I'm having problems with running C-interop on an O...

# kotlin-native

[Alexander Larsson]

I'm having problems with running C-interop on an Objective C framework with a header that imports Foundation. The cinterop task fails with an exception:

> Task :shared:cinteropObjektiveSSLIos FAILED
1 actionable task: 1 executed
Exception in thread "main" java.lang.Error: /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.4.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObjCRuntime.h:492:1: error: expected identifier or '('
	at org.jetbrains.kotlin.native.interop.indexer.UtilsKt.ensureNoCompileErrors(Utils.kt:152)
	at org.jetbrains.kotlin.native.interop.indexer.IndexerKt.indexDeclarations(Indexer.kt:1003)
	at org.jetbrains.kotlin.native.interop.indexer.IndexerKt.buildNativeIndexImpl(Indexer.kt:992)
	at org.jetbrains.kotlin.native.interop.indexer.NativeIndexKt.buildNativeIndex(NativeIndex.kt:91)
	at org.jetbrains.kotlin.native.interop.gen.jvm.MainKt.processCLib(main.kt:230)
	at org.jetbrains.kotlin.native.interop.gen.jvm.MainKt.interop(main.kt:46)
	at org.jetbrains.kotlin.cli.utilities.InteropCompilerKt.invokeInterop(InteropCompiler.kt:44)
	at org.jetbrains.kotlin.cli.utilities.MainKt.mainImpl(main.kt:19)
	at org.jetbrains.kotlin.cli.utilities.MainKt.main(main.kt:37)

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':shared:cinteropObjektiveSSLIos'.
> Process 'command '/Applications/IntelliJ IDEA <http://CE.app/Contents/jbr/Contents/Home/bin/java|CE.app/Contents/jbr/Contents/Home/bin/java>'' finished with non-zero exit value 1

Line 492 in NSObjCRuntime.h is:

@class NSString, Protocol;

Is this a bug in Kotlin/Native or the cinterop tool?

I can remove the import of Foundation to "fix" this bug but then it fails with error: unknown type name 'NSData' so I obviously need to keep it in there.

Any workarounds?

[Alexander Larsson]

It seems to work if I add language = Objective-C in the .def file. Is this documented anywhere? In that case I haven't found it 😅

[Alexander Larsson]

I found it used in an old GitHub issue, along with some other options for the .def file I have no idea what it does (but can guess) and have never seen documented anywhere.

https://github.com/JetBrains/kotlin-native/issues/1841

[Artyom Degtyarev [JB]]

Yep, this one seems to be missing from the documentation. Thank you for pointing it out!
By default, cinterop always assume input files as plain C headers.