module m1
  implicit none
contains
  subroutine foo(x)
    real :: x
  end subroutine
end module

!Note: PGI, Intel, GNU, and NAG allow this; Sun does not
module m2
  use m1
  implicit none
  !ERROR: 'foo' is already declared in this scoping unit
  interface foo
    module procedure s
  end interface
contains
  subroutine s(i)
    integer :: i
  end subroutine
end module