eql?

/*
 *  call-seq:
 *     rxp == other_rxp      => true or false
 *     rxp.eql?(other_rxp)   => true or false
 *  
 *  Equality---Two regexps are equal if their patterns are identical, they have
 *  the same character set code, and their <code>casefold?</code> values are the
 *  same.
 *     
 *     /abc/  == /abc/x   #=> false
 *     /abc/  == /abc/i   #=> false
 *     /abc/u == /abc/n   #=> false
 */

static VALUE
rb_reg_equal(re1, re2)
    VALUE re1, re2;
{
    if (re1 == re2) return Qtrue;
    if (TYPE(re2) != T_REGEXP) return Qfalse;
    rb_reg_check(re1); rb_reg_check(re2);
    if (RREGEXP(re1)->len != RREGEXP(re2)->len) return Qfalse;
    if (memcmp(RREGEXP(re1)->str, RREGEXP(re2)->str, RREGEXP(re1)->len) == 0 &&
        rb_reg_cur_kcode(re1) == rb_reg_cur_kcode(re2) &&
        RREGEXP(re1)->ptr->options == RREGEXP(re2)->ptr->options) {
        return Qtrue;
    }
    return Qfalse;
}