[MC-196736] Hoglins break their leash when zombifying, despite zoglins being leashable

The bug

After zombifying, hoglins break their leash when they convert into a zoglin. This seems somewhat inconsistent, as zoglins can be leashed.

The video attachment shows a hoglin breaking its leash connected to a fence after it finishes its zombifying process; hoglins also break its leash when the player is holding the lead, not just when connected to a fence.

Code analysis

Code analysis and fix by @unknown can be found in this comment.

Linked issues

relates to 1

MCPE-77211 Lead attached to hoglin does not break when hoglin turns into zoglin Resolved

Attachments

HoglinLeashBreak3.mp4

Comments 12

BlockOfNetherite 2020-08-06T04:52:46Z

Added video attachment, and I can still reproduce in 1.16.2pre2

BlockOfNetherite 2020-08-06T17:47:15Z

Able to reproduce in pre3

anthony cicinelli 2020-10-02T19:59:50Z

I can confirm for 1.16.3

Avoma 2021-01-16T10:56:54Z

Can confirm in 20w51a.

Avoma 2021-01-31T19:40:35Z

Can confirm in 21w03a.

2 more comments

Avoma 2021-06-04T17:35:30Z

Can confirm in 1.16.5 and 1.17 Release Candidate 1.

Avoma 2021-06-12T16:37:43Z

Can confirm in 1.17.

ampolive 2021-08-09T01:13:32Z

Can confirm in 1.17.1.

ampolive 2022-11-18T17:57:14Z

Code analysis (Mojang mappings, 1.19.2): there is no code in Mob#convertTo(...) to transfer the leash holder from a mob to another. Ideally, this should be fixed in this function for future-proofing. But this can also be fixed (hack-fixed?) by changing Hoglin#finishConversion(ServerLevel).

Potential (not ideal) fix (might cause other issues):
Change Hoglin#finishConversion(ServerLevel) from

private void finishConversion(ServerLevel $$0) {
        Zoglin $$1 = this.convertTo(EntityType.ZOGLIN, true);
        if ($$1 != null) {
            $$1.addEffect(new MobEffectInstance(MobEffects.CONFUSION, 200, 0));
        }
    }

private void finishConversion(ServerLevel $$0) {
        Entity leashHolder = this.getLeashHolder();
        if (leashHolder != null) {
            this.dropLeash(false, false);
        }
        Zoglin $$1 = this.convertTo(EntityType.ZOGLIN, true);
        if ($$1 != null) {
            if (leashHolder != null) {
                $$1.setLeashedTo(leashHolder, true);
            }
            $$1.addEffect(new MobEffectInstance(MobEffects.CONFUSION, 200, 0));
        }
    }

ampolive 2024-09-05T11:21:44Z

This has been fixed in 24w36a.