release: neptune v12.1.0

[github-actions]

This is a release PR for version 12.1.0.

You will still need to manually publish the cargo crate:

$ make VERSION=12.1.0 release

[huitseeker]

`cargo public-api diff latest` output

Removed items from the public API
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(none)

Changed items in the public API
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Added items to the public API
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+impl core::clone::Clone for neptune::poseidon::HashMode
+pub fn neptune::poseidon::HashMode::clone(&self) -> neptune::poseidon::HashMode
+impl core::marker::Copy for neptune::poseidon::HashMode
+impl<T> alloc::borrow::ToOwned for neptune::poseidon::HashMode where T: core::clone::Clone
+pub type neptune::poseidon::HashMode::Owned = T
+pub fn neptune::poseidon::HashMode::clone_into(&self, target: &mut T)
+pub fn neptune::poseidon::HashMode::to_owned(&self) -> T
+pub fn neptune::poseidon::PoseidonConstants<F, A>::new_from_parameters(width: usize, m: alloc::vec::Vec<alloc::vec::Vec<F>>, round_constants: alloc::vec::Vec<F>, full_rounds: usize, partial_rounds: usize, hash_type: neptune::hash_type::HashType<F, A>, strength: neptune::Strength) -> Self

[porcuquine]

Temporarily blocking until receiving explicit confirmation this isn't a minor release with a major bump of common downstream dependencies.

[huitseeker]

OK, so for my own memory:

The original sin is we (unnecessarily) bumped the `bellpepper-core` version to 0.3.0, which is a leftmost bump marking incompatibility.

[email protected]➜~/tmp/bellpepper(main)» cargo public-api -p bellpepper-core diff v0.3.0..v0.4.0
 Documenting bellpepper-core v0.3.0 (/Users/huitseeker/tmp/bellpepper/crates/bellpepper-core)
    Finished dev [unoptimized + debuginfo] target(s) in 0.26s
 Documenting bellpepper-core v0.4.0 (/Users/huitseeker/tmp/bellpepper/crates/bellpepper-core)
    Finished dev [unoptimized + debuginfo] target(s) in 0.26s
Removed items from the public API
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Changed items in the public API
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(none)

Added items to the public API
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(none)

[email protected]➜~/tmp/bellpepper(main)» cargo public-api -p bellpepper diff v0.3.0..v0.4.0
 Documenting bellpepper v0.3.0 (/Users/huitseeker/tmp/bellpepper/crates/bellpepper)
    Finished dev [unoptimized + debuginfo] target(s) in 0.23s
 Documenting bellpepper v0.4.0 (/Users/huitseeker/tmp/bellpepper/crates/bellpepper)
    Finished dev [unoptimized + debuginfo] target(s) in 0.23s
Removed items from the public API
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(none)

Changed items in the public API
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(none)

Added items to the public API
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+impl<Scalar> bellpepper::util_cs::witness_cs::WitnessCS<Scalar> where Scalar: ff::PrimeField
+pub fn bellpepper::util_cs::witness_cs::WitnessCS<Scalar>::aux_assignment(&self) -> &[Scalar]
+pub fn bellpepper::util_cs::witness_cs::WitnessCS<Scalar>::input_assignment(&self) -> &[Scalar]

And anyone that depends on bellpepper-core through crate versions which are *not* inherited from `neptune` will import two versions of this crate, which implementations will resolve to be incompatible.

So this needs to be a major version bump. 🙄