Constant fold expressions of type Null and Unit

[nicolasstucki]

Compiler version

3.0.0-RC3

Expectation

Constant folding should be able to handle Null and Unit.

Possible use cases

class A[T]:
  val x: T
object B extends A[Unit]:
    val x: Unit = ()
object C extends A[Null]:
    val x: Null = ()
def test1 =  B.x // should be constant folded to `()`
def test2 = C.x // should be constant folded to `null`

inline val n = null
inline val u = ()
def test1 = n // should be constant folded to `null`
def test2 = u // should be constant folded to `()`

[sjrd]

The first use case is probably invalid because it won't account for exceptions during initialization. Notably val x: Unit = ???.

[nicolasstucki]

In the first case, we could still transform C.x into { C; null } which might be used for further constant folding and avoid the call of the x getter.