Literal singleton type accepting wrong value

[kavedaa]

Compiler version

3.0.0-RC3

Minimized code

scala> val pi: 3.14 = 3
val pi: 3.14 = 3.0

scala> pi
val res0: Double = 3.14

Expectation

2.13.4

scala> val pi: 3.14 = 3
                      ^
       error: type mismatch;
        found   : Double(3.0)
        required: 3.14

[som-snytt]

Worth adding this was a good one. Earlier I checked List[3.14](3.14, 3). I also checked in the example that 3.0 is stored in the field, but I didn't check what REPL is reporting when it prints the RHS. I also wondered whether it matters what is stored in the field.

No one would complain about

scala> var x: 3.14 = null.asInstanceOf[3.14]
var x: 3.14 = 0.0

oh wait

scala> x                                                                                                            
val res1: Double = 0.0

which I guess is due to unstable x but still surprises me. x has to be 3.14 even if I lied in initializing it.

Scala 2 throws in the isInstanceOf case. I don't know why without consulting code or spec.

scala> trait T { inline val pi = 3.14 }
// defined trait T

scala> (null: T).pi
val res0: Double = 3.14

scala> null.asInstanceOf[T].pi
1 |null.asInstanceOf[T].pi
  |^^^^^^^^^^^^^^^^^^^^^^^
  |getter pi is declared as erased, but is in fact used