How to do a GTK release?

Before we begin

Make sure you have suitable versions of Meson and Ninja.

Save all your work, then move to the branch from which you want to release. Go back to a pristine working directory. With Git, this works:

$ git clean -dfx

$ meson setup _build
$ meson compile -C _build

Update NEWS based on the content of git log; follow the format of prior entries. This includes finding noteworthy new features, collecting summaries for all the fixed bugs that are referenced and collecting all updated translations. Also collect the names of all contributors that are mentioned. We don't discriminate between bug reporters, patch writers, committers, etc. Anybody who is mentioned in the commit log gets a credit, but only real names, not email addresses or nicknames.
Update the pot file and commit the changes:

$ ninja -C _build gtk40-pot

If this is a major, stable, release, verify that the release notes in the API reference contain the relevant items.
Verify that the version in meson.build has been bumped after the last release. Note: this is critical, a slip-up here will cause the soname to change.
Make sure that meson test is happy (ninja dist will also run the test suite, but it's better to catch issues before committing and tagging the release). Typical problems to expect here (depending on whether this is a devel snapshot or a stable release):

* forgotten source files
* new symbols missing the `GDK_AVAILABLE_IN_` annotation
* wrong introspection annotations
* missing documentation

If this is a devel release, make sure that the docs for new symbols are in good shape. Look at the -unused.txt files and add stuff found there to the corresponding -sections.txt file. Look at the -undocumented.txt files and see if there is anything in there that should be documented. If it is, this may be due to typos in the doc comments in the source. Make sure that all new symbols have proper Since: tags, and that there is an index in the main -docs.xml for the next stable version.
Run meson dist -C_build to generate the tarball.
Fix broken stuff found by 8), commit changes, repeat.
Once dist succeeds, verify that the tree is clean and all the changes needed to make the release have been committed: git diff should come up empty. The last commit must be the commit that bumps up the version of the release in the meson.build file. Use git rebase if you had to add more commits after the version bump and dist successfully passing. If you change the history, remember to rebuild the tarball.
Now you've got the tarball. Check that the tarball size looks reasonable compared to previous releases. If the size goes down a lot, likely the docs went missing for some reason. Or the translations. If the size goes up by a lot, something else may be wrong.
Tag the release. The git command for doing that looks like:

$ git tag -m "GTK 4.2.0" 4.2.0

Bump the version number in meson.build, and add a section for the next release in NEWS and commit the change.
Push the changes upstream, and push the tag as well. The git command for doing that is:

$ git push origin
$ git push origin 4.2.0

Upload the tarball to master.gnome.org and run ftpadmin install to transfer it to download.gnome.org. If you don't have an account on master.gnome.org, find someone who can do it for you. The command for this looks like:

$ scp gtk-4.2.0.tar.xz matthiasc@master.gnome.org:
$ ssh matthiasc@master.gnome.org
$ ftpadmin install gtk-4.2.0.tar.xz

Go to the gnome-announce list archives, find the last announce message, create a new message in the same form, replacing version numbers, commentary at the top about "what this release is about" and the summary of changes.