[MC-260628] Mobs can spawn on mangrove roots

The bug

Mobs can spawn on mangrove roots, though they don't spawn on leaves, which behave similarly. This did not occur in 1.19 Pre-release 2, but started occurring on 1.19 Pre-release 3.

To reproduce

Create a single superflat world with a layer of mangrove roots on top.
Set time to night.
Notice how mobs start spawning on top of the roots.

Code analysis

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

Linked issues

is duplicated by 1

MC-260629 Mobs spawn on Mangrove Roots Resolved

relates to 1

MC-266096 Mobs can spawn on oxidized or waxed copper grates Resolved

Attachments

Comments 16

SchimmelGelenk 2023-02-27T22:46:34Z

can confirm 1.19

AutumnintheNorth 2023-02-27T23:17:56Z

Can confirm present in 1.19.3

Birder24 2023-02-27T23:50:18Z

Can confirm, in 1.19 pre release 2 mobs don't spawn on mangrove roots. However, in pre release 3 and above they will.

SchimmelGelenk 2023-02-27T23:53:00Z

+1 Birder24's comment

1.19 pre release 2 not affected

1.19 pre release 3 is affected

Marmor1001 2023-02-27T23:59:05Z

can confirm bug exists

more detailed information in Bug report nr MC-260629

6 more comments

ampolive 2023-02-28T00:17:14Z

This issue was already confirmed. There is no need to add any further comments, unless they are to add another (recent) affected version.

Birder24 2023-03-08T22:08:23Z

Confirmed in 1.19.4 pre releases 3 and 4.

Flaco2393 2023-03-15T16:54:06Z

Confirmed. The bug is present in Minecraft 1.19.4

Birder24 2023-04-05T16:21:25Z

Confirmed in 23w14a.

Birder24 2023-04-20T20:08:55Z

Confirmed in 23w16a.

SchimmelGelenk 2023-06-09T00:45:09Z

Since 1.19-pre2 is not affected and 1.19-pre3 is, I did a small code analysis. I decompile both versions using hube12/DecompilerMC and compared Blocks.java.

net.minecraft.world.level.block.Blocks.java line 344

// in 1.19-pre2
public static final Block MANGROVE_ROOTS = Blocks.register("mangrove_roots", new MangroveRootsBlock(BlockBehaviour.Properties.of(Material.WOOD, MaterialColor.PODZOL).strength(0.7f).randomTicks().sound(SoundType.MANGROVE_ROOTS).noOcclusion().isValidSpawn((arg_0, arg_1, arg_2, arg_3) -> Blocks.ocelotOrParrot(arg_0, arg_1, arg_2, arg_3)).isSuffocating((arg_0, arg_1, arg_2) -> Blocks.never(arg_0, arg_1, arg_2)).isViewBlocking((arg_0, arg_1, arg_2) -> Blocks.never(arg_0, arg_1, arg_2)).noOcclusion()));

// in 1.19-pre3
public static final Block MANGROVE_ROOTS = Blocks.register("mangrove_roots", new MangroveRootsBlock(BlockBehaviour.Properties.of(Material.WOOD, MaterialColor.PODZOL).strength(0.7f).randomTicks().sound(SoundType.MANGROVE_ROOTS).noOcclusion().isSuffocating((arg_0, arg_1, arg_2) -> Blocks.never(arg_0, arg_1, arg_2)).isViewBlocking((arg_0, arg_1, arg_2) -> Blocks.never(arg_0, arg_1, arg_2)).noOcclusion()));

Notice that the bold part is missing in version 1.19-pre3 is the attribute .isValidSpawn. Both the name and it's removal point to the issue on hand. I added to the before mentioned missing part to the 1.19.4 source code using Hexeption/MCP-Reborn and compiled the code to a .jar. In this modified version of Minecraft version 1.19.4 mobs do not spawn on mangrove roots, as intended.

Thanks chrrs for the help.

Zanteri 2023-06-16T17:57:50Z

Seems to still be around in 1.20, confirmation from someone else might be good.

Birder24 2023-09-22T22:41:47Z

Confirmed in 1.20.2.

AMGAMES04 2023-11-10T14:53:20Z

Can confirm in 23w45a

Jess Mooney 2023-12-23T14:32:11Z

Confirming this is happening on 1.20.1

Fantastime 2024-04-18T07:20:21Z

Thank you for your report!
After consideration, the issue is being closed as Working as Intended.

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