Core/Units: add new functionality for units to block or enable combat entirely via helper to reflect what CREATURE_DIFFICULTYFLAGS_IGNORE_COMBAT and client ai functions imply

src/server/game/Combat/CombatManager.cpp

@@ -44,12 +44,9 @@
         return false;
     if (a->HasUnitState(UNIT_STATE_IN_FLIGHT) || b->HasUnitState(UNIT_STATE_IN_FLIGHT))
         return false;
-    if (Creature const* aCreature = a->ToCreature())
-        if (aCreature->IsCombatDisallowed())
-            return false;
-    if (Creature const* bCreature = b->ToCreature())
-        if (bCreature->IsCombatDisallowed())
-            return false;
+    // ... both units must not be ignoring combat
+    if (a->IsIgnoringCombat() || b->IsIgnoringCombat())
+        return false;
     if (a->IsFriendlyTo(b) || b->IsFriendlyTo(a))
         return false;
     Player const* playerA = a->GetCharmerOrOwnerPlayerOrPlayerItself();

src/server/game/Entities/Creature/Creature.cpp

@@ -647,6 +647,9 @@ bool Creature::UpdateEntry(uint32 entry, CreatureData const* data /*= nullptr*/,
     if (GetMovementTemplate().IsRooted())
         SetControlled(true, UNIT_STATE_ROOT);
 
+    if (cInfo->flags_extra & CREATURE_FLAG_EXTRA_NO_COMBAT)
+        SetIgnoringCombat(true);
+
     UpdateMovementFlags();
     LoadCreaturesAddon();
     LoadTemplateImmunities();

src/server/game/Entities/Unit/Unit.cpp

@@ -328,7 +328,7 @@ Unit::Unit(bool isWorldObject) :
     m_removedAurasCount(0), i_motionMaster(new MotionMaster(this)), m_vehicle(nullptr),
     m_vehicleKit(nullptr), m_unitTypeMask(UNIT_MASK_NONE), m_Diminishing(),
     m_isEngaged(false), m_combatManager(this), m_threatManager(this), _lastDamagedTime(0),
-    m_spellHistory(new SpellHistory(this))
+    m_spellHistory(new SpellHistory(this)), _isIgnoringCombat(false)
 {
     m_objectType |= TYPEMASK_UNIT;
     m_objectTypeId = TYPEID_UNIT;

src/server/game/Entities/Unit/Unit.h

@@ -1922,6 +1922,11 @@ class TC_GAME_API Unit : public WorldObject
 
         float GetCollisionHeight() const override;
 
+        // returns if the unit is allowed to enter combat
+        bool IsIgnoringCombat() const { return _isIgnoringCombat; }
+        // enables/disables combat permission of this unit
+        void SetIgnoringCombat(bool apply) { _isIgnoringCombat = apply; }
+
     protected:
         explicit Unit (bool isWorldObject);
 
@@ -2063,6 +2068,8 @@ class TC_GAME_API Unit : public WorldObject
         FormationFollowerGUIDContainer _formationFollowers;
 
         std::array<std::unordered_set<AbstractPursuer*>, AsUnderlyingType(PursuingType::Max)> _unitsPursuingMe;
+
+        bool _isIgnoringCombat;
 };
 
 namespace Trinity