Fix #5039: Handle null:_* as varargs parameter

Author: nicolasstucki

compiler/src/dotty/tools/dotc/typer/Applications.scala

@@ -556,6 +556,8 @@ trait Applications extends Compatibility { self: Typer with Dynamic =>
             args match {
               case arg :: Nil if isVarArg(arg) =>
                 addTyped(arg, formal)
+              case Typed(Literal(Constant(null)), _) :: Nil =>
+                addTyped(args.head, formal)
               case _ =>
                 val elemFormal = formal.widenExpr.argTypesLo.head
                 val typedArgs =

tests/pending/fuzzy/AE-c00f7074d074a942f48e3e24845e7f7054b76b69.scala renamed to tests/fuzzy/AE-c00f7074d074a942f48e3e24845e7f7054b76b69.scala

@@ -0,0 +1,8 @@
+class I0 {
+  List(null:_*)
+  List[Null](null:_*)
+  List[Nothing](null:_*)
+  List(1, 2, null:_*)
+  List(null, null:_*)
+  List(???, null:_*)
+}