[0.17.52] Item request icon does not disappear on blueprinted train, when fueled by other means than builderbots

[Impatient]

When a BP of a fueled train is placed and that train is fueled before builderbots can deliver that fuel, the item request icon does not disappear.

Steps to reproduce:
- Place a locomotive and fuel it with one type of fuel.
- Create a BP of that locomotive that includes the fuel.
- Place that BP without builderbots being able to deliver that fuel type.
- Fully fuel locomotive manually with ANY - even the same - type of fuel.

Observed result:
The item request icon on the locomotive does not disappear. When enabling builder bots to deliver the requested fuel after that, they move to the locomotive with the fuel and depart again taking it with them. The item request icon then disappears.

Expected result:
The item request icon disappears, as soon as builderbots would not be able to insert any fuel item into the locomotive. Eg if there is 101 items of coal in the locomotive and the BP includes coal as fuel, the bots still could insert 49 coal. Then it would be ok to show the item request icon. But eg, with the same BP, all slots are filled with solid or with 150 coal, the icon should disappear, as no coal could be inserted any more. With modules in assembling machines it works that way and here it should be the same imo.

Probably related: viewtopic.php?f=7&t=72627

[Rseding91]

Thanks for the report however this is working as intended. The item request slots do not sit and constantly scan the entity inventory to see if some external means delivered the items they where told to deliver. That would be incredibly bad for performance and defeat the entire purpose of using them.

They exist as a way to tell robots to deliver items to something. If you instead do it yourself then you might as well not use them - and just exclude fuel from your blueprints when making trains.

[DaveMcW]

As a workaround, right-click the fuel icon to cancel it. Moving the train will also cancel it.

[Impatient]

As a workaround, right-click the fuel icon to cancel it. Moving the train will also cancel it.

Thanks.

For me it is just a matter of consistency after being conditioned. I am used from the case of missing modules, that when this icon is displayed, something should be delivered - something is "incomplete". The first time I saw it on a locomotive, I didn't even know this was used for blueprinted fuel as well and was confused. After understanding why it was displayed and because I discovered another bug in the same session (linked above), I thought it is a bug due to copying and pasting code. So I thought this also should go away, the same way as the item request icon goes away when missing modules are inserted manually into an assembling machine. Rseding91's answer/explanation did not make me understand entirely why requests for modules are cancelled but those for fuel are not. With module slots the engine seems to do exactly what he says it can not do with fuel slots:
" ... constantly scan the entity inventory to see if some external means delivered the items they where told to deliver. ..."

Maybe the difference is, that the fuel slots are a specially marked part of a vehicles inventory? Where this scan can not be performed cost efficient? From a users perspective it still feels inconsitent. However, if it is not possible to implement this without considerable performance cost, I gladly accept it.

To come back to your recommendations: Now, as I know how it behaves, I will just ignore it and only pay attention to the "fuel-needed" icon. And like you say, as soon as the train moves it disappears, which usually is soon after placing it.

IMO it could be left out entirely on vehicles when it concerns fuel, as they have this "fuel-needed" icon anyways. What do you think?