Primitive unboxed inconsistently with coverage enabled

[hearnadam]

Compiler version

• 3.3.4
• 3.6.4

Minimized code

//> using option "-coverage-out:coverage"
object Unbox extends App {
    val m = new java.util.HashMap[String, Double]()
    def method: Option[Double] = Option(m.get(""))
    println(method)
}

Output

With coverage:

Some(0.0)

Without coverage:

None

Expectation

Unboxing of null Boxed primitives should not depend on coverage being enabled/disabled. I would expect None to be printed in both contexts.

[som-snytt]

This is due to normal unboxing when the subexpression is pulled out.

scala> val m = new java.util.HashMap[String, Double]()
val m: java.util.HashMap[String,Double] = {}

scala> m.get("")
val res0: Double = 0.0

scala> Option(m.get(""))
val res1: Option[Double] = None

scala> val d: Double = null.asInstanceOf[Double]
val d: Double = 0.0

There was a Scala 2 issue for types of temporaries for "stablisation" or "right-associative evaluation".