Get rid of "pointer assignment might outlive the pointer target" in Fortran

Question

I have a code similar to this:

module mod
    implicit none
    real, pointer :: p1=>null(), p2=>null()
end module mod

program target_lifetime
    use mod
    implicit none
    real, target  :: t(2)

    p1 => t(1)
    p2 => t(2)

    nullify( p1, p2 )

end program target_lifetime

When I compile this code with gfortran -Wall target_lifetime.f90 I obtain

target_lifetime.f90:14:4:

   14 |     p1 => t(1)
      |    1
Warning: Pointer at (1) in pointer assignment might outlive the pointer target [-Wtarget-lifetime]
target_lifetime.f90:15:4:

   15 |     p2 => t(2)
      |    1
Warning: Pointer at (1) in pointer assignment might outlive the pointer target [-Wtarget-lifetime]

What is the correct way to code this in order to get rid of the warning?

Answer 1

The warning here is clearly bogus because of the lifetime of the main program variable is until the end of the program and the t array is implicitly save.

There is not much you can do. You can open a bug with GCC and ask whether it is possible to change the behaviour here.

I can see that it could be triggered by internally implementing the __MAIN (or some other name) procedure as a subroutine (actually a funciton in C or GIMPLE) and then treating the variables as local variables in some checks. But then the standard still says that the variables in the main program are save implicitly.