Tested and reworked the 'unit upgrades for free' unique till it worked (#6555)

core/src/com/unciv/logic/map/MapUnit.kt

@@ -513,8 +513,9 @@ class MapUnit {
         if (name == unitToUpgradeTo.name) return false
         val rejectionReasons = unitToUpgradeTo.getRejectionReasons(civInfo)
         if (rejectionReasons.isEmpty()) return true
+        if (ignoreRequired && rejectionReasons.filterTechPolicyEraWonderRequirements().isEmpty()) return true
 
-        if (rejectionReasons.size == 1 && rejectionReasons.contains(RejectionReason.ConsumesResources)) {
+        if (rejectionReasons.contains(RejectionReason.ConsumesResources)) {
             // We need to remove the unit from the civ for this check,
             // because if the unit requires, say, horses, and so does its upgrade,
             // and the civ currently has 0 horses, we need to see if the upgrade will be buildable

core/src/com/unciv/models/ruleset/unique/UniqueTriggerActivation.kt

@@ -494,7 +494,7 @@ object UniqueTriggerActivation {
                 return true
             }
             OneTimeUnitUpgrade -> {
-                val upgradeAction = UnitActions.getUpgradeAction(unit, true)
+                val upgradeAction = UnitActions.getFreeUpgradeAction(unit)
                     ?: return false
                 upgradeAction.action!!()
                 if (notification != null)

core/src/com/unciv/ui/worldscreen/unit/UnitActions.kt

@@ -311,14 +311,14 @@ object UnitActions {
         if (upgradeAction != null) actionList += upgradeAction
     }
 
-    fun getUpgradeAction(unit: MapUnit, isFree: Boolean = false): UnitAction? {
+    fun getUpgradeAction(unit: MapUnit): UnitAction? {
         val tile = unit.currentTile
-        if (unit.baseUnit().upgradesTo == null || !unit.canUpgrade()) return null
+        if (unit.baseUnit().upgradesTo == null) return null
-        if (tile.getOwner() != unit.civInfo && !isFree) return null
+        if (!unit.canUpgrade()) return null
-        val goldCostOfUpgrade =
+        if (tile.getOwner() != unit.civInfo) return null
-            if (isFree) 0
+        
-            else unit.getCostOfUpgrade()
         val upgradedUnit = unit.getUnitToUpgradeTo()
+        val goldCostOfUpgrade = unit.getCostOfUpgrade()
 
         return UnitAction(UnitActionType.Upgrade,
             title = "Upgrade to [${upgradedUnit.name}] ([$goldCostOfUpgrade] gold)",
@@ -339,13 +339,36 @@ object UnitActions {
                     newUnit.currentMovement = 0f
                 }
             }.takeIf {
-                isFree ||
-                (
                 unit.civInfo.gold >= goldCostOfUpgrade
                 && unit.currentMovement > 0
                 && !unit.isEmbarked()
+            }
         )
     }
+    
+    fun getFreeUpgradeAction(unit: MapUnit): UnitAction? {
+        if (unit.baseUnit().upgradesTo == null) return null
+        val upgradedUnit = unit.civInfo.getEquivalentUnit(unit.baseUnit().upgradesTo!!)
+        if (!unit.canUpgrade(upgradedUnit, true)) return null
+
+        return UnitAction(UnitActionType.Upgrade,
+            title = "Upgrade to [${upgradedUnit.name}] (FREE)",
+            action = {
+                val unitTile = unit.getTile()
+                unit.destroy()
+                val newUnit = unit.civInfo.placeUnitNearTile(unitTile.position, upgradedUnit.name)
+
+                /** We were UNABLE to place the new unit, which means that the unit failed to upgrade!
+                 * The only known cause of this currently is "land units upgrading to water units" which fail to be placed.
+                 */
+                if (newUnit == null) {
+                    val readdedUnit = unit.civInfo.placeUnitNearTile(unitTile.position, unit.name)
+                    unit.copyStatisticsTo(readdedUnit!!)
+                } else { // Managed to upgrade
+                    unit.copyStatisticsTo(newUnit)
+                    newUnit.currentMovement = 0f
+                }
+            }
         )
     }
 
@@ -357,9 +380,8 @@ object UnitActions {
                 else -> return null
             }
         val upgradedUnit =
-            unit.civInfo.getEquivalentUnit(
+            unit.civInfo.getEquivalentUnit(unit.civInfo.gameInfo.ruleSet.units[upgradedUnitName]!!)
-                unit.civInfo.gameInfo.ruleSet.units[upgradedUnitName]!!
+        
-            )
         if (!unit.canUpgrade(upgradedUnit,true)) return null
 
         return UnitAction(UnitActionType.Upgrade,