Dwarf Fortress Bug Tracker - Dwarf Fortress
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0011099Dwarf FortressDwarf Mode -- Buildings, Generalpublic2019-05-25 13:052019-05-26 09:31
WindowsWin 8.1 Pro
0011099: Constructed Walls change their building material seemingly at random
In rare cases, constructed walls can change the material they are made of instantly. In my case a Willow block wall changed into a marble block wall and vice versa. This should obviously not happen and stone walls should stay stone walls.
Screenshot here: https://imgur.com/a/G2lMrIq [^]
Savefile here: http://dffd.bay12games.com/file.php?id=14388 [^]

Load the save file and observe the left wall visible in the screenshot. Inspect the wall and see that those are marble walls with one willow wall among them. Order a construction of a willow block floor (I also reproduced it with a different material) on the tile directly north of the northern staircase (directly to the west of the willow wall). When completed, this changes the willow wall to a marble wall and 2 marble walls to willow walls. This was reproduced 4/4 times.
Bit of Background: I noticed this bizarre bug when attempting to construct a giant marble pyramid. The bug seems to only occur on the first floor above ground level (at least that's where I noticed it). It definitely never happened on the ground level, where the corner tiles are still the initial construction markers. When I initially noticed a bunch of willow walls, I assumed I had accidentally chosen the wrong building material, since my scaffolding was made out of willow. But I noticed more of these tiles appearing and got suspicious. This bug did not occur on 2 other smaller buildings that I had built earlier. It also only occurred with marble and willow (blocks respectively), not any other material.

Speculation: The walls on this section were constructed when there were still trees in the immediate area, so a few accidents and collapses occurred and some construction orders were cancelled. Maybe this was not properly handled? I can't think of anything else that distinguishes these sections of wall from any other.
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Issue History
2019-05-25 13:05CosinusNew Issue
2019-05-25 15:05CosinusNote Added: 0039378
2019-05-26 09:31LociNote Added: 0039381
2019-05-26 09:31LociAssigned To => Loci
2019-05-26 09:31LociStatusnew => confirmed

2019-05-25 15:05   
Update: My suspicion about the trees is growing. When I dismantled a wall after it had turned from a marble to a willow wall, I got both a marble and a willow block. More importantly, the tile is now shown as "tree", even though there is a wall below and no tree anywhere near.
2019-05-26 09:31   
It appears that there are two walls in the problematic tiles, and the game is confused about which to display "on top".

I was able to reproduce the bug:

* build wall_1 on the ground under a tree
* build wall_2 on the tree tile directly above wall_1
* do not build any additional support for the wall_2
* chop down the tree (cave-in, wall_2 disappears, material is not freed)
* build wall_3 on the same tile as wall_2
* build other constructions around that tile to swap display of wall_2 and wall_3