Mojira Archive
MC-69876

Pistons at Y=1 do not push downwards / at Y=254 do not push upwards

The bug

A piston placed at Y=1 will not push downwards. This also happens at Y=254 with an upward facing piston.

Code analysis

Based on 1.11 decompiled using MCP 9.35 rc1

The method net.minecraft.block.BlockPistonBase.canPush(IBlockState, World, BlockPos, EnumFacing, boolean) allows piston movement only if the piston is not facing downwards or the potential block to move is not at y 0. It should allow piston movement as well if the block is air or has EnumPushReaction.DESTROY as push reaction.