Add void and error types; rejigger pointer types

- Added TypeVoid for statements, which produce no type.
- Added TypeError for expressions whose arguments are incompatible.
- Pointers now derive from PBasicType instead of PInt. Since they have their own register sets in the VM, this seems to make more sense than treating them as integers.

src/dobjtype.cpp

@@ -61,6 +61,8 @@ FTypeTable TypeTable;
 TArray<PClass *> PClass::AllClasses;
 bool PClass::bShutdown;
 
+PErrorType *TypeError;
+PVoidType *TypeVoid;
 PInt *TypeSInt8,  *TypeUInt8;
 PInt *TypeSInt16, *TypeUInt16;
 PInt *TypeSInt32, *TypeUInt32;
@@ -73,7 +75,6 @@ PStatePointer *TypeState;
 PFixed *TypeFixed;
 PAngle *TypeAngle;
 
-
 // PRIVATE DATA DEFINITIONS ------------------------------------------------
 
 // A harmless non-NULL FlatPointer for classes without pointers.
@@ -81,6 +82,9 @@ static const size_t TheEnd = ~(size_t)0;
 
 // CODE --------------------------------------------------------------------
 
+IMPLEMENT_CLASS(PErrorType)
+IMPLEMENT_CLASS(PVoidType)
+
 void DumpTypeTable()
 {
 	int used = 0;
@@ -300,6 +304,8 @@ void PType::GetTypeIDs(intptr_t &id1, intptr_t &id2) const
 
 void PType::StaticInit()
 {
+	RUNTIME_CLASS(PErrorType)->TypeTableType = RUNTIME_CLASS(PErrorType);
+	RUNTIME_CLASS(PVoidType)->TypeTableType = RUNTIME_CLASS(PVoidType);
 	RUNTIME_CLASS(PInt)->TypeTableType = RUNTIME_CLASS(PInt);
 	RUNTIME_CLASS(PFloat)->TypeTableType = RUNTIME_CLASS(PFloat);
 	RUNTIME_CLASS(PString)->TypeTableType = RUNTIME_CLASS(PString);
@@ -320,6 +326,8 @@ void PType::StaticInit()
 	RUNTIME_CLASS(PFixed)->TypeTableType = RUNTIME_CLASS(PFixed);
 	RUNTIME_CLASS(PAngle)->TypeTableType = RUNTIME_CLASS(PAngle);
 
+	TypeTable.AddType(TypeError = new PErrorType);
+	TypeTable.AddType(TypeVoid = new PVoidType);
 	TypeTable.AddType(TypeSInt8 = new PInt(1, false));
 	TypeTable.AddType(TypeUInt8 = new PInt(1, true));
 	TypeTable.AddType(TypeSInt16 = new PInt(2, false));
@@ -877,9 +885,8 @@ IMPLEMENT_CLASS(PStatePointer)
 //==========================================================================
 
 PStatePointer::PStatePointer()
-: PInt(sizeof(FState *), true)
+: PBasicType(sizeof(FState *), __alignof(FState *))
 {
-	Align = __alignof(FState *);
 }
 
 
@@ -896,9 +903,8 @@ END_POINTERS
 //==========================================================================
 
 PPointer::PPointer()
-: PInt(sizeof(void *), true), PointedType(NULL)
+: PBasicType(sizeof(void *), __alignof(void *)), PointedType(NULL)
 {
-	Align = __alignof(void *);
 }
 
 //==========================================================================
@@ -908,9 +914,8 @@ PPointer::PPointer()
 //==========================================================================
 
 PPointer::PPointer(PType *pointsat)
-: PInt(sizeof(void *), true), PointedType(pointsat)
+: PBasicType(sizeof(void *), __alignof(void *)), PointedType(pointsat)
 {
-	Align = __alignof(void *);
 }
 
 //==========================================================================

src/dobjtype.h

@@ -165,6 +165,22 @@ public:
 	static void StaticInit();
 };
 
+// Not-really-a-type types --------------------------------------------------
+
+class PErrorType : public PType
+{
+	DECLARE_CLASS(PErrorType, PType);
+public:
+	PErrorType() : PType(0, 1) {}
+};
+
+class PVoidType : public PType
+{
+	DECLARE_CLASS(PVoidType, PType);
+public:
+	PVoidType() : PType(0, 1) {}
+};
+
 // Some categorization typing -----------------------------------------------
 
 class PBasicType : public PType
@@ -290,16 +306,16 @@ public:
 
 // Pointers -----------------------------------------------------------------
 
-class PStatePointer : public PInt
+class PStatePointer : public PBasicType
 {
-	DECLARE_CLASS(PStatePointer, PInt);
+	DECLARE_CLASS(PStatePointer, PBasicType);
 public:
 	PStatePointer();
 };
 
-class PPointer : public PInt
+class PPointer : public PBasicType
 {
-	DECLARE_CLASS(PPointer, PInt);
+	DECLARE_CLASS(PPointer, PBasicType);
 	HAS_OBJECT_POINTERS;
 public:
 	PPointer(PType *pointsat);
@@ -316,17 +332,14 @@ protected:
 	PPointer();
 };
 
-class PClass;
 class PClassPointer : public PPointer
 {
 	DECLARE_CLASS(PClassPointer, PPointer);
 	HAS_OBJECT_POINTERS;
 public:
-	PClassPointer(PClass *restrict);
+	PClassPointer(class PClass *restrict);
 
-	PClass *ClassRestriction;
+	class PClass *ClassRestriction;
-
-	typedef PClass *Type2;
 
 	virtual bool IsMatch(intptr_t id1, intptr_t id2) const;
 	virtual void GetTypeIDs(intptr_t &id1, intptr_t &id2) const;
@@ -625,6 +638,8 @@ PPrototype *NewPrototype(const TArray<PType *> &rettypes, const TArray<PType *>
 
 // Built-in types -----------------------------------------------------------
 
+extern PErrorType *TypeError;
+extern PVoidType *TypeVoid;
 extern PInt *TypeSInt8,  *TypeUInt8;
 extern PInt *TypeSInt16, *TypeUInt16;
 extern PInt *TypeSInt32, *TypeUInt32;
@@ -662,6 +677,8 @@ public:
 	};
 
 	PSymbolConstNumeric(FName name, PType *type=NULL) : PSymbolConst(name, type) {}
+	PSymbolConstNumeric(FName name, PType *type, int val) : PSymbolConst(name, type), Value(val) {}
+	PSymbolConstNumeric(FName name, PType *type, double val) : PSymbolConst(name, type), Float(val) {}
 	PSymbolConstNumeric() {}
 };