getting Suspicious application of an implicit view when converting from Option(lang.Long) to Long

Question

after adding this flag to scalacoptions :

  "-Xlint:option-implicit"

I don't understand why am I getting this and how to resolve it

Error:(47, 34) Suspicious application of an implicit view (scala.Predef.Long2long) in the argument to Option.apply. val x: Long = Option[Long](timestamp()).getOrElse(1L)

The code looks like this

val x: Long = Option[Long](timestamp()).getOrElse(1L)

the function timestamp can be null or return java Long

Answer 1

I was able to replicate the message with the following code:

$ scala -Xlint:option-implicit
Welcome to Scala 2.13.0 (OpenJDK 64-Bit Server VM, Java 1.8.0_222).
Type in expressions for evaluation. Or try :help.

scala> def timestamp(): java.lang.Long = new java.lang.Long("10")

scala> val x: Long = Option[Long](timestamp()).getOrElse(1L)
warning: Suspicious application of an implicit view (scala.Predef.Long2long) in the argument to Option.apply.

Now, you can fix it the following way.

val x: Long = Option(Long.unbox(timestamp())).getOrElse(1L)

// Or, supposing opt is of type Option[java.lang.Long]
val x: Long = opt.fold(ifEmpty = 1L)(Long.unbox)