File: gfortran-bug3.f90

module trivial
contains
  function my_copy(str) result(s)
  implicit none
  character(*), intent(in):: str
  character(len(str)) s
  s = str
  return
  end function my_copy
end module trivial

program boom
  use trivial
  implicit none
  print *, my_copy('Boom!')
end program boom

Result:

% gfortran gfortran-bug3.f90 
f951: ../../gcc/gcc/fortran/trans-expr.c:1042: gfc_conv_function_call: Assertion
`sym->ts.cl && sym->ts.cl->length && sym->ts.cl->length->expr_type ==
EXPR_CONSTANT' failed.
gfortran-bug3.f90: In function `MAIN__':
gfortran-bug3.f90:15: internal compiler error: Aborted
Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:http://gcc.gnu.org/bugs.html> for instructions.