_cpp_pop_buffer()

/* Pops a single buffer, with a file change call-back if appropriate.
   Then pushes the next -include file, if any remain.  */
void
_cpp_pop_buffer (cpp_reader *pfile)
{
  cpp_buffer *buffer = pfile->buffer;
  struct _cpp_file *inc = buffer->file;
  struct if_stack *ifs;
  const unsigned char *to_free;
  enum include_type inc_type;

  /* Walk back up the conditional stack till we reach its level at
     entry to this file, issuing error messages.  */
  for (ifs = buffer->if_stack; ifs; ifs = ifs->next)
    cpp_error_with_line (pfile, CPP_DL_ERROR, ifs->line, 0,
             "unterminated #%s", dtable[ifs->type].name);

  if (inc)
  {
    inc_type = buffer->inc_type;
    if (CPP_WHEADER_GUARD (pfile) && pfile->mi_valid)
      warn_header_guard (pfile);
  }

  /* In case of a missing #endif.  */
  pfile->state.skipping = 0;

  /* _cpp_do_file_change expects pfile->buffer to be the new one.  */
  pfile->buffer = buffer->prev;

  to_free = buffer->to_free;
  free (buffer->notes);

  /* Free the buffer object now; we may want to push a new buffer
     in _cpp_push_next_include_file.  */
  obstack_free (&pfile->buffer_ob, buffer);

  if (inc)
    {
      _cpp_pop_file_buffer (pfile, inc, to_free, inc_type);

      _cpp_do_file_change (pfile, LC_LEAVE, 0, 0, 0);
    }
}