build-emacs-for-macos

Use this script at your own risk. As of writing (2020-02-02) it works for me on my own machine to build the emacs-27 release branch. My machine is a late-2016 13-inch Touchbar MacBook Pro runnning macOS 10.15.2 and Xcode 11.3.

Your luck may vary.

The build produced does have some limitations:

It is not a universal application. The CPU architecture of the built application will be that of the machine it was built on.
The minimum required macOS version of the built application will be the same as that of the machine it was built on.

Why?

To use new features available from master or pre-release branches, which have not made it into a official stable release yet.
Homebrew builds of Emacs are not self-contained applications, making it very difficult when doing HEAD builds and you need to rollback to a earlier version.
Builds from emacsformacosx.com has had no new nightly builds for two months right now.
Both Homebrew HEAD builds, and nightly builds from emacsformacosx.com are built from the master branch. This script allows you to choose any branch you want. I am currently building from the emacs-27 branch which is the basis of the upcoming Emacs 27 release, meaning it should be more stable than master builds.

Requirements

Xcode
Homebrew
All Homebrew formula listed in the Brewfile, which can all easily be installed by running:
```
brew bundle
```

Usage

Then to download a tarball of the master branch, build Emacs.app:

./build-emacs-for-macos

If you want to build the emacs-27 git branch, run:

./build-emacs-for-macos emacs-27

If you want to build the stable emacs-26.3 git tag, run:

./build-emacs-for-macos emacs-26.3

Resulting applications are saved to the builds directory in a bzip2 compressed tarball.

Internals

The script downloads the source code as a gzipped tar archive from the GitHub mirror repository, as it makes it very easy to get a tarball of any given git reference.

It then runs ./configure with a various options, partly based on what David Caldwell's build-emacs scripts do, including copying various dynamic libraries into the application itself. So the built application should in theory run on a macOS install that does not have homebrew, or do no have the relevant brew formula installed.

Code quality, is well, non-existent. The build script started life a super-quick hack back in 2013, and now it's even more of a dirty hack. I might clean it up and add unit tests if I end up relying on this script for a prolonged period of time. For now I plan to use it until Emacs 27 is officially released.

License