bug_submod_modproc.f90

module mod
  use iso_fortran_env, only: wp=>real64
  implicit none

  private
  public :: myfun
  interface myfun
    module function fun1(n, x) result(y)
      integer,  intent(in)    :: n
      real(wp), intent(in)    :: x
      real(wp), dimension(n)  :: y
    end function fun1
  end interface myfun

end module mod

submodule (mod) submod
  use iso_fortran_env, only: wp=>real64
  implicit none
contains

  module function fun1(n, x) result(y)
    integer,  intent(in)    :: n
    real(wp), intent(in)    :: x
    real(wp), dimension(n)  :: y

    y = x * 2.d0

  end function fun1

  ! module procedure fun1
  !
  !   y = x * 2.d0
  !
  ! end procedure fun1

end submodule submod

program main
  use mod, only: myfun
  use iso_fortran_env, only: wp=>real64
  implicit none

  integer :: n = 2

  print*, myfun(n, 1.d0)

end program main