There seems to be a general dupe issue with the block dismantling mechanic of the wrench.
I think it is not per se a bug in Create, but definitively something that should be considered/discussed.
This might be a duplicate of #1467 , however, I am not sure, and since this problem may affect many other mods, I decided to open a separate issue.

Description

In my mod I want to prevent the player from placing blocks (under certain conditions). So I cancel the EntityPlaceEvent event. This works as intended.
However, this is causing a item dupe with Create (TeamLapen/Vampirism#1011). Create's Wrench allows dismantling some blocks (e.g. a cogwheel). Shift-rightclicking the block while destroy it and place it in the player's inventory.
When I cancel the EntityPlaceEvent though, the block is not broken, yet the item is placed in the inventory anyways.
Here is why:
On serverside when rightclicking a block with an item ForgeHooks#onPlaceItemIntoWorld is called. This starts caching any block changes. Then Item#useOn is called. Create's wrench uses this to destroy the block and place a item in the inventory.
Afterwards, the Forge code checks for any captured block changes, notices one (create block -> air) and fires the EntityPlaceEvent. I cancel that event and Forge restores the block snapshot. Thereby, the destroyed block is restored but the item remains in the player's inventory.

A workaround is to check if the new block in EntityPlaceEvent is air on my side (so basically a block break, not a block place).

However, similar issues may occur with other mods. At least in my opinion, it is not obvious that the EntityPlaceEvent is fired when a block is removed or a it could cause a dupe.

Possible workarounds

Maybe the dismantling code could be moved to Item#onUseFirst or moved to the block's interact method.

The fix proposed in #2141 does not solve this issue (did not test, but since the block is only restored after the onUse method is complete, the isAir check will likely always succeed.

Links

WrenchItem:

Most of duplication glitches like this were in 1.12.2 version.
with:

1. Botania
   Aggregator of life using on spawner, spawner remains and aggregator with.
   Wand of forest using at force relay, relay just dropped and remains.
2. Bloodmagic
   Ritual dismantler using on rituals, ritual deconstructed without wasting stones.
3. Astral Sorcery
   Conversion wand doesn't replace block but it dropped.

I checked it all in 1.16.5 and result:

1. Botania
   all doesn't work.
2. Blood magic
   Dismantler deleted.
3. Astral sorcery
   Works.
   Also you can use boxes from Botania to store and duplicate all items.

There are more items can duplicate from other mods.
Usually this is interacting items that can break blocks using right click or something.

This issue has been marked as stale because it has been inactive for 3 weeks. It will be closed if it remains inactive for another 3 weeks.

This issue has been closed since it has been inactive for 3 weeks since it was marked as stale.