[Bug fortran/103394] New: Bad object code for structure constructor

[Bug fortran/103394] New: Bad object code for structure constructor

[neil.n.carlson at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103394

            Bug ID: 103394
           Summary: Bad object code for structure constructor
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: neil.n.carlson at gmail dot com
  Target Milestone: ---

Bad object code is being generated for the structure constructor expression in
the example below. This occurs for the current 12.0 trunk and any of the
earlier 9.x, 10.x and 11.x versions I've tried. It seems that things go wrong
with the expression foo_vector_func(this) when both the foo_vector_func type is
an extension and the variable this is also polymorphic.

module foo_type

  type :: foo
  contains
    procedure :: alloc_foo_vector_func
  end type

  type, abstract :: vector_func
  end type

  type, extends(vector_func) :: foo_vector_func
    type(foo), pointer :: ptr
  end type

contains

  subroutine alloc_foo_vector_func(this, vf)
    class(foo), intent(in), target :: this
    class(vector_func), allocatable, intent(out) :: vf
    allocate(vf, source=foo_vector_func(this))  ! DOESN'T WORK CORRECTLY
    !vf = foo_vector_func(this)  ! DOESN'T WORK EITHER
  end subroutine

end module

program main
  use foo_type
  type(foo), target :: x
  class(vector_func), allocatable :: vf
  call x%alloc_foo_vector_func(vf)
  select type (vf)
  type is (foo_vector_func)
    if (.not.associated(vf%ptr, x)) stop 1  ! SHOULD NOT EXIT HERE
  end select
end program

[Bug fortran/103394] Bad object code for structure constructor

[neil.n.carlson at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103394

--- Comment #1 from Neil Carlson <neil.n.carlson at gmail dot com> ---
I've experimented some more and have reduced things further to this example.
I'm not positive it captures everything that is going wrong in the original.

program example

type :: foo
end type

type :: bar
  type(foo), pointer :: fptr
end type

class(foo), pointer :: f
allocate(foo :: f)

call sub(bar(f))

contains

  subroutine sub(b)
    type(bar), intent(in) :: b
    if (.not.associated(b%fptr, f)) stop 1
  end subroutine

end program

The example works correctly if "class(foo), pointer :: f" is replaced by
"type(foo), pointer :: f", so it seems pretty clear that intrinsic structure
constructor is not properly making the assignment "bar%fptr => f".