Patch releases


Change Amaranth versioning from major.minor to major.minor.patch after version 0.4, and define the backport policy for patch releases.


Amaranth 0.3 was released on 2021-12-16; almost two years ago. Several important bugs have been fixed in main since, most notably depending on a version of Jinja2 that is no longer installable. At the moment the policy is to issue only major.minor releases, which was OK in the early days but no longer fits the project.

We should change the policy that is used for the next Amaranth release and later ones.


Amaranth feature releases all have the version of major.minor.0. The policy for these releases is unchanged and is tied to our two-step process for making breaking changes.

In addition to these releases, Amaranth now has bug-fix releases with the major.minor.patch versions. These are intended to address the need of the community to have bugs fixed before a next feature release can be made, and the policy is designed to minimize developer time spent on them.

Bug-fix releases are made when all of the following conditions are satisfied:

  • There is an issue that is fixed in the main branch.
  • A member of the community requests this issue to be fixed in a point release.
  • It is possible to fix the issue such that there is a high degree of confidence that the change will not break existing code using Amaranth with a ~=major.minor version constraint.
  • A community member steps up to backport the fix to the release branch.
    • This could be one of the Amaranth maintainers, or anyone else. Amaranth maintainers have no obligation to back-port any fix.


This creates additional work for maintainers.

Rationale and alternatives

  • It would be possible to backport all feasible fixes as a policy.
    • This would significantly increase maintainer workload.
  • It is possible to keep the current policy.
    • Because we do not control all of the upstream dependencies (including Python), this seems untenable.

Prior art

Rust has an even stricter bug-fix release policy: the Rust project only issues patch releases in cases of security issues, widespread miscompilations, or unintentional breaking changes.

Unresolved questions

Should Amaranth SoC adopt the same policy?

Future possibilities

Eventually, Amaranth may gain release engineers who will maintain long-living release branches.