Overhaul cheat handling during rom load/close

- Stop overwriting/deleting other games' cheat files after rom change
- Always clear/update references to disposed memory domains
- Keep current cheats after core restart

Author: kalimag

src/BizHawk.Client.Common/tools/Cheat.cs

@@ -73,7 +73,11 @@ public Cheat(Cheat cheat)
 
 		public int? Compare => _compare.HasValue && !IsSeparator ? _compare : null;
 
-		public MemoryDomain Domain => _watch.Domain;
+		public MemoryDomain Domain
+		{
+			get =>	_watch.Domain;
+			set => _watch.Domain = value;
+		}
 
 		public WatchSize Size => _watch.Size;
 

src/BizHawk.Client.Common/tools/CheatList.cs

@@ -404,6 +404,24 @@ public bool Load(IMemoryDomains domains, string path, bool append)
 			return true;
 		}
 
+		public void UpdateDomains(IMemoryDomains domains)
+		{
+			for (int i = _cheatList.Count - 1; i >= 0; i--)
+			{
+				var cheat = _cheatList[i];
+				var newDomain = domains[cheat.Domain.Name];
+				if (newDomain is not null)
+				{
+					cheat.Domain = newDomain;
+				}
+				else
+				{
+					_cheatList.RemoveAt(i);
+					Changes = true;
+				}
+			}
+		}
+
 		private static readonly RigidMultiPredicateSort<Cheat> ColumnSorts
 			= new RigidMultiPredicateSort<Cheat>(new Dictionary<string, Func<Cheat, IComparable>>
 			{

src/BizHawk.Client.EmuHawk/MainForm.cs

@@ -3783,21 +3783,32 @@ private bool LoadRomInternal(string path, LoadRomArgs args, out bool failureIsFr
 						}
 					}
 
+					var previousRom = CurrentlyOpenRom;
 					CurrentlyOpenRom = oaOpenrom?.Path ?? openAdvancedArgs;
 					CurrentlyOpenRomArgs = args;
 
 					Tools.Restart(Config, Emulator, Game);
 
-					if (Config.Cheats.LoadFileByGame && Emulator.HasMemoryDomains())
+					if (previousRom != CurrentlyOpenRom)
 					{
-						CheatList.SetDefaultFileName(Tools.GenerateDefaultCheatFilename());
-						if (CheatList.AttemptToLoadCheatFile(Emulator.AsMemoryDomains()))
+						CheatList.NewList(Tools.GenerateDefaultCheatFilename(), autosave: true);
+						if (Config.Cheats.LoadFileByGame && Emulator.HasMemoryDomains())
 						{
-							AddOnScreenMessage("Cheats file loaded");
+							if (CheatList.AttemptToLoadCheatFile(Emulator.AsMemoryDomains()))
+							{
+								AddOnScreenMessage("Cheats file loaded");
+							}
+						}
+					}
+					else
+					{
+						if (Emulator.HasMemoryDomains())
+						{
+							CheatList.UpdateDomains(Emulator.AsMemoryDomains());
 						}
-						else if (CheatList.Any())
+						else
 						{
-							CheatList.Clear();
+							CheatList.NewList(Tools.GenerateDefaultCheatFilename(), autosave: true);
 						}
 					}
 
@@ -3838,6 +3849,7 @@ private bool LoadRomInternal(string path, LoadRomArgs args, out bool failureIsFr
 					DisplayManager.UpdateGlobals(Config, Emulator);
 					DisplayManager.Blank();
 					ExtToolManager.BuildToolStrip();
+					CheatList.NewList("", autosave: true);
 					OnRomChanged();
 					return false;
 				}
@@ -3973,6 +3985,7 @@ public void CloseRom(bool clearSram = false)
 				PauseOnFrame = null;
 				CurrentlyOpenRom = null;
 				CurrentlyOpenRomArgs = null;
+				CheatList.NewList("", autosave: true);
 				OnRomChanged();
 			}
 		}

src/BizHawk.Client.EmuHawk/tools/ToolManager.cs

@@ -586,11 +586,6 @@ public void Restart(Config config, IEmulator emulator, IGameInfo game)
 			_emulator = emulator;
 			_game = game;
 			_apiProvider = null;
-			// If Cheat tool is loaded, restarting will restart the list too anyway
-			if (!Has<Cheats>())
-			{
-				_owner.CheatList.NewList(GenerateDefaultCheatFilename(), autosave: true);
-			}
 
 			var unavailable = new List<IToolForm>();