[MC-111753] Hopper/Dropper will not input water bottles into brewing stand after potions have been removed by a hopper from brewing stand

The bug

Brewing stands will not take water bottles from hoppers or droppers when the bottles that were in it are taken out with a hopper below.

Steps to reproduce

Place a brewing stand
Place a hopper below it and on the side of it
Put three water bottles into the side hopper
Any additional water bottles will stay in the hopper

Code analysis

Based on 1.11.2 decompiled using MCP 9.35 rc1

The problem seems to be that the method net.minecraft.tileentity.TileEntityBrewingStand.isItemValidForSlot(int, ItemStack) does more than it should. Assuming that it should only return if an item type is valid. In this case it would make also more sense to replace the ItemStack parameter with an Item parameter because the count should not matter. If this is the intended behavior the method net.minecraft.tileentity.TileEntityFurnace.isItemValidForSlot(int, ItemStack) is not correctly working then.

Nevertheless the problem here is the change from representing empty slots with null to representing them with 1 ⨯ air:0. The problem here is that reducing the stack size results in 0 ⨯ air:0 objects but the method TileEntityBrewingStand.isItemValidForSlot(int, ItemStack) tests for a 1 ⨯ air:0 constant. The method net.minecraft.item.ItemStack.isEmpty(), which tests if an item is valid, should probably be used instead.

Attachments

Comments 33

Néomorphos Allomorphis 2016-12-22T00:17:00Z

Hi i think this is clearly related to my bug report: https://bugs.mojang.com/browse/MC-111749
Hoping they'll take a look at it

Aubrey Timothy Leach 2016-12-23T23:04:42Z

i reported this but it looks like several beat me to it. when i destroy the brewing stand and set it up a set of water bottles flow into it just fine but once my potion is brewed and flushed and i try to feed water bottles a second time it jams and won't flow.

Jacob Belliveau 2016-12-23T23:07:10Z

Same here Aubrey

JamestheDouglas 2016-12-24T15:32:35Z

I have been affected by this issue too. I found that upon re-logging the next set of water bottles would be allowed through to brew but this did not fix the issue and any further bottles were prevented from going through.

Andrew Gerenz 2016-12-25T09:41:51Z

I was just learning how to make an automatic brewer for the first time and I thought I was doing something wrong XD

23 more comments

[Mod] Neko 2016-12-26T21:03:45Z

Most likely caused by fixing MC-7222.

Adam P 2016-12-27T17:00:39Z

This one was driving me crazy for a while yesterday- hopefully we can get it some attention!
It is certainly the act of hopping the potions out of the brewing stand that "jams" each individual bottle slot. Breaking and replacing the stand, as well as removing a potion from each slot manually will clear it up, but as soon as a potion is removed from a slot in the brewing stand via hopper, that slot "jams" and won't accept a new water bottle by hopper. I can also add that the bug is NOT in 1.11, but does show up in 1.11.1 and 1.11.2

Charles Faulconer 2016-12-31T19:29:13Z

Did the same experiments as Adam P and got the same results. Surprised that everyone with an automated brewing system hasn't reported this bug. Didn't find anything on an Internet search. For now I have to remove the bottom hopper and extract all my potions manually. Makes me wonder what other automated systems are broken.

Ethan Clegg 2017-01-03T07:12:02Z

My automatic brewer is broken because of this bug. 😞 I hope fixing it is a priority, because this is pretty major for me. I nearly went mad thinking that the redstone's programming had changed slightly or something like that, and that I'd have to completely redesign my machine, which was a nightmare to design in the first place. I'm glad it's just a bug. PLEASE FIX IT! ._.

tobias gabathuler 2017-01-04T12:56:37Z

I can confirm the bug. My automatic Brewing Stand does not work anymore 😞

Jon Kruk 2017-01-04T16:10:43Z

In addition to that I'd like to mention that it works in 1.11 but not in 1.11.2. Moreover, it neither works when a hopper extracts water bottles nor when removing the bottles with the drop key (Q). Water bottles just refill from a hopper if removing the bottles by left mouse click.

Jan Lesniewski 2017-01-04T23:30:37Z

Automatic brewing stand was one of my very first redstone projects in Minecraft.. It used to work fine since I started MC 1.8 before 1.11 came out..
I can 100% confirm that bug. The collection hopper (bottom one) works fine when putting bottles MANUALLY IN to the brewing stand. The feeding hopper (side one) works fine when putting bottles MANUALLY OUT from the brewing stand. They NEVER** work simultaneously.

**they accept only 3 bottles in/out when I teleport far away from them and back.

Admiral Fwiffo 2017-01-06T03:34:46Z

Narrowing the minimal case down a bit - a hopper below the brewing stand is not necessary. A hopper with water bottles pointing into the brewing stand is sufficient. The first three water bottles in the hopper will be put into the brewing stand, but if you take them out by any means, no more will be fed in.

Also, saving and reloading the world seems to get it unstuck for one round of bottles, although the brewing stand sometimes shows an incorrect number. I also was able to reproduce in 1.11.1, so it may have been introduced earlier than 1.11.2

Rusianmophia 2017-01-17T03:53:54Z

I just came across this problem in my new sorting system and I can confirm that this is a bug from 1.11.1 to the current version of the game. There were no problems with this bug in 1.11.0 however from my tests, a hopper beneath the brewing stand is required, at least in 1.11.2

Liam Silk 2017-01-18T01:00:40Z

I have encountered exactly the same problem. Worked once the first time then thereafter no bottles were fed from the side hopper. It's an Auto-Brewer and suffering from all mentioned problems as explained in the previous comments.

Dan Eveland 2017-01-25T22:54:39Z

Same issue as others have stated. Auto brewer will not work past 1 cycle before becoming stuck.

Fizzgig 2017-01-26T04:26:54Z

My auto brewing station does not work in 1.11.2. I had to roll back to 1.11. Here is my world folder if anyone is interested: https://www.dropbox.com/s/14okqbztcejcdka/1.11_Brew_Station_MC_World_Folder.zip So many hours spent on this. I really hope this bug will get fixed in 1.11.3 and beyond. Thanks.

williewillus 2017-01-28T00:05:39Z

I submitted a fix for this to Forge in the meantime https://github.com/MinecraftForge/MinecraftForge/commit/ba875418fd2cb23ad45c6f78e7ef1afb4d1e9ac5

Xavom 2017-02-08T00:23:08Z

Problem confirmed using either a hopper or a dropper to feed intem into the side of the brewing stand. Once each bottle slot has a bottle removed via a hopper below the stand, no more water bottles can be fed into that slot via hopper or dropper from any side direction (N S E W).
Jeb tweeted a 1.12 snapshot coming soon. So question is, this is going on over a month with 120+ votes, and many other similar bug reports marked as resolved, and still no assignee. Are we to wait for 1.12 for a fix?

mauro medina 2017-02-08T16:44:33Z

Still broken in 17w06a (1.12)

gnembon 2017-03-20T17:16:44Z

If I could only suggest not to use the proposed fix that was applied to the forge version a few posts back. The true reason why this doesn't work is not because hoppers cannot place items inside brewing stands, but because when hoppers pick up items from containers, they leave 'air:0', instead of 'air:1' which doens't match the definition of empty inventory slot, which is 'air:1'. Currently this bug only affects potion brewers, but if not fixed properly and just patched, it may cause problems in the future. Just make sure that hopper leaves 'air:1' for empty inventory slots, and current brewer code will work as expected without changes to it.

marcono1234 2017-03-22T15:17:29Z

@@unknown it would need to be net.minecraft.item.ItemStack.EMPTY since the method TileEntityBrewingStand.isItemValidForSlot(int, ItemStack) tests for reference equality. I hope the code analysis in the description describes this correctly and you can agree with the suggested fix.

Frank D. George 2017-03-30T10:23:35Z

Confirmed in 17w13a

Alfie Chen 2017-04-08T14:53:40Z

Confirmed in 17w14a, I'm building an auto brewer for the first time but from comments above this bug seems to have hung around a while... no auto brewer for now then i guess...

[Mod] Neko 2017-04-09T07:45:31Z

Please remember before commenting that this is not a discussion forum. Go over to the Mojira Reddit to discuss.

Jan Lesniewski 2017-04-12T13:23:35Z

Confirmed in 17w15a... :'(