Adding an argument to an implicit object creation doesn't trigger AddParameter.
Similarly, GenerateConstructor doesn't trigger on C c = new(1, 2, 3, 4); to offer to add a constructor with 4 parameters.
class C
{
C(int i) { }
void M()
{
C c = new(1 $$); // typing a second argument here should trigger AddParameter
}
}
Relates to #28489 (target-typed new feature)