aarch64 windows

[zhmushan]

Could we build an installer for aarch64-pc-windows-msvc ? (I'm working on Surface Pro X)

[kinnison]

In theory we could. std and host are built for this target. We need to know by what means (cross from Windows x86_64? cross from Linux?) and for that I shall request a hint from @pietroalbini on how we build that target's rustc/cargo.

[emilyalbini]

For rustc/cargo we're cross-compiling from Windows x86_64.

[kinnison]

Cool, would you expect GH Actions to just work if I rustup target install aarch64-pc-windows-msvc and then cargo build --target=aarch64-pc-windows-msvc ? If so I should be able to add the action pretty easily.

[emilyalbini]

I'm not sure exactly, I was not involved in setting that CI up. I guess trying won't hurt?

[kinnison]

Probably wouldn't hurt, no. I'll see if I can knock up a PR to check

[kinnison]

A brief test suggests this will be a significantly bigger job than thought.

Hyper doesn't support tokio 0.3 yet. tokio 0.2 relies on mio 0.6 - mio 0.6 relies on winapi 0.2.

I believe the fixes for aarch64 didn't make it into winapi 0.2 so we'd need to fix hyper to work on tokio 0.3 (and redo our test suite with that, which is less hassle) in order to eliminate incompatible winapi deps.

[kinnison]

tokio v0.2.24
├── h2 v0.2.7
│   └── hyper v0.13.9
│       ├── hyper-rustls v0.21.0
│       │   └── reqwest v0.10.10
│       │       └── download v0.6.8 (/home/dsilvers/dev-git/rustup/download)
│       │           └── rustup v1.23.1 (/home/dsilvers/dev-git/rustup)
│       ├── hyper-tls v0.4.3
│       │   └── reqwest v0.10.10 (*)
│       └── reqwest v0.10.10 (*)
├── hyper v0.13.9 (*)
├── hyper-rustls v0.21.0 (*)
├── hyper-tls v0.4.3 (*)
├── reqwest v0.10.10 (*)
├── tokio-rustls v0.14.1
│   ├── hyper-rustls v0.21.0 (*)
│   └── reqwest v0.10.10 (*)
├── tokio-socks v0.3.0
│   └── reqwest v0.10.10 (*)
├── tokio-tls v0.3.1
│   ├── hyper-tls v0.4.3 (*)
│   └── reqwest v0.10.10 (*)
└── tokio-util v0.3.1
    └── h2 v0.2.7 (*)

[kinnison]

When tokio 1.0 releases, hyper intends to do a release: hyperium/hyper#2352 - In particular, hyperium/hyper#2352 (comment) suggests that we should wait for Tokio 1.0 to come out, then hyper will be updated for that, then presumably reqwest, and finally we can update. That might pave the way for this target.

[Alovchin91]

It should already be possible to compile it by switching the backend from reqwest to curl. I managed to compile v1.22.1 some time ago. Didn't test it though as I'd prefer to do this kind of tests in a virtual machine and I don't run Insiders build, but maybe I'm just being too cautious 🤔

[kinnison]

Given that Tokio 1.0 came out today I'm more inclined to wait and then update as described above.

[Alovchin91]

I'm not suggesting to completely switch to curl. What I'm saying is — it can already be used to test as there's probably more to it (e.g. I know for sure MSVC detection in Cargo doesn't work on Windows arm64).

[kinnison]

If you want to test it and submit patches for anything broken, then you can try building on/for aarch64 windows yourself. However if you think Cargo is broken currently, then it seems counterproductive for me to fight to sort CI builds out for a platform I cannot test at all and that you think won't work anyway, rather than to work on other things.

If you want help setting up a build then I can guide you, though it should be fairly easy to try:

$ cargo build --no-default-features --features vendored-openssl,curl-backend --target aarch64-pc-windows-msvc

at a guess.