Add clang64 toolchain to pkgsCross by umbrageodotus · Pull Request #450796 · NixOS/nixpkgs

umbrageodotus · 2025-10-10T20:58:13Z

Added support for the clang64 toolchain which should be cached. Clang32 should also be added and ucrtAarch64 should be renamed to fit the scheme, but those are future PRs - as I need this in nixpkgs unstable URGENTLY.

Things done

Add a 👍 reaction to pull requests you find important.

RossComputerGuy · 2025-10-10T21:06:00Z

lib/systems/examples.nix


-  # LLVM-based mingw-w64 for ARM
+  # LLVM-based urct64s
+  clang64 = {


I feel like this needs a better name so people don't end up confusing it as being similar to pkgsLLVM.

clang64 is the official name of the toolchain.

I still think it's too unambiguously

Clang 64 is a name that only makes since within the MSYS2 family of toolchains, where MinGW is a baseline assumption.

I would call it ucrt64-llvm.

Good suggestion, or even msys2-clang64 is fine. Just something which indicates to people that it is a part of the MSYS2 family of toolchains or wouldn't confuse people who don't read documentation or comments.

I don't like putting the toolchain between the libc and arch. I would prefer the more important things (libc and arch) go first, and the less important thing (toolchain) go second.

Even the existing ucrt64 name I don't like, because it falsely assumes the 64 has an unambiguous interpretation as x86_64, when this is not the case, and the ucrtAarch64 option right below proves it!

I would like to see both names cleaned up, ideally.

Could that be another PR, though? Just so I don't break shit.

Sure. It can be a separate PR, For this PR, I just want to be clear that ucrt64 is not good precedent --- it's a bad name we probably should not have ever gone with.

lib/systems/examples.nix has quite a bit of bad naming, I think it's best to not create more names which can cause confusion.

umbrageodotus · 2025-10-10T21:21:57Z

@RossComputerGuy looks good? Also, sorry for the pressure but when can I expect this on unstable? My work depends on this.

philiptaron · 2025-10-10T21:51:23Z

Hey @umbrageodotus, if you need it urgently, I recommend that you maintain your own fork of Nixpkgs that holds it. We're often fast, but adding whole package sets needs a lot more discussion than a quick LGTM and ship it.

umbrageodotus · 2025-10-10T21:55:22Z

@philiptaron Then I won't have caching - if that's what I wanted I could've just used an override afaik...

umbrageodotus · 2025-10-10T21:56:04Z

This was done before with the introduction of ucrt64 and that was OK. This is that but with LLVM.

K900 · 2025-10-10T22:01:49Z

What's the urgency?

umbrageodotus · 2025-10-10T22:03:30Z

Using it to build rust code. The rust code needs -Clinker-plugin-lto which doesn't work with the gnu ld.

K900 · 2025-10-10T22:03:55Z

OK, and why is this urgent? And why is this a nixpkgs wide urgency?

umbrageodotus · 2025-10-10T22:06:23Z

It's not a nixpkgs wide urgency. That doesn't mean it shouldn't have been there SO much sooner.

umbrageodotus · 2025-10-10T22:06:36Z

And it's urgent because of my job.

K900 · 2025-10-10T22:08:06Z

It definitely does, to be honest, and you, my friend, need to lay off the gas. No one is going to add an entire new platform definition to nixpkgs overnight because one person's work requires it, and this change won't even achieve what you think it does to begin with.

RossComputerGuy · 2025-10-10T22:08:17Z

That's not a nixpkgs urgency

umbrageodotus · 2025-10-10T22:18:31Z

I understand that and apologize. Talked with my boss and he was comprehensive about it. Carry on, no pressure anymore.

K900 · 2025-10-12T08:27:28Z

Before the naming discussion devolves into fisticuffs, I would like to remind everyone, and OP in particular, that adding this alias will not, in fact, make Hydra build anything.

umbrageodotus · 2025-10-12T09:54:13Z

@rosd hmm...? Howd I get hydra to build & cache it?

K900 · 2025-10-12T10:41:40Z

You'd do that by adding it to release-cross.nix, which is the only entry point that gets built for cross jobs, as a separate jobset.

umbrageodotus · 2025-10-12T12:26:11Z

Okay.

lib/systems/examples.nix

Eveeifyeve

It looks good, but I just need an answer if the llvm platforms that don't support gcc work and also the issues need to be ci issues needs to be fixed before merging.

Eveeifyeve · 2025-12-21T17:44:39Z

@Ericson2314 all is left to do is fix the ci errors on this pr.

Ericson2314 · 2025-12-22T01:14:00Z

@Eveeifyeve yes, but I'm waiting for Alyssa first. The important thing to do here is decide what we want, e.g. how much CI time to we want to devote to MinGW via release-cross.nix. once we decide, fixing the CI errors is trivial and very quick.

philiptaron · 2026-01-06T02:22:21Z

I'm interested in what Alyssa thinks, too.

alyssais

Makes sense to me. Happy to defer to the experts on naming.

alyssais · 2026-01-07T12:55:47Z

pkgs/top-level/release-cross.nix

+  cross-mingw-msvcrt-x86_64 = mapTestOnCross systems.examples.mingw-msvcrt-x86_64 windowsCommon;
+  cross-mingw-ucrt-x86_64 = mapTestOnCross systems.examples.mingw-ucrt-x86_64 windowsCommon;
+  cross-mingw-ucrt-x86_64-llvm = mapTestOnCross systems.examples.mingw-ucrt-x86_64-llvm windowsCommon;
+  cross-mingw-ucrt-aarch64 = mapTestOnCross systems.examples.mingw-ucrt-aarch64 windowsCommon;


Do we really need all of these on Hydra?

Yes it would have helped us on the journey of creating this pr and catching issues earlier eg. this pr. This is also will be required for building bash needed for the stdenv for windows migrating it to powershell = hundreds of thousands of packages not working.

These are currently very small jobsets, so I am hoping that it should be fine.

If we ever cross-compile more stuff at scale, I might only do (UCRT-LLVM) * (x86_64, Aarch64). How does that sound?

(I am hoping we'll eventually do more native compilation at scale, and we fund-raise around this, and have more or fewer package sets accordingly.)

lib/systems/examples.nix

Co-authored-by: Eveeifyeve <88671402+Eveeifyeve@users.noreply.github.com>

Ericson2314 · 2026-01-13T02:57:48Z

Added the TODO. Anything else, anyone?

Eveeifyeve · 2026-01-13T07:57:11Z

I would say I want @alyssais to re-review this again.

nixpkgs-ci · 2026-01-15T14:55:22Z

Successfully created backport PR for release-25.11:

[Backport release-25.11] Add clang64 toolchain to pkgsCross #480388

Eveeifyeve · 2026-01-16T09:25:55Z

So I will be able to cross compile nix?

K900 · 2026-01-16T09:27:51Z

Not any more than you were able before this.

nix-owners bot requested review from Artturin, Ericson2314, RossComputerGuy, alyssais, emilazy, philiptaron and reckenrode October 10, 2025 21:04

RossComputerGuy reviewed Oct 10, 2025

View reviewed changes

umbrageodotus requested a review from RossComputerGuy October 10, 2025 21:45

Eveeifyeve reviewed Dec 21, 2025

View reviewed changes

lib/systems/examples.nix Show resolved Hide resolved

Eveeifyeve approved these changes Dec 21, 2025

View reviewed changes

nixpkgs-ci bot added the 12.approvals: 1 This PR was reviewed and approved by one person. label Dec 21, 2025

Eveeifyeve requested a review from alyssais December 22, 2025 10:38

alyssais reviewed Jan 7, 2026

View reviewed changes

Eveeifyeve reviewed Jan 9, 2026

View reviewed changes

lib/systems/examples.nix Outdated Show resolved Hide resolved

lib.systems.examples: Add LLVM x86-64 UCRT platform and clean up

7d03468

Co-authored-by: Eveeifyeve <88671402+Eveeifyeve@users.noreply.github.com>

Ericson2314 force-pushed the patch-1 branch from c4c96ae to 7d03468 Compare January 13, 2026 02:57

nixpkgs-ci bot removed the 10.rebuild-darwin: 1 This PR causes 1 package to rebuild on Darwin. label Jan 13, 2026

github-project-automation bot added this to Nixpkgs Lib Jan 13, 2026

Eveeifyeve requested a review from alyssais January 13, 2026 07:56

alyssais approved these changes Jan 15, 2026

View reviewed changes

nixpkgs-ci bot added 12.approvals: 2 This PR was reviewed and approved by two persons. and removed 12.approvals: 1 This PR was reviewed and approved by one person. labels Jan 15, 2026

Ericson2314 marked this pull request as ready for review January 15, 2026 14:48

Ericson2314 added this pull request to the merge queue Jan 15, 2026

Merged via the queue into NixOS:master with commit 3ea6894 Jan 15, 2026
26 of 28 checks passed

github-project-automation bot moved this to Done in Nixpkgs Lib Jan 15, 2026

nixpkgs-ci bot removed the 12.first-time contribution This PR is the author's first one; please be gentle! label Jan 15, 2026

nixpkgs-ci bot mentioned this pull request Jan 15, 2026

[Backport release-25.11] Add clang64 toolchain to pkgsCross #480388

Open

github-actions bot added the 8.has: port to stable This PR already has a backport to the stable release. label Jan 15, 2026

Uh oh!

Conversation

umbrageodotus commented Oct 10, 2025

Things done

Uh oh!

Choose a reason for hiding this comment

Uh oh!

umbrageodotus Oct 10, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

umbrageodotus commented Oct 10, 2025

Uh oh!

philiptaron commented Oct 10, 2025

Uh oh!

umbrageodotus commented Oct 10, 2025

Uh oh!

umbrageodotus commented Oct 10, 2025

Uh oh!

K900 commented Oct 10, 2025

Uh oh!

umbrageodotus commented Oct 10, 2025

Uh oh!

K900 commented Oct 10, 2025

Uh oh!

umbrageodotus commented Oct 10, 2025

Uh oh!

umbrageodotus commented Oct 10, 2025

Uh oh!

K900 commented Oct 10, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

RossComputerGuy commented Oct 10, 2025

Uh oh!

umbrageodotus commented Oct 10, 2025

Uh oh!

K900 commented Oct 12, 2025

Uh oh!

umbrageodotus commented Oct 12, 2025

Uh oh!

K900 commented Oct 12, 2025

Uh oh!

umbrageodotus commented Oct 12, 2025

Uh oh!

Uh oh!

Eveeifyeve left a comment • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Eveeifyeve commented Dec 21, 2025

Uh oh!

Ericson2314 commented Dec 22, 2025

Uh oh!

philiptaron commented Jan 6, 2026

Uh oh!

alyssais left a comment

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Eveeifyeve Jan 7, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

umbrageodotus Oct 10, 2025 •

edited

Loading

K900 commented Oct 10, 2025 •

edited

Loading

Eveeifyeve left a comment •

edited

Loading

Eveeifyeve Jan 7, 2026 •

edited

Loading

Ericson2314 Jan 8, 2026 •

edited

Loading