The bug
Shift clicking ignores stacking restrictions of a slot if this slot already contains the same item. This does not affect all slots with stacking restrictions because some of them do not use the (probably?) new method Slot.getSlotStackLimit()
.
How to reproduce
Place a brewing stand
Place a glass bottle in the first potion slot
Place a single glass bottle in your inventory and shift click it
→ You will see that the glass bottle stacked despite the potion slots of a brewing stand only permitting item stacks with a count of 1
Code analysis
Based on 1.11.2 decompiled using MCP 9.35 rc1
The method net.minecraft.inventory.Container.mergeItemStack(ItemStack, int, int, boolean)
ignores the stacking restrictions of a slot if the same item is already in it.
Linked issues
is duplicated by 3
relates to 2
Attachments
Comments 5
Affects 21w18a
Affects 1.17

Can confirm in 1.17.1.

Confirm in 1.19.3
Affects 20w46a