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build: Windows bootstrapping support#88775

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compnerd merged 25 commits into
swiftlang:mainfrom
compnerd:bootstrapping
May 26, 2026
Merged

build: Windows bootstrapping support#88775
compnerd merged 25 commits into
swiftlang:mainfrom
compnerd:bootstrapping

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@compnerd

@compnerd compnerd commented May 1, 2026

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  • 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 compnerd requested a review from a team as a code owner May 1, 2026 06:15
@compnerd compnerd marked this pull request as draft May 1, 2026 06:15
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compnerd commented May 1, 2026

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@swift-ci please test Windows platform

DougGregor
DougGregor approved these changes May 1, 2026
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Thank you!

@compnerd

compnerd commented May 1, 2026

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@swift-ci please smoke test windows platform

@compnerd

compnerd commented May 3, 2026

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@swift-ci please test windows platform

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

compnerd commented May 6, 2026

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@swift-ci please test Windows platform

@compnerd

compnerd commented May 7, 2026

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@swift-ci please test Windows platform

1 similar comment
@compnerd

compnerd commented May 7, 2026

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@swift-ci please test Windows platform

@compnerd

compnerd commented May 7, 2026

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@swift-ci please test Windows platform

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

compnerd commented May 8, 2026

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@swift-ci please test Windows platform

@compnerd

compnerd commented May 8, 2026

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@swift-ci please test Windows platform

@compnerd

compnerd commented May 9, 2026

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@swift-ci please test Windows platform

@compnerd

compnerd commented May 10, 2026

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@swift-ci please smoke test Windows platform

@compnerd compnerd marked this pull request as ready for review May 11, 2026 12:50
@compnerd
utils: bind staged Windows tools to private SxS runtimes
a4c76ff 
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

compnerd commented May 21, 2026

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@swift-ci please test Windows platform

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compnerd commented May 21, 2026

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

@swift-ci please build toolchain Windows platform

compnerd and others added 6 commits May 21, 2026 16:07
@compnerd
utils: bind Stage2 test tools to the SDK runtime
7249c26 
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.
@compnerd
utils: use staged toolchain inputs for package tests
c68327f 
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.
@compnerd
test: Use host SDK resources for Windows host-build-swift
fc6d841 
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.
@compnerd
cmake: reuse prebuilt libdispatch package
604bc52 
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.
@compnerd
build: avoid compiler-local libdispatch builds
3c71b48 
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.
@compnerd
Runtimes: propagate SwiftRT objects via swiftCore
e86c870 
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

compnerd commented May 21, 2026

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

@swift-ci please build toolchain Windows platform

@compnerd

compnerd commented May 21, 2026

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

@swift-ci please test Windows platform

@compnerd

compnerd commented May 22, 2026

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

@swift-ci please test Windows platform

@compnerd

compnerd commented May 22, 2026

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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

compnerd commented May 22, 2026

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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

compnerd commented May 22, 2026

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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

compnerd commented May 23, 2026

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

@swift-ci please build toolchain Windows platform

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@compnerd

compnerd commented May 23, 2026

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

@swift-ci please build toolchain Windows platform

@compnerd

compnerd commented May 23, 2026

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

@swift-ci please build toolchain Windows platform

DougGregor
DougGregor approved these changes May 23, 2026
View reviewed changes
Comment thread test/CMakeLists.txt
Comment thread utils/windows-clang-overrides.cmake
@compnerd

compnerd commented May 26, 2026

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

@swift-ci please build toolchain Windows platform

@compnerd compnerd merged commit 44f0fb0 into swiftlang:main May 26, 2026
3 of 4 checks passed
@compnerd compnerd deleted the bootstrapping branch May 26, 2026 15:40
@tshortli

tshortli commented May 27, 2026

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

@compnerd

compnerd commented May 27, 2026

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@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.

@ktoso

ktoso commented Jun 1, 2026 •
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Seeing a lot of CI failures after this landed:

Also

@compnerd

@finagolfin

finagolfin commented Jun 1, 2026 •
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We've been discussing the second one, I think it should be fixed by #89599.

This was referenced Jun 17, 2026
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