Swift.org – Swift 3.0 Release Process

May 6, 2016

Ted Kremenek is a member of the Swift Core Team and manages the Languages and Runtimes group at Apple.

This post describes the goals, release process, and estimated schedule for Swift
3.0.

Swift 3.0 is a major release that is not source-compatible with Swift 2.2. It
contains fundamental changes to the language and Swift Standard Library. A
comprehensive list of implemented changes for Swift 3.0 can be found on the
Swift evolution
site.

Swift 3.0 is also the first release to include the Swift Package Manager. While the Swift Package Manager is still early
in its development, it supports the development and distribution of
cross-platform Swift packages. The Swift Package Manager will be available on
both Darwin and Linux.

For Linux, Swift 3 will also be the first release to contain the Swift Core
Libraries.

Swift 3.0 is expected to be released sometime in late 2016. In addition to its
Swift.org release, Swift 3.0 will ship in a future version of Xcode.

Developer Previews

• Swift 3.0 will have a series of developer previews (i.e., “seeds” or “betas”)
  that provide qualified and converged builds of Swift 3. The goal is to
  provide users with more stable and qualified Swift binaries that they can
  download and try out (and file bugs against)
  instead of just grabbing the latest snapshot of master.

• The cadence between Developer Previews will likely be irregular, but likely
  every 4-6 weeks. They will be partially driven by the volume of change going
  into master and how much time is needed to stabilize a developer preview
  branch.

• Swift 3.0 will be declared “GM” from the last developer preview branch.

• Content going into developer previews will be managed by the appropriate
  release manager (see below).

Getting Changes into Swift 3.0

Branches

• master: Development of Swift 3.0 happens in master. All changes
  going in master will be part of the final Swift 3.0 release until the
  last developer preview branch is created. At that point master tracks
  development for future Swift releases.

• swift-3.0-preview-<X>-branch: Branches for developer previews will be
  created from master. All changes to those branches will need to be submitted
  via pull requests that initiate testing on continuous integration. The release
  manager for the given repository approves merging a pull request into the
  developer preview branch.

• swift-3.0-branch: The last developer preview branch created from master
  will be called swift-3.0-branch. This will be the final “release branch”.

Philosophy on Taking Changes into Swift 3.0

• As Swift 3.0 converges only changes that align with the core goals of the
  release will be considered.

• Source-breaking changes to the language will be
  considered on a case-by-case basis.

• All language and API changes for Swift 3.0 will go through the Swift
  Evolution process.

• Criteria — as set by the release manager — for accepting changes
  will becoming increasingly restrictive over time as the release
  converges. The same policy applies to developer preview branches, which
  are essentially mini-releases.

Schedule

• The first developer preview branch swift-3.0-preview-1-branch will
  be created from master on May 12. It will be released 4-6 weeks
  later.

• The date for creating the last developer preview branch
  — swift-3.0-branch — has
  not yet been established. When that date is determined the plan will be
  communicated both on swift-dev and by updating this post.

Impacted Repositories

The following repositories will have
swift-3.0-preview-<X>-branch/swift-3.0-branch branches to track
sources as part of Swift 3.0 release:

The following repositories will only have a swift-3.0-branch instead of
developer preview branches, as they have already effectively converged:

Release Managers

The overall management of the release will be overseen by the following
individuals, who will announce when stricter control of change
goes into effect for the Swift 3.0 release as the release converges:

Please feel free to email swift-dev or Ted Kremenek directly concerning any
questions about the release management process.

Pull Requests for Developer Previews

All pull requests nominating changes for inclusion in developer preview
branches should include the following information:

• Explanation: A description of the issue being fixed or
  enhancement being made. This can be brief, but it should be
  clear.

• Scope: An assessment of the impact/importance of the change.
  For example, is the change a source-breaking language change, etc.

• SR Issue: The SR if the change fixes/implements an
  issue/enhancement on bugs.swift.org.

• Risk: What is the (specific) risk to the release for taking this
  change?

• Testing: What specific testing has been done or needs to be done
  to further validate any impact of this change?

One or more code owners for the impacted
components should review the change. Technical review can be delegated
by a code owner or otherwise requested as deemed appropriate or
useful.

All change going into developer preview branches must go through
pull requests that are accepted by the corresponding release manager.