reject

VALUE
rb_hash_reject(VALUE hash)
{
    VALUE result;

    RETURN_SIZED_ENUMERATOR(hash, 0, 0, hash_enum_size);
    if (RTEST(ruby_verbose)) {
        VALUE klass;
        if (HAS_EXTRA_STATES(hash, klass)) {
#if HASH_REJECT_COPY_EXTRA_STATES
            rb_warn("copying extra states: %+"PRIsVALUE, hash);
            rb_warn("following states will not be copied in the future version:");
            if (klass) {
                rb_warn("  subclass: %+"PRIsVALUE, klass);
            }
            if (FL_TEST(hash, FL_EXIVAR)) {
                rb_warn("  instance variables: %+"PRIsVALUE,
                        rb_obj_instance_variables(hash));
            }
            if (FL_TEST(hash, FL_TAINT)) {
                rb_warn("  taintedness");
            }
            if (FL_TEST(hash, HASH_PROC_DEFAULT)) {
                rb_warn("  default proc: %+"PRIsVALUE, RHASH_IFNONE(hash));
            }
            else if (!NIL_P(RHASH_IFNONE(hash)))
                rb_warn("  default value: %+"PRIsVALUE, RHASH_IFNONE(hash));
#else
            rb_warn("extra states are no longer copied: %+"PRIsVALUE, hash);
#endif
        }
    }
#if HASH_REJECT_COPY_EXTRA_STATES
    result = rb_hash_dup_empty(hash);
#else
    result = rb_hash_new();
#endif
    if (!RHASH_EMPTY_P(hash)) {
        rb_hash_foreach(hash, reject_i, result);
    }
    return result;
}