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0011496Dwarf FortressDwarf Mode -- Environmentpublic2020-04-06 11:202021-04-02 05:51
0011496: Chopping trees destroys walls
Building above ground with logs (faster than making stone blocks and I've got oodles of logs anway).
Build some walls & floors, then chop down a tree that has parts overhanging the construction.
Some squares under the ex-tree have had the constructions replaced by twigs or leaves.
Happened regularly enough that I have started chopping all trees anywhere with ten squares of walls before starting construction.
Build, then chop.
Seems a duplicate of 0007127, but not resolved since I'm seeing it in 47.04
I will go back and start building under trees to try & reproduce.
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Issue History
2020-04-06 11:20DwarfChefNew Issue
2020-09-07 12:18praptakNote Added: 0040717
2021-04-02 05:51Moeteru62Note Added: 0041010

2020-09-07 12:18   
I think I've got the same issue. My steps to reproduce:

1. build a several levels tall wall near a tree. It seems that dwarves will happily build on squares where parts of the tree is.
1.1. I'm building from rock blocks.

2. Chop down the tree.
2.1. Now some squares of the wall are converted to 'floor'.
2.2. I cannot build walls on these 'floor' squares ('Construction present').

3. Bonus points: I can designate these squares for construction removal. This converts 'floor' to 'tree'.

It seems that building walls does not interact well with trees.

My version is 0.47.04 too.
2021-04-02 05:51   
I've just had this happen in 0.47.05 with natural obsidian walls formed by pouring magma into a flooded cavern.
The cavern had 2 z-levels of water in some places, so the top layer was turned into obsidian while the bottom layer was still water. Cutting down one of the trees left the obsidian floor intact, but removed a circular section of obsidian walls below and even left a hole in the water on the bottom layer. There's a single tile of dry gneiss cavern floor surrounded by 7/7 water on all sides.

I'm guessing that trees claim a volume of tiles when they grow, and then when they're cut down they just delete anything inside that volume without checking whether it's part of the tree or not.