &P) -> Result<Q, E>;
-
-    /// Provides the translation public keys hashes P::Hash -> Q::Hash
-    fn pkh(&mut self, pkh: &P::Hash) -> Result<Q::Hash, E>;
-}
-
-impl<P, Q, E, T> Translator<P, Q, E> for T
-where
-    T: PkTranslator<P, Q, E>,
-    P: MiniscriptKey,
-    Q: MiniscriptKey<Sha256 = P::Sha256, Hash256 = P::Hash256>,
-{
-    fn pk(&mut self, pk: &P) -> Result<Q, E> {
-        <Self as PkTranslator<P, Q, E>>::pk(self, pk)
-    }
-
-    fn pkh(&mut self, pkh: &<P as MiniscriptKey>::Hash) -> Result<<Q as MiniscriptKey>::Hash, E> {
-        <Self as PkTranslator<P, Q, E>>::pkh(self, pkh)
-    }
-
-    fn sha256(&mut self, sha256: &<P as MiniscriptKey>::Sha256) -> Result<<Q>::Sha256, E> {
-        Ok(sha256.clone())
-    }
-
-    fn hash256(&mut self, hash256: &<P as MiniscriptKey>::Hash256) -> Result<<Q>::Hash256, E> {
-        Ok(hash256.clone())
-    }
-}
-
 /// Converts a descriptor using abstract keys to one using specific keys. Uses translator `t` to do
 /// the actual translation function calls.
 pub trait TranslatePk<P, Q>

src/macros.rs

@@ -31,14 +31,14 @@ macro_rules! translate_assoc_clone {
     ($source: ty, $target:ty, $error_ty: ty) => {
         fn sha256(
             &mut self,
-            _sha256: &<$source as MiniscriptKey>::Sha256,
+            sha256: &<$source as MiniscriptKey>::Sha256,
         ) -> Result<<$target as MiniscriptKey>::Sha256, $error_ty> {
             Ok(sha256.clone())
         }
 
         fn hash256(
             &mut self,
-            _hash256: &<$source as MiniscriptKey>::Hash256,
+            hash256: &<$source as MiniscriptKey>::Hash256,
         ) -> Result<<$target as MiniscriptKey>::Hash256, $error_ty> {
             Ok(hash256.clone())
         }

src/psbt/mod.rs

@@ -36,8 +36,8 @@ use crate::miniscript::limits::SEQUENCE_LOCKTIME_DISABLE_FLAG;
 use crate::miniscript::satisfy::{After, Older};
 use crate::prelude::*;
 use crate::{
-    descriptor, interpreter, Descriptor, DescriptorPublicKey, MiniscriptKey, PkTranslator,
-    Preimage32, Satisfier, ToPublicKey, TranslatePk,
+    descriptor, interpreter, Descriptor, DescriptorPublicKey, MiniscriptKey, Preimage32, Satisfier,
+    ToPublicKey, TranslatePk, Translator,
 };
 
 mod finalizer;
@@ -937,7 +937,7 @@ struct XOnlyHashLookUp(
     pub secp256k1::Secp256k1<VerifyOnly>,
 );
 
-impl PkTranslator<DescriptorPublicKey, bitcoin::PublicKey, descriptor::ConversionError>
+impl Translator<DescriptorPublicKey, bitcoin::PublicKey, descriptor::ConversionError>
     for XOnlyHashLookUp
 {
     fn pk(
@@ -957,6 +957,13 @@ impl PkTranslator<DescriptorPublicKey, bitcoin::PublicKey, descriptor::Conversio
         self.0.insert(hash, xonly);
         Ok(hash)
     }
+
+    // Clone all the associated types in translation
+    translate_assoc_clone!(
+        DescriptorPublicKey,
+        bitcoin::PublicKey,
+        descriptor::ConversionError
+    );
 }
 
 // Traverse the pkh lookup while maintaining a reverse map for storing the map
@@ -966,7 +973,7 @@ struct KeySourceLookUp(
     pub secp256k1::Secp256k1<VerifyOnly>,
 );
 
-impl PkTranslator<DescriptorPublicKey, bitcoin::PublicKey, descriptor::ConversionError>
+impl Translator<DescriptorPublicKey, bitcoin::PublicKey, descriptor::ConversionError>
     for KeySourceLookUp
 {
     fn pk(
@@ -987,6 +994,12 @@ impl PkTranslator<DescriptorPublicKey, bitcoin::PublicKey, descriptor::Conversio
     ) -> Result<hash160::Hash, descriptor::ConversionError> {
         Ok(self.pk(xpk)?.to_pubkeyhash())
     }
+
+    translate_assoc_clone!(
+        DescriptorPublicKey,
+        bitcoin::PublicKey,
+        descriptor::ConversionError
+    );
 }
 
 fn update_input_with_descriptor_helper(