Swift | LLVM Project |
---|---|
main | swift/main |
main
is the place for active development on Swift. If you're just working on Swift, that's where you'll spend most of your time.
LLVM Project repo automatically merge changes from the latest release branch (see below) into swift/main
. This generally means swift/main
is just an alias for the latest release branch. If you want to do Swift-related development on LLVM projects, see "The Upstream Branches" below.
To switch from one set of branches to another, you can use utils/update-checkout
in the Swift repository with the --scheme
option. You can use any of the branch names as the argument to --scheme
: in this case, either main
or swift/main
.
Swift | LLVM Project |
---|---|
release/x.y | swift/release/x.y |
At some point before a release, a release branch will be created in every repository with a name like release/5.3
. (The actual number is chosen by Apple.) After the branch has been created, commits must make it to this branch to make it into the release. In some cases, the release manager for the branch will decide to merge in all additional changes from main
; otherwise, cherry-picking changes and making a new pull request is the way to go. If there are any "patch" releases (e.g. Swift 5.3.1), they will also come from this branch.
Note that these branches come not from the "development" branches (above), but the "upstream" branches (below). This is because they need to contain the latest changes not just from Swift, but from the LLVM project as well. For some releases, the release branch for the LLVM project will be timed to coincide with the corresponding llvm.org release branch.
Swift | LLVM Project |
---|---|
next | swift/next |
swift/next
is a branch for LLVM that includes all changes necessary to support Swift. Changes from llvm.org's main branch are automatically merged in. Why isn't this just swift/main
? Well, because LLVM changes very rapidly, and that wouldn't be very stable. However, we do want to make sure the Swift stuff keeps working.
If you are making changes to LLVM to support Swift, you'll probably need to work on them in swift/main
to test them against Swift itself, but they should be committed to swift/next
, and cherry-picked to the current release branch (swift/release/x.y
) if needed. Remember, the release branches are automerged into swift/main
on a regular basis.
(If you're making changes to LLVM Project that aren't about Swift, they should generally be made on llvm.org instead, then cherry-picked to the active release branch or swift/main
.)
next
is an effort to keep Swift building with the latest LLVM changes. Ideally when LLVM changes, no Swift updates are needed, but that isn't always the case. In these situations, any adjustments can go into Swift's next
branch. Changes from Swift's main
are automatically merged into next
as well.
swift/utils/update-checkout --scheme [branch]
You can use any of the branch names as the argument to --scheme
, such as main
or swift/main
. See update-checkout --help
for more options.
-
Swift: new commits go to
main
-
LLVM Project: the destination branch depends on the kind of change that must be made:
-
LLVM Project changes that don't depend on Swift
-
New commits go to
main
in the upstream llvm-project. -
Then cherry-pick these commits to an appropriate,
swift/main
alignedapple/stable/*
branch in Apple's fork of llvm-project. Please see Apple's branching scheme document to determine whichapple/stable/*
branch you should cherry-pick to.
Note that no new changes should be submitted directly to
apple/main
. We are actively working on eliminating the differences from upstream LLVM. -
-
Changes that depend on Swift (this only applies to LLDB)
-
New commits go to
swift/main
(not anapple/stable/*
branch, as these shouldn't contain changes that depend on Swift). -
Then cherry-pick these commits to
swift/next
. -
If necessary, cherry-pick to the release branch (
swift/release/x.y
), following the appropriate release process. (Usually this means filling out a standard template, finding someone to review your code if that hasn't already happened, and getting approval from that repo's release manager.)
-
In the long term we want to eliminate the differences from upstream LLVM for these changes as well, but for now there is no concrete plan. So, submitting to
swift/next
continues to be allowed. -
Some branches are automerged into other branches, to keep them in sync. This is just a process that runs git merge
at a regular interval. These are run by Apple and are either on a "frequent" (sub-hourly) or nightly schedule.
main
is automerged intonext
swift/release/x.y
(the latest release branch) is automerged intoswift/main
- llvm.org's
main
is automerged intoswift/next
- llvm.org's release branch may be automerged into
swift/release/x.y
, if they are in sync
To update the Branch/Tag requirements, please follow these steps:
- Create pull requests to update the branch/tag in the following repositories:
- in
swiftlang/swift
modifyupdate-checkout-config.json
- in
swiftlang/swift-source-compat-suite
repository modifycommon.py
- in
- Notify @shahmishal after creating the pull requests