CHANGELOG.md

Changelog

0.2.7 (2026-06-17)

Performance improvements

• The exhaust-macros package no longer depends on itertools. This may improve build parallelism, and if cross-compiling, avoids building itertools for the host as well as the target.
• The dependency on itertools can now use version 0.15, in addition to versions 0.13 through 0.14. This has no effect on the functionality of exhaust.

0.2.6 (2026-05-07)

Added

• impl Exhaust for core::num::Saturating
• Iterators for several standard library enums now implement ExactSizeIterator.
• Iterators for NonZero<u*> now implement DoubleEndedIterator and ExactSizeIterator.

Fixed

• Iterators for BTreeSet and HashSet now produce their elements (sets) in the order that is sorted according to BTreeSet’s Ord implementation, rather than producing the sets in order from smallest to largest. This follows the general recommendation for all Exhaust implementations. (BTreeMap’s and HashMap’s ordering have also changed, but it is not yet the case that BTreeMap exhaustion occurs in sorted order.)
• Corrected incorrect bounds on a FusedIterator implementation. (It is not possible to obtain a misbehaving value of this undocumented type, but this change could technically cause some code to stop compiling.)

Performance improvements

• Iterators for NonZero<u*> have been simplified.
• Iterators for NonZero<i*> now have an improved but not perfect size_hint().
• exhaust::Iter now forwards nth(), nth_back(), and last() to the underlying iterator.

0.2.5 (2026-03-14)

Added

• #[derive(Exhaust)] now supports a configuration attribute #[exhaust(factory_is_self)], which disables generation of a separate Exhaust::Factory type. This can be used to simplify the macro-generated code to improve build performance, but requires the type and its fields to implement Clone and Debug, similar to what was required in exhaust v0.1; see the derive macro’s documentation for details.

Performance improvements

• derive(Exhaust) iterators now implement size_hint() exactly in some cases; most notably, fieldless enums. (They still do not implement ExactSizeIterator.)
• derive(Exhaust) iterators now take up less memory when a struct, or a variant of an enum, has exactly one field.

0.2.4 (2025-08-25)

Added

• derive(Exhaust) now supports types with const generic parameters.

Fixed

• derive(Exhaust) will no longer produce spurious warnings when the type of a field is uninhabited.

Performance improvements

• derive(Exhaust) generates simpler code to improve build performance (and readability).
  • Replaced use of Option::unwrap() with pattern matching.
  • Replaced recursion in enum iterator next() with iteration.
  • Factories for unit structs no longer include an inner type.
  • Removed superfluous && trues.

0.2.3 (2025-08-24)

This release was published erroneously and is functionally equivalent to 0.2.2.

0.2.2 (2025-03-08)

Added

• impl Exhaust for ...

  • core::fmt::Alignment
  • core::fmt::Error
  • core::cell::OnceCell
  • core::ops::Bound
  • core::ops::ControlFlow
  • core::ops::RangeFrom
  • core::ops::RangeFull
  • core::ops::RangeTo
  • core::ops::RangeToInclusive
  • std::sync::OnceLock
  • std::sync::mpsc::RecvError
  • std::sync::mpsc::RecvTimeoutError
  • std::sync::mpsc::SendError
  • std::sync::mpsc::TryRecvError
  • std::sync::mpsc::TrySendError

• The dependency on itertools can now use either version 0.14 or version 0.13. This has no effect on the functionality of exhaust.

0.2.1 (2024-09-26)

Added

• Cell<T> implements Exhaust even when T does not implement Copy.
• Documentation contains examples for the Exhaust derive macro and iteration::carry.

Changed

• The macro-generated types are now always named Exhaust<your type name><some suffix>. This makes it possible to reliably avoid name conflicts in the narrow case that they can happen, and is more systematic than the previous naming scheme.
• Explicitly allow(nonstandard_style) in macro generated code. Together with the above name change, this should prevent lint from the macro-generated code when using rust-analyzer.

0.2.0 (2024-09-18)

Breaking: No Clone Requirement

The Exhaust trait no longer requires Self: Clone. This allows it to be implemented for many more types, such as Mutex and Atomic*, which can be constructed with arbitrary data but not cloned.

In order to support this, the Exhaust trait now separates iteration over the possible data (which still must be cloneable) from construction of the final value. The new definition of the trait is:

pub trait Exhaust: Sized {
    type Iter: FusedIterator<Item = Self::Factory> + Clone;
    type Factory: Clone;                                    // New

    // Required methods
    fn exhaust_factories() -> Self::Iter;                   // New
    fn from_factory(factory: Self::Factory) -> Self;        // New

    // Provided method
    fn exhaust() -> impl Iterator<Item = Self>;
}

The Factory is the cloneable data, so named since it is a means of constructing many Self. Implementors must return an iterator which produces Factory instead of Self. They may then perform the final construction in from_factory().

Existing implementations may be migrated by adding type Factory = Self and renaming fn exhaust() to fn exhaust_factories(). However, it may be possible to simplify the iterator by moving some code into fn from_factory().

Added

• impl Exhaust for ...

  • core::cell::UnsafeCell
  • core::sync::AtomicBool
  • core::sync::Atomic{U,I}{8,16,32}
  • alloc::borrow::Cow<'_ T>, when T implements only ToOwned rather than Clone.
  • std::io::BufReader
  • std::io::BufWriter
  • std::io::Chain
  • std::io::LineWriter
  • std::io::Repeat
  • std::io::Sink
  • std::io::Stderr
  • std::io::Stdin
  • std::io::Stdout

• exhaust::Iter<T> is a single generic iterator for all T: Exhaust. It is now the type returned by Exhaust::exhaust().

Changed

• The minimum supported Rust version is now 1.80.
• Breaking: The derive macro derive(Exhaust) now hides its generated items. They can only be accessed through the trait implementation’s associated types.
• Breaking: Exhaust::Iter types now must implement Debug and FusedIterator.

Removed

• <Option<T> as Exhaust>::Iter no longer implements DoubleEndedIterator. This might be added back in the future.
• Removed exhaust::ExhaustArray from the crate root.
• Removed exhaust::brute_force_search().
• Removed the public module exhaust::impls. The iterators can only be accessed through the trait implementation’s associated types.

0.1.2 (2024-09-18)

There are no changes to functionality in this release.

• Improved documentation.
• Depends on itertools version 0.13 instead of 0.10.
• Added rust-version (minimum supported Rust version) information, chosen to be 1.60.
• exhaust::ExhaustArray is now marked as #[deprecated] (use exhaust::impls::ExhaustArray instead).

0.1.1 (2023-04-09)

Added

• impl Exhaust for ...
  • Tuples of length up to 12
  • core::cell::Cell
  • core::cell::RefCell
  • core::cmp::Ordering
  • core::future::Pending
  • core::future::Ready
  • core::hash::BuildHasherDefault
  • core::iter::Reverse
  • core::marker::PhantomPinned
  • core::num::FpCategory
  • core::num::NonZero*
  • core::result::Result
  • core::task::Poll
  • alloc::borrow::Cow
  • alloc::collections::BTreeMap
  • alloc::collections::BTreeSet
    • Note: Does not produce lexicographic ordering.
  • Pin<Box<T>>
  • std::collections::HashMap
  • std::collections::HashSet
  • std::io::Cursor
  • std::io::Empty
  • std::io::Sink
• Documentation example of a custom impl Exhaust.

Changed

• derive(Exhaust) generates more detailed documentation for the iterator.

Meta

• Added license texts.
• Configured GitHub Actions CI.

0.1.0 (2022-02-14)

Initial public release.