Remove now-useless overrides of `decoder`

diff --git a/consensus_encoding/src/decode/decoders.rs b/consensus_encoding/src/decode/decoders.rs
index c95d676d..372e69cb 100644
--- a/consensus_encoding/src/decode/decoders.rs
+++ b/consensus_encoding/src/decode/decoders.rs
@@ -927,7 +927,6 @@ mod tests {
     #[cfg(feature = "alloc")]
     impl Decode for Inner {
         type Decoder = InnerDecoder;
-        fn decoder() -> Self::Decoder { InnerDecoder(ArrayDecoder::<4>::new()) }
     }
 
     #[cfg(feature = "alloc")]
@@ -959,7 +958,6 @@ mod tests {
     #[cfg(feature = "alloc")]
     impl Decode for Test {
         type Decoder = TestDecoder;
-        fn decoder() -> Self::Decoder { TestDecoder(VecDecoder::new()) }
     }
 
     #[test]
diff --git a/consensus_encoding/src/decode/mod.rs b/consensus_encoding/src/decode/mod.rs
index 8c2adfa6..0d1ffeb7 100644
--- a/consensus_encoding/src/decode/mod.rs
+++ b/consensus_encoding/src/decode/mod.rs
@@ -36,7 +36,6 @@ use crate::{DecodeError, UnconsumedError};
 ///
 /// impl Decode for Foo {
 ///     type Decoder = FooDecoder;
-///     fn decoder() -> Self::Decoder { FooDecoder(ArrayDecoder::new()) }
 /// }
 ///
 /// let foo: Foo = decode_from_slice(&[0xde, 0xad, 0xbe, 0xef]).unwrap();
diff --git a/consensus_encoding/tests/api.rs b/consensus_encoding/tests/api.rs
index b68d7cc2..ee0e2a38 100644
--- a/consensus_encoding/tests/api.rs
+++ b/consensus_encoding/tests/api.rs
@@ -91,7 +91,6 @@ impl Decoder for FooDecoder {
 
 impl Decode for Foo {
     type Decoder = FooDecoder;
-    fn decoder() -> Self::Decoder { FooDecoder(ArrayDecoder::new()) }
 }
 
 /// A struct that includes all types that implement `Clone`.
diff --git a/consensus_encoding/tests/compact_size.rs b/consensus_encoding/tests/compact_size.rs
index 5976de3a..26a4acc1 100644
--- a/consensus_encoding/tests/compact_size.rs
+++ b/consensus_encoding/tests/compact_size.rs
@@ -44,7 +44,6 @@ impl Decoder for CompactSizeUsizeDecoderWrapper {
 #[cfg(feature = "alloc")]
 impl Decode for CompactSizeUsize {
     type Decoder = CompactSizeUsizeDecoderWrapper;
-    fn decoder() -> Self::Decoder { CompactSizeUsizeDecoderWrapper(CompactSizeDecoder::new()) }
 }
 
 /// A `u64` value encoded and decoded as a compact size integer.
@@ -82,7 +81,6 @@ impl Decoder for CompactSizeU64DecoderWrapper {
 #[cfg(feature = "alloc")]
 impl Decode for CompactSizeU64 {
     type Decoder = CompactSizeU64DecoderWrapper;
-    fn decoder() -> Self::Decoder { CompactSizeU64DecoderWrapper(CompactSizeU64Decoder::new()) }
 }
 
 #[test]
diff --git a/consensus_encoding/tests/composition.rs b/consensus_encoding/tests/composition.rs
index 60ddf059..2ed79aa0 100644
--- a/consensus_encoding/tests/composition.rs
+++ b/consensus_encoding/tests/composition.rs
@@ -79,8 +79,6 @@ impl Decoder for CompositeDataDecoder {
 
 impl Decode for CompositeData {
     type Decoder = CompositeDataDecoder;
-
-    fn decoder() -> Self::Decoder { CompositeDataDecoder::new() }
 }
 
 #[test]
diff --git a/consensus_encoding/tests/decode.rs b/consensus_encoding/tests/decode.rs
index 06e67179..2bc27c38 100644
--- a/consensus_encoding/tests/decode.rs
+++ b/consensus_encoding/tests/decode.rs
@@ -233,7 +233,6 @@ struct TestArray([u8; 4]);
 
 impl Decode for TestArray {
     type Decoder = TestArrayDecoder;
-    fn decoder() -> Self::Decoder { TestArrayDecoder { inner: ArrayDecoder::new() } }
 }
 
 #[derive(Default)]
@@ -417,7 +416,6 @@ impl Decoder for InnerDecoder {
 #[cfg(feature = "alloc")]
 impl Decode for Inner {
     type Decoder = InnerDecoder;
-    fn decoder() -> Self::Decoder { InnerDecoder(ArrayDecoder::<4>::new()) }
 }
 
 #[cfg(feature = "alloc")]
@@ -448,7 +446,6 @@ impl Decoder for TestDecoder {
 #[cfg(feature = "alloc")]
 impl Decode for Test {
     type Decoder = TestDecoder;
-    fn decoder() -> Self::Decoder { TestDecoder(VecDecoder::new()) }
 }
 
 // Stress test the push_bytes impl by passing in a single byte slice repeatedly.
diff --git a/io/src/lib.rs b/io/src/lib.rs
index db7474a4..cc9bfeb2 100644
--- a/io/src/lib.rs
+++ b/io/src/lib.rs
@@ -806,7 +806,6 @@ mod tests {
 
     impl Decode for TestArray {
         type Decoder = TestArrayDecoder;
-        fn decoder() -> Self::Decoder { TestArrayDecoder { inner: ArrayDecoder::new() } }
     }
 
     #[derive(Default)]
diff --git a/p2p/src/address.rs b/p2p/src/address.rs
index e4e0015a..9bd2a5ad 100644
--- a/p2p/src/address.rs
+++ b/p2p/src/address.rs
@@ -184,13 +184,6 @@ impl encoding::Decoder for AddressDecoder {
 
 impl encoding::Decode for Address {
     type Decoder = AddressDecoder;
-    fn decoder() -> Self::Decoder {
-        AddressDecoder(encoding::Decoder3::new(
-            ServiceFlags::decoder(),
-            encoding::ArrayDecoder::<16>::new(),
-            encoding::ArrayDecoder::<2>::new(),
-        ))
-    }
 }
 
 /// Data type received in an `addr` message.
@@ -247,13 +240,6 @@ impl encoding::Decoder for AddrV1MessageDecoder {
 
 impl encoding::Decode for AddrV1Message {
     type Decoder = AddrV1MessageDecoder;
-
-    fn decoder() -> Self::Decoder {
-        AddrV1MessageDecoder(AddrV1MessageInnerDecoder::new(
-            ArrayDecoder::new(),
-            Address::decoder(),
-        ))
-    }
 }
 
 /// Supported networks for use in BIP-0155 addrv2 message
@@ -589,10 +575,6 @@ impl encoding::Decoder for AddrV2Decoder {
 
 impl encoding::Decode for AddrV2 {
     type Decoder = AddrV2Decoder;
-
-    fn decoder() -> Self::Decoder {
-        AddrV2Decoder(Decoder2::new(ArrayDecoder::new(), ByteVecDecoder::new()))
-    }
 }
 
 /// Address received from BIP-0155 addrv2 message
@@ -686,15 +668,6 @@ impl encoding::Decoder for AddrV2MessageDecoder {
 
 impl encoding::Decode for AddrV2Message {
     type Decoder = AddrV2MessageDecoder;
-
-    fn decoder() -> Self::Decoder {
-        AddrV2MessageDecoder(AddrV2MessageInnerDecoder::new(
-            ArrayDecoder::new(),
-            CompactSizeU64Decoder::new(),
-            AddrV2::decoder(),
-            ArrayDecoder::new(),
-        ))
-    }
 }
 
 /// Error types for address messages.
diff --git a/p2p/src/bip152.rs b/p2p/src/bip152.rs
index 0dd18675..7bfef4e0 100644
--- a/p2p/src/bip152.rs
+++ b/p2p/src/bip152.rs
@@ -109,13 +109,6 @@ impl encoding::Decoder for PrefilledTransactionDecoder {
 
 impl encoding::Decode for PrefilledTransaction {
     type Decoder = PrefilledTransactionDecoder;
-
-    fn decoder() -> Self::Decoder {
-        PrefilledTransactionDecoder(Decoder2::new(
-            CompactSizeDecoder::new(),
-            TransactionDecoder::new(),
-        ))
-    }
 }
 
 /// Trait that abstracts over a transaction identifier i.e., `Txid` and `Wtxid`.
@@ -236,8 +229,6 @@ impl encoding::Decoder for ShortIdDecoder {
 
 impl encoding::Decode for ShortId {
     type Decoder = ShortIdDecoder;
-
-    fn decoder() -> Self::Decoder { ShortIdDecoder(ShortIdInnerDecoder::new()) }
 }
 
 /// A structure to relay a block header, short IDs, and a select few transactions.
@@ -340,15 +331,6 @@ impl encoding::Decoder for HeaderAndShortIdsDecoder {
 
 impl encoding::Decode for HeaderAndShortIds {
     type Decoder = HeaderAndShortIdsDecoder;
-
-    fn decoder() -> Self::Decoder {
-        HeaderAndShortIdsDecoder(Decoder4::new(
-            Header::decoder(),
-            ArrayDecoder::new(),
-            VecDecoder::<ShortId>::new(),
-            VecDecoder::<PrefilledTransaction>::new(),
-        ))
-    }
 }
 
 impl HeaderAndShortIds {
@@ -466,8 +448,6 @@ impl encoding::Decoder for OffsetDecoder {
 
 impl encoding::Decode for Offset {
     type Decoder = OffsetDecoder;
-
-    fn decoder() -> Self::Decoder { OffsetDecoder(CompactSizeDecoder::new()) }
 }
 
 /// A [`BlockTransactionsRequest`] structure is used to list transaction indexes
@@ -582,10 +562,6 @@ impl encoding::Decoder for BlockTransactionsRequestDecoder {
 
 impl encoding::Decode for BlockTransactionsRequest {
     type Decoder = BlockTransactionsRequestDecoder;
-
-    fn decoder() -> Self::Decoder {
-        BlockTransactionsRequestDecoder(Decoder2::new(BlockHashDecoder::new(), VecDecoder::new()))
-    }
 }
 
 /// A [`BlockTransactions`] structure is used to provide some of the transactions
@@ -653,13 +629,6 @@ impl encoding::Decoder for BlockTransactionsDecoder {
 
 impl encoding::Decode for BlockTransactions {
     type Decoder = BlockTransactionsDecoder;
-
-    fn decoder() -> Self::Decoder {
-        BlockTransactionsDecoder(Decoder2::new(
-            BlockHashDecoder::new(),
-            VecDecoder::<Transaction>::new(),
-        ))
-    }
 }
 
 impl BlockTransactions {
diff --git a/p2p/src/lib.rs b/p2p/src/lib.rs
index 1d0e9870..c2c75302 100644
--- a/p2p/src/lib.rs
+++ b/p2p/src/lib.rs
@@ -161,7 +161,6 @@ impl encoding::Decoder for ProtocolVersionDecoder {
 
 impl encoding::Decode for ProtocolVersion {
     type Decoder = ProtocolVersionDecoder;
-    fn decoder() -> Self::Decoder { ProtocolVersionDecoder(encoding::ArrayDecoder::<4>::new()) }
 }
 
 /// Flags to indicate which network services a node supports.
@@ -356,7 +355,6 @@ impl encoding::Decoder for ServiceFlagsDecoder {
 
 impl encoding::Decode for ServiceFlags {
     type Decoder = ServiceFlagsDecoder;
-    fn decoder() -> Self::Decoder { ServiceFlagsDecoder(encoding::ArrayDecoder::<8>::new()) }
 }
 
 /// Network magic bytes to identify the cryptocurrency network the message was intended for.
@@ -490,8 +488,6 @@ impl encoding::Decoder for MagicDecoder {
 
 impl encoding::Decode for Magic {
     type Decoder = MagicDecoder;
-
-    fn decoder() -> Self::Decoder { MagicDecoder(ArrayDecoder::new()) }
 }
 
 impl AsRef<[u8]> for Magic {
diff --git a/p2p/src/merkle_tree.rs b/p2p/src/merkle_tree.rs
index 38717dd6..a57bf02c 100644
--- a/p2p/src/merkle_tree.rs
+++ b/p2p/src/merkle_tree.rs
@@ -168,9 +168,6 @@ impl encoding::Decoder for MerkleBlockDecoder {
 
 impl encoding::Decode for MerkleBlock {
     type Decoder = MerkleBlockDecoder;
-    fn decoder() -> Self::Decoder {
-        MerkleBlockDecoder(Decoder2::new(block::Header::decoder(), PartialMerkleTree::decoder()))
-    }
 }
 
 /// Data structure that represents a partial Merkle tree.
@@ -547,14 +544,6 @@ impl encoding::Decoder for PartialMerkleTreeDecoder {
 
 impl encoding::Decode for PartialMerkleTree {
     type Decoder = PartialMerkleTreeDecoder;
-
-    fn decoder() -> Self::Decoder {
-        PartialMerkleTreeDecoder(Decoder3::new(
-            ArrayDecoder::new(),
-            VecDecoder::new(),
-            ByteVecDecoder::new(),
-        ))
-    }
 }
 
 /// Error types for merkle tree messages.
diff --git a/p2p/src/message.rs b/p2p/src/message.rs
index 1e1efbbd..0ad20f63 100644
--- a/p2p/src/message.rs
+++ b/p2p/src/message.rs
@@ -129,8 +129,6 @@ impl encoding::Encode for CommandString {
 
 impl encoding::Decode for CommandString {
     type Decoder = CommandStringDecoder;
-
-    fn decoder() -> Self::Decoder { CommandStringDecoder { inner: encoding::ArrayDecoder::new() } }
 }
 
 /// Encoder for the [`CommandString`] type
@@ -301,14 +299,6 @@ impl encoding::Decoder for V1MessageHeaderDecoder {
 
 impl encoding::Decode for V1MessageHeader {
     type Decoder = V1MessageHeaderDecoder;
-    fn decoder() -> Self::Decoder {
-        V1MessageHeaderDecoder(encoding::Decoder4::new(
-            encoding::ArrayDecoder::<4>::new(),
-            CommandString::decoder(),
-            encoding::ArrayDecoder::<4>::new(),
-            encoding::ArrayDecoder::<4>::new(),
-        ))
-    }
 }
 
 /// A Network message using the v2 p2p protocol defined in BIP-0324.
@@ -367,9 +357,6 @@ impl encoding::Decoder for InventoryPayloadDecoder {
 
 impl encoding::Decode for InventoryPayload {
     type Decoder = InventoryPayloadDecoder;
-    fn decoder() -> Self::Decoder {
-        InventoryPayloadDecoder(VecDecoder::<message_blockdata::Inventory>::new())
-    }
 }
 
 /// A list of legacy p2p address messages.
@@ -419,7 +406,6 @@ impl encoding::Decoder for AddrPayloadDecoder {
 
 impl encoding::Decode for AddrPayload {
     type Decoder = AddrPayloadDecoder;
-    fn decoder() -> Self::Decoder { AddrPayloadDecoder(VecDecoder::new()) }
 }
 
 /// A list of v2 address messages.
@@ -472,7 +458,6 @@ impl encoding::Decoder for AddrV2PayloadDecoder {
 
 impl encoding::Decode for AddrV2Payload {
     type Decoder = AddrV2PayloadDecoder;
-    fn decoder() -> Self::Decoder { AddrV2PayloadDecoder(VecDecoder::new()) }
 }
 
 /// The `feefilter` message, wrapper around [`FeeRate`] for P2P wire format encoding.
@@ -553,8 +538,6 @@ impl encoding::Decoder for FeeFilterDecoder {
 
 impl encoding::Decode for FeeFilter {
     type Decoder = FeeFilterDecoder;
-
-    fn decoder() -> Self::Decoder { FeeFilterDecoder::new() }
 }
 
 #[cfg(feature = "arbitrary")]
@@ -621,7 +604,6 @@ impl encoding::Decoder for PingDecoder {
 
 impl encoding::Decode for Ping {
     type Decoder = PingDecoder;
-    fn decoder() -> Self::Decoder { PingDecoder(encoding::ArrayDecoder::<8>::new()) }
 }
 
 /// Serializer for Pong
@@ -678,7 +660,6 @@ impl encoding::Decoder for PongDecoder {
 
 impl encoding::Decode for Pong {
     type Decoder = PongDecoder;
-    fn decoder() -> Self::Decoder { PongDecoder(encoding::ArrayDecoder::<8>::new()) }
 }
 
 /// A Network message payload. Proper documentation is available at
@@ -1464,19 +1445,6 @@ impl encoding::Decoder for V1NetworkMessageDecoder {
 
 impl encoding::Decode for V1NetworkMessage {
     type Decoder = V1NetworkMessageDecoder;
-
-    fn decoder() -> Self::Decoder {
-        V1NetworkMessageDecoder {
-            state: DecoderState::ReadingHeader {
-                header_decoder: encoding::Decoder4::new(
-                    encoding::ArrayDecoder::new(),
-                    CommandStringDecoder { inner: encoding::ArrayDecoder::new() },
-                    encoding::ArrayDecoder::new(),
-                    encoding::ArrayDecoder::new(),
-                ),
-            },
-        }
-    }
 }
 
 /// Encoder for [`V2NetworkMessage`].
@@ -1631,10 +1599,6 @@ impl encoding::Decoder for NetworkHeaderDecoder {
 
 impl encoding::Decode for NetworkHeader {
     type Decoder = NetworkHeaderDecoder;
-
-    fn decoder() -> Self::Decoder {
-        NetworkHeaderDecoder(Decoder2::new(block::Header::decoder(), ArrayDecoder::new()))
-    }
 }
 
 /// A list of bitcoin block headers.
@@ -1700,8 +1664,6 @@ impl encoding::Decoder for HeadersMessageDecoder {
 
 impl encoding::Decode for HeadersMessage {
     type Decoder = HeadersMessageDecoder;
-
-    fn decoder() -> Self::Decoder { HeadersMessageDecoder(VecDecoder::new()) }
 }
 
 // State machine for decoding a [`V2NetworkMessage`].
@@ -1911,12 +1873,6 @@ impl encoding::Decoder for V2NetworkMessageDecoder {
 
 impl encoding::Decode for V2NetworkMessage {
     type Decoder = V2NetworkMessageDecoder;
-
-    fn decoder() -> Self::Decoder {
-        V2NetworkMessageDecoder {
-            state: V2NetworkMessageDecoderState::ShortId(encoding::ArrayDecoder::new()),
-        }
-    }
 }
 
 /// Does a double-SHA256 on `data` and returns the first 4 bytes.
diff --git a/p2p/src/message_blockdata.rs b/p2p/src/message_blockdata.rs
index 29706d73..33ef1f7d 100644
--- a/p2p/src/message_blockdata.rs
+++ b/p2p/src/message_blockdata.rs
@@ -135,9 +135,6 @@ impl encoding::Decoder for InventoryDecoder {
 
 impl encoding::Decode for Inventory {
     type Decoder = InventoryDecoder;
-    fn decoder() -> Self::Decoder {
-        InventoryDecoder(Decoder2::new(ArrayDecoder::<4>::new(), ArrayDecoder::<32>::new()))
-    }
 }
 
 /// A block locator.
@@ -246,7 +243,6 @@ impl encoding::Decoder for BlockLocatorDecoder {
 
 impl encoding::Decode for BlockLocator {
     type Decoder = BlockLocatorDecoder;
-    fn decoder() -> Self::Decoder { BlockLocatorDecoder::new() }
 }
 
 // Some simple messages
@@ -371,24 +367,10 @@ impl encoding::Decoder for GetBlocksMessageDecoder {
 
 impl encoding::Decode for GetBlocksMessage {
     type Decoder = GetBlocksMessageDecoder;
-    fn decoder() -> Self::Decoder {
-        GetBlocksMessageDecoder(Decoder3::new(
-            ProtocolVersionDecoder::new(),
-            BlockLocatorDecoder::new(),
-            BlockHashDecoder::new(),
-        ))
-    }
 }
 
 impl encoding::Decode for GetHeadersMessage {
     type Decoder = GetHeadersMessageDecoder;
-    fn decoder() -> Self::Decoder {
-        GetHeadersMessageDecoder(Decoder3::new(
-            ProtocolVersionDecoder::new(),
-            BlockLocatorDecoder::new(),
-            BlockHashDecoder::new(),
-        ))
-    }
 }
 
 /// Error types for blockdata messages.
diff --git a/p2p/src/message_bloom.rs b/p2p/src/message_bloom.rs
index a2da0f9f..a7998354 100644
--- a/p2p/src/message_bloom.rs
+++ b/p2p/src/message_bloom.rs
@@ -96,15 +96,6 @@ impl encoding::Decoder for FilterLoadDecoder {
 
 impl encoding::Decode for FilterLoad {
     type Decoder = FilterLoadDecoder;
-
-    fn decoder() -> Self::Decoder {
-        FilterLoadDecoder(Decoder4::new(
-            ByteVecDecoder::new(),
-            ArrayDecoder::new(),
-            ArrayDecoder::new(),
-            BloomFlags::decoder(),
-        ))
-    }
 }
 
 /// Bloom filter update flags
@@ -177,8 +168,6 @@ impl encoding::Decoder for BloomFlagsDecoder {
 
 impl encoding::Decode for BloomFlags {
     type Decoder = BloomFlagsDecoder;
-
-    fn decoder() -> Self::Decoder { BloomFlagsDecoder(ArrayDecoder::new()) }
 }
 
 /// `filteradd` message updates the current filter with new data
@@ -232,8 +221,6 @@ impl encoding::Decoder for FilterAddDecoder {
 
 impl encoding::Decode for FilterAdd {
     type Decoder = FilterAddDecoder;
-
-    fn decoder() -> Self::Decoder { FilterAddDecoder(FilterAddInnerDecoder::new()) }
 }
 
 /// Error types for bloom filter messages.
diff --git a/p2p/src/message_compact_blocks.rs b/p2p/src/message_compact_blocks.rs
index 6a4b0b2b..a6136087 100644
--- a/p2p/src/message_compact_blocks.rs
+++ b/p2p/src/message_compact_blocks.rs
@@ -65,10 +65,6 @@ impl encoding::Decoder for SendCmpctDecoder {
 
 impl encoding::Decode for SendCmpct {
     type Decoder = SendCmpctDecoder;
-
-    fn decoder() -> Self::Decoder {
-        SendCmpctDecoder(Decoder2::new(ArrayDecoder::new(), ArrayDecoder::new()))
-    }
 }
 
 /// Error types for [`SendCmpct`] messages.
diff --git a/p2p/src/message_filter.rs b/p2p/src/message_filter.rs
index 1d0f7819..94c5f3f1 100644
--- a/p2p/src/message_filter.rs
+++ b/p2p/src/message_filter.rs
@@ -102,8 +102,6 @@ impl encoding::Decoder for FilterHashDecoder {
 
 impl encoding::Decode for FilterHash {
     type Decoder = FilterHashDecoder;
-
-    fn decoder() -> Self::Decoder { FilterHashDecoder(ArrayDecoder::new()) }
 }
 
 /// Decoder for the [`FilterHeader`] type.
@@ -131,8 +129,6 @@ impl encoding::Decoder for FilterHeaderDecoder {
 
 impl encoding::Decode for FilterHeader {
     type Decoder = FilterHeaderDecoder;
-
-    fn decoder() -> Self::Decoder { FilterHeaderDecoder(ArrayDecoder::new()) }
 }
 
 #[cfg(feature = "arbitrary")]
@@ -205,14 +201,6 @@ impl encoding::Decoder for GetCFiltersDecoder {
 
 impl encoding::Decode for GetCFilters {
     type Decoder = GetCFiltersDecoder;
-
-    fn decoder() -> Self::Decoder {
-        GetCFiltersDecoder(Decoder3::new(
-            ArrayDecoder::new(),
-            BlockHeightDecoder::new(),
-            BlockHashDecoder::new(),
-        ))
-    }
 }
 
 /// cfilter message
@@ -283,14 +271,6 @@ impl encoding::Decoder for CFilterDecoder {
 
 impl encoding::Decode for CFilter {
     type Decoder = CFilterDecoder;
-
-    fn decoder() -> Self::Decoder {
-        CFilterDecoder(Decoder3::new(
-            ArrayDecoder::new(),
-            BlockHashDecoder::new(),
-            ByteVecDecoder::new(),
-        ))
-    }
 }
 
 /// getcfheaders message
@@ -349,14 +329,6 @@ impl encoding::Decoder for GetCFHeadersDecoder {
 
 impl encoding::Decode for GetCFHeaders {
     type Decoder = GetCFHeadersDecoder;
-
-    fn decoder() -> Self::Decoder {
-        GetCFHeadersDecoder(Decoder3::new(
-            ArrayDecoder::new(),
-            BlockHeightDecoder::new(),
-            BlockHashDecoder::new(),
-        ))
-    }
 }
 
 /// cfheaders message
@@ -435,15 +407,6 @@ impl encoding::Decoder for CFHeadersDecoder {
 
 impl encoding::Decode for CFHeaders {
     type Decoder = CFHeadersDecoder;
-
-    fn decoder() -> Self::Decoder {
-        CFHeadersDecoder(Decoder4::new(
-            ArrayDecoder::new(),
-            BlockHashDecoder::new(),
-            FilterHeader::decoder(),
-            VecDecoder::new(),
-        ))
-    }
 }
 
 /// getcfcheckpt message
@@ -499,10 +462,6 @@ impl encoding::Decoder for GetCFCheckptDecoder {
 
 impl encoding::Decode for GetCFCheckpt {
     type Decoder = GetCFCheckptDecoder;
-
-    fn decoder() -> Self::Decoder {
-        GetCFCheckptDecoder(Decoder2::new(ArrayDecoder::new(), BlockHashDecoder::new()))
-    }
 }
 
 /// cfcheckpt message
@@ -573,14 +532,6 @@ impl encoding::Decoder for CFCheckptDecoder {
 
 impl encoding::Decode for CFCheckpt {
     type Decoder = CFCheckptDecoder;
-
-    fn decoder() -> Self::Decoder {
-        CFCheckptDecoder(Decoder3::new(
-            ArrayDecoder::new(),
-            BlockHashDecoder::new(),
-            VecDecoder::new(),
-        ))
-    }
 }
 
 /// Error types for client side block filtering messages.
diff --git a/p2p/src/message_network.rs b/p2p/src/message_network.rs
index 507c68b8..f722c33c 100644
--- a/p2p/src/message_network.rs
+++ b/p2p/src/message_network.rs
@@ -139,25 +139,6 @@ impl encoding::Encode for VersionMessage {
 
 impl encoding::Decode for VersionMessage {
     type Decoder = VersionMessageDecoder;
-
-    #[inline]
-    fn decoder() -> Self::Decoder {
-        VersionMessageDecoder(encoding::Decoder2::new(
-            encoding::Decoder3::new(
-                crate::ProtocolVersion::decoder(),
-                crate::ServiceFlags::decoder(),
-                encoding::ArrayDecoder::<8>::new(),
-            ),
-            encoding::Decoder6::new(
-                crate::address::Address::decoder(),
-                crate::address::Address::decoder(),
-                encoding::ArrayDecoder::<8>::new(),
-                UserAgent::decoder(),
-                encoding::ArrayDecoder::<4>::new(),
-                encoding::ArrayDecoder::<1>::new(),
-            ),
-        ))
-    }
 }
 
 impl encoding::Decoder for VersionMessageDecoder {
diff --git a/primitives/src/block.rs b/primitives/src/block.rs
index 294d0691..771716cc 100644
--- a/primitives/src/block.rs
+++ b/primitives/src/block.rs
@@ -376,9 +376,6 @@ crate::decoder_newtype! {
 #[cfg(feature = "alloc")]
 impl encoding::Decode for Block<Unchecked> {
     type Decoder = BlockDecoder;
-    fn decoder() -> Self::Decoder {
-        BlockDecoder(Decoder2::new(Header::decoder(), VecDecoder::<Transaction>::new()))
-    }
 }
 
 /// Computes the Merkle root for a list of transactions.
@@ -609,16 +606,6 @@ impl HeaderDecoder {
 
 impl encoding::Decode for Header {
     type Decoder = HeaderDecoder;
-    fn decoder() -> Self::Decoder {
-        HeaderDecoder(Decoder6::new(
-            VersionDecoder::new(),
-            BlockHashDecoder::new(),
-            TxMerkleNodeDecoder::new(),
-            BlockTimeDecoder::new(),
-            CompactTargetDecoder::new(),
-            encoding::ArrayDecoder::new(),
-        ))
-    }
 }
 
 impl From<Header> for BlockHash {
@@ -760,7 +747,6 @@ crate::decoder_newtype! {
 
 impl encoding::Decode for Version {
     type Decoder = VersionDecoder;
-    fn decoder() -> Self::Decoder { VersionDecoder(encoding::ArrayDecoder::<4>::new()) }
 }
 
 /// Error types for Bitcoin blocks.
diff --git a/primitives/src/hash_types/block_hash.rs b/primitives/src/hash_types/block_hash.rs
index 25492329..50a5f3a0 100644
--- a/primitives/src/hash_types/block_hash.rs
+++ b/primitives/src/hash_types/block_hash.rs
@@ -42,8 +42,6 @@ impl encoding::Encode for BlockHash {
 
 impl encoding::Decode for BlockHash {
     type Decoder = BlockHashDecoder;
-    #[inline]
-    fn decoder() -> Self::Decoder { BlockHashDecoder(encoding::ArrayDecoder::<32>::new()) }
 }
 
 encoding::encoder_newtype_exact! {
diff --git a/primitives/src/hash_types/transaction_merkle_node.rs b/primitives/src/hash_types/transaction_merkle_node.rs
index a679c5dd..62b43f3a 100644
--- a/primitives/src/hash_types/transaction_merkle_node.rs
+++ b/primitives/src/hash_types/transaction_merkle_node.rs
@@ -62,8 +62,6 @@ impl encoding::Encode for TxMerkleNode {
 
 impl encoding::Decode for TxMerkleNode {
     type Decoder = TxMerkleNodeDecoder;
-    #[inline]
-    fn decoder() -> Self::Decoder { TxMerkleNodeDecoder(encoding::ArrayDecoder::<32>::new()) }
 }
 
 encoding::encoder_newtype_exact! {
diff --git a/primitives/src/hash_types/witness_merkle_node.rs b/primitives/src/hash_types/witness_merkle_node.rs
index c36e22a5..b3dc1c23 100644
--- a/primitives/src/hash_types/witness_merkle_node.rs
+++ b/primitives/src/hash_types/witness_merkle_node.rs
@@ -62,8 +62,6 @@ impl encoding::Encode for WitnessMerkleNode {
 
 impl encoding::Decode for WitnessMerkleNode {
     type Decoder = WitnessMerkleNodeDecoder;
-    #[inline]
-    fn decoder() -> Self::Decoder { WitnessMerkleNodeDecoder(encoding::ArrayDecoder::<32>::new()) }
 }
 
 encoding::encoder_newtype_exact! {
diff --git a/primitives/src/script/owned.rs b/primitives/src/script/owned.rs
index 759c37c6..16d55022 100644
--- a/primitives/src/script/owned.rs
+++ b/primitives/src/script/owned.rs
@@ -213,7 +213,6 @@ impl<T> encoding::Decoder for ScriptBufDecoder<T> {
 
 impl<T> encoding::Decode for ScriptBuf<T> {
     type Decoder = ScriptBufDecoder<T>;
-    fn decoder() -> Self::Decoder { ScriptBufDecoder(ByteVecDecoder::new(), PhantomData) }
 }
 
 #[cfg(feature = "arbitrary")]
diff --git a/primitives/src/transaction.rs b/primitives/src/transaction.rs
index 1be97d64..54ffd823 100644
--- a/primitives/src/transaction.rs
+++ b/primitives/src/transaction.rs
@@ -654,7 +654,6 @@ impl encoding::Decoder for TransactionDecoder {
 #[cfg(feature = "alloc")]
 impl encoding::Decode for Transaction {
     type Decoder = TransactionDecoder;
-    fn decoder() -> Self::Decoder { TransactionDecoder::new() }
 }
 
 /// The state of the transiting decoder.
@@ -857,13 +856,6 @@ crate::decoder_newtype! {
 #[cfg(feature = "alloc")]
 impl encoding::Decode for TxIn {
     type Decoder = TxInDecoder;
-    fn decoder() -> Self::Decoder {
-        TxInDecoder(Decoder3::new(
-            OutPointDecoder::new(),
-            ScriptSigBufDecoder::new(),
-            SequenceDecoder::new(),
-        ))
-    }
 }
 
 /// Bitcoin transaction output.
@@ -930,9 +922,6 @@ crate::decoder_newtype! {
 #[cfg(feature = "alloc")]
 impl encoding::Decode for TxOut {
     type Decoder = TxOutDecoder;
-    fn decoder() -> Self::Decoder {
-        TxOutDecoder(Decoder2::new(AmountDecoder::new(), ScriptPubKeyBufDecoder::new()))
-    }
 }
 
 /// A reference to a transaction output.
@@ -1049,7 +1038,6 @@ crate::decoder_newtype! {
 
 impl encoding::Decode for OutPoint {
     type Decoder = OutPointDecoder;
-    fn decoder() -> Self::Decoder { OutPointDecoder::default() }
 }
 
 #[cfg(feature = "serde")]
@@ -1274,7 +1262,6 @@ crate::decoder_newtype! {
 
 impl encoding::Decode for Version {
     type Decoder = VersionDecoder;
-    fn decoder() -> Self::Decoder { VersionDecoder(encoding::ArrayDecoder::<4>::new()) }
 }
 
 /// Error types for Bitcoin transactions.
diff --git a/primitives/src/witness.rs b/primitives/src/witness.rs
index f2c5555c..9c0c23bd 100644
--- a/primitives/src/witness.rs
+++ b/primitives/src/witness.rs
@@ -526,7 +526,6 @@ impl encoding::Decoder for WitnessDecoder {
 
 impl encoding::Decode for Witness {
     type Decoder = WitnessDecoder;
-    fn decoder() -> Self::Decoder { WitnessDecoder::default() }
 }
 
 // Note: we use `Borrow` in the following `PartialEq` impls specifically because of its additional
diff --git a/units/src/amount/unsigned.rs b/units/src/amount/unsigned.rs
index 786706e5..26607827 100644
--- a/units/src/amount/unsigned.rs
+++ b/units/src/amount/unsigned.rs
@@ -628,9 +628,6 @@ impl encoding::Encode for Amount {
 #[cfg(feature = "encoding")]
 impl encoding::Decode for Amount {
     type Decoder = AmountDecoder;
-
-    #[inline]
-    fn decoder() -> Self::Decoder { AmountDecoder(encoding::ArrayDecoder::<8>::new()) }
 }
 
 #[cfg(feature = "encoding")]
diff --git a/units/src/block.rs b/units/src/block.rs
index 4f053c2e..cc17f79b 100644
--- a/units/src/block.rs
+++ b/units/src/block.rs
@@ -218,9 +218,6 @@ impl encoding::Encode for BlockHeight {
 #[cfg(feature = "encoding")]
 impl encoding::Decode for BlockHeight {
     type Decoder = BlockHeightDecoder;
-
-    #[inline]
-    fn decoder() -> Self::Decoder { BlockHeightDecoder(encoding::ArrayDecoder::<4>::new()) }
 }
 
 #[cfg(feature = "encoding")]
diff --git a/units/src/locktime/absolute/mod.rs b/units/src/locktime/absolute/mod.rs
index cab27ced..4f9da2bd 100644
--- a/units/src/locktime/absolute/mod.rs
+++ b/units/src/locktime/absolute/mod.rs
@@ -411,9 +411,6 @@ impl encoding::Encode for LockTime {
 #[cfg(feature = "encoding")]
 impl encoding::Decode for LockTime {
     type Decoder = LockTimeDecoder;
-
-    #[inline]
-    fn decoder() -> Self::Decoder { LockTimeDecoder(encoding::ArrayDecoder::<4>::new()) }
 }
 
 #[cfg(feature = "encoding")]
diff --git a/units/src/pow.rs b/units/src/pow.rs
index 0d4c0b32..994bd007 100644
--- a/units/src/pow.rs
+++ b/units/src/pow.rs
@@ -316,9 +316,6 @@ impl encoding::Encode for CompactTarget {
 #[cfg(feature = "encoding")]
 impl encoding::Decode for CompactTarget {
     type Decoder = CompactTargetDecoder;
-
-    #[inline]
-    fn decoder() -> Self::Decoder { CompactTargetDecoder(encoding::ArrayDecoder::<4>::new()) }
 }
 
 #[cfg(feature = "encoding")]
diff --git a/units/src/sequence.rs b/units/src/sequence.rs
index b97dce37..5abaa062 100644
--- a/units/src/sequence.rs
+++ b/units/src/sequence.rs
@@ -272,9 +272,6 @@ impl encoding::Encode for Sequence {
 #[cfg(feature = "encoding")]
 impl encoding::Decode for Sequence {
     type Decoder = SequenceDecoder;
-
-    #[inline]
-    fn decoder() -> Self::Decoder { SequenceDecoder(encoding::ArrayDecoder::<4>::new()) }
 }
 
 #[cfg(feature = "encoding")]
diff --git a/units/src/time.rs b/units/src/time.rs
index 6524fd69..672a0705 100644
--- a/units/src/time.rs
+++ b/units/src/time.rs
@@ -131,9 +131,6 @@ impl encoding::Encode for BlockTime {
 #[cfg(feature = "encoding")]
 impl encoding::Decode for BlockTime {
     type Decoder = BlockTimeDecoder;
-
-    #[inline]
-    fn decoder() -> Self::Decoder { BlockTimeDecoder(encoding::ArrayDecoder::<4>::new()) }
 }
 
 #[cfg(feature = "encoding")]