Use AURA_INTERRUPT_FLAG_UNK2 to remove some aura on cast

There is still a discution about how to correctly delete an holder by avoiding to restart constently from the bigining of the holder list. I think this should be adressed in the future and in the entire code.

Thank @killerwife for his suggestion and help.

src/game/Spell.cpp

@@ -3020,13 +3020,8 @@ void Spell::prepare(SpellCastTargets const* targets, Aura* triggeredByAura)
     // set timer base at cast time
     ReSetTimer();
 
-    // stealth must be removed at cast starting (at show channel bar)
-    // skip triggered spell (item equip spell casting and other not explicit character casts/item uses)
-    if (!m_IsTriggeredSpell && isSpellBreakStealth(m_spellInfo))
-    {
-        m_caster->RemoveSpellsCausingAura(SPELL_AURA_MOD_STEALTH);
-        m_caster->RemoveSpellsCausingAura(SPELL_AURA_FEIGN_DEATH);
-    }
+    if (!m_IsTriggeredSpell)
+        m_caster->RemoveAurasOnCast(m_spellInfo);
 
     // add non-triggered (with cast time and without)
     if (!m_IsTriggeredSpell)

src/game/Unit.cpp

@@ -4754,6 +4754,46 @@ void Unit::RemoveAurasWithAttribute(uint32 flags)
     }
 }
 
+void Unit::RemoveAurasOnCast(SpellEntry const* castedSpellEntry)
+{
+    for (SpellAuraHolderMap::iterator iter = m_spellAuraHolders.begin(); iter != m_spellAuraHolders.end();)
+    {
+        SpellAuraHolder* holder = iter->second;
+        SpellEntry const* spellEntry = holder->GetSpellProto();
+        bool removeThisHolder = false;
+
+        if (spellEntry->AuraInterruptFlags & AURA_INTERRUPT_FLAG_UNK2)
+        {
+            if (castedSpellEntry->HasAttribute(SPELL_ATTR_EX_NOT_BREAK_STEALTH))
+            {
+                bool foundStealth = false;
+                for (int32 i = 0; i < MAX_EFFECT_INDEX; ++i)
+                {
+                    if (Aura* aura = holder->m_auras[i])
+                    {
+                        if (aura->GetModifier()->m_auraname == SPELL_AURA_MOD_STEALTH)
+                        {
+                            foundStealth = true;
+                            break;
+                        }
+                    }
+                }
+                removeThisHolder = !foundStealth;
+            }
+            else
+                removeThisHolder = true;
+        }
+
+        if (removeThisHolder)
+        {
+            RemoveSpellAuraHolder(iter->second);
+            iter = m_spellAuraHolders.begin();
+        }
+        else
+            ++iter;
+    }
+}
+
 void Unit::RemoveNotOwnTrackedTargetAuras(uint32 newPhase)
 {
     // tracked aura targets from other casters are removed if the phase does no more fit

src/game/Unit.h

@@ -1737,6 +1737,9 @@ class MANGOS_DLL_SPEC Unit : public WorldObject
         void RemoveAllAurasOnDeath();
         void RemoveAllAurasOnEvade();
 
+        // remove specific aura on cast
+        void RemoveAurasOnCast(SpellEntry const* castedSpellEntry);
+
         // removing specific aura FROM stack by diff reasons and selections
         void RemoveAuraHolderFromStack(uint32 spellId, uint32 stackAmount = 1, ObjectGuid casterGuid = ObjectGuid(), AuraRemoveMode mode = AURA_REMOVE_BY_DEFAULT);
         void RemoveAuraHolderDueToSpellByDispel(uint32 spellId, uint32 stackAmount, ObjectGuid casterGuid, Unit* dispeller);