# Changelog

All notable changes to this crate are documented in this file.

The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
and this crate adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).

## [3.7.0] - 2024-11-18

### Added

- Allow decoding with a memory limit. ([616](https://github.com/paritytech/parity-scale-codec/pull/616))
- Introduce `CountedInput`, an wrapper on `Input` that counts the bytes read. ([630](https://github.com/paritytech/parity-scale-codec/pull/630))

### Changed

- This release bumps some dependencies, primarily bumping `syn` to 2. ([#640](https://github.com/paritytech/parity-scale-codec/pull/640)).

### Fixed

- Fix MaxEncodedLen derive macro for enum with skipped variant ([#622](https://github.com/paritytech/parity-scale-codec/pull/622))
- Use MAX_PREALLOCATION consistently [#605](https://github.com/paritytech/parity-scale-codec/pull/605)

## [3.6.4] - 2023-07-14

### Added

- Now `#[derive(Encode)]` implements the `size_hint()` method for structures and enumerations.
  This improves the performance of the `encode()` method by pre-allocating memory.

## [3.6.3] - 2023-07-03

### Fixed

- Provide full path to elements from `::core` in `Decode` derivation (caused compilation error when 
  `no-implicit-prelude` was used).

## [3.6.2] - 2023-06-30

### Fixed

- Trying to deserialize a boxed newtype containing a big array won't overflow the stack anymore.

## [3.6.1] - 2023-06-19

### Fixed

- Deriving `Decode` will not trigger clippy warnings anymore

## [3.6.0] - 2023-06-15

### Added

- Added `Decode::decode_into` to allow deserializing into unitialized memory.
- Added a `DecodeFinished` type to be used with `Decode::decode_into`.

### Fixed

- Trying to deserialize a big boxed array (e.g. `Box<[u8; 1024 * 1024 * 1024]>`) won't overflow the stack anymore.
- Trying to deserialize big nested enums with many variants won't overflow the stack anymore.
- Elements of partially read arrays will now be properly dropped if the whole array wasn't decoded.

### Changed

- The derive macros will now be reexported only when the `derive` feature is enabled,
  as opposed to how it was previously where enabling `parity-scale-codec-derive` would suffice.
- The `max-encoded-len` feature won't automatically enable the derive macros nor pull in the
  `parity-scale-codec-derive` dependency.

## [3.5.0]

### Added

- `ConstEncodedLen` marker trait for types that implement `MaxEncodedLen`. [#428](https://github.com/paritytech/parity-scale-codec/pull/428)

## [3.4.0]

This release renders the `full` feature defunct. The implementations guarded behind
this feature are now always provided.

### Changes

- All implementations guarded behind `full` are not unconditionally implemented.

## [3.3.0]

This release exports `decode_vec_with_len` to support custom decoding of `Vec`s.

### Added

- Export `decode_vec_with_len`.

## [3.2.1] - 2022-09-14

This release fixes compilation on no-std envs.

### Changed

 - Use core RangeInclusive instead of std [#378](https://github.com/paritytech/parity-scale-codec/pull/378)

## [3.2.0] - 2022-09-13

This release (specifically [#375](https://github.com/paritytech/parity-scale-codec/pull/375)) bumps the MSRV to 1.60.0 as it depends on the Cargo.toml weak dependency feature.

### Changed

- Don't include bitvec with std feature unless asked for explicitly. [#375](https://github.com/paritytech/parity-scale-codec/pull/375)
- Implement `MaxEncodedLen` on more core lib types. [#350](https://github.com/paritytech/parity-scale-codec/pull/350)

## [3.1.5] - 2022-06-11

A quick release to fix an issue introduced in 3.1.4 that broke compiling on no-std.

### Changed

- Fix compiling on no-std. (see https://github.com/paritytech/parity-scale-codec/commit/c25f14a46546c75e4208363ced9d89aa81c85e7f)

## [3.1.3] - 2022-06-10

### Changed

- Impl `MaxEncodedLen` for `Box<T>`. [#349](https://github.com/paritytech/parity-scale-codec/pull/349)
- Add `decode_from_bytes`. [#342](https://github.com/paritytech/parity-scale-codec/pull/342)

## [3.1.2] - 2022-03-22

Be aware that version 3.0.0. up to 3.1.1 contained some bugs in the `BitVec` encoder that could lead to an invalid encoding. Thus, we yanked these crate version and it is advised to upgrade to 3.1.2. Any release before 3.0.0 wasn't affected by this bug.

### Changed

- Optimised the `Decode::decode` for `[T; N]` by @xgreenx. [#299](https://github.com/paritytech/parity-scale-codec/pull/299)
- Add some doc for the derive macro by @thiolliere. [#301](https://github.com/paritytech/parity-scale-codec/pull/301)
- Add bytes::Bytes implementation by @vorot93. [#309](https://github.com/paritytech/parity-scale-codec/pull/309)
- Upgrade to BitVec 1.0 by @bkchr. [#311](https://github.com/paritytech/parity-scale-codec/pull/311)
- BREAKING CHANGE: DecodeLimit and DecodeAll extensions now advance input by @wigy-opensource-developer. [#314](https://github.com/paritytech/parity-scale-codec/pull/314)
- Make `CompactRef` public by @andrenth. [#321](https://github.com/paritytech/parity-scale-codec/pull/321)
- Add ability to re-export parity-scale-codec crate by @gshep. [#325](https://github.com/paritytech/parity-scale-codec/pull/325)
- BitVec: Improve the encoding and consolidate the implementations by @bkchr. [#327](https://github.com/paritytech/parity-scale-codec/pull/327)
- Fix crate access by putting a leading `::` by @bkchr. [#328](https://github.com/paritytech/parity-scale-codec/pull/328)

## [3.0.0] - 2022-02-02

### Fix

- Optimised the Decode::decode for [T; N] [#299](https://github.com/paritytech/parity-scale-codec/pull/299)

### Changed

- Migrated to 2021 edition, enforcing MSRV of `1.56.1`. [#298](https://github.com/paritytech/parity-scale-codec/pull/298)
- Upgrade to BitVec 1.0 [#311](https://github.com/paritytech/parity-scale-codec/pull/311)
- DecodeLimit and DecodeAll extensions now advance input [#314](https://github.com/paritytech/parity-scale-codec/pull/314)

### Added

- Add bytes::Bytes implementation [#309](https://github.com/paritytech/parity-scale-codec/pull/309)

## [2.3.1] - 2021-09-28

### Fix

- Improve macro hygiene of `Encode` and `Decode` proc. macro expansions. ([#291](https://github.com/paritytech/parity-scale-codec/pull/291), [#293](https://github.com/paritytech/parity-scale-codec/pull/293))

## [2.3.0] - 2021-09-11

### Added

- `decode_and_advance_with_depth_limit` to the `DecodeLimit` trait. This allows advancing the cursor while decoding the input. PR #286

## [2.2.0] - 2021-07-02

### Added

- Add support for custom where bounds `codec(mel_bound(T: MaxEncodedLen))` when deriving the traits. PR #279
- `MaxEncodedLen` trait for items that have a statically known maximum encoded size. ([#268](https://github.com/paritytech/parity-scale-codec/pull/268))
- `#[codec(crate = <path>)]` top-level attribute to be used with the new `MaxEncodedLen`
trait, which allows to specify a different path to the crate that contains the `MaxEncodedLen` trait.
Useful when using generating a type through a macro and this type should implement `MaxEncodedLen` and the final crate doesn't have `parity-scale-codec` as dependency.

## [2.1.3] - 2021-06-14

### Changed

- Lint attributes now pass through to the derived impls of `Encode`, `Decode` and `CompactAs`. PR #272

## [2.1.0] - 2021-04-06

### Fix

- Add support for custom where bounds `codec(encode_bound(T: Encode))` and `codec(decode_bound(T: Decode))` when
deriving the traits. Pr #262
- Switch to const generics for array implementations. Pr #261

## [2.0.1] - 2021-02-26

### Fix

- Fix type inference issue in `Decode` derive macro. Pr #254

## [2.0.0] - 2021-01-26

### Added

- `Decode::skip` allows to skip some encoded types. Pr #243
- `Decode::encoded_fixed_size` allows to get the fixed encoded size of a type. PR #243
- `Error` now contains a chain of causes. This full error description can also be activated on
  no std using the feature `chain-error`. PR #242
- `Encode::encoded_size` allows to get the encoded size of a type more efficiently. PR #245

### Changed

- `CompactAs::decode_from` now returns result. This allow for decoding to fail from their compact
  form.
- derive macro use literal index e.g. `#[codec(index = 15)]` instead of `#[codec(index = "15")]`
- Version of crates `bitvec` and `generic-array` is updated.
- `Encode::encode_to` now bounds the generic `W: Output + ?Sized` instead of `W: Output`.
- `Output` can now be used as a trait object.

### Removed

- `EncodeAppend::append` is removed in favor of `EncodeAppend::append_or_new`.
- `Output::push` is removed in favor of `Encode::encode_to`.
- Some bounds on `HasCompact::Type` are removed.
- `Error::what` is removed in favor of `Error::to_string` (implemented through trait `Display`).
- `Error::description` is removed in favor of `Error::to_string` (implemented through trait `Display`).