Hostile mobs can spawn on magma block

Still in the 1.10-pre1.

I think it makes sense, since the magma block light level permits it, plus the magma block is a solid block. If they made magma block a transparent block, then light would go right through, which isn't better in the terms of making sense. This is surely overpowered for mob farms, but for the properties that the block has, this makes perfect sense, and therefore not something I'd consider as a bug.

I'm not really sure that this is even a bug. It's a solid block (although solid/transparent is sometimes not clear with light blocks, especially for this one), so mobs can spawn on it. It's nice to have a block on which mobs spawn and instantly die for farms, but that's of course not an argument against it being a bug. But as I said, solid block->mob spawn.

You do realize that @unknown tried to fix it, right?
This should be considered a bug as mobs should not spawn in/on blocks that damage them.

Mob don't spawn on the cactus.

Saying that this block is useful and nice for farms in my opinion does count as a good argument to this bug. BUDs are a bug, but because it's useful and people like it it hasn't been fixed. I feel that the same should apply to this bug and that this should be left unfixed.

Please, @unknown, don't spam emails with your edits. Use preview function (a blue rectangle with white lines)

Cacti are not full blocks, they are 7/8 of a block tall. Mojang could make mobs spawning on magma blocks a feature or count it as a bug. The facts are (The block is solid and full size, the block has a light level that is low enough for them to spawn), the only thing that can differ it from being a bug or feature is whether or not Mojang would like to allow mobs to spawn on blocks that hurt them.

Chicken jockeys still spawn in the 1.16.2 on magma blocks 

Please create a new report for that.