Dwarf Fortress Bug Tracker - Dwarf Fortress
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0008253Dwarf FortressDwarf Mode -- Jobs, Building Construction and Destructionpublic2014-09-06 18:412015-03-26 12:34
0008253: Dwarf removing construction gets "creature swapped" onto construction tile, removes floor beneath his feet
A dwarf removing a walkable construction can be "creature swapped" onto the construction he is removing. If this happens, he will happily finish removing the construction and potentially plummet to his doom.

build a 1-tile wide span of floor tiles
order a middle tile removed
use station orders to march military dwarves back and forth across the span until the removing dwarf ends up on the tile being removed
("Creature swapping" is when a creature in tile A moves into tile B and a creature occupying tile B is automatically relocated to tile A. Creature swapping occurs more frequently with animals and visiting creatures, however fortress dwarves will occasionally swap tiles as well.)
creature swap
related to 0003371new  Non-fliers end up on top of walls (swapped positions with flying pets etc?) 
has duplicate 0008671resolved Dwarfu Dwarves will deconstruct floors under (themselves/neighboring dwarves?) causing them to fall 
related to 0007976new  Minecarts suddenly 'inaccessible' while being guided 
related to 0008845new  Caravan dwarves stuck in one-tile-wide corridor, trying to precede each other. 
Issue History
2014-09-06 18:41LociNew Issue
2014-09-06 20:31smjjamesNote Added: 0030006
2014-09-07 01:01FootkerchiefRelationship addedrelated to 0003371
2014-09-07 12:18LociNote Added: 0030019
2014-09-07 12:19LociNote Edited: 0030019bug_revision_view_page.php?bugnote_id=0030019#r11687
2014-09-07 12:59smjjamesNote Added: 0030023
2015-01-09 06:29FootkerchiefRelationship addedrelated to 0008671
2015-03-26 12:34LociTag Attached: creature swap
2015-03-29 07:56FootkerchiefRelationship addedrelated to 0007976
2015-03-29 07:56FootkerchiefRelationship addedrelated to 0008845
2016-05-11 21:54DwarfuRelationship replacedhas duplicate 0008671
2016-05-11 21:54DwarfuIssue Monitored: Detros

2014-09-06 20:31   
This is a really old bug that goes back to 40D at least, maybe older. Also related is that they'll remove a construction while another dwarf is standing on it and sometimes (as is often the case for stairs), they'll stand right on the stair they're removing, causing them to fall.
2014-09-07 12:18   
(edited on: 2014-09-07 12:19)
@smjjames: Some of those details are outdated. Dwarves will cancel removal if another dwarf is standing on the tile (though there appears to be a timing window where the tile will still be removed right after another dwarf moves to it). The fact that they don't cancel when they are the ones standing on the construction becomes all the more buggy in comparison.

The stair removal problem, however, still applies.

2014-09-07 12:59   
It's entirely possible that I've been observing the 'creature swap' issue.