Warning.[]=

static VALUE
rb_warning_s_aset(VALUE mod, VALUE category, VALUE flag)
{
    unsigned int mask = rb_warning_category_mask(category);
    unsigned int disabled = warning_disabled_categories;
    if (!RTEST(flag))
        disabled |= mask;
    else
        disabled &= ~mask;
    warning_disabled_categories = disabled;
    return flag;
}