Can An Allocatable Intent(inout) Argument Be Optional?

I have problem trying to define a subroutine, whose argument contains an allocatable, optional, intent(inout) variable shown below. The code compiles fine, but get runtime error of "Segmentation fault - invalid memory reference".

Subroutine test_routine.f90

SUBROUTINE test_routine(A,B)

IMPLICIT NONE

    REAL,ALLOCATABLE,INTENT(IN)               :: A(:,:)
    REAL,ALLOCATABLE,OPTIONAL,INTENT(INOUT)   :: B(:,:)

    B = A
    B(:,:) = 1

END SUBROUTINE

This subroutine is packed in a module, and is called in Main.

Module test_module.f90

MODULE test_module

IMPLICIT NONE

    INTERFACE test_routine
        MODULE PROCEDURE test_routine
    END INTERFACE

END MODULE test_module

Main test_main.f90

PROGRAM main

    USE test_module

IMPLICIT NONE

    REAL,ALLOCATABLE    :: A(:,:),B(:,:)

    ALLOCATE(A(6,6))
    ALLOCATE(B(6,6))
    A(:,:) = 0
    CALL test_routine(A,B)    ! WORKS FINE
    CALL test_routine(A)      ! DOESN'T WORK!

END PROGRAM main

Then I tried to assign another variable op_B, to make up for B, which doesn't actually exist if the main routine doesn't pass it in. However the following code still doesn't work.

SUBROUTINE test_routine(A,B)

IMPLICIT NONE

    REAL,ALLOCATABLE,INTENT(IN)    :: A(:,:)
    REAL,ALLOCATABLE,OPTIONAL,INTENT(INOUT)   :: B(:,:)
    REAL,ALLOCATABLE               :: op_B(:,:)

    IF(.NOT. PRESENT(B)) THEN
        ALLOCATE(op_B(SIZE(A,1),SIZE(A,2)))
        B = op_B
    END IF
    B = A
    B(:,:) = 1

END SUBROUTINE

By the way, I also tried using fixed size array, but still doesn't help. I wonder if it's impossible to do such things?