From b7e0a8d2c74cf7907cf44d12ee97f608b0cf0c21 Mon Sep 17 00:00:00 2001
From: "alexey.lysiuk" <alexey.lysiuk@gmail.com>
Date: Thu, 11 Jul 2019 11:07:09 +0300
Subject: [PATCH] - added validation for presence of drop item classes

https://forum.zdoom.org/viewtopic.php?t=65307
---
 src/scripting/thingdef.cpp | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/src/scripting/thingdef.cpp b/src/scripting/thingdef.cpp
index 261b07f72..bc8f1a876 100644
--- a/src/scripting/thingdef.cpp
+++ b/src/scripting/thingdef.cpp
@@ -419,6 +419,27 @@ static void CheckStates(PClassActor *obj)
 	}
 }
 
+void CheckDropItems(const PClassActor *const obj)
+{
+	const FDropItem *dropItem = obj->ActorInfo()->DropItems;
+
+	while (dropItem != nullptr)
+	{
+		if (dropItem->Name != NAME_None)
+		{
+			const char *const dropItemName = dropItem->Name.GetChars();
+
+			if (dropItemName[0] != '\0' && PClass::FindClass(dropItem->Name) == nullptr)
+			{
+				Printf(TEXTCOLOR_ORANGE "Undefined drop item class %s referenced from actor %s\n", dropItemName, obj->TypeName.GetChars());
+				FScriptPosition::WarnCounter++;
+			}
+		}
+
+		dropItem = dropItem->Next;
+	}
+}
+
 //==========================================================================
 //
 // LoadActors
@@ -500,6 +521,8 @@ void LoadActors()
 			// PASSMOBJ is irrelevant for normal missiles, but not for bouncers.
 			defaults->flags2 |= MF2_PASSMOBJ;
 		}
+
+		CheckDropItems(ti);
 	}
 	if (FScriptPosition::ErrorCounter > 0)
 	{