Hello, When compiling for mac (using `./gradlew linkNative`) I get an error when I return `null` in...

# kotlin-native

[Tristan]

Hello,

When compiling for mac (using ./gradlew linkNative) I get an error when I return null in a function, such as:

// commonMain
interface GetManufacturerUseCase {
    operator fun invoke(): String?
}

// nativeMain
class GetManufacturerUseCaseImpl : GetManufacturerUseCase {
    override fun invoke() = null
}

It produces this error

/var/folders/v4/tsnbm2mj12qcqd5mzx022z0m0000gp/T/konan_temp15915856283221827637/api.cpp:482:21: error: unknown type name 'libNative_kref_kotlin_Nothing'; did you mean 'libNative_kref_kotlin_Long'?
                    libNative_kref_kotlin_Nothing (*invoke)(libNative_kref_com_me_myproject_deviceInfo_domain_usecase_GetManufacturerUseCaseImpl thiz);
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                    libNative_kref_kotlin_Long

To fix it, I return an empty string 😕 But that’s not really what I want.

Is this a bug, or a limitation?

[ephemient]

have you tried

override fun invoke(): String? = null

? the null is inferred to be Nothing? if not given a narrower type, and it seems that isn't interoperable

[Tristan]

Thanks @ephemient, that was it. It worked.

Since it was working on iOS targets, I assume it would be the case here too. Thanks again!