Releasing a stable version

This checklist walks you through releasing a stable version. See below for the checklist for release candidates.

We'll use v4.6.0 as the intended release version as a running example.

  • Run script/release_checklist.py v4.6.0 to check the status of the release. This script is idempotent, and should be safe to run at any stage of the release process. Note that as of v4.19.0, this script takes some autonomous actions, which can be prevented via --dry-run.
  • git checkout releases/v4.6.0 (This branch should already exist, from the release candidates.)
  • git pull
  • In src/CMakeLists.txt, verify you see
    • set(LEAN_VERSION_MINOR 6) (for whichever 6 is appropriate)
    • set(LEAN_VERSION_IS_RELEASE 1)
    • (all of these should already be in place from the release candidates)
  • git tag v4.6.0
  • git push $REMOTE v4.6.0, where $REMOTE is the upstream Lean repository (e.g., origin, upstream)
  • Now wait, while CI runs.
    • You can monitor this at https://github.com/leanprover/lean4/actions/workflows/ci.yml, looking for the v4.6.0 tag.
    • This step can take up to two hours.
    • If you are intending to cut the next release candidate on the same day, you may want to start on the release candidate checklist now.
  • Next we need to prepare the release notes.
    • If the stable release is identical to the last release candidate (this should usually be the case), you can reuse the release notes that are already in the Lean Language Reference.
    • If you want to regenerate the release notes, run script/release_notes.py --since v4.5.0 on the releases/v4.6.0 branch, and see the section "Writing the release notes" below for more information.
    • Release notes live in https://github.com/leanprover/reference-manual, in e.g. Manual/Releases/v4.6.0.lean. It's best if you update these at the same time as a you update the lean-toolchain for the reference-manual repository, see below.
  • Go to https://github.com/leanprover/lean4/releases and verify that the v4.6.0 release appears.
    • Verify on Github that "Set as the latest release" is checked.
  • Next, we will move a curated list of downstream repos to the latest stable release.
    • In order to have the access rights to push to these repositories and merge PRs, you will need to be a member of the lean-release-managers team at both leanprover-community and leanprover. Contact Kim Morrison (@kim-em) to arrange access.
    • For each of the repositories listed in script/release_repos.yml,
      • Run script/release_steps.py v4.6.0 <repo> (e.g. replacing <repo> with batteries), which will walk you through the following steps:
        • Create a new branch off master/main (as specified in the branch field), called bump_to_v4.6.0.
        • Update the contents of lean-toolchain to leanprover/lean4:v4.6.0.
        • In the lakefile.toml or lakefile.lean, if there are dependencies on specific version tags of dependencies, update them to the new tag. If they depend on main or master, don't change this; you've just updated the dependency, so lake update will take care of modifying the manifest.
        • Run lake update
        • Commit the changes as chore: bump toolchain to v4.6.0 and push.
        • Create a PR with title "chore: bump toolchain to v4.6.0".
      • Merge the PR once CI completes.
      • Re-running script/release_checklist.py will then create the tag v4.6.0 from master/main and push it (unless toolchain-tag: false in the release_repos.yml file)
      • script/release_checklist.py will then merge the tag v4.6.0 into the stable branch and push it (unless stable-branch: false in the release_repos.yml file).
    • Special notes on repositories with exceptional requirements:
      • doc-gen4 has addition dependencies which we do not update at each toolchain release, although occasionally these break and need to be updated manually.
      • verso:
        • The subverso dependency is unusual in that it needs to be compatible with every Lean release simultaneously. Usually you don't need to do anything. If you think something is wrong here please contact David Thrane Christiansen (@david-christiansen)
        • Warnings during lake update and lake build are expected.
      • reference-manual: the release notes generated by script/release_notes.py as described above must be included in Manual/Releases/v4.6.0.lean, and import and include statements adding in Manual/Releases.lean.
      • ProofWidgets4 uses a non-standard sequential version tagging scheme, e.g. v0.0.29, which does not refer to the toolchain being used. You will need to identify the next available version number from https://github.com/leanprover-community/ProofWidgets4/releases, and push a new tag after merging the PR to main.
      • mathlib4:
        • The lakefile.toml should always refer to dependencies via their main or master branch, not a toolchain tag (with the exception of ProofWidgets4, which must use a sequential version tag).
        • Push the PR branch to the main Mathlib repository rather than a fork, or CI may not work reliably
      • repl: There are two copies of lean-toolchain/lakefile.lean: in the root, and in test/Mathlib/. Edit both, and run lake update in both directories.
  • An awkward situtation that sometimes occurs (e.g. with Verso) is that the master/main branch has already been moved to a nightly toolchain that comes after the stable toolchain we are targeting. In this case it is necessary to create a branch releases/v4.6.0 from the last commit which was on an earlier toolchain, move that branch to the stable toolchain, and create the toolchain tag from that branch.
  • Run script/release_checklist.py v4.6.0 one last time to check that everything is in order.
  • Finally, make an announcement! This should go in https://leanprover.zulipchat.com/#narrow/stream/113486-announce, with topic v4.6.0. Please see previous announcements for suggested language. You will want a few bullet points for main topics from the release notes. If there is a blog post, link to that from the zulip announcement.
  • Make sure that whoever is handling social media knows the release is out.

Time estimates:

  • Initial checks and push the tag: 10 minutes.
  • Waiting for the release: 120 minutes.
  • Preparing release notes: 10 minutes.
  • Bumping toolchains in downstream repositories, up to creating the Mathlib PR: 60 minutes.
  • Waiting for Mathlib CI and bors: 120 minutes.
  • Finalizing Mathlib tags and stable branch, and updating REPL: 20 minutes.
  • Posting announcement and/or blog post: 30 minutes.

Creating a release candidate.

This checklist walks you through creating the first release candidate for a version of Lean.

We'll use v4.7.0-rc1 as the intended release version in this example.

  • Decide which nightly release you want to turn into a release candidate. We will use nightly-2024-02-29 in this example.
  • It is essential to choose the nightly that will become the release candidate as early as possible, to avoid confusion.
  • Throughout this process you can use script/release_checklist.py v4.7.0-rc1 to track progress. This script will also try to do some steps autonomously. It is idempotent and safe to run at any point. You can prevent it taking any actions using --dry-run.
  • It is essential that Batteries and Mathlib already have reviewed branches compatible with this nightly.
    • Check that both Batteries and Mathlib's bump/v4.7.0 branch contain nightly-2024-02-29 in their lean-toolchain.
    • The steps required to reach that state are beyond the scope of this checklist, but see below!
  • Create the release branch from this nightly tag: 
    git remote add nightly https://github.com/leanprover/lean4-nightly.git
git fetch nightly tag nightly-2024-02-29
git checkout nightly-2024-02-29
git checkout -b releases/v4.7.0
git push --set-upstream origin releases/v4.18.0
  • In src/CMakeLists.txt,
    • verify that you see set(LEAN_VERSION_MINOR 7) (for whichever 7 is appropriate); this should already have been updated when the development cycle began.
    • change the LEAN_VERSION_IS_RELEASE line to set(LEAN_VERSION_IS_RELEASE 1) (this should be a change; on master and nightly releases it is always 0).
    • Commit your changes to src/CMakeLists.txt, and push.
  • git tag v4.7.0-rc1
  • git push origin v4.7.0-rc1
  • Now wait, while CI runs.
    • The CI setup parses the tag to discover the -rc1 special description, and passes it to cmake using a -D option. The -rc1 doesn't need to be placed in the configuration file.
    • You can monitor this at https://github.com/leanprover/lean4/actions/workflows/ci.yml, looking for the v4.7.0-rc1 tag.
    • This step can take up to two hours.
  • Verify that the release appears at https://github.com/leanprover/lean4/releases/, marked as a prerelease (this should have been done automatically by the CI release job).
  • Next we need to prepare the release notes.
    • Run script/release_notes.py --since v4.6.0 on the releases/v4.7.0 branch, which will report diagnostic messages on stderr (including reporting commits that it couldn't associate with a PR, and hence will be omitted) and then a chunk of markdown on stdout. See the section "Writing the release notes" below for more information.
    • Release notes live in https://github.com/leanprover/reference-manual, in e.g. Manual/Releases/v4.7.0.lean. It's best if you update these at the same time as a you update the lean-toolchain for the reference-manual repository, see below.
  • Next, we will move a curated list of downstream repos to the release candidate.
    • This assumes that for each repository either:
      • There is already a reviewed branch bump/v4.7.0 containing the required adaptations. The preparation of this branch is beyond the scope of this document.
      • The repository does not need any changes to move to the new version.
      • Note that sometimes there are unreviewed but necessary changes on the nightly-testing branch of the repository. If so, you will need to merge these into the bump_to_v4.7.0-rc1 branch manually.
    • For each of the repositories listed in script/release_repos.yml,
      • Run script/release_steps.py v4.7.0-rc1 <repo> (e.g. replacing <repo> with batteries), which will walk you through the following steps:
        • Create a new branch off master/main (as specified in the branch field), called bump_to_v4.7.0-rc1.
        • Merge origin/bump/v4.7.0 if relevant (i.e. bump-branch: true appears in release_repos.yml).
        • Update the contents of lean-toolchain to leanprover/lean4:v4.7.0-rc1.
        • In the lakefile.toml or lakefile.lean, if there are dependencies on nightly-testing, bump/v4.7.0, or specific version tags, update them to the new tag. If they depend on main or master, don't change this; you've just updated the dependency, so lake update will take care of modifying the manifest.
        • Run lake update
        • Run lake build && if lake check-test; then lake test; fi to check things are working.
        • Commit the changes as chore: bump toolchain to v4.7.0-rc1 and push.
        • Create a PR with title "chore: bump toolchain to v4.7.0-rc1".
      • Merge the PR once CI completes.
      • Re-running script/release_checklist.py will then create the tag v4.7.0-rc1 from master/main and push it (unless toolchain-tag: false in the release_repos.yml file)
    • We do this for the same list of repositories as for stable releases, see above for notes about special cases. As above, there are dependencies between these, and so the process above is iterative. It greatly helps if you can merge the bump/v4.7.0 PRs yourself!
    • It is essential for Mathlib and Batteries CI that you then create the next bump/v4.8.0 branch for the next development cycle. Set the lean-toolchain file on this branch to same nightly you used for this release.
  • Run script/release_checklist.py v4.7.0-rc1 one last time to check that everything is in order.
  • Make an announcement! This should go in https://leanprover.zulipchat.com/#narrow/stream/113486-announce, with topic v4.7.0-rc1. Please see previous announcements for suggested language. You will want a few bullet points for main topics from the release notes. Please also make sure that whoever is handling social media knows the release is out.
  • Begin the next development cycle (i.e. for v4.8.0) on the Lean repository, by making a PR that:
    • Uses branch name dev_cycle_v4.8.
    • Updates src/CMakeLists.txt to say set(LEAN_VERSION_MINOR 8)
    • Titled "chore: begin development cycle for v4.8.0"

Time estimates:

Slightly longer than the corresponding steps for a stable release. Similar process, but more things go wrong. In particular, updating the downstream repositories is significantly more work (because we need to merge existing bump/v4.7.0 branches, not just update a toolchain).

Preparing bump/v4.7.0 branches

While not part of the release process per se, this is a brief summary of the work that goes into updating Batteries/Aesop/Mathlib to new versions.

Please read https://leanprover-community.github.io/contribute/tags_and_branches.html

  • Each repo has an unreviewed nightly-testing branch that receives commits automatically from master, and has its toolchain updated automatically for every nightly. (Note: the aesop branch is not automated, and is updated on an as needed basis.) As a consequence this branch is often broken. A bot posts in the (private!) "Mathlib reviewers" stream on Zulip about the status of these branches.
  • We fix the breakages by committing directly to nightly-testing: there is no PR process.
    • This can either be done by the person managing this process directly, or by soliciting assistance from authors of files, or generally helpful people on Zulip!
  • Each repo has a bump/v4.7.0 which accumulates reviewed changes adapting to new versions.
  • Once nightly-testing is working on a given nightly, say nightly-2024-02-15, we will create a PR to bump/v4.7.0.
  • For Mathlib, there is a script in scripts/create-adaptation-pr.sh that automates this process.
  • For Batteries and Aesop it is currently manual.
  • For all of these repositories, the process is the same:
    • Make sure bump/v4.7.0 is up to date with master (by merging master, no PR necessary)
    • Create from bump/v4.7.0 a bump/nightly-2024-02-15 branch.
    • In that branch, git merge nightly-testing to bring across changes from nightly-testing.
    • Sanity check changes, commit, and make a PR to bump/v4.7.0 from the bump/nightly-2024-02-15 branch.
    • Solicit review, merge the PR into bump/v4.7.0.
  • It is always okay to merge in the following directions: master -> bump/v4.7.0 -> bump/nightly-2024-02-15 -> nightly-testing. Please remember to push any merges you make to intermediate steps!

Writing the release notes

Release notes are automatically generated from the commit history, using script/release_notes.py.

Run this as script/release_notes.py --since v4.6.0, where v4.6.0 is the previous release version. This script should be run on the releases/v4.7.0 branch. This will generate output for all commits since that tag. Note that there is output on both stderr, which should be manually reviewed, and on stdout, which should be manually copied into the reference-manual repository, in the file Manual/Releases/v4.7.0.lean.

The output on stderr should mostly be about commits for which the script could not find an associated PR, usually because a PR was rebase-merged because it contained an update to stage0. Some judgement is required here: ignore commits which look minor, but manually add items to the release notes for significant PRs that were rebase-merged.

There can also be pre-written entries in ./releases_drafts, which should be all incorporated in the release notes and then deleted from the branch. See ./releases_drafts/README.md for more information.