eval.c:997
static void
error_pos()
{
    ruby_set_current_source();
    if (ruby_sourcefile) {
	if (ruby_frame->last_func) {
	    warn_printf("%s:%d:in `%s'", ruby_sourcefile, ruby_sourceline,
			rb_id2name(ruby_frame->last_func));
	}
	else if (ruby_sourceline == 0) {
	    warn_printf("%s", ruby_sourcefile);
	}
	else {
	    warn_printf("%s:%d", ruby_sourcefile, ruby_sourceline);
	}
    }
}
