Development Processes

Landing PRs

• Even after the code of a PR is approved, it should only be landed if the CI on github is green, or the failures are known intermittent things (with very strong reason to think they unrelated to the current PR).
• If you see an approved PR of someone without commit access (that either you or someone else approved), land it for them (after checking CI as mentioned earlier).
• If you approve a PR by someone with commit access, if there is no urgency then leave it for them to land. (They may have other PRs to land alongside it, etc.)
• It is strongly recommended to land PRs with github's “squash” option, which turns the PR into a single commit. This makes sense if the PR is small, which is also strongly recommended. However, sometimes separate commits may make more sense, if and only if:
  • The PR is not easily separable into a series of small PRs (e.g., review must consider all the commits, either because the commits are hard to understand by themselves, or because review of a later PR may influence an earlier PR's discussion).
  • The individual commits have value (e.g., they are easier to understand one by one).
  • The individual commits are compatible with bisection (i.e., all tests should pass after each commit). When landing multiple commits in such a scenario, use the “rebase” option, to avoid a merge commit.

Release Processes

Minor version updates (1.X.Y to 1.X.Y+1)

When:

• Such an update ensures we clear the cache, so it should be done when required (for example, a change to libc or libc++).
• The emsdk compiled versions are based on the version number, so periodically we can do this when we want a new precompiled emsdk version to be available.

Requirements:

• emscripten-releases build CI is green on all OSes for the desired hash (where the hash is the git hash in the emscripten-releases repo, which then specifies through DEPS exactly which revisions to use in all other repos).
• GitHub CI is green on the main branch.

How:

1. Run ./scripts/create_release.py in the emsdk repository. This script will update emscripten-releases-tags.json, adding a new version. You can either specify the desired hash, or let the script pick the current tot build. The script will create a new git branch that can be uploaded as a PR.
2. Tag the emsdk repo with the new version number, on the commit that does the update, after it lands on main.
3. Tag the emscripten repo with the new version number, on the commit referred to in the DEPS file above.
4. Update emscripten-version.txt and ChangeLog.md in the emscripten repo to refer the next, upcoming, version.

Major version update (1.X.Y to 1.(X+1).0)

When:

• We should do such an update when we have a reasonable assurance of stability.

Requirements:

• All the requirements for a minor update.
• No major change recently landed.
• No major recent regressions have been filed.
• All tests pass locally for the person doing the update, including the main test suite (no params passed to runner.py), other, browser, sockets, sanity, binaryen*. (Not all of those are run on all the bots.)
• A minor version was recently tagged, no major bugs have been reported on it, and nothing major landed since it did. (Bugs are often only found on tagged versions, so a big feature should first be in a minor version update before it is in a major one.)

How:

1. Follow the same steps for a minor version update.

Updating the emscripten.org Website

The site is currently hosted in gh-pages branch of the separate site repository. To update the docs, rebuild them and copy them there, that is:

1. In your emscripten repo checkout, enter site.
2. Run make html.
3. Run make install EMSCRIPTEN_SITE=\[path-to-a-checkout-of-the-site-repo\]
4. Go to the site repo, commit the changes, and push.

You will need the specific sphinx version installed, which you can do using pip3 install -r requirements-dev.txt (depending on your system, you may then need to add ~/.local/bin to your path, if pip installs to there).

Updating the emcc.py help text

emcc --help output is generated from the main documentation under site/, so it is the same as shown on the website, but it is rendered to text. After updating emcc.rst in a PR, the following should be done:

1. In your emscripten repo checkout, enter site.
2. Run make clean (without this, it may not emit the right output).
3. Run make text.
4. Copy the output build/text/docs/tools_reference/emcc.txt to ../docs/emcc.txt (both paths relative to the site/ directory in emscripten that you entered in step 1), and add that change to your PR.

See notes above on installing sphinx.