- fixed: WP_NOCHANGE had different values in native and script code, resulting in problems with weapon selection.

This now explicitly allocates a single object it can safely point to instead of trying to hack around it.

src/d_player.h

@@ -235,7 +235,7 @@ enum
 // The VM cannot deal with this as an invalid pointer because it performs a read barrier on every object pointer read.
 // This doesn't have to point to a valid weapon, though, because WP_NOCHANGE is never dereferenced, but it must point to a valid object
 // and the class descriptor just works fine for that.
-#define WP_NOCHANGE ((AWeapon*)RUNTIME_CLASS_CASTLESS(AWeapon))
+extern AWeapon *WP_NOCHANGE;
 
 
 #define MAXPLAYERNAME	15

src/dobjtype.cpp

@@ -74,6 +74,12 @@ TArray<VMFunction**> PClass::FunctionPtrList;
 bool PClass::bShutdown;
 bool PClass::bVMOperational;
 
+// Originally this was just a bogus pointer, but with the VM performing a read barrier on every object pointer write
+// that does not work anymore. WP_NOCHANGE needs to point to a vaild object to work as intended.
+// This Object does not need to be garbage collected, though, but it needs to provide the proper structure so that the
+// GC can process it.
+AWeapon *WP_NOCHANGE;
+DEFINE_GLOBAL(WP_NOCHANGE);
 
 
 // PRIVATE DATA DEFINITIONS ------------------------------------------------
@@ -218,6 +224,10 @@ void PClass::StaticInit ()
 	// I'm not sure if this is really necessary to maintain any sort of sync.
 	qsort(&AllClasses[0], AllClasses.Size(), sizeof(AllClasses[0]), cregcmp);
 
+	// WP_NOCHANGE must point to a valid object, although it does not need to be a weapon.
+	// A simple DObject is enough to give the GC the ability to deal with it, if subjected to it.
+	WP_NOCHANGE = (AWeapon*)new DObject;
+	WP_NOCHANGE->Release();
 }
 
 //==========================================================================
@@ -230,6 +240,12 @@ void PClass::StaticInit ()
 
 void PClass::StaticShutdown ()
 {
+	if (WP_NOCHANGE != nullptr)
+	{
+		WP_NOCHANGE->ObjectFlags |= OF_YesReallyDelete;
+		delete WP_NOCHANGE;
+	}
+
 	// delete all variables containing pointers to script functions.
 	for (auto p : FunctionPtrList)
 	{

src/scripting/thingdef_data.cpp

@@ -70,14 +70,6 @@ static TArray<FieldDesc> FieldTable;
 extern int				BackbuttonTime;
 extern float			BackbuttonAlpha;
 
-// Argh. It sucks when bad hacks need to be supported. WP_NOCHANGE is just a bogus pointer but is used everywhere as a special flag.
-// It cannot be defined as constant because constants can either be numbers or strings but nothing else, so the only 'solution'
-// is to create a static variable from it that points to an otherwise unused object and reference that in the script. Yuck!!!
-// This must point to a valid DObject derived object so that the garbage collector can deal with it.
-// The global VM types are the most convenient options here because they get created before the compiler is started and they
-// are not exposed in other ways to scripts - and they do not change unless the engine is shut down.
-DEFINE_GLOBAL_NAMED(TypeSInt32, wp_nochange);
-
 //==========================================================================
 //
 // List of all flags