CI: Add build check for WebAssembly SDK

[kateinoigakukun]

Add build check CI for WebAssembly SDK

Motivation:

It's very difficult to keep the code with WebAssembly/WASI compatible, and we need to apply some fixes sometimes #3156

Modifications:

Added a job to check if swift build --swift-sdk wasm32-unknown-wasi passes.

Result:

Setting up the CI job makes it easier to detect such incompatibility before merging.

[FranzBusch]

We sadly cannot accept this PR at this time. Currently WASM is not an officially supported platform by Swift and there is no official toolchain for it. This is something for the Platforms Steering Group to address. Once both issues have been solved we would love to add CI for WASM. cc @al45tair

[kateinoigakukun]

Thanks for sharing! That's a good motivation to make it official :)

[scottmarchant]

We sadly cannot accept this PR at this time. Currently WASM is not an officially supported platform by Swift…

@FranzBusch Curious what your thoughts are about allowing wasm builds into swif-nio, but as optional actions rather than required?

This would improve visibility on wasm breakages without imposing a requirement for official support. Right now, contributors are likely a bit blind to any wasm breakages. If there is a way to improve awareness without imposing extra burden on contributors, feels like a win-win.

I believe we could make it optional by adding the following config to wasm-sdk here.

continue-on-error: true

[scottmarchant]

cc @MaxDesiatov in case you have any insight on this as well.

[FranzBusch]

@FranzBusch Curious what your thoughts are about allowing wasm builds into swif-nio, but as optional actions rather than required?

I'm fully empathetic on making sure we are not breaking WASM support. However, at this point we just can't use an externally produced toolchain here. That's why I would like to push the Platforms Steering Group on considering WASM as an official platform so that we can start producing official toolchains that we can use in our CI.

[scottmarchant]

One more data point on this topic, currently swiftlang/swift has at least some wasm CI visibility. It doesn't look like it is a requirement in Pull Requests. But the wasm build status for swift is reported prominently on the repository welcome page.

[al45tair]

It doesn't look like it is a requirement in Pull Requests.

It might not look like it, but actually the Linux PR tests do do some WASM testing, and it is required to pass.

[MaxDesiatov]

6.2 and main snapshots now have corresponding Swift SDKs distributed on swift.org https://www.swift.org/install/

[scottmarchant]

@kateinoigakukun This is awesome, thanks so much!

[kateinoigakukun]

I updated the workflow to use Swift SDK for WebAssembly distributed from swift.org. Here is a successful job in my fork: https://github.com/kateinoigakukun/swift-nio/actions/runs/16553038350/job/46810622526

[rnro]

This change looks good in general thank you! I'd like to see Max's suggestions merged but other than that it looks good. Apologies, I spotted far too late that the testing changes I commented on were in a separate PR; nevertheless that does need to be backed out before we can merge this.

[kateinoigakukun]

Ok, I applied the wording suggestions and reverted the test commit

[rnro]

@FranzBusch Do you continue to have reservations about this PR?

[FranzBusch]

Nope this looks awesome to me! Thanks for the work

[rnro]

Invalid workflow file: .github/workflows/pull_request.yml#L96
error parsing called workflow
".github/workflows/pull_request.yml"
-> "apple/swift-nio/.github/workflows/wasm_sdk.yml@main"
: failed to fetch workflow: workflow was not found.

I think we'll have to merge the re-usable workflow in one PR and then enable it in pull_request.yml and main.yml in a separate one sorry. Thanks so much for contributing this.

[kateinoigakukun]

@rnro I just split this out into two PRs to merge changes gracefully

• [wasm][1/2] Add reusable WebAssembly workflow #3331
• [wasm][2/2] Include WebAssembly SDK checks in PR and main workflows #3332