build: Windows bootstrapping support by compnerd · Pull Request #88775 · swiftlang/swift

compnerd · 2026-05-01T06:15:38Z

Explanation: Setup a bootstrapped compiler on Windows
Scope: Enable a multi-stage bootstrap for Windows to get a compiler able to be used for bootstrapping
Issues:
Risk: medium risk; this changes the entire toolchain build on Windows
Testing:

compnerd · 2026-05-01T06:16:02Z

@swift-ci please test Windows platform

DougGregor

Thank you!

compnerd · 2026-05-01T18:10:48Z

@swift-ci please smoke test windows platform

compnerd · 2026-05-03T20:30:46Z

@swift-ci please test windows platform

compnerd · 2026-05-06T23:00:07Z

@swift-ci please test Windows platform

compnerd · 2026-05-07T05:23:08Z

@swift-ci please test Windows platform

compnerd · 2026-05-07T06:00:05Z

@swift-ci please test Windows platform

compnerd · 2026-05-07T19:39:35Z

@swift-ci please test Windows platform

compnerd · 2026-05-08T06:50:55Z

@swift-ci please test Windows platform

compnerd · 2026-05-08T23:19:12Z

@swift-ci please test Windows platform

compnerd · 2026-05-09T18:47:33Z

@swift-ci please test Windows platform

compnerd · 2026-05-10T03:55:40Z

@swift-ci please smoke test Windows platform

When CMake configures Android builds, it may auto-detect the NDK clang as the target compiler. Sending that compiler through clang-cache.exe from the staged Windows toolchain can mix LLVM versions. That version skew makes dependency scanning look for builtin headers in the wrong resource directory. Skip the launcher for Android SDK builds while keeping caching for paths that use the staged compiler directly.

The staged compiler table carries MSVC-style clang-cl entries in .C/.CXX and GNU-style clang entries in .GNUC/.GNUCXX. Select the GNU drivers for non-Windows SDK dependencies, compiler-rt, and dispatch so Android builds do not receive MSVC-only flags such as /GS- and /Gw.

Build Android swift-inspect with a target-aware compiler view that exposes the stage1 GNU clang drivers under .C/.CXX. This keeps the NDK clang from seeing MSVC-style flags while still using the stage1 Swift compiler and Android SDK.

Add Set-WindowsManifestDependencies to merge dependency entries into an embedded manifest and re-embed it with mt. This gives later SxS binding steps a shared path for binding tools without replacing unrelated manifest content.

Stage each Swift runtime DLL needed by the laid-out toolchain as a private per-DLL SxS assembly under usr/bin. Compute each EXE's static import graph and write the full Swift runtime closure into the EXE's application manifest. Disable linker-generated DLL manifests for Swift's CMake-built DLLs and for the mimalloc MSBuild project, then validate existing DLL manifest resources before binding: reject UAC execution-level metadata and unexpected reserved RT_MANIFEST resource IDs so implicit linker manifests cannot poison SxS activation. Keep the checked-in WiX authoring canonical and warn when the live import graph drifts from bld/cli/dbg/ide package ownership.

compnerd · 2026-05-21T15:45:19Z

@swift-ci please test Windows platform

compnerd · 2026-05-21T15:50:13Z

@swift-ci please test with following PRs:
swiftlang/swift-installer-scripts#524

@swift-ci please build toolchain Windows platform

Build the Stage2 test-time tools needed by check-swift before the final test build. Bind the runtime-loading EXEs to the platform SDK runtime they are tested against. Use the build-host architecture so host-run tools remain runnable when the final toolchain target differs. Keep this separate from the distribution SxS pass because these tools execute from the build tree.

Run the dispatch, XCTest, and llbuild test builds with the Stage1 compiler artifacts instead of the legacy Compilers cache. The swift-format and SourceKit-LSP SwiftPM tests also need SwiftSyntax from the Stage2 compiler build, matching the CMake build rules for those projects. Use the Stage2 host library path there and fix the stale swift-markdown CAtomic include path in the SourceKit-LSP test arguments.

When %host-build-swift builds plugin DLLs on Windows, those DLLs are loaded by the compiler under test. Pass the configured host SDK and resource directory so the plugins link against the runtime that compiler will load instead of the Stage2 stdlib resources.

Allow non-Darwin compiler builds to consume an already-built libdispatch package instead of always creating a nested ExternalProject. When dispatch_DIR is set, import the dispatch package and use it for the host SDK dispatch target. Continue building libdispatch for other non-Darwin target SDKs so cross-compilation still gets target-specific dispatch variants.

Disable dispatch in the Windows bootstrap compiler caches. Stage0 and Stage1 do not build SourceKit or the runtime SDK, so they do not need Swift's Libdispatch.cmake path to configure nested libdispatch ExternalProjects. Keep passing the staged DynamicCDispatch package to the Stage2 compiler build, where SourceKit and tool components still need host dispatch. Drop the Stage0CDispatch build and stop feeding dispatch packages to Stage0 and Stage1.

Runtime clients of swiftCore need the SwiftRT image-registration object on their link lines. On COFF this object supplies pSwiftImageConstructor and the .sw5* section range symbols used to register Swift metadata and conformances for each image. CMake propagates usage requirements when an OBJECT library appears in an INTERFACE_LINK_LIBRARIES chain, but it does not add that object's payload to the final consumer link line. Keep the swiftrt targets in the interface for their usage requirements, and explicitly propagate their object files with TARGET_OBJECTS.

compnerd · 2026-05-21T23:39:39Z

@swift-ci please test with following PRs:
swiftlang/swift-installer-scripts#524

@swift-ci please build toolchain Windows platform

compnerd · 2026-05-21T23:39:45Z

@swift-ci please test with following PRs:
swiftlang/swift-installer-scripts#524

@swift-ci please test Windows platform

compnerd · 2026-05-22T16:11:28Z

Please test with following PRs:
swiftlang/llvm-project#13046
swiftlang/swift-installer-scripts#524

@swift-ci please test Windows platform

compnerd · 2026-05-22T18:33:29Z

Please test with following PRs:
swiftlang/llvm-project#13046
swiftlang/swift-installer-scripts#524
swiftlang/sourcekit-lsp#2664

@swift-ci please build toolchain Windows platform

compnerd · 2026-05-22T18:33:46Z

Please test with following PRs:
swiftlang/llvm-project#13046
swiftlang/swift-installer-scripts#524
swiftlang/sourcekit-lsp#2664

@swift-ci please smoke test macOS platform

compnerd · 2026-05-22T18:33:54Z

Please test with following PRs:
swiftlang/llvm-project#13046
swiftlang/swift-installer-scripts#524
swiftlang/sourcekit-lsp#2664

@swift-ci please smoke test Linux platform

compnerd · 2026-05-23T02:01:13Z

Please test with following PRs:
swiftlang/llvm-project#13046
swiftlang/swift-installer-scripts#524

@swift-ci please build toolchain Windows platform

compnerd · 2026-05-23T06:29:32Z

Please test with following PRs:
swiftlang/llvm-project#13046
swiftlang/swift-installer-scripts#524

@swift-ci please build toolchain Windows platform

compnerd · 2026-05-23T18:19:53Z

Please test with following PRs:
swiftlang/llvm-project#13046
swiftlang/swift-installer-scripts#524

@swift-ci please build toolchain Windows platform

compnerd · 2026-05-26T15:28:38Z

Please test with following PRs:
swiftlang/swift-installer-scripts#524

@swift-ci please build toolchain Windows platform

tshortli · 2026-05-27T14:58:45Z

@compnerd Merging this without swiftlang/llvm-project#13046 or swiftlang/llvm-project#13069 broke PR testing for Windows

compnerd · 2026-05-27T15:44:09Z

@compnerd Merging this without swiftlang/llvm-project#13046 or swiftlang/llvm-project#13069 broke PR testing for Windows

That showed up later - the LLDB tests have been painful and constantly regressing as people keep adding new tests with long names. There was a second patch that @adrian-prantl had committed to shorten the names I believe.

compnerd requested a review from a team as a code owner May 1, 2026 06:15

compnerd marked this pull request as draft May 1, 2026 06:15

DougGregor approved these changes May 1, 2026

View reviewed changes

compnerd force-pushed the bootstrapping branch from f2ca291 to a96794e Compare May 3, 2026 19:37

compnerd force-pushed the bootstrapping branch 4 times, most recently from ce6e7d1 to 587b830 Compare May 6, 2026 22:58

compnerd force-pushed the bootstrapping branch from 587b830 to acec09d Compare May 7, 2026 05:22

compnerd force-pushed the bootstrapping branch from acec09d to 1044859 Compare May 7, 2026 19:39

compnerd force-pushed the bootstrapping branch 2 times, most recently from 67e6ba6 to c3f6aa1 Compare May 8, 2026 06:50

compnerd force-pushed the bootstrapping branch from b5f9f24 to a66a0ab Compare May 8, 2026 23:18

compnerd force-pushed the bootstrapping branch from a66a0ab to 26d995e Compare May 9, 2026 18:47

compnerd force-pushed the bootstrapping branch from 26d995e to 09040e5 Compare May 10, 2026 03:55

compnerd marked this pull request as ready for review May 11, 2026 12:50

compnerd requested review from edymtt, etcwilde and justice-adams-apple as code owners May 11, 2026 12:50

compnerd and others added 5 commits May 21, 2026 08:44

utils: pass GNU drivers to Android swift-inspect

fc7c61c

Build Android swift-inspect with a target-aware compiler view that exposes the stage1 GNU clang drivers under .C/.CXX. This keeps the NDK clang from seeing MSVC-style flags while still using the stage1 Swift compiler and Android SDK.

utils: add Windows manifest dependency helper

5450656

Add Set-WindowsManifestDependencies to merge dependency entries into an embedded manifest and re-embed it with mt. This gives later SxS binding steps a shared path for binding tools without replacing unrelated manifest content.

compnerd force-pushed the bootstrapping branch from 6aac73a to ab42791 Compare May 21, 2026 15:44

compnerd and others added 6 commits May 21, 2026 16:07

compnerd force-pushed the bootstrapping branch from ab42791 to e86c870 Compare May 21, 2026 23:38

DougGregor approved these changes May 23, 2026

View reviewed changes

Comment thread test/CMakeLists.txt

Comment thread utils/windows-clang-overrides.cmake

compnerd merged commit 44f0fb0 into swiftlang:main May 26, 2026
3 of 4 checks passed

compnerd deleted the bootstrapping branch May 26, 2026 15:40

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