Swift 5.4 Release Process

This post describes the goals, release process, and estimated schedule for Swift 5.4. Swift 5.4 is a release focused on quality and performance enhancements.

Snapshots of Swift 5.4

Downloadable snapshots of the Swift 5.4 release branch will be posted regularly as part of continuous integration testing. As support is available, snapshot downloads will be added for newly supported platforms.

Once Swift 5.4 is released, the official final builds will also be posted in addition to the snapshots.

Getting Changes into Swift 5.4

On Dec 14, 2020 the release/5.4 branch will be cut in the swift repository and most related project repositories. This will contain the changes that will be released in Swift 5.4. After the branch is cut, changes can be landed on the branch via pull request if they meet the criteria for the release.

The following projects will cut their Swift 5.4 branches on Jan 7, 2021:

The same policies will apply to these projects: once the branch is cut, changes can be landed on the branch via pull request if they meet the criteria for the release.

Philosophy on Taking Changes into Swift 5.4

  • All language and API changes for Swift 5.4 will go through the Swift
    process. Evolution
    proposals should aim to be completed by the branch date in order to
    increase their chances of impacting the Swift 5.4 release. Exceptions
    will be considered on a case-by-case basis, particularly if they tie
    in with the core goal of the release.

  • Other changes (e.g., bug fixes, diagnostic improvements, SourceKit interface
    improvements) will be accepted based on their risk and impact.

  • Low-risk test tweaks will also be accepted late into the release branch if
    it aids in the qualification of the release.

  • As the release converges, the criteria for accepted changes will become
    increasingly restrictive.

Impacted Repositories

The following repositories will have a release/5.4 branch to track
sources as part of Swift 5.4 release:

The llvm-project will have a corresponding swift/release/5.4 branch.

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 5.4 release as the release converges.

Platform Release Managers

Please feel free to post on the development forum
or contact Ted Kremenek directly concerning any questions about the release management

Pull Requests for Release Branch

In order for a pull request to be considered for inclusion in the release
branch (release/5.4) after it has been cut, it must include the following

  • 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

  • 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?

  • Reviewer: 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

All changes going on the release/5.4 branch must go through pull requests that are
accepted by the corresponding release manager.


My apologies if this isn't the right place to raise this issue, but if 5.4 is going to focus on quality, can it please also focus on fixing some outstanding issues that affect those of us trying to use/teach Swift outside of the Apple ecosystem?

The REPL in particular has always been a source of frustration for me. It could be a great teaching tool for a first introduction to the language, but unfortunately, it has never been reliable.

For example, on Linux, it has a serious bug (https://bugs.swift.org/browse/SR-13029), and on Windows, it doesn't work at all (https://bugs.swift.org/browse/SR-13804). There's also cases where it doesn't support some basic language features (https://bugs.swift.org/browse/SR-1743) or behaves differently from the normal language rules (https://bugs.swift.org/browse/SR-12043).

Getting these issues fixed would already be a big improvement!


Will there be a 5.4 development snapshot release before the holiday break? They are useful for downstream packagers like me to start putting together a 5.4 package from a source release.

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