utils: enable early swift driver on Windows #76574

+    -SwiftSDK (Get-PinnedToolchainSDK -OS $BuildPlatform.OS -Identifier "$($BuildPlatform.OS)Experimental") `
+    -BuildTargets default `
+    -Defines @{
+      BUILD_SHARED_LIBS = "NO";


As far as I understand (recalling from SwiftPM work I did last year) this is Windows specific because the swift-driver that is build with the "target" compiler is going to be placed close to the executable and that's the way how windows handles dynamic libraries (they have to be either close to the binary that uses them or on the PATH), so we have to link "host" built driver to things that are going to use it, do I understand this correctly?

I was helping Artem with new driver integration into swift-ide-test and the question is whether it's worth the trouble to maintain dynamic library for earlyswiftdriver on Linux/macOS as well (and put it in lib/swift/host/swift in the toolchain) or make it a static library as well, maybe you have thoughts?

As far as I understand (recalling from SwiftPM work I did last year) this is Windows specific because the swift-driver that is build with the "target" compiler is going to be placed close to the executable and that's the way how windows handles dynamic libraries (they have to be either close to the binary that uses them or on the PATH), so we have to link "host" built driver to things that are going to use it, do I understand this correctly?

I don't follow this. The terminology makes this challenging to follow. There are only two builds involved:

build: the machine that the build is running on

host: the machine that the product will run on

Given that this is a build tool, we know that build == host.

You are correct that Windows (amongst others) do not support RPATH and so you need to copy the DLLs to specific locations (i.e. in Path or the executable directory).

I was helping Artem with new driver integration into swift-ide-test and the question is whether it's worth the trouble to maintain dynamic library for earlyswiftdriver on Linux/macOS as well (and put it in lib/swift/host/swift in the toolchain) or make it a static library as well, maybe you have thoughts?

Windows definitely cannot support dynamic linking for the early swift-driver. The placement and Path adjustment interferes with the testing of the swift driver. That was the motivation for finally addressing the shortcoming (and the remainder of the issues like the ClangImporter, Foundation, build, etc).

The CMake build can do the full dependency tree build and avoids any type of copying. I would like to see lib/swift/host/swift removed and would think that especially for developer tools and build tools, static linking is preferable. We do not need to consider binary sizes there due to these tools being used only on the build machine and not being shipped. The performance implications of these tools is a separate concern, but again, I think that the increased memory pressure is worth the simplicity.

compnerd · 2025-07-23T16:29:31Z

swiftlang/swift-foundation#1421
swiftlang/swift-foundation-icu#66

@swift-ci please build toolchain Windows platform

compnerd · 2025-07-23T20:07:26Z

swiftlang/swift-foundation#1421
swiftlang/swift-foundation-icu#66

@swift-ci please build toolchain Windows platform

compnerd · 2025-07-24T01:24:06Z

swiftlang/swift-foundation#1421
swiftlang/swift-foundation-icu#66

@swift-ci please build toolchain Windows platform

compnerd · 2025-07-24T04:12:23Z

swiftlang/swift-foundation#1421
swiftlang/swift-foundation-icu#66

@swift-ci please build toolchain Windows platform

compnerd · 2025-07-24T06:50:35Z

swiftlang/swift-foundation#1421
swiftlang/swift-foundation-icu#66

@swift-ci please build toolchain Windows platform

The early swift-driver on Windows requires statically linking to the runtime. Update to a snapshot that is new enough to contain the static runtime with the appropriate fixes to enable building the early swift-driver.

This prepares the swift-driver building on Windows. By statically linking the runtime and its dependencies, this will allow us to avoid the runtime shuffling that is required to get the runtime required to get the swift-driver working.

Enable the use of the early swift-driver to build the Swift toolchain. This is the first step towards removing the accumulated debt and workarounds when building the toolchain on Windows.

compnerd · 2025-07-25T00:16:48Z

swiftlang/swift-foundation#1421
swiftlang/swift-foundation-icu#66

@swift-ci please build toolchain Windows platform

compnerd force-pushed the early-driver-win branch from 4f3524d to c44c098 Compare September 30, 2024 18:34

compnerd force-pushed the early-driver-win branch 3 times, most recently from 0083a3c to 808146f Compare October 3, 2024 01:13

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compnerd marked this pull request as ready for review November 14, 2024 01:25

compnerd force-pushed the early-driver-win branch from f629b58 to 503a318 Compare November 14, 2024 19:19

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Steelskin mentioned this pull request Nov 21, 2024

Early driver win #77789

Closed

compnerd force-pushed the early-driver-win branch from 13ca693 to c3001fe Compare November 25, 2024 22:33

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xedin reviewed Jul 23, 2025

View reviewed changes

compnerd force-pushed the early-driver-win branch from 2a8212e to c04d663 Compare July 23, 2025 16:16

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compnerd force-pushed the early-driver-win branch from 9b75b00 to a69b772 Compare July 24, 2025 01:20

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compnerd added 4 commits July 24, 2025 16:46

utils: build early swift-driver on Windows

89ee145

This prepares the swift-driver building on Windows. By statically linking the runtime and its dependencies, this will allow us to avoid the runtime shuffling that is required to get the runtime required to get the swift-driver working.

utils: enable the early swift-driver for Windows

a0aa12b

Enable the use of the early swift-driver to build the Swift toolchain. This is the first step towards removing the accumulated debt and workarounds when building the toolchain on Windows.

DNM: Foundation build debugging

d4db5b8

compnerd force-pushed the early-driver-win branch from 81d1a52 to d4db5b8 Compare July 25, 2025 00:16

utils: enable early swift driver on Windows #76574

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utils: enable early swift driver on Windows #76574

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