[Flang] Execution error when a variable with optional and pointer attributes defined is used as an argument to a subroutine

[ohno-fj]

Version of flang-new : 20.0.0(2603c8b23be06116bc61bda36fae05b81d906c3f)/AArch64

When a variable with optional and pointer attributes defined is used as an argument to a subroutine, a run-time error occurs (Segmentation fault (core dumped)).
When pointer attribute is changed to allocatable attribute, the execution also fails.
When pointer and allocatable attributes are not specified, the execution succeeds.

The following are the test program, Flang-new, Gfortran and ifort compilation/execution result.

F01_12.f90:

program main
  call sub3()
  print*,"Pass"
contains
  subroutine sub3(ptr)
    integer,optional,pointer :: ptr(:)       ! Segmentation fault
!    integer,optional,allocatable :: ptr(:)  ! Segmentation fault
!    integer,optional :: ptr(:)              ! OK
    call sub(ptr)
  end subroutine sub3
  subroutine sub(dmy)
    integer,optional::dmy(:)
    write(6,*) "present(dmy) = ", present(dmy)
  end subroutine sub
end program main

$ flang-new F01_12.f90; ./a.out
Segmentation fault (core dumped)
$

$ gfortran F01_12.f90; ./a.out
 present(dmy) =  F
 Pass
$

$ ifort -diag-disable=10448 F01_12.f90; ./a.out
 present(dmy) =  F
 Pass
$

[klausler]

The test seems valid, though I can find only two Fortran compilers with which it passes.

F'2023 15.5.2.13: "A dummy argument or an entity that is host associated with a dummy argument is not present if the dummy argument
• does not correspond to an actual argument,
• corresponds to an actual argument that is not present, or ..."

In this case, the second bullet point applies in the call to sub.

[klausler]

Jean pointed out that 15.5.2.13: "(7) If it is a pointer, it shall not be allocated, deallocated, nullified, pointer-assigned, or supplied as an actual argument corresponding to an optional nonpointer dummy argument." also applies, so the program does not conform.

[klausler]

Also: gfortran "works" here when the argument is an assumed-shape array, but not when it is a scalar.

[klausler]

I think that 15.5.2.13 p3 (7) is dispositive here, and that the program is non-conforming.