[flang] Incorrect intrinsic assignment of derived type parent component

[DanielCChen]

Consider the following reducer.

  type t
    integer :: a
  end type
  type, extends(t) :: t2
    integer :: b
  end type

  type(t), allocatable :: a(:)
  class(t), allocatable :: b(:)
  allocate(b(5), source=(/t2(1,1),t2(2,2),t2(3,3),t2(4,4),t2(5,5)/))
  a = b                                                                                                   !! a should get b%a
  print*, a%a
  if (any(a%a /= (/1,2,3,4,5/))) stop 2
end

Flang failed to assign b%a to a%a in intrinsic assignment a = b.

gfortran and XLF works fine.

[llvmbot]

@llvm/issue-subscribers-flang-frontend

Author: Daniel Chen (DanielCChen)

Consider the following reducer. ``` type t integer :: a end type type, extends(t) :: t2 integer :: b end type

type(t), allocatable :: a(:)
class(t), allocatable :: b(:)
allocate(b(5), source=(/t2(1,1),t2(2,2),t2(3,3),t2(4,4),t2(5,5)/))
a = b !! a should get b%a
print*, a%a
if (any(a%a /= (/1,2,3,4,5/))) stop 2
end

Flang failed to assign `b%a` to `a%a` in intrinsic assignment `a = b`. 

gfortran and XLF works fine.
</details>

[DanielCChen]

This may be related to #152758 .

[klausler]

This is a duplicate of #152758 and is also fixed by the same PR.