Question about defined assignment

in the following example, should the program not behave the same way,whether I assign a variable to itself enclosed or not in parentheses ?

module m_test

    type t_1
        integer :: i,j,k
        contains
            procedure, private :: t_1_ass_t_1
            generic :: assignment(=)    => t_1_ass_t_1
    end type
  contains
    subroutine t_1_ass_t_1(var, expr)
        class(t_1), intent(out) :: var
        class(t_1), intent(in)  :: expr
        var%i = 0
        var%j = 0
        var%k = 0
        if (expr%i > 0) then
            var%i = expr%i
            var%j = expr%j
            var%k = expr%k
        endif
    end subroutine
end module
program test
    use m_test

    type(t_1) :: x,y

    x = t_1(1,2,3)
    x = x
    print *, x
    y = t_1(1,2,3)
    y = (y)
    print *, y
end program

However the output is:

C:\TEMP>ifort test.f90
Intel(R) Visual Fortran Intel(R) 64 Compiler for applications running on Intel(R) 64, Version 16.0.0.110 Build 20150815
Copyright (C) 1985-2015 Intel Corporation.  All rights reserved.

Microsoft (R) Incremental Linker Version 11.00.61030.0
Copyright (C) Microsoft Corporation.  All rights reserved.

-out:test.exe
-subsystem:console
test.obj

C:\TEMP>test
           0           0           0
           1           2           3

C:\TEMP>

In clause 12.4.3.4.3 the Fortran 2008 standard says "A defined assignment is treated as a reference to the subroutine, with the left-hand side as the first argument and the right-hand side enclosed in parentheses as the second argument."

Johny