a.f90

module a
    implicit none
    abstract interface
      function foo(x)
        integer, intent(in) :: x
        integer :: foo
      end function foo
    end interface
    type handle
        procedure(foo), pointer, nopass :: foo1 => NULL()
        procedure(foo), pointer, nopass :: foo2 => NULL()
    end type handle
end module a

b.f90

module b
    use a
    implicit none
contains
    integer function bar1(foo1)
        implicit none
        procedure(foo) :: foo1
        
        bar1 = 42
    end function bar1

    integer function bar2(h)
        implicit none
        type(handle) :: h

        procedure(foo), pointer :: f1 => NULL()
        procedure(foo), pointer :: f2 => NULL()

        integer :: res

        f1 => h%foo1

        res = bar1(f1)

        bar2 = res
    end function bar2
end module b