io.c:3171
static VALUE
rb_f_getc()
{
    rb_warn("getc is obsolete; use STDIN.getc instead");
    if (TYPE(rb_stdin) != T_FILE) {
	return rb_funcall3(rb_stdin, rb_intern("getc"), 0, 0);
    }
    return rb_io_getc(rb_stdin);
}
