Nvfortran: user defined assignment not triggered

If a derived type with defined is part of an other derived type, the assignment of the wrapping type does not trigger the user defined assignment of the contained type. The code below should trigger the user defined assignment and print 41 at the end, but it fails to do so.

module testmod
  implicit none

  ! Wrapping everything dirty (needing user defined assignment into a special type)
  type :: dirty_t
    integer :: val = -1
    procedure :: dirty_assign
    generic :: assignment(=) => dirty_assign
  end type dirty_t

  ! Extends abstract interface
  type :: container_t
    type(dirty_t) :: dirty
  end type container_t


  subroutine dirty_assign(this, other)
    class(dirty_t), intent(out) :: this
    type(dirty_t), intent(in) :: other

    this%val = other%val - 1
    print "(a, i0, a, i0, a)", "dirty_assign (", other%val, " -> ", this%val, ")"

  end subroutine dirty_assign

end module testmod

program testprog
  use testmod
  implicit none

  type(container_t), allocatable :: stat1, stat2
  class(container_t), allocatable :: dyn
  stat1%dirty%val = 42
  stat2 = stat1
  print "(a, i0)", "stat2 value: ", stat2%dirty%val
  dyn = stat2
  print "(a, i0)", "dyn value: ", dyn%dirty%val

end program testprog

See also some more details on the topic at

Thanks BalintAradi, I’ve recreated the issue here and have sent it to engineering for further review. Filed as TPR #31205.