Fwd: variable-length arguments in an external function

[Daan van Vugt <daanvanvugt at gmail dot com>]

Hi all,

I'm new to fortran and I'm having trouble understanding the behaviour
of the following program. It seems that passing an array to an
external function results in odd behaviour.
I would expect the code attached below to return 2.0 and 2.0, instead
of 0.0 and 2.0.

Could anyone point me to the cause and a possible solution of this? Is
it related to the implementation or have I done something illegal in
fortran (in which case I wonder why the gfortran did not warn me)

Best,
Daan van Vugt




module test
contains
  subroutine test_external(f, extra_args)
    implicit none
    real(kind=8), external :: f
    real(kind=8), intent(in), dimension(:) :: extra_args

    write(*,*) f(extra_args)
  end subroutine test_external

  real(kind=8) function f(args)
    implicit none
    real(kind=8), intent(in), dimension(:) :: args
    f = sum(args)
  end function f
end module test

program external_test
  use test
  implicit none
  call test_external(f, (/1.0,1.0/))
  write(*,*) f((/1.0,1.0/))
end