Docgen doesn't render field types in generics with when

[add-IV]

Docgen on Options Library is missing field types

https://nim-lang.org/docs/options.html#7

expected:

type
  Option[T] = object
    when T is SomePointer:
      val: T
    else:
      val: T
      has: bool

current:

Option[T] = object
  when T is SomePointer:
    val
  else:
      val
      has

[timotheecour]

same problem since at least 1.0

type Option1* = object
    val0: int
    when true:
      val: int
    else:
      val: float

type Option2* = object
    val0: int
    when true:
      val: int
    else:
      val: float

type Option3*[T] = object
    val0: int
    when true:
      val: int
    else:
      val: float

1, 2 work, 3 fails

[ringabout]

duplicated of #9899