consensus_encoding: Add decode_from_hex_with

diff --git a/consensus_encoding/api/all-features.txt b/consensus_encoding/api/all-features.txt
index 277f9814..b4944685 100644
--- a/consensus_encoding/api/all-features.txt
+++ b/consensus_encoding/api/all-features.txt
@@ -1560,6 +1560,7 @@ pub fn bitcoin_consensus_encoding::check_decoder<D: bitcoin_consensus_encoding::
 pub fn bitcoin_consensus_encoding::check_encode<T: bitcoin_consensus_encoding::Encode + ?core::marker::Sized>(value: &T, expected: &[u8])
 pub fn bitcoin_consensus_encoding::check_encoder<T: bitcoin_consensus_encoding::Encoder + ?core::marker::Sized>(encoder: &mut T, expected: &[u8])
 pub fn bitcoin_consensus_encoding::decode_from_hex<T: bitcoin_consensus_encoding::Decode>(hex: &str) -> core::result::Result<T, bitcoin_consensus_encoding::error::FromHexError<<<T as bitcoin_consensus_encoding::Decode>::Decoder as bitcoin_consensus_encoding::Decoder>::Error>>
+pub fn bitcoin_consensus_encoding::decode_from_hex_with<D: bitcoin_consensus_encoding::Decoder + core::default::Default>(hex: &str) -> core::result::Result<<D as bitcoin_consensus_encoding::Decoder>::Output, bitcoin_consensus_encoding::error::FromHexError<<D as bitcoin_consensus_encoding::Decoder>::Error>>
 pub fn bitcoin_consensus_encoding::decode_from_read<T, R>(reader: R) -> core::result::Result<T, bitcoin_consensus_encoding::error::ReadError<<<T as bitcoin_consensus_encoding::Decode>::Decoder as bitcoin_consensus_encoding::Decoder>::Error>> where T: bitcoin_consensus_encoding::Decode, R: std::io::BufRead
 pub fn bitcoin_consensus_encoding::decode_from_read_unbuffered<T, R>(reader: R) -> core::result::Result<T, bitcoin_consensus_encoding::error::ReadError<<<T as bitcoin_consensus_encoding::Decode>::Decoder as bitcoin_consensus_encoding::Decoder>::Error>> where T: bitcoin_consensus_encoding::Decode, R: std::io::Read
 pub fn bitcoin_consensus_encoding::decode_from_read_unbuffered_with<T, R, const BUFFER_SIZE: usize>(reader: R) -> core::result::Result<T, bitcoin_consensus_encoding::error::ReadError<<<T as bitcoin_consensus_encoding::Decode>::Decoder as bitcoin_consensus_encoding::Decoder>::Error>> where T: bitcoin_consensus_encoding::Decode, R: std::io::Read
diff --git a/consensus_encoding/src/decode/mod.rs b/consensus_encoding/src/decode/mod.rs
index 137617e7..a1776fba 100644
--- a/consensus_encoding/src/decode/mod.rs
+++ b/consensus_encoding/src/decode/mod.rs
@@ -143,11 +143,37 @@ impl DecoderStatus {
 pub fn decode_from_hex<T: Decode>(
     hex: &str,
 ) -> Result<T, FromHexError<<T::Decoder as Decoder>::Error>> {
+    decode_from_hex_internal(hex, T::decoder())
+}
+
+/// Decodes an object from a hex string without heap allocations using a [`Decoder`] type.
+///
+/// Unlike [`decode_from_hex`], this takes a generic [`Decoder`] parameter, allowing use with
+/// decoders which don't have a dedicated [`Decode`] implementer (e.g. [`CompactSizeDecoder`]).
+///
+/// # Errors
+///
+/// [`FromHexError`] if the string has an odd number of characters, any character is not a
+/// valid hex digit, or if decoding the type fails, including if bytes remain unconsumed
+/// after the decoder completes.
+///
+/// [`CompactSizeDecoder`]: crate::CompactSizeDecoder
+#[cfg(feature = "hex")]
+pub fn decode_from_hex_with<D: Decoder + Default>(
+    hex: &str,
+) -> Result<D::Output, FromHexError<D::Error>> {
+    decode_from_hex_internal(hex, D::default())
+}
+
+#[cfg(feature = "hex")]
+fn decode_from_hex_internal<D: Decoder>(
+    hex: &str,
+    mut decoder: D,
+) -> Result<D::Output, FromHexError<D::Error>> {
     let iter = hex::HexSliceToBytesIter::new(hex)
         .map_err(FromHexErrorInner::OddLength)
         .map_err(FromHexError)?;
 
-    let mut decoder = T::decoder();
     let mut buffer = [0u8; 4096];
     let mut index = 0;
 
diff --git a/consensus_encoding/src/lib.rs b/consensus_encoding/src/lib.rs
index cd8d6a36..8981aa0b 100644
--- a/consensus_encoding/src/lib.rs
+++ b/consensus_encoding/src/lib.rs
@@ -48,6 +48,7 @@
 //! * [`decode_from_read_with`]: Counterpart to [`decode_from_read`].
 //! * [`decode_from_slice_with`]: Counterpart to [`decode_from_slice`].
 //! * [`decode_from_slice_unbounded_with`]: Counterpart to [`decode_from_slice_unbounded`].
+//! * [`decode_from_hex_with`]: Counterpart to [`decode_from_hex`].
 //!
 //! And on the encoding side we provide:
 //!
@@ -62,8 +63,8 @@
 //!
 //! * `std` - Enables std lib I/O driver functions and `std::error::Error` impls (implies `alloc`).
 //! * `alloc` - Enables [`encode_to_vec`], `Vec`-based decoders, and allocation-based helpers.
-//! * `hex` - Enables [`decode_from_hex`], [`encode_to_hex`] and [`drain_to_hex`]. Encoding also
-//!   requires `alloc`.
+//! * `hex` - Enables [`decode_from_hex`], [`decode_from_hex_with`], [`encode_to_hex`] and
+//!   [`drain_to_hex`]. Encoding also requires `alloc`.
 
 #![no_std]
 // Coding conventions.
@@ -93,7 +94,7 @@ pub mod serde_as_consensus;
 pub use self::compact_size::{CompactSizeDecoder, CompactSizeEncoder, CompactSizeU64Decoder};
 #[cfg(feature = "hex")]
 #[doc(inline)]
-pub use self::decode::decode_from_hex;
+pub use self::decode::{decode_from_hex, decode_from_hex_with};
 #[doc(inline)]
 pub use self::decode::decoders::{ArrayDecoder, Decoder2, Decoder3, Decoder4, Decoder6};
 #[cfg(feature = "alloc")]
diff --git a/consensus_encoding/tests/decode.rs b/consensus_encoding/tests/decode.rs
index 05c65e3d..11639ea2 100644
--- a/consensus_encoding/tests/decode.rs
+++ b/consensus_encoding/tests/decode.rs
@@ -7,7 +7,7 @@ use std::io::{Cursor, Read};
 
 use bitcoin_consensus_encoding as encoding;
 #[cfg(feature = "hex")]
-use bitcoin_consensus_encoding::decode_from_hex;
+use bitcoin_consensus_encoding::{decode_from_hex, decode_from_hex_with};
 #[cfg(feature = "alloc")]
 use encoding::check_decode;
 use encoding::{
@@ -295,6 +295,10 @@ fn decode_from_hex_test() {
     assert_eq!(result.unwrap().0, [0x01, 0x02, 0x03, 0x04]);
     let result: Result<TestArray, _> = decode_from_hex("DEADBEEF");
     assert_eq!(result.unwrap().0, [0xDE, 0xAD, 0xBE, 0xEF]);
+    let result = decode_from_hex_with::<TestArrayDecoder>("01020304");
+    assert_eq!(result.unwrap().0, [0x01, 0x02, 0x03, 0x04]);
+    let result = decode_from_hex_with::<TestArrayDecoder>("DEADBEEF");
+    assert_eq!(result.unwrap().0, [0xDE, 0xAD, 0xBE, 0xEF]);
 }
 
 #[test]