type AH() =
      member val X = 0 with get,set

   type GM() =
      member val ah = AH() with get,set
      static member F() = GM()

   let foo(ah: AH) =
      let x = GM()
      x.ah.X <- ah.X // look here
      x

   type AH() =
      member val X = 0 with get,set

   type GM() =
      member val Ah = AH() with get,set // change
      static member F() = GM()

   let foo(ah: AH) =
      let x = GM()
      x.Ah.X <- ah.X // change
      x