[flang-commits] [flang] [OpenMP][Flang] Emit default declare mappers implicitly for derived types (PR #140562)

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https://github.com/agozillon approved this pull request.

Hey Akash, this LGTM.

However, could you please add a test to the map-types-and-sizes.f90 test or create an equivalent for the mapper work! Would be good to keep track of what we expect the lowered LLVM-IR to be.

I also don't believe this PR handles more complicated mapping cases like below (please do correct me if I am wrong):

```
program main
    type :: bottom_layer
      integer(4), allocatable :: array_j3(:)
    end type bottom_layer

    type :: middle_layer
     type(bottom_layer), allocatable :: nest
     real(4), allocatable :: array_j2(:)
    end type middle_layer

    type :: top_layer
    integer, allocatable :: array_j(:)
    type(middle_layer), allocatable :: nested
    end type top_layer

    type(top_layer), allocatable :: top_dtype

    allocate(top_dtype)
    allocate(top_dtype%nested)
    allocate(top_dtype%nested%nest)
    allocate(top_dtype%array_j(10))
    allocate(top_dtype%nested%array_j2(10))
    allocate(top_dtype%nested%nest%array_j3(10))

!$omp target
  top_dtype%array_j(1) = 10
  top_dtype%nested%array_j2(1) = 20
  top_dtype%nested%nest%array_j3(1) = 30
!$omp end target

  print *, top_dtype%nested%nest%array_j3(1)
  print *, top_dtype%nested%array_j2(1)
  print *, top_dtype%array_j(1)

end program main

```

How difficult would it be to extend this work to handle the above cases? As I think that'd be the ideal next step for this work!

A really nice end goal for this work would be to handle slightly more complicated case than even the above with arbitrary nestings of array of allocatable derived types with allocatable types (arrays, scalars etc.)!


https://github.com/llvm/llvm-project/pull/140562