Pathfinder - Units in formation stuck frequently

[elexis]

Since formations were enabled again in r17028, units in formation are stuck frequently at obstructions, mostly at resources. They seem to become stuck once one of the units are stuck and don't retry finding a path. When using no formation, they are stuck rather rarerly.

Often many walk-orders are required to resolve it.

This is probably the same bug as #3471, there is also a unit stuck without obstruction:

[elexis]

Here a fairly small replay for r17117.

[elexis]

The replay where those 5 units of the blue player from the gif got stuck. Notice they are not inside an obstruction and also don't touch one. The entity IDs of the units are 1149-1153 and they were stuck after a command ordered them to move on turn 2080 (17min 19sec).

[elexis]

The replay above is for r17131.

This ticket sounds like a duplicate of #3471 as units here are also stuck without touching any obstruction.

---

If you replace the construct order with an identical walk order in the minimal replay (attachment:commands.txt​) then the units will not be stuck.

466c466
< cmd 1 {"type":"construct","template":"structures/ptol_house","x":854.0781860351562,"z":361.5915222167969,"angle":2.356194490192345,"actorSeed":34134,"entities":[10090,10091,10109,10110,10111,10112,10113,10114,10115,10116,10117,10118],"autorepair":true,"autocontinue":true,"queued":false}
---
> cmd 1 {"type":"walk","x":854.0781860351562,"z":361.5915222167969,"entities":[10090,10091,10109,10110,10111,10112,10113,10114,10115,10116,10117,10118],"queued":false}

So maybe it has something to do with new obstructions not being taken into account correctly.

[elexis]

Very short replay. Two men stuck after building houses. r17131

[elexis]

By adding debug output and/or enabling the pathfinder-developer-overlay, you will see that those stuck units request tickets for computing a short path indefinitely. Each time zero waypoints are returned.

Reproduce stuck units::

1. Have some units standing in formation (= our obstacle).
2. Select one unit (without formation) or some units in formation and tell them to walk "inside" of the units in formation of 1.

The unit(s) will get close to the formation but never get inside. Yet they do a ComputeShortPath every turn, which returns 0 waypoints each time.

[elexis]

Reproduce: Select 2 ranged + 2 melee units. Switch from line-closed to skirmish formation.