fix(logic): Improve validation of building placement for Sneak Attack

[stephanmeesters]

This PR fixes potential cheating in the placement of a Sneak Attack, where the validity of the building placement was only checked locally. This means a Sneak Attack could be placed in the fog, on top of any other building, steep mountain slope, water etc. A second check is placed that runs on all clients and mirrors the first check at InGameUI:1688.

Todo

• Replicate in Generals (first commit only)

[greptile-apps]

Greptile Summary

Fixes a multiplayer cheat vector where Sneak Attack building placement was validated only client-side. The new server-side check runs on all clients and mirrors the existing InGameUI:1688 placement validation using isLocationLegalToBuild with identical flags, gated behind #if RETAIL_COMPATIBLE_CRC for CRC compatibility. The builderObject parameter across BuildAssistant is also correctly tightened to const Object*.

Confidence Score: 5/5

Safe to merge; the anti-cheat logic correctly mirrors the existing InGameUI placement check with no functional regressions.

All findings are P2 style/cleanup. The core logic is correct and directly mirrors the reference check at InGameUI:1688 using identical flags and parameters. The const-correctness changes are appropriate. No P0 or P1 issues found.

ActionManager.cpp — minor bib cleanup omission after isLocationLegalToBuild call

Important Files Changed

Filename	Overview
GeneralsMD/Code/GameEngine/Source/Common/RTS/ActionManager.cpp	Core anti-cheat fix: SPECIAL_SNEAK_ATTACK moved from shroud-only check to full isLocationLegalToBuild validation mirroring InGameUI:1688; bib cleanup side effect not addressed
GeneralsMD/Code/GameEngine/Include/Common/BuildAssistant.h	Const-correctness: builderObject parameter tightened from Object* to const Object*
GeneralsMD/Code/GameEngine/Source/Common/System/BuildAssistant.cpp	Const propagation: builderObject and AIUpdateInterface* now const-qualified
Generals/Code/GameEngine/Include/Common/BuildAssistant.h	Same const-correctness fix applied to vanilla Generals header
Generals/Code/GameEngine/Source/Common/System/BuildAssistant.cpp	Same const-correctness propagation applied to vanilla Generals BuildAssistant

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[canDoSpecialPowerAtLocation] --> B{mod != nullptr?}
    B -- No --> Z[return false]
    B -- Yes --> C[Switch 1: Terrain check\ne.g. paradrop on water]
    C --> D[Switch 2: Shroud check\nfor damaging powers]
    D -- other powers --> Y[return shroud/map result]
    D -- SNEAK_ATTACK removed --> E[Switch 3: Building placement NEW]
    E --> F{RETAIL_COMPATIBLE_CRC?}
    F -- Yes --> G[Shroud-only check\nold behavior preserved]
    F -- No --> H[getReferenceThingTemplate]
    H -- null --> I[return FALSE]
    H -- valid --> J[isLocationLegalToBuild\nUSE_QUICK_PATHFIND\nTERRAIN_RESTRICTIONS\nCLEAR_PATH\nNO_OBJECT_OVERLAP\nSHROUD_REVEALED\nIGNORE_STEALTHED\nSame flags as InGameUI:1688]
    J --> K{== LBC_OK?}
    K -- Yes --> L[return true]
    K -- No --> M[return false]

Loading

Prompt To Fix All With AI

This is a comment left during a code review.
Path: GeneralsMD/Code/GameEngine/Source/Common/RTS/ActionManager.cpp
Line: 1605-1613

Comment:
**Missing `removeAllBibs()` cleanup after `isLocationLegalToBuild`**

`isLocationLegalToBuild` adds bib visual feedback as a documented side effect — `AIPlayer.cpp:694` notes: `// isLocationLegalToBuild adds bib feedback, turn it off. jba.` Every other call site in `AIPlayer` and `AISkirmishPlayer` follows up with `TheTerrainVisual->removeAllBibs()`. Since `canDoSpecialPowerAtLocation` runs on all clients (per the PR description), stray bibs will briefly appear on every client's screen each time a Sneak Attack placement is validated.

```suggestion
				Bool const result = TheBuildAssistant->isLocationLegalToBuild(
					loc, referenceThing, angle,
					BuildAssistant::USE_QUICK_PATHFIND |
					BuildAssistant::TERRAIN_RESTRICTIONS |
					BuildAssistant::CLEAR_PATH |
					BuildAssistant::NO_OBJECT_OVERLAP |
					BuildAssistant::SHROUD_REVEALED |
					BuildAssistant::IGNORE_STEALTHED,
					obj, nullptr) == LBC_OK;
				TheTerrainVisual->removeAllBibs();
				return result;
```

How can I resolve this? If you propose a fix, please make it concise.

_{Reviews (4): Last reviewed commit: "Replicate to Generals" | Re-trigger Greptile}

[Skyaero42]

Not entirely sure what the convention is, but I would prefer

• the loc parameter on its own line too
• The parameters indented only once (2 spaces / 1 tab)

[xezon]

Makes sense.

[xezon]

Is fine, but also could format like so:

const Real angle = thing->getPlacementViewAngle();

return TheBuildAssistant->isLocationLegalToBuild(
	loc, thing, angle,
	BuildAssistant::USE_QUICK_PATHFIND |
	BuildAssistant::TERRAIN_RESTRICTIONS |
	BuildAssistant::CLEAR_PATH |
	BuildAssistant::NO_OBJECT_OVERLAP |
	BuildAssistant::SHROUD_REVEALED |
	BuildAssistant::IGNORE_STEALTHED,
	obj, nullptr) == LBC_OK;

Is perhaps a tiny bit easier to read and debug and in line with how the rest of the code base writes this function.