Dynamic virtualscope checking. May yet be buggy.

src/scripting/backend/codegen.cpp

@@ -89,6 +89,34 @@ static const FLOP FxFlops[] =
 	{ NAME_TanH,	FLOP_TANH,		[](double v) { return g_tanh(v); } },
 };
 
+
+//==========================================================================
+//
+// [ZZ] Magic methods to be used in vmexec.h for runtime checking of scope
+//
+//==========================================================================
+
+// this can be imported in vmexec.h
+void FScopeBarrier_ValidateNew(PClass* cls, PFunction* callingfunc)
+{
+	int outerside = FScopeBarrier::SideFromFlags(callingfunc->Variants[0].Flags);
+	int innerside = FScopeBarrier::SideFromObjectFlags(cls->ObjectFlags);
+	if ((outerside != innerside) && (innerside != FScopeBarrier::Side_PlainData)) // "cannot construct ui class ... from data context"
+		ThrowAbortException(X_OTHER, "Cannot construct %s class %s from %s context", FScopeBarrier::StringFromSide(innerside), cls->TypeName.GetChars(), FScopeBarrier::StringFromSide(outerside));
+}
+// this can be imported in vmexec.h
+void FScopeBarrier_ValidateCall(PFunction* calledfunc, PFunction* callingfunc, PClass* selftype)
+{
+	int outerside = FScopeBarrier::SideFromFlags(callingfunc->Variants[0].Flags);
+	if (outerside == FScopeBarrier::Side_Virtual)
+		outerside = FScopeBarrier::Side_PlainData;
+	int innerside = FScopeBarrier::SideFromFlags(calledfunc->Variants[0].Flags);
+	if (innerside == FScopeBarrier::Side_Virtual)
+		innerside = FScopeBarrier::SideFromObjectFlags(selftype->ObjectFlags);
+	if ((outerside != innerside) && (innerside != FScopeBarrier::Side_PlainData))
+		ThrowAbortException(X_OTHER, "Cannot call %s function %s from %s context", FScopeBarrier::StringFromSide(innerside), calledfunc->SymbolName.GetChars(), FScopeBarrier::StringFromSide(outerside));
+}
+
 //==========================================================================
 //
 // FCompileContext
@@ -8300,6 +8328,7 @@ FxVMFunctionCall::FxVMFunctionCall(FxExpression *self, PFunction *func, FArgumen
 	ArgList = std::move(args);
 	EmitTail = false;
 	NoVirtual = novirtual;
+	CallingFunction = nullptr;
 }
 
 //==========================================================================
@@ -8373,6 +8402,7 @@ FxExpression *FxVMFunctionCall::Resolve(FCompileContext& ctx)
 		return nullptr;
 	}
 
+	CallingFunction = ctx.Function;
 	if (ArgList.Size() > 0)
 	{
 		bool foundvarargs = false;
@@ -8580,6 +8610,15 @@ ExpEmit FxVMFunctionCall::Emit(VMFunctionBuilder *build)
 	ExpEmit selfemit;
 	if (Function->Variants[0].Flags & VARF_Method)
 	{
+		// [ZZ]
+		if (Function->Variants[0].Implementation && Function->Variants[0].Implementation->BarrierSide == FScopeBarrier::Side_Virtual)
+		{
+			// pass this even before Self, because otherwise we can't silently advance the arguments.
+			// this is not even implicit arguments.
+			build->Emit(OP_PARAM, 0, REGT_POINTER | REGT_KONST, build->GetConstantAddress(Function, ATAG_OBJECT));
+			build->Emit(OP_PARAM, 0, REGT_POINTER | REGT_KONST, build->GetConstantAddress(CallingFunction, ATAG_OBJECT));
+			count += 2;
+		}
 		assert(Self != nullptr);
 		selfemit = Self->Emit(build);
 		assert((selfemit.RegType == REGT_POINTER) || (selfemit.Fixed && selfemit.Target));

src/scripting/backend/codegen.h

@@ -70,7 +70,8 @@ class FxCompoundStatement;
 class FxLocalVariableDeclaration;
 typedef TDeletingArray<FxExpression*> FArgumentList;
 
-// [ZZ] this is kind of related to compile context as well
+//
+// [ZZ] this really should be in codegen.h, but vmexec needs to access it
 struct FScopeBarrier
 {
 	bool callable;
@@ -86,9 +87,9 @@ struct FScopeBarrier
 	enum Side
 	{
 		Side_PlainData = 0,
-		Side_UI,
-		Side_Play,
-		Side_Virtual
+		Side_UI = 1,
+		Side_Play = 2,
+		Side_Virtual = 3 // do NOT change the value
 	};
 	int sidefrom;
 	int sidelast;
@@ -152,7 +153,7 @@ struct FScopeBarrier
 	// this modifies VARF_ flags and sets the side properly.
 	static int ChangeSideInFlags(int flags, int side)
 	{
-		flags &= ~(VARF_UI | VARF_Play);
+		flags &= ~(VARF_UI | VARF_Play | VARF_VirtualScope);
 		flags |= FlagsFromSide(side);
 		return flags;
 	}
@@ -208,28 +209,31 @@ struct FScopeBarrier
 		if ((sideto == Side_UI) && (sidefrom != Side_UI)) // only ui -> ui is readable
 		{
 			readable = false;
-			readerror.Format("Can't read %s field %s from %s context", StringFromSide(sideto), name, StringFromSide(sidefrom));
+			if (name) readerror.Format("Can't read %s field %s from %s context", StringFromSide(sideto), name, StringFromSide(sidefrom));
 		}
 
 		if (!readable)
 		{
 			writable = false;
 			callable = false;
-			writeerror.Format("Can't write %s field %s from %s context (not readable)", StringFromSide(sideto), name, StringFromSide(sidefrom));
-			callerror.Format("Can't call %s function %s from %s context (not readable)", StringFromSide(sideto), name, StringFromSide(sidefrom));
+			if (name)
+			{
+				writeerror.Format("Can't write %s field %s from %s context (not readable)", StringFromSide(sideto), name, StringFromSide(sidefrom));
+				callerror.Format("Can't call %s function %s from %s context (not readable)", StringFromSide(sideto), name, StringFromSide(sidefrom));
+			}
 			return;
 		}
 
 		if (writable && (sidefrom != sideto)) // only matching types are writable (plain data implicitly takes context type by default, unless overridden)
 		{
 			writable = false;
-			writeerror.Format("Can't write %s field %s from %s context", StringFromSide(sideto), name, StringFromSide(sidefrom));
+			if (name) writeerror.Format("Can't write %s field %s from %s context", StringFromSide(sideto), name, StringFromSide(sidefrom));
 		}
 
 		if (callable && (sidefrom != sideto) && !(flags2 & VARF_ReadOnly)) // readonly on methods is used for plain data stuff that can be called from ui/play context.
 		{
 			callable = false;
-			callerror.Format("Can't call %s function %s from %s context", StringFromSide(sideto), name, StringFromSide(sidefrom));
+			if (name) callerror.Format("Can't call %s function %s from %s context", StringFromSide(sideto), name, StringFromSide(sidefrom));
 		}
 	}
 };
@@ -1873,6 +1877,7 @@ class FxVMFunctionCall : public FxExpression
 	// for multi assignment
 	int AssignCount = 0;
 	TArray<ExpEmit> ReturnRegs;
+	PFunction *CallingFunction;
 
 public:
 	FxVMFunctionCall(FxExpression *self, PFunction *func, FArgumentList &args, const FScriptPosition &pos, bool novirtual);

src/scripting/thingdef.cpp

@@ -163,6 +163,10 @@ PFunction *CreateAnonymousFunction(PClass *containingclass, PType *returntype, i
 	// Functions that only get flagged for actors do not need the additional two context parameters.
 	int fflags = (flags& (SUF_OVERLAY | SUF_WEAPON | SUF_ITEM)) ? VARF_Action | VARF_Method : VARF_Method;
 
+	// [ZZ] give anonymous functions the scope of their class 
+	//      (just give them VARF_Play, whatever)
+	fflags |= VARF_Play;
+
 	rets[0] = returntype != nullptr? returntype : TypeError;	// Use TypeError as placeholder if we do not know the return type yet.
 	SetImplicitArgs(&args, &argflags, &argnames, containingclass, fflags, flags);
 

src/scripting/vm/vm.h

@@ -8,6 +8,11 @@
 #include "doomerrors.h"
 #include "memarena.h"
 
+// [ZZ] there are serious circular references between this and the rest of ZScript code, so it needs to be done like this
+//		these are used in vmexec.h
+void FScopeBarrier_ValidateNew(PClass* cls, PFunction* callingfunc);
+void FScopeBarrier_ValidateCall(PFunction* calledfunc, PFunction* callingfunc, PClass* selftype);
+
 extern FMemArena ClassDataAllocator;
 
 #define MAX_RETURNS		8	// Maximum number of results a function called by script code can return
@@ -712,7 +717,7 @@ public:
 
 	class PPrototype *Proto;
 
-	VMFunction(FName name = NAME_None) : Native(false), ImplicitArgs(0), Name(name), Proto(NULL) 
+	VMFunction(FName name = NAME_None) : Native(false), ImplicitArgs(0), Name(name), Proto(NULL)
 	{
 		AllFunctions.Push(this);
 	}

src/scripting/vm/vmexec.h

@@ -648,13 +648,25 @@ begin:
 			VMReturn returns[MAX_RETURNS];
 			int numret;
 
+			// [ZZ] hax!
+			b = B;
+			if (call->BarrierSide == 3) // :( - this is Side_Virtual. Side_Virtual should receive special arguments.
+			{
+				PFunction* calledfunc = (PFunction*)(reg.param + f->NumParam - b)[0].a;
+				PFunction* callingfunc = (PFunction*)(reg.param + f->NumParam - b)[1].a;
+				DObject* dobj = (DObject*)(reg.param + f->NumParam - b)[2].a; // this is the self pointer. it should be in, since Side_Virtual functions are always non-static methods.
+				PClass* selftype = dobj->GetClass();
+				FScopeBarrier_ValidateCall(calledfunc, callingfunc, selftype);
+				b -= 2;
+			}
+
 			FillReturns(reg, f, returns, pc+1, C);
 			if (call->Native)
 			{
 				try
 				{
 					VMCycles[0].Unclock();
-					numret = static_cast<VMNativeFunction *>(call)->NativeCall(reg.param + f->NumParam - B, call->DefaultArgs, B, returns, C);
+					numret = static_cast<VMNativeFunction *>(call)->NativeCall(reg.param + f->NumParam - b, call->DefaultArgs, b, returns, C);
 					VMCycles[0].Clock();
 				}
 				catch (CVMAbortException &err)
@@ -670,7 +682,7 @@ begin:
 				VMCalls[0]++;
 				VMScriptFunction *script = static_cast<VMScriptFunction *>(call);
 				VMFrame *newf = stack->AllocFrame(script);
-				VMFillParams(reg.param + f->NumParam - B, newf, B);
+				VMFillParams(reg.param + f->NumParam - b, newf, b);
 				try
 				{
 					numret = Exec(stack, script->Code, returns, C);
@@ -801,6 +813,9 @@ begin:
 			if (!callingfunc || pcls != callingfunc->OwningClass)
 				ThrowAbortException(X_OTHER, "Cannot instantiate class %s directly", cls->TypeName.GetChars());
 		}
+		// [ZZ] validate readonly and between scope construction
+		if (callingfunc)
+			FScopeBarrier_ValidateNew(cls, callingfunc);
 		reg.a[a] = cls->CreateNew();
 		reg.atag[a] = ATAG_OBJECT;
 		NEXTOP;

src/scripting/zscript/zcc_compile.cpp

@@ -2401,6 +2401,17 @@ void ZCCCompiler::CompileFunction(ZCC_StructWork *c, ZCC_FuncDeclarator *f, bool
 			sym->Variants[0].Implementation->DefaultArgs = std::move(argdefaults);
 		}
 
+		if (sym->Variants[0].Implementation != nullptr)
+		{
+			// [ZZ] unspecified virtual function inherits old scope. virtual function scope can't be changed.
+			if (varflags & VARF_UI)
+				sym->Variants[0].Implementation->BarrierSide = FScopeBarrier::Side_UI;
+			if (varflags & VARF_Play)
+				sym->Variants[0].Implementation->BarrierSide = FScopeBarrier::Side_Play;
+			if (varflags & VARF_VirtualScope)
+				sym->Variants[0].Implementation->BarrierSide = FScopeBarrier::Side_Virtual;
+		}
+
 		PClass *clstype = static_cast<PClass *>(c->Type());
 		if (varflags & VARF_Virtual)
 		{
@@ -2412,13 +2423,6 @@ void ZCCCompiler::CompileFunction(ZCC_StructWork *c, ZCC_FuncDeclarator *f, bool
 			
 			if (varflags & VARF_Final)
 				sym->Variants[0].Implementation->Final = true;
-			// [ZZ] unspecified virtual function inherits old scope. virtual function scope can't be changed.
-			if (varflags & VARF_UI)
-				sym->Variants[0].Implementation->BarrierSide = FScopeBarrier::Side_UI;
-			if (varflags & VARF_Play)
-				sym->Variants[0].Implementation->BarrierSide = FScopeBarrier::Side_Play;
-			if (varflags & VARF_VirtualScope)
-				sym->Variants[0].Implementation->BarrierSide = FScopeBarrier::Side_Virtual;
 			if (varflags & VARF_ReadOnly)
 				sym->Variants[0].Implementation->FuncConst = true;