[MC-127748] The loot table function set_damage not applied if the item is unbreakable

The bug

See title, the tool is not getting a Damage value when it is also setting Unbreakable.

Loot table used to test:

{
    "pools": [
        {
            "rolls": 1,
            "entries": [
                {
                    "type": "item",
                    "name": "minecraft:fishing_rod",
                    "functions": [
                        {
                            "function": "set_nbt",
                            "tag": "{Unbreakable:1b}"
                        },
                        {
                            "function": "set_damage",
                            "damage": 0.5
                        }
                    ]
                }
            ]
        }
    ]
}

{
    "pools": [
        {
            "rolls": 1,
            "entries": [
                {
                    "type": "item",
                    "name": "minecraft:fishing_rod",
                    "functions": [
                        {
                            "function": "set_nbt",
                            "tag": "{Unbreakable:1b}"
                        },
                        {
                            "function": "set_damage",
                            "damage": 0.5
                        }
                    ]
                }
            ]
        }
    ]
}

The log file returns the following:

[20:27:25] [Server thread/WARN]: Couldn't set damage of loot item 1xitem.minecraft.fishing_rod

[20:27:25] [Server thread/WARN]: Couldn't set damage of loot item 1xitem.minecraft.fishing_rod

Code analysis

Using MCP1.12 names, in method net.minecraft.world.storage.loot.functions.apply(), it checks if the item can be damaged using isItemStackDamageable(), which returns false if the item does have a damage value but is set to Unbreakable. It could check instead if getMaxDamage() isn't 0.

Comments 12

[Mod] Neko 2018-06-24T04:32:34Z

Tested in both 1.12.2 and 1.13-pre3.

This loot table doesn't work in either. However, changing the damage to 0.5 works in both. 0.98 also works fine.

After looking at the code, 0.985 gets rounded to 0.99, a float "f" is set as 1.0 - 0.99 = 0.01, 0.01 is multiplied by the max stack damage 64 which equals 0.64, and is floored to 0, resulting in no change.