Gain free building uniqueType'D

core/src/com/unciv/logic/city/CityInfo.kt

@@ -160,7 +160,7 @@ class CityInfo {
 
         civInfo.civConstructions.tryAddFreeBuildings()
 
-        for (unique in getMatchingUniques("Gain a free [] []")) {
+        for (unique in getMatchingUniques(UniqueType.GainFreeBuildings)) {
             val freeBuildingName = unique.params[0]
             if (matchesFilter(unique.params[1])) {
                 if (!cityConstructions.isBuilt(freeBuildingName))

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

@@ -53,6 +53,15 @@ enum class UniqueParameterType(val parameterName:String) {
             return null
         }
     },
+    BuildingName("buildingName") {
+        override fun getErrorSeverity(
+            parameterText: String,
+            ruleset: Ruleset
+        ): UniqueType.UniqueComplianceErrorSeverity? {
+            if (ruleset.buildings.containsKey(parameterText)) return null
+            return UniqueType.UniqueComplianceErrorSeverity.RulesetSpecific
+        }
+    },
     Unknown("param") {
         override fun getErrorSeverity(parameterText: String, ruleset: Ruleset):
                 UniqueType.UniqueComplianceErrorSeverity? {

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

@@ -27,7 +27,7 @@ enum class UniqueType(val text:String, val replacedBy: UniqueType? = null) {
     DecreasedUnitMaintenanceCostsGlobally("-[amount]% unit upkeep costs", UnitMaintenanceDiscount), // No conditional support
     @Deprecated("As of 3.16.16", ReplaceWith("Stats <>"))
     StatBonusForNumberOfSpecialists("[stats] if this city has at least [amount] specialists"), // No conditional support
-    
+    GainFreeBuildings("Gain a free [buildingName] [cityFilter]"),
     
     CityStateStatsPerTurn("Provides [stats] per turn"), // Should not be Happiness!
     CityStateStatsPerCity("Provides [stats] [cityFilter]"),