https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117643
--- Comment #1 from kargls at comcast dot net ---
Here's a testcase (obviously untested).
!
! { dg-do run }
!
program foo
use iso_c_binding, only : c_null_char, f_c_string
logical, volatile :: asis
character(len=6, kind=c_char) s1
character(len=:, kind=c_char), allocatable :: s2
s1 = 'abc '
s2 = f_c_string(s1)
if (len(s2) /= len_trim(s1) + 1) stop 1
s2 = f_c_string(s1, .true.)
if (len(s2) /= len(s1) + 1) stop 2
s2 = f_c_string(s1, .false.)
if (len(s2) /= len_trim(s1) + 1) stop 3
asis = .true.
s2 = f_c_string(s1, asis)
if (len(s2) /= len(s1) + 1) stop 4
asis = .false.
s2 = f_c_string(s1, asis)
if (len(s2) /= len_trim(s1) + 1) stop 5
end program foo
