0004257: Infinite Cave-In Loop makes a fortress unplayable, even on reclaim

Dwarf Fortress Bug Tracker - Dwarf Fortress

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0004257

Dwarf Fortress

Dwarf Mode -- Environment

public

2011-03-21 01:42

2011-03-31 19:10

Reporter

GreenSpinach

Assigned To

Footkerchief

Priority

immediate

Severity

major

Reproducibility

have not tried

Status

resolved

Resolution

unable to reproduce

Platform

OS Version

Product Version

0.31.18

Target Version

Fixed in Version

Summary

0004257: Infinite Cave-In Loop makes a fortress unplayable, even on reclaim

Description

If a cave-in involves ice, it is possible to get caught in an infinite loop of cave-ins. I accidentally caused a cave-in with ice. (To be exact, I was trying to make water for a well, but caused the cave-in prematurely.) Some dwarves died. (One was crushed and one drowned in water that was only 2/7 deep, after being stunned.) The cave-in left behind one rock wall at the bottom of the pit. I mined away this wall, thinking there was no reason not to, because it was not supporting anything. (Unless you count the one floor tile right on top of that wall.) This triggered a neverending cycle of glitch cave-ins where nothing falls because there is nothing to fall, yet somehow dwarves are crushed to death by a magical invisible ceiling of nothing that comes out nowhere and magically kills dwarves and creates dust and mist. So far I have had one normal cave-in, and 194 glitchy cave-ins of magical nothingness, the last 104 of which were consecutive in the Announcements list.
The cave-ins happen in every single frame, which is about a dozen cave-ins for each step that my dwarves take.
During about the first 40 or 50 or so cave-ins, I saw some weird things. In addition to the usual "mist" listed in purple, there were also things like "loamy sand" and "rhyolite" listed in purple. Even if cave-in dust is supposed to be listed as specific material types, it shouldn't include "loamy sand" on an embark site that contains NO SOIL at all.
I abandoned the fortress and tried to reclaim, only to have an infinite loop of magical glitchy cave-ins in my reclaim attempt. That embark site is totally fucked forever.
During all of the glitchy cave-ins, I saw that there was water suspended in mid-air in complete defiance of gravity one Z-level above the bottom of the pit. Not only was it still there after the first 194 glitchy cave-ins (194 frames), it was still there after I tried to reclaim, and waited for 200 more cave-ins. And it hadn't diminished. Maybe it was resting on the magical invisible floor that spawns an endless stream of copies of itself.
My Dwarf Fortress version is 0.31.18.
To reproduce this bug, try dropping a big section of ice, at least 2 Z-levels tall, with the bottom layer being partly ice and partly stone, and all other layers being pure ice. Then Dig away the stone walls from the stuff you dropped in the first cave-in.
You need to fix this bug urgently, because it not only wrecks a fortress, it ruins the site for all reclaim attempts. And don't just do something lame like disabling the melting of ice in cave-ins, because dropping ice to get water is almost totally essential on glacial embark sites.

Steps To Reproduce

1. Embark on a site with a glacier at least 4 Z-levels thick.
2. Cause a cave-in underground where you drop a section of ice that is at least 2x2x2. The bottom layer of this slab of ice should be partly ice and partly stone, and the other layer(s) should be purely ice. And it must land on a stone floor.
3. Dig away the stone wall that remains from the caved-in material.
4. Suffer a horrible neverending loop of cave-ins.
5. Optionally, Reclaim Fortress and observe that this horrible problem persists.

Additional Information

I have a save-game, but am not sure where I should upload it.