Homebrew/homebrew-core Maintainer Guide

Quick merge checklist

A detailed checklist can be found below. This is all that really matters:

Checking dependencies is important, because they will probably stick around forever. Nobody really checks if they are necessary or not.

Depend on as little stuff as possible. Disable X11 functionality if possible. For example, we build Wireshark, but not the heavy GUI.

Homebrew is about Unix software. Stuff that builds to an .app should be in Homebrew Cask instead.

Merging, rebasing, cherry-picking

For most PRs that make formula modifications, you can simply approve the PR and an automatic merge (with bottles) will be performed by @BrewTestBot. See Brew Test Bot For Core Contributors for more information.

Certain PRs may not be merged automatically by @BrewTestBot, even after they’ve been approved. This includes PRs with the new formula, automerge-skip, and linux-only labels. To trigger a merge for these PRs, run brew pr-publish.

PRs modifying formulae that don’t need bottles or making changes that don’t require new bottles to be pulled should use GitHub’s squash & merge or rebase & merge workflows. See the table below for more details.

Otherwise, you should use brew pr-pull (or rebase/cherry-pick contributions).

Don’t rebase until you finally push. Once master is pushed, you can’t rebase: you’re a maintainer now!

Cherry-picking changes the date of the commit, which kind of sucks.

Don’t merge unclean branches. So if someone is still learning git and their branch is filled with nonsensical merges, then rebase and squash the commits. Our main branch history should be useful to other people, not confusing.

Here’s a flowchart for managing a PR which is ready to merge:

Flowchart for managing pull requests

Only one maintainer is necessary to approve and merge the addition of a new or updated formula which passes CI. However, if the formula addition or update proves controversial the maintainer who adds it will be expected to answer requests and fix problems that arise with it in future.

How to merge without bottles

Here are guidelines about when to use squash & merge versus rebase & merge. These options should only be used with PRs where bottles are not affected.

  PR modifies a single formula PR modifies multiple formulae
Commits look good rebase & merge or squash & merge rebase & merge
Commits need work squash & merge manually merge using the command line

Naming

The name is the strictest item, because avoiding a later name change is desirable.

Choose a name that’s the most common name for the project. For example, we initially chose objective-caml but we should have chosen ocaml. Choose what people say to each other when talking about the project.

Formulae that are also packaged by other package managers (e.g. Debian, Ubuntu) should be named consistently (subject to minor differences due to Homebrew formula naming conventions).

Add other names as aliases as symlinks in Aliases in the tap root. Ensure the name referenced on the homepage is one of these, as it may be different and have underscores and hyphens and so on.

We now accept versioned formulae as long as they meet the requirements.

Testing

We need to at least check that it builds. Use the Brew Test Bot for this.

Verify the formula works if possible. If you can’t tell (e.g. if it’s a library) trust the original contributor, it worked for them, so chances are it is fine. If you aren’t an expert in the tool in question, you can’t really gauge if the formula installed the program correctly. At some point an expert will come along, cry blue murder that it doesn’t work, and fix it. This is how open source works. Ideally, request a test do block to test that functionality is consistently available.

If the formula uses a repository, then the url parameter should have a tag or revision. urls have versions and are stable (not yet implemented!).

Don’t merge any formula updates with failing brew tests. If a test do block is failing it needs to be fixed. This may involve replacing more involved tests with those that are more reliable. This is fine: false positives are better than false negatives as we don’t want to teach maintainers to merge red PRs. If the test failure is believed to be due to a bug in Homebrew/brew or the CI system, that bug must be fixed, or worked around in the formula to yield a passing test, before the PR can be merged.

Duplicates

We now accept stuff that comes with macOS as long as it uses keg_only :provided_by_macos to be keg-only by default.

Removing formulae

Formulae that:

should not be removed from Homebrew. The exception to this rule are versioned formulae for which there are higher standards of usage and a maximum number of versions for a given formula.

For more information about deprecating, disabling and removing formulae, see the Deprecating, Disabling, and Removing Formulae page.

Detailed merge checklist

The following checklist is intended to help maintainers decide on whether to merge, request changes or close a PR. It also brings more transparency for contributors in addition to the Acceptable Formulae requirements.

Common build failures and how to handle them

Test errors

“undefined reference to …”

This error might pop up when parameters passed to gcc are in the wrong order.

An example from libmagic formula:

==> brew test libmagic --verbose
Testing libmagic
==> /usr/bin/gcc -I/home/linuxbrew/.linuxbrew/Cellar/libmagic/5.38/include -L/home/linuxbrew/.linuxbrew/Cellar/libmagic/5.38/lib -lmagic test.c -o test
/tmp/ccNeDVRt.o: In function `main':
test.c:(.text+0x15): undefined reference to `magic_open'
test.c:(.text+0x4a): undefined reference to `magic_load'
test.c:(.text+0x81): undefined reference to `magic_file'
collect2: error: ld returned 1 exit status

Solution:

if OS.mac?
    system ENV.cc, "-I#{include}", "-L#{lib}", "-lmagic", "test.c", "-o", "test"
else
    system ENV.cc, "test.c", "-I#{include}", "-L#{lib}", "-lmagic", "-o", "test"
end

For an explanation of why this happens, read the Ubuntu 11.04 Toolchain documentation.

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