When your inlined function calls a function type passed to it as a parameter from a different execution context than the body of the inline function, such as a nested function call, the compiler will not allow it because the function type may have a non-local control flow. In such cases, you can add the crossinline keyword to the function type parameter to tell the compiler that a non-local control flow is not allowed. The following example compiles because we have the crossinline keyword:

fun firstFunctionType(f: () -> String) {
    println(f.invoke())
}

inline fun secondFunctionType(crossinline f: () -> String) {
    firstFunctionType {
        f.invoke()
    }
}

If you remove the crossinline keyword, the compiler will throw an error.