Configure options for the prebuilt binaries

[kenichi-asai]

What are the options given to configure when compiling the prebuilt binaries in the MacVim releases? (I want to build the same binary as in the releases but using the gettext compiled with homebrew libiconv to avoid the buggy system libiconv.)

[ychin]

It's a little convoluted to figure out but it's all defined in the .github/workflows/macvim-buildtest.yaml file. If you search for "CONFOPT:" in the CI runs, you will see it print something like this:

--with-local-dir=/opt/homebrew --with-features=huge --enable-netbeans --with-tlib=ncurses --enable-cscope --enable-gui=macvim --with-compiledby=GitHub Actions --enable-perlinterp=dynamic --enable-pythoninterp=dynamic --enable-python3interp=dynamic --with-python3-stable-abi=3.9 --enable-rubyinterp=dynamic --enable-luainterp=dynamic --with-lua-prefix=/opt/homebrew --with-macarchs=x86_64 arm64

The details for what the configure flags do are documented in https://github.com/macvim-dev/macvim/wiki/Building#how-to-build-macvim.

You need to do more than just using the right configure flags though because the environmental variables in the form of vi_cv_*, MACOSX_DEPLOYMENT_TARGET, CC also matters and they are picked up by the configure scripts, so you need to set those as well by taking the values from the YAML file.

There are also some messy bits where it modifies the configured parameters. It's not pretty but it works… (some of this comes from emulating how Vim is built upstream):

1. First mod:

          sed -i.bak -f ci/config.mk.sed -f ci/config.mk.clang.sed -f ci/config.mk.xcode.sed src/auto/config.mk
          sed -i.bak -f ci/config.mk.clang-12.sed src/auto/config.mk
   
          # Additional optimizations like link-time optimizations that are a bit slower to build.
          sed -i.bak -f ci/config.mk.optimized.sed src/auto/config.mk

2. Second mod:

          # Ruby is keg-only in Homebrew, so need to manually link in the path so Vim will know where to look for the binaries.
          perl -p -i -e "s#(?<=-DDYNAMIC_RUBY_DLL=\\\\\").*?(?=\\\\\")#${vi_cv_dll_name_ruby}#" src/auto/config.mk

The version of gettext and libsodium used for building MacVim are also not the vanilla Homebrew version, as we need to rebuild those packages locally to be universal x86/arm64, and also use the correct deployment target so MacVim works from 10.9 to macOS 26. I highly doubt you want to do that for a local build. This is done by the universal-package GitHub action in the .github/actions/universal-package folder.

Honestly you may not want to build MacVim identically to the released binary because e.g. it still works with Python 2 which you very likely do not care about and you would have no reason to install Python 2 on a local machine otherwise. You also don't need to MACOSX_DEPLOYMENT_TARGET to anything lower than your current OS. We set it as low as possible so the binary will work everywhere. You probably also don't want the --with-marcarchs flag which is only needed if you want your binary to work on Intel x86 Macs, and doing unified builds like that complicates the process.

It's been on my backlog to support reproducible builds (#1506) which would necessarily provide a more clearly documented way how each released build is built exactly and reproducibly, so maybe I should get on that.

---

Just to summarize, given that I assume you aren't trying to re-release MacVim and only building for personal use and don't care about say Python 2, this is what I would do rather than mirroring the released binary exactly (MacVim is not reproducibly built at the moment as I mentioned earlier, so you won't be get a binary-identical build to MacVim anyway):

1. Set the vi_cv_* env vars according to the CI script.
2. Install Homebrew Ruby, Python 3, Lua.
3. (The key step that you want to do) Build your own version of Homebrew gettext against Homebrew iconv. It's easiest if you just replace the /opt/homebrew/ version of gettext with your own so the configure script will just find that and use it.
4. Use configure flags:

   --with-local-dir=/opt/homebrew --enable-netbeans --with-tlib=ncurses --enable-cscope --enable-perlinterp=dynamic --enable-python3interp=dynamic --with-python3-stable-abi=3.9 --enable-rubyinterp=dynamic --enable-luainterp=dynamic --with-lua-prefix=/opt/homebrew
   

5. Modify configured results:

   sed -i.bak -f ci/config.mk.sed -f ci/config.mk.clang.sed -f ci/config.mk.xcode.sed src/auto/config.mk
   sed -i.bak -f ci/config.mk.clang-12.sed src/auto/config.mk
   sed -i.bak -f ci/config.mk.optimized.sed src/auto/config.mk
   # Only do this if you want Ruby support
   perl -p -i -e "s#(?<=-DDYNAMIC_RUBY_DLL=\\\\\").*?(?=\\\\\")#${vi_cv_dll_name_ruby}#" src/auto/config.mk

6. Build using the Makefile.

[kenichi-asai]

Thank you for the thorough explanation! I could successfully build MacVim with my own gettext and libiconv. For record, here is what I did:

1. brew install libiconv
2. Edit the formula for gettext to include depends_on "libiconv" so that it uses homebrew libiconv. Then env HOMEBREW_NO_INSTALL_FROM_API=1 brew reinstall --build-from-source --verbose --debug gettext to reinstall gettext.
3. ./configure with your suggested flags in the environment where the following environment variables are set.

CFLAGS=-I/opt/homebrew/opt/libiconv/include
LDFLAGS="-L/opt/homebrew/opt/libiconv/lib -liconv"
MACOSX_DEPLOYMENT_TARGET='10.13'
CC=clang
MACVIM_ARCHS="arm64"

4. Modify the configured results as you suggest.
5. make

I did not understand vi_cv_* variables, so I simply ignored them; I will consider them when something went wrong. (I did not think of better way to specify which libiconv to include, other than setting CFLAGS and LDFLAGS.)

Thank you again. It was extremely helpful.