[cxx-interop] Enabling C++ interop leads to linking errors with URL.bookmark()

[hyp]

As reported here: https://forums.swift.org/t/undefined-symbol-when-using-c-interop-and-url-bookmark/65444

[hyp]

@plotfi could you check this one out?

[plotfi]

@plotfi could you check this one out?

yeah I was already looking at it, thanks @hyp.

So far I can't seem to repro it with a standalone compiler, but I will try the xcode project.

[plotfi]

Good news, @hyp I have gotten the xcode project to repro. Just gotta extract the clang invocations and see if they repro on the latest main toolchain.

[plotfi]

Made a little bit of progress, minimized the test case:

///   ContentView.swift

import Foundation

public struct ContentView {
    public init() {
        let url = URL(string: "https://foo.bar")!
        print(url)

        try? url.bookmarkData()
    }
}

/Applications/Xcode-beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift-frontend \
  -frontend -c \
  -target arm64-apple-ios17.0-simulator \
  -sdk /Applications/Xcode-beta.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator17.0.sdk \
  -enable-objc-interop \
  -cxx-interoperability-mode=default \
  -o ContentView.o  \
  ContentView.swift

/Applications/Xcode-beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ld \
  -syslibroot /Applications/Xcode-beta.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator17.0.sdk \
-o a.out \
-L/Applications/Xcode-beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator \
-L/usr/lib/swift \
ContentView.o

Alter the swift-frontend like to the following and it links:

/Applications/Xcode-beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift-frontend \
  -frontend -c \
  -target arm64-apple-ios17.0-simulator \
  -sdk /Applications/Xcode-beta.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator17.0.sdk \
  -enable-objc-interop \
  -o ContentView.o  \
  ContentView.swift

[plotfi]

Here are the symbol diffs (from nm dump)

bad.symbols.txt
good.symbols.txt

Difference is:

< U _$s10Foundation3URLV12bookmarkData7options30includingResourceValuesForKeys10relativeToAA0D0VSo5NSURLC23BookmarkCreationOptionsV_ShySo16NSURLResourceKeyaGSgACSgtKF
< U _$s10Foundation3URLV12bookmarkData7options30includingResourceValuesForKeys10relativeToAA0D0VSo5NSURLC23BookmarkCreationOptionsV_ShySo16NSURLResourceKeyaGSgACSgtKFfA_
---
> U _$s10Foundation3URLV12bookmarkData7options30includingResourceValuesForKeys10relativeToAA0D0VSo28NSURLBookmarkCreationOptionsV_ShySo16NSURLResourceKeyaGSgACSgtKF
> T _$s10Foundation3URLV12bookmarkData7options30includingResourceValuesForKeys10relativeToAA0D0VSo28NSURLBookmarkCreationOptionsV_ShySo16NSURLResourceKeyaGSgACSgtKFfA_

Meaning:

1,2c1,2
< U Foundation.URL.bookmarkData(options: __C.NSURL.BookmarkCreationOptions, includingResourceValuesForKeys: Swift.Set<__C.NSURLResourceKey>?, relativeTo: Foundation.URL?) throws -> Foundation.Data
< U default argument 0 of Foundation.URL.bookmarkData(options: __C.NSURL.BookmarkCreationOptions, includingResourceValuesForKeys: Swift.Set<__C.NSURLResourceKey>?, relativeTo: Foundation.URL?) throws -> Foundation.Data
---
> U Foundation.URL.bookmarkData(options: __C.NSURLBookmarkCreationOptions, includingResourceValuesForKeys: Swift.Set<__C.NSURLResourceKey>?, relativeTo: Foundation.URL?) throws -> Foundation.Data
> T default argument 0 of Foundation.URL.bookmarkData(options: __C.NSURLBookmarkCreationOptions, includingResourceValuesForKeys: Swift.Set<__C.NSURLResourceKey>?, relativeTo: Foundation.URL?) throws -> Foundation.Data

[plotfi]

Difference appears to be a missing dot '.' in NSURL.BookmarkCreationOptions, I may have fixed this in #66619

[plotfi]

I tested things out with a swiftc built from top of tree, the issue appears to be fixed already.

plotfi@plotfi-mbp GH66501 % /Users/plotfi/opt/dev/S/build/RelWithDebInfo/BinaryCache/toolchain/bin/swift-frontend \
  -frontend -c \
  -target arm64-apple-ios17.0-simulator \
  -sdk /Applications/Xcode-beta.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator17.0.sdk \
  -enable-objc-interop \
  -cxx-interoperability-mode=default \
  -o ContentView.o  \
  ContentView.swift

/Applications/Xcode-beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ld \
  -syslibroot /Applications/Xcode-beta.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator17.0.sdk \
-o a.out \
-L/Applications/Xcode-beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator \
-L/usr/lib/swift \
ContentView.o

ContentView.swift:11:9: warning: result of 'try?' is unused
        try? url.bookmarkData()
        ^~~~~~~~~~~~~~~~~~~~~~~
plotfi@plotfi-mbp GH66501 % ls ContentView.o a.out
ContentView.o	a.out

[hyp]

Thanks!

[hyp]

Let's leave it open for now until we have an Xcode beta out with the fix but this appears to be fixed.

[plotfi]

Let's leave it open for now until we have an Xcode beta out with the fix but this appears to be fixed.

Agreed, I want to close once we are sure an upcoming Xcode build fixes this.