special case for next field of colon colon in global init checker

Author: willerf

compiler/src/dotty/tools/dotc/transform/init/Objects.scala

@@ -812,7 +812,8 @@ class Objects(using Context @constructorOnly):
  else
  Bottom
  else if target.exists then
- if target.isOneOf(Flags.Mutable) then
+ def isNextFieldOfColonColon: Boolean = ref.klass == defn.ConsClass && target.name.toString == "next"
+ if target.isOneOf(Flags.Mutable) && !isNextFieldOfColonColon then
  if ref.hasVar(target) then
  val addr = ref.varAddr(target)
  if addr.owner == State.currentObject then

tests/init-global/pos/list-colon-colon-next.scala

@@ -0,0 +1,5 @@
+object A:
+ val a: List[Int] = List(1, 2, 3)
+
+object B:
+ val b = A.a.size