Imported From: https://issues.scala-lang.org/browse/SI-10025?orig=1
Reporter: Wade Waldron (wade.waldron)
Affected Versions: 2.11.8, 2.12.0

Wade Waldron (wade.waldron) said:
With a bit more investigation, we have learned that this seems to not be limited to Lower Bounds situations.

scala> new AnyRef
res3: Object = java.lang.Object@33f8bccc

@soc said (edited on Nov 4, 2016 2:13:05 PM UTC):
Think of AnyRef as an alias for Object:

scala> type Foo = String
defined type alias Foo

scala> new Foo
res0: String = ""

scala> :power

scala> val x = symbolOf[AnyRef]
x: $r.intp.global.TypeSymbol = type AnyRef

scala> x.isAliasType
res6: Boolean = true

scala> x.tpe.dealias
res7: $r.intp.global.Type = Object

Assuming that you didn't find any case where something compiled with AnyRef, but was rejected when using Object (or the other way around), I'd say that this isn't a bug.

I guess the main question is: Should we prefer displaying AnyRef over Object? Always, or are there any exceptions?

Yeah, doesn't look like a bug to me either.

simpler reproducer is

scala 2.13.11> class A; class B; List(new A, new B)
                                 ^
               warning: a type was inferred to be `Object`; this may indicate a programming error.
class A
class B
val res0: List[Object] = List(A@1bb172dd, B@1cdd31a4)

not sure whether to label this "fixed in Scala 3" — Scala 3 infers a union type instead. (And, not sure how dealiasing and printing interact with other in Scala 3.)