Zig 0.16 migration

[pluiedev]

Zig 0.16 has landed on April 13, 2026, so it's time to do this all over again :)

The major breaking change this time is the new std.Io interface that will be part of any code that has to access basically any system interface (filesystem, threads, timers, etc.), and OS-specific APIs like std.posix has almost been completely removed. This will likely be an even greater challenge compared to Writergate due to how much we rely on libxev for these sorts of tasks. I would recommend trying to port the codebase to use a generic std.Io implementation, and polyfilling in the features we need but aren't quite in the standard library yet — then we could either try to run the whole program off of std.Io.Evented, or try to repackage libxev as yet another std.Io implementation.

Other than libxev, these other Zig dependencies need to be migrated:

• libvaxis — open PR: Zig 0.16 port rockorager/libvaxis#316
• z2d — has a Zig 0.16 branch: https://github.com/vancluever/z2d/tree/zig-0.16
• zig-objc — merged PR: Zig 0.16 Compatibility mitchellh/zig-objc#34
• zig-js — merged PR: migrate to 0.16.0-dev.3142+5ccfeb926 mitchellh/zig-js#10
• uucode — has switched to Zig 0.16 for its main branch
• libxev — Zig 0.16 Compatibility mitchellh/libxev#220
• zig-wayland — has switched to Zig 0.16 for its main branch
• zf — No ongoing migration upstream
• gobject — New 0.16-compatible release
• zon2nix — merged PR: zon2nix: update to a version that is compatible with Zig 0.16 #12259

[francisqureshi]

I'd love to help out with this, I've been wanting to start contributing on Ghostty for some time and I've been working on Zig Master on my own Zig projects that use zig-objc so can for sure help there as I have a simple fork at the moment.

[pluiedev]

If you can make a PR to zig-objc that will be great, as I only have access to a Linux machine :)

[pluiedev]

@jacobsandlund Looks like the API changed a lot with the Zig 0.16 branch. I'm not smart enough to figure out how to port our uucode setup to the new system — could you maybe lend a hand?

Update: never mind, I figured this out myself :)

[francisqureshi]

If you can make a PR to zig-objc that will be great, as I only have access to a Linux machine :)

Please see PR via: mitchellh/zig-objc#34 - as mentioned this will need a zig-objc 0.16 branch

[pluiedev]

In-progress branch at https://github.com/pluiedev/ghostty/tree/zig-0.16 — the port is even trickier than I thought not just because of std.Io, but also because we apparently access environment variables somewhat haphazardly throughout the codebase which means a std.process.Environ object has to be lugged around everywhere. The fact that most of std.posix got nuked doesn't help, either.

[jcollie]

because we apparently access environment variables somewhat haphazardly throughout the codebase which means a std.process.Environ object has to be lugged around everywhere.

#11172

[jcollie]

#11969 does something similar for arg parsing.

[ReillyBrogan]

0.16.0 was tagged a couple of hours ago.

[jcollie]

0.16.0 was tagged a couple of hours ago.

Yep. There's a lot of work to do so this won't happen soon.

[jacobsandlund]

@jacobsandlund Looks like the API changed a lot with the Zig 0.16 branch. I'm not smart enough to figure out how to port our uucode setup to the new system — could you maybe lend a hand?

ah shoot @pluiedev i meant to make a pr before 0.16 went out to make this easier. ty for getting this!

@jcollie's pr on uucode is merged too.

i also intend to switch main to 0.16, maybe in a day or so when i have time

edit: main is now 0.16

[jcollie]

Probably should remove all uses of @cImport to get ahead of:
https://codeberg.org/ziglang/zig/pulls/31892