Skip to content

Have the frontend and new swift-driver look in an external -sdk for non-Darwin platform runtime libraries and modules too #79621

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Draft
wants to merge 1 commit into
base: main
Choose a base branch
from

Conversation

finagolfin
Copy link
Member

as done originally in #25990 with the legacy C++ Driver, but since lost in the new swift-driver

This is another attempt to fix swiftlang/swift-driver#1562 and avoid the various workarounds that have been put in elsewhere to spackle over this root cause.

This worked for me with the compiler validation suite running natively on an Android device, with the exception of one SourceKit test. Let's run it through all the platforms on the CI before explaining fully what it's doing and adding a test to make sure it doesn't regress.

@finagolfin
Copy link
Member Author

@swift-ci please test

@finagolfin
Copy link
Member Author

swiftlang/swift-driver#1822
@swift-ci please test linux

1 similar comment
@finagolfin
Copy link
Member Author

swiftlang/swift-driver#1822
@swift-ci please test linux

FrontendOpts.UseSharedResourceFolder ? "swift" : "swift_static",
getPlatformNameForTriple(Triple));
// Check for eg <sdkRoot>/usr/lib/swift/linux/
if (llvm::sys::fs::exists(SDKResourcePath)) {
Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I initially tried simply checking if <sdkRoot>/usr/lib/swift/, ie a Swift resource directory, existed, but around 100 tests from the compiler validation suite failed with that, as they pass in a separate -sdk that simply has a Swift resource directory with a few different API notes or something, but does not contain the platform-specific files needed in <sdkRoot>/usr/lib/swift/<os>/. Actually checking for this OS-specific directory makes sure the Swift resource directory in -sdk contains the required platform-specific modules and libraries, and falls back to the Swift resource directory in the toolchain itself otherwise. However, that implies mixing and matching files from two different Swift resource directories, so maybe it will be better to enforce that only one Swift resource directory is used and modify all those tests instead?

For an example of such mixing already taking place, the Windows CI failed with this pull, right before trying to compile the trunk Foundation macros for the Windows host:

-- Check for working Swift compiler: T:/5/bin/swiftc.exe - broken
CMake Error at C:/Program Files/CMake/share/cmake-3.29/Modules/CMakeTestSwiftCompiler.cmake:40 (message):
  The Swift compiler

    "T:/5/bin/swiftc.exe"

  is not able to compile a simple test program.

  It fails with the following output:

    Change Dir: 'T:/x86_64-unknown-windows-msvc/FoundationMacros/CMakeFiles/CMakeScratch/TryCompile-6u6j6e'
    
    Run Build Command(s): C:/PROGRA~1/MICROS~2/2022/COMMUN~1/Common7/IDE/COMMON~1/MICROS~1/CMake/Ninja/ninja.exe -v cmTC_bc87d
    [1/2][ 50%][0.084s] T:\5\bin\swiftc.exe -target x86_64-unknown-windows-msvc -j 36 -num-threads 36 -c  -module-name cmTC_bc87d -sdk T:/toolchains/swift-6.0.3-RELEASE-windows10/LocalApp/Programs/Swift/Platforms/6.0.3/Windows.platform/Developer/SDKs/Windows.sdk -gnone -Xlinker /INCREMENTAL:NO -Xlinker /OPT:REF -Xlinker /OPT:ICF  -incremental -output-file-map CMakeFiles\cmTC_bc87d.dir\\output-file-map.json  T:\x86_64-unknown-windows-msvc\FoundationMacros\CMakeFiles\CMakeScratch\TryCompile-6u6j6e\main.swift
    FAILED: CMakeFiles/cmTC_bc87d.dir/main.swift.obj 
    T:\5\bin\swiftc.exe -target x86_64-unknown-windows-msvc -j 36 -num-threads 36 -c  -module-name cmTC_bc87d -sdk T:/toolchains/swift-6.0.3-RELEASE-windows10/LocalApp/Programs/Swift/Platforms/6.0.3/Windows.platform/Developer/SDKs/Windows.sdk -gnone -Xlinker /INCREMENTAL:NO -Xlinker /OPT:REF -Xlinker /OPT:ICF  -incremental -output-file-map CMakeFiles\cmTC_bc87d.dir\\output-file-map.json  T:\x86_64-unknown-windows-msvc\FoundationMacros\CMakeFiles\CMakeScratch\TryCompile-6u6j6e\main.swift
    <unknown>:0: warning: using (deprecated) legacy driver, Swift installation does not contain swift-driver at: 'C:\Users\swift-ci\jenkins\workspace\swift-PR-windows\build\5\bin\swift-driver-new.exe'
    <unknown>:0: warning: option '-incremental' is only supported in swift-driver
    <unknown>:0: error: module compiled with Swift 6.0.3 cannot be imported by the Swift 6.2 compiler: T:/toolchains/swift-6.0.3-RELEASE-windows10/LocalApp/Programs/Swift/Platforms/6.0.3/Windows.platform/Developer/SDKs/Windows.sdk\usr\lib\swift\windows\Swift.swiftmodule\x86_64-unknown-windows-msvc.swiftmodule

    ninja: build stopped: subcommand failed.

The issue appears to be that they're trying to build the trunk Foundation macros with the freshly-built trunk 6.2 Swift compiler, but passing in a Swift 6.0.3 SDK with -sdk T:/toolchains/swift-6.0.3-RELEASE-windows10/LocalApp/Programs/Swift/Platforms/6.0.3/Windows.platform/Developer/SDKs/Windows.sdk to build it. The trunk Swift 6.2 compiler then quietly ignores that 6.0.3 Swift resource directory and likely uses the 6.2 Swift resource directory next to the toolchain instead. This pull, by enforcing that the Swift resource directory in the 6.0.3 -sdk that is passed in is used because <6.0.3-sdkRoot>/usr/lib/swift/windows/ exists, then fails because the 6.0.3 modules cannot be used with the trunk Swift 6.2 compiler.

@weliveindetail, do you know if that's merely a configuration mistake when building the Foundation and Testing macros on the Windows CI, which should be easily fixed, or something more complicated?

@@ -2258,6 +2259,18 @@ static bool ParseSearchPathArgs(SearchPathOptions &Opts, ArgList &Args,

if (const Arg *A = Args.getLastArg(OPT_resource_dir))
Opts.RuntimeResourcePath = A->getValue();
else if (!Triple.isOSDarwin() && Args.hasArg(OPT_sdk)) {
Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This code explicitly follows what the original C++ Driver has long done when looking for the Swift runtime libraries, swiftrt.o, and a few other files found in the Swift resource directory:

if (const Arg *A = args.getLastArg(options::OPT_resource_dir)) {
    StringRef value = A->getValue();
    resourceDirPath.append(value.begin(), value.end());
  } else if (!getTriple().isOSDarwin() && args.hasArg(options::OPT_sdk)) {
    StringRef value = args.getLastArg(options::OPT_sdk)->getValue();
    resourceDirPath.append(value.begin(), value.end());
    llvm::sys::path::append(resourceDirPath, "usr");
    CompilerInvocation::appendSwiftLibDir(resourceDirPath, shared);
  } else {
    auto programPath = getDriver().getSwiftProgramPath();
    CompilerInvocation::computeRuntimeResourcePathFromExecutablePath(
        programPath, shared, resourceDirPath);
  }

Note how the SDK is only looked in if a non-Darwin -sdk is explicitly specified: Saleem later tried to expand that to Darwin also in #26361, but he may have never got it to work.

That C++ Driver setup now matches this Frontend setup, because the default in both is now to look relative to the compiler, which is done first in this Frontend here, ie usr/bin/../lib/swift/. If a -resource-dir is set, that is given first priority, then a non-Darwin -sdk is given second priority, ie the C++ Driver and the Frontend now match in where they look.

This is important for two reasons:

  1. The new swift-driver simply queries the Frontend and uses whatever Swift resource directory it uses, so now the new swift-driver finally matches the original C++ Driver's behavior, and piecemeal workarounds like that in [Unix] Go back to only checking the runtime resource path for swiftrt.o swift-driver#1822 can now be eliminated.
  2. The Frontend will now look in the same Swift resource directory for stdlib/corelibs swiftmodules as the swift-driver is looking for runtime libraries and swiftrt.o, eliminating any confusion between the two by centralizing the Swift resource directory lookup here. That already found one bug in the Windows CI, see my other code comment.

However, unlike the C++ Driver, my -sdk code below actually checks if the -sdk path contains a Swift resource directory for the platform triple and does not use the -sdk for this if not, falling back to the aforementioned default next to the compiler in that case. This is because an -sdk is not guaranteed to have a Swift resource directory and may have only a C/C++ sysroot.

We should probably tighten this up to require an explicit -sdk to have a Swift resource directory, with the only exception when an explicit -resource-dir is also specified, but I'm open to debate here. The C++ Driver doesn't even check if the non-Darwin -sdk has a Swift resource directory and simply assumes one is there, we can do a bit better than that.

@finagolfin
Copy link
Member Author

Alright, this tiny pull and the resulting swiftlang/swift-driver#1822 cleanup now pass the linux CI, have no effect on Darwin, and found a seeming bug in the Windows CI. I'm going to test this more in comparison to the C++ Driver and examine more tests to see if I can use it to flush out more cross-compilation bugs with an explicit non-Darwin -sdk.

In the meantime, the basic functionality works and is ready for review. I will add tests once the few remaining smaller design choices mentioned above are hammered out.

@artemcm, @etcwilde, and @compnerd, please take a look: I'm looking for feedback on both this current patch and the remaining issues and questions in my detailed comments above.

@finagolfin finagolfin marked this pull request as ready for review February 27, 2025 09:44
@finagolfin
Copy link
Member Author

swiftlang/swift-driver#1827
@swift-ci please build toolchain

@finagolfin
Copy link
Member Author

swiftlang/swift-driver#1827
@swift-ci please test source compatibility

@finagolfin
Copy link
Member Author

Is there anything preventing this PR from being marked ready for review?

This needs some tests fixed and a build script update to pass the CI, plus some discussion if the warning and falling back is the best approach. I plan to get that done in the next week.

Is it blocked by swiftlang/swift-driver#1822?

No, as noted there, "ready to go, a partial revert of swiftlang/swift-driver#1667, independent of the linked changes in #79621." That swift-driver pull alone fixes the bug you've run into with using external C/C++ SDKs with SDK bundles, you don't need this one.

This pull simply tries to implement setting the location of the Swift resource path correctly, but given how buggy that has been in the past, warrants some discussion on how we want to finally approach it.

@finagolfin
Copy link
Member Author

@swift-ci smoke test

@finagolfin
Copy link
Member Author

@swift-ci smoke test linux

@finagolfin
Copy link
Member Author

@swift-ci smoke test

1 similar comment
@finagolfin
Copy link
Member Author

@swift-ci smoke test

@finagolfin
Copy link
Member Author

@swift-ci smoke test

@finagolfin
Copy link
Member Author

@swift-ci smoke test

@finagolfin
Copy link
Member Author

@swift-ci smoke test macos

@finagolfin
Copy link
Member Author

@swift-ci smoke test macos

@finagolfin
Copy link
Member Author

@swift-ci smoke test windows

@finagolfin
Copy link
Member Author

@swift-ci smoke test

@finagolfin
Copy link
Member Author

@compnerd, getting close to the finish line with this pull, with the macOS CI passing and the linux CI almost there, looking into those last few test failures. However, the Windows CI fails when building DynamicFoundation, because it now gets confused between the Dispatch in the prebuilt Windows SDK and the freshly built one:

T:\Program Files\Swift\Platforms\Windows.platform\Developer\SDKs\Windows.sdk\usr\lib\swift\dispatch\module.modulemap:1:8: error: redefinition of module 'Dispatch'
 1 | module Dispatch {
   |        `- error: redefinition of module 'Dispatch'
 2 | 	requires blocks
 3 | 	export *

C:\Users\swift-ci\jenkins\workspace\swift-PR-windows\swift-corelibs-libdispatch\dispatch\module.modulemap:1:8: note: previously defined here
 1 | module Dispatch {
   |        `- note: previously defined here
 2 | 	requires blocks
 3 | 	export *

The failing command is

"C:\\Users\\swift-ci\\jenkins\\workspace\\swift-PR-windows\\build\\5\\bin\\swiftc.exe" -frontend -c -filelist "T:\\tmp\\sources-c87a7a" -primary-file "C:\\Users\\swift-ci\\jenkins\\workspace\\swift-PR-windows\\swift-corelibs-foundation\\Sources\\Foundation\\Measurement.swift" -emit-module-path "Sources\\Foundation\\CMakeFiles\\Foundation.dir\\Measurement.swift.swiftmodule" -emit-module-doc-path "Sources\\Foundation\\CMakeFiles\\Foundation.dir\\Measurement.swift.swiftdoc" -emit-module-source-info-path "Sources\\Foundation\\CMakeFiles\\Foundation.dir\\Measurement.swift.swiftsourceinfo" -target x86_64-unknown-windows-msvc -disable-objc-interop -sdk "T:/Program Files/Swift/Platforms/Windows.platform/Developer/SDKs/Windows.sdk" -I "T:\\x86_64-unknown-windows-msvc\\DynamicFoundation\\swift" -I "C:\\Users\\swift-ci\\jenkins\\workspace\\swift-PR-windows\\swift-corelibs-foundation\\Sources\\CoreFoundation\\include" -I "C:\\Users\\swift-ci\\jenkins\\workspace\\swift-PR-windows\\swift-foundation\\Sources\\_FoundationCShims\\include" -I "C:\\Users\\swift-ci\\jenkins\\workspace\\swift-PR-windows\\swift-foundation-icu\\icuSources\\include" -I "T:\\x86_64-unknown-windows-msvc\\Dispatch\\src\\swift\\swift" -I "T:\\x86_64-unknown-windows-msvc\\Dispatch" -I "C:\\Users\\swift-ci\\jenkins\\workspace\\swift-PR-windows\\swift-corelibs-libdispatch" -I "C:\\Users\\swift-ci\\jenkins\\workspace\\swift-PR-windows\\swift-corelibs-libdispatch\\src" -I "T:\\x86_64-unknown-windows-msvc\\Dispatch\\src" -I "C:\\Users\\swift-ci\\jenkins\\workspace\\swift-PR-windows\\swift-corelibs-libdispatch\\src\\BlocksRuntime" -vfsoverlay T:/x86_64-unknown-windows-msvc/Dispatch/dispatch-vfs-overlay.yaml -gnone -module-link-name Foundation -swift-version 6 -O -D Foundation_EXPORTS -D DEPLOYMENT_RUNTIME_SWIFT -D SWIFT_CORELIBS_FOUNDATION_HAS_THREADS -require-explicit-sendable -in-process-plugin-server-path "C:\\Users\\swift-ci\\jenkins\\workspace\\swift-PR-windows\\build\\5\\bin\\SwiftInProcPluginServer.dll" -plugin-path "C:\\Users\\swift-ci\\jenkins\\workspace\\swift-PR-windows\\build\\5\\bin" -Xcc -v -Xcc -fmodule-map-file=C:/Users/swift-ci/jenkins/workspace/swift-PR-windows/swift-corelibs-foundation/Sources/CoreFoundation/include/module.modulemap -Xcc -fmodule-map-file=C:/Users/swift-ci/jenkins/workspace/swift-PR-windows/swift-foundation/Sources/_FoundationCShims/include/module.modulemap -Xcc -fmodule-map-file=C:/Users/swift-ci/jenkins/workspace/swift-PR-windows/swift-foundation-icu/icuSources/include/_foundation_unicode/module.modulemap -autolink-library oldnames -autolink-library msvcrt -Xcc -D_MT -Xcc -D_DLL -parse-as-library -module-name Foundation -num-threads 36 -o "Sources\\Foundation\\CMakeFiles\\Foundation.dir\\Measurement.swift.obj"

with the -sdk "T:/Program Files/Swift/Platforms/Windows.platform/Developer/SDKs/Windows.sdk" flag likely now causing the problem after this pull, as the Swift frontend now actually uses the Swift resource directory at T:/Program Files/Swift/Platforms/Windows.platform/Developer/SDKs/Windows.sdk/usr/lib/swift whereas before it was likely silently ignored.

Since a fresh Swift SDK build on the CI doesn't need an old Windows.sdk's Swift runtime resources to build fresh corelibs, should build.ps1 be modified to pass -sysroot "T:/Program Files/Swift/Platforms/Windows.platform/Developer/SDKs/Windows.sdk" instead, so C/C++ Windows headers from that path can still be found? Let me know how we should remedy this build failure for Windows.

@compnerd
Copy link
Member

compnerd commented Aug 5, 2025

No, -sysroot is not the right flag, -sysroot would point to the VC Runtime directory. I think that we need to figure out how to make this work with the changes.

@finagolfin
Copy link
Member Author

OK, do you need any C/C++ headers or libraries from that Windows.sdk/ path to build Foundation? We can always pass them in using -I/-L when building fresh trunk corelibs like Foundation, if needed.

@finagolfin
Copy link
Member Author

@swift-ci smoke test linux

… non-Darwin platform runtime libraries and modules too

as done originally in swiftlang#25990 with the legacy C++ Driver, but since lost in the new swift-driver. Only difference
is this checks if a Swift resource directory exists in `-sdk` and falls back to the default if not.
@finagolfin
Copy link
Member Author

@swift-ci test

@finagolfin
Copy link
Member Author

Finally passed linux CI, but one mac test now regressed and still need to fix Windows build.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
None yet
Projects
None yet
Development

Successfully merging this pull request may close these issues.

This driver no longer looks in a passed-in -sdk for the Swift modules and libraries
3 participants