The /spreadplayers command spreads people onto signs, making it possible to spawn above a high abyss.
Steps to reproduce
Run the following command on a superflat with void preset
/fill 10 -61 6 6 -61 10 minecraft:acacia_sign
Run the spreadplayers command
/spreadplayers 8 8 0 2 false @p
Observe that you will spawn atop the signs and fall through the signs
Replace some signs with solid blocks and observe that you will still be placed above the signs even though there are possible blocks to spread to.
Linked issues
relates to 2
Attachments
Comments 3
confirmed in 18w05a. Any non solid block is treated as an acceptable place to move a player on top of. Spots such as on top of doors, open trap doors, and open fence gates are allowed as well. Being placed on a fence, stone wall, or closed fence gate causes the entity to fall through it. Putting the spreadplayers command in a repeating command block and placing non solid blocks around the center spot will cause the entity to accumulate fall distance which eventually kills it. It seems that only water, lava, and air are invalid spots.
Things that may be intentional: entities can be placed onto hazardous blocks such as magma blocks and cacti. Also, entities are not ejected from minecarts or boats when spreadplayers is used, which differs from using /teleport. However, if a player is riding a boat or minecart when spreadplayers is activated, it will appear as though you very briefly move to another spot before instantly snapping back. Getting out of the boat/minecart afterward still works normally.
Relates to MC-58061