From e065263ff258bea7fa30c4e87b46ca407c8aa62b Mon Sep 17 00:00:00 2001
From: vadosnaprimer <feykomylce@gmail.com>
Date: Sun, 30 Apr 2023 14:07:02 +0300
Subject: [PATCH] MAME does mark bad dumps, but it only keeps their info if
 good dump is not known yet. once a good dump appears, its info replaces the
 bad one.

so simply sticking to newest rom sets is the safest, otherwise there's little user control, because there's no global list of all known dumps with indications which of them are bad and what to use instead.
---
 .../Arcades/MAME/MAME.ISettable.cs                 |  7 +++++++
 src/BizHawk.Emulation.Cores/Arcades/MAME/MAME.cs   | 14 +++++++++++++-
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/src/BizHawk.Emulation.Cores/Arcades/MAME/MAME.ISettable.cs b/src/BizHawk.Emulation.Cores/Arcades/MAME/MAME.ISettable.cs
index d362d67357..fdaacf4cea 100644
--- a/src/BizHawk.Emulation.Cores/Arcades/MAME/MAME.ISettable.cs
+++ b/src/BizHawk.Emulation.Cores/Arcades/MAME/MAME.ISettable.cs
@@ -4,6 +4,7 @@ using System.ComponentModel;
 using System.Linq;
 
 using BizHawk.Common;
+using BizHawk.Common.StringExtensions;
 using BizHawk.Emulation.Common;
 
 namespace BizHawk.Emulation.Cores.Arcades.MAME
@@ -164,6 +165,12 @@ namespace BizHawk.Emulation.Cores.Arcades.MAME
 					}
 					else
 					{
+						if (hashdata.Contains("^"))
+						{
+							hashdata = hashdata.RemoveSuffix("^");
+							name = name + " (BAD DUMP)";
+						}
+
 						hashdata = hashdata.Replace("R", "CRC:").Replace("S", " SHA:");
 						_romHashes.Add(name, hashdata);
 					}
diff --git a/src/BizHawk.Emulation.Cores/Arcades/MAME/MAME.cs b/src/BizHawk.Emulation.Cores/Arcades/MAME/MAME.cs
index 99954da76a..f825f4d3b5 100644
--- a/src/BizHawk.Emulation.Cores/Arcades/MAME/MAME.cs
+++ b/src/BizHawk.Emulation.Cores/Arcades/MAME/MAME.cs
@@ -99,7 +99,19 @@ namespace BizHawk.Emulation.Cores.Arcades.MAME
 
 			lp.Game.Name = _gameFullName;
 			lp.Game.Hash = SHA1Checksum.ComputeDigestHex(Encoding.ASCII.GetBytes(hashes));
-			lp.Game.Status = _romHashes.Values.Any(static s => s is "NO GOOD DUMP KNOWN") ? RomStatus.Unknown : RomStatus.GoodDump;
+
+			if (_romHashes.Values.Any(static s => s is "NO GOOD DUMP KNOWN"))
+			{
+				lp.Game.Status = RomStatus.Unknown;
+			}
+			else if (_romHashes.Keys.Any(static s => s.Contains("BAD DUMP")))
+			{
+				lp.Game.Status = RomStatus.BadDump;
+			}
+			else
+			{
+				lp.Game.Status = RomStatus.GoodDump;
+			}
 
 			_core.mame_info_get_warnings_string(_infoCallback);
 			_infoCallback = null;