docker nightly images are missing Visual Studio

[czechboy0]

Description

error: 'errno.h' file not found in Windows nightly-main introduced on Aug 6, 2025.

C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Platforms\0.0.0\Windows.platform\Developer\SDKs\Windows.sdk\usr\lib\swift\shims\LibcOverlayShims.h:27:10: error: 'errno.h' file not found

This morning we got a new failure in Swift OpenAPI Generator's nightly CI, on Windows, nightly-main toolchain: https://github.com/apple/swift-openapi-generator/actions/runs/16760157537/job/47453097021. It passed the day before (https://github.com/apple/swift-openapi-generator/actions/runs/16744400715).

Reproduction

See the CI result: https://github.com/apple/swift-openapi-generator/actions/runs/16760157537/job/47453097021

It runs swift test --explicit-target-dependency-import-check error of the Swift OpenAPI Generator repo.

The project is also part of the Swift compat suite: https://github.com/swiftlang/swift-source-compat-suite/blob/3bd87039a7f566a653b4a8572d6f21ba0a5c710f/projects.json#L3776, but it seems Windows isn't being run there yet.

Expected behavior

The CI would keep passing.

Environment

Swift version 6.2-dev (LLVM e8174df1120add3, Swift 051d0b6)
Target: x86_64-unknown-windows-msvc
Build config: +assertions
Image: swiftlang/swift:nightly-main-windowsservercore-ltsc2022

Additional information

No response

[compnerd]

This is a docker issue, not a toolchain issue. Please verify by building a custom image with the toolchain.

[czechboy0]

Unfortunately I don't have a dev environment available where I could do that. It's possible it's a regression in the Docker image build, I just filed it the same day it regressed, so hopefully it'll be easy to revert the change that broke it?

Feel free to transfer the issue to the Docker image tooling repo, as well.

[bnbarham]

Should be fixed by swiftlang/swift-docker#491 - the latest build tools no longer include Windows11SDK.22000, we've pinned to an earlier for now.