1! { dg-do run }
2  character(len=1) :: s
3  character(len=0) :: s0
4  s = " "
5  s0 = ""
6  call bar ("")
7  call bar (s)
8  call bar (s0)
9  call bar (trim(s))
10  call bar (min(s0,s0))
11contains
12  subroutine bar (s)
13    character(len=*), optional :: s
14    if (.not. present (S)) call abort
15  end subroutine bar
16end
17