Enable nullable reference types in BizInvoke

src/BizHawk.BizInvoke/BizExvoker.cs

@@ -71,10 +71,10 @@ namespace BizHawk.BizInvoke
 				foreach (var a in methods)
 				{
 					MethodBuilder unused;
-					var delegateType = BizInvokeUtilities.CreateDelegateType(a.Info, a.Attr.CallingConvention, typeBuilder, out unused).CreateType();
+					var delegateType = BizInvokeUtilities.CreateDelegateType(a.Info, a.Attr!.CallingConvention, typeBuilder, out unused).CreateType()!;
 					DelegateTypes.Add(new StoredDelegateInfo(a.Info, delegateType, a.Attr.EntryPoint ?? a.Info.Name));
 				}
-				StorageType = typeBuilder.CreateType();
+				StorageType = typeBuilder.CreateType()!;
 				OriginalType = type;
 			}
 		}
@@ -105,18 +105,18 @@ namespace BizHawk.BizInvoke
 
 		public static IImportResolver GetExvoker(object o, ICallingConventionAdapter a)
 		{
-			DelegateStorage ds;
+			DelegateStorage? ds;
 			lock (Impls)
 			{
 				var type = o.GetType();
 				if (!Impls.TryGetValue(type, out ds))
 				{
 					ds = new DelegateStorage(type);
-					Impls.Add(type, ds);
+					Impls.Add(type, ds!);
 				}
 			}
 
-			return new ExvokerImpl(o, ds, a);
+			return new ExvokerImpl(o, ds!, a);
 		}
 	}
 
@@ -127,7 +127,7 @@ namespace BizHawk.BizInvoke
 		public CallingConvention CallingConvention { get; }
 
 		/// <remarks>The annotated method's name is used iff <see langword="null"/>.</remarks>
-		public string EntryPoint { get; set; }
+		public string? EntryPoint { get; set; } = null;
 
 		public BizExportAttribute(CallingConvention c)
 		{

src/BizHawk.BizInvoke/BizHawk.BizInvoke.csproj

@@ -5,7 +5,6 @@
 	<Import Project="../MainSlnCommon.props" />
 	<PropertyGroup>
 		<AllowUnsafeBlocks>true</AllowUnsafeBlocks>
-		<Nullable>disable</Nullable>
 	</PropertyGroup>
 	<ItemGroup>
 		<ProjectReference Include="$(ProjectDir)../BizHawk.Common/BizHawk.Common.csproj" />

src/BizHawk.BizInvoke/BizInvokeUtilities.cs

@@ -54,7 +54,7 @@ namespace BizHawk.BizInvoke
 			}
 
 			{
-				var p = delegateInvoke.DefineParameter(0, ParameterAttributes.Retval, method.ReturnParameter.Name);
+				var p = delegateInvoke.DefineParameter(0, ParameterAttributes.Retval, method.ReturnParameter!.Name);
 				foreach (var a in method.ReturnParameter.GetCustomAttributes(false))
 				{
 					p.SetCustomAttribute(GetAttributeBuilder(a));
@@ -64,7 +64,9 @@ namespace BizHawk.BizInvoke
 			delegateInvoke.SetImplementationFlags(MethodImplAttributes.Runtime | MethodImplAttributes.Managed);
 
 			// add the [UnmanagedFunctionPointer] to the delegate so interop will know how to call it
-			var attr = new CustomAttributeBuilder(typeof(UnmanagedFunctionPointerAttribute).GetConstructor(new[] { typeof(CallingConvention) }), new object[] { nativeCall });
+			var attr = new CustomAttributeBuilder(
+				typeof(UnmanagedFunctionPointerAttribute).GetConstructor(new[] { typeof(CallingConvention) })!,
+				new object[] { nativeCall });
 			delegateType.SetCustomAttribute(attr);
 
 			invokeMethod = delegateInvoke;
@@ -80,7 +82,7 @@ namespace BizHawk.BizInvoke
 			var t = o.GetType();
 			if (t == typeof(OutAttribute) || t == typeof(InAttribute))
 			{
-				return new CustomAttributeBuilder(t.GetConstructor(Type.EmptyTypes), new object[0]);
+				return new CustomAttributeBuilder(t.GetConstructor(Type.EmptyTypes)!, new object[0]);
 			}
 
 			throw new InvalidOperationException($"Unknown parameter attribute {t.Name}");

src/BizHawk.BizInvoke/BizInvoker.cs

@@ -18,7 +18,7 @@ namespace BizHawk.BizInvoke
 		{
 			private readonly Action<object, ICallingConventionAdapter> _connectCallingConventionAdapter;
 
-			private readonly Action<object, IMonitor> _connectMonitor;
+			private readonly Action<object, IMonitor>? _connectMonitor;
 
 			private readonly List<Action<object, IImportResolver, ICallingConventionAdapter>> _hooks;
 
@@ -29,7 +29,7 @@ namespace BizHawk.BizInvoke
 			public InvokerImpl(
 				List<Action<object, IImportResolver, ICallingConventionAdapter>> hooks,
 				Type implType,
-				Action<object, IMonitor> connectMonitor,
+				Action<object, IMonitor>? connectMonitor,
 				Action<object, ICallingConventionAdapter> connectCallingConventionAdapter)
 			{
 				_connectCallingConventionAdapter = connectCallingConventionAdapter;
@@ -39,15 +39,15 @@ namespace BizHawk.BizInvoke
 				IsMonitored = connectMonitor != null;
 			}
 
-			public object Create(IImportResolver dll, IMonitor monitor, ICallingConventionAdapter adapter)
+			public object Create(IImportResolver dll, IMonitor? monitor, ICallingConventionAdapter adapter)
 			{
-				var ret = Activator.CreateInstance(_implType);
+				var ret = Activator.CreateInstance(_implType)!;
 				_connectCallingConventionAdapter(ret, adapter);
 				foreach (var f in _hooks)
 				{
 					f(ret, dll, adapter);
 				}
-				_connectMonitor?.Invoke(ret, monitor);
+				_connectMonitor?.Invoke(ret, monitor!);
 				return ret;
 			}
 		}
@@ -94,18 +94,18 @@ namespace BizHawk.BizInvoke
 			where T : class
 		{
 			var nonTrivialAdapter = adapter.GetType() != CallingConventionAdapters.Native.GetType();
-			InvokerImpl impl;
+			InvokerImpl? impl;
 			lock (Impls)
 			{
 				var baseType = typeof(T);
 				if (!Impls.TryGetValue(baseType, out impl))
 				{
 					impl = CreateProxy(baseType, false, nonTrivialAdapter);
-					Impls.Add(baseType, impl);
+					Impls.Add(baseType, impl!);
 				}
 			}
 
-			if (impl.IsMonitored)
+			if (impl!.IsMonitored)
 			{
 				throw new InvalidOperationException("Class was previously proxied with a monitor!");
 			}
@@ -118,18 +118,18 @@ namespace BizHawk.BizInvoke
 			where T : class
 		{
 			var nonTrivialAdapter = adapter.GetType() != CallingConventionAdapters.Native.GetType();
-			InvokerImpl impl;
+			InvokerImpl? impl;
 			lock (Impls)
 			{
 				var baseType = typeof(T);
 				if (!Impls.TryGetValue(baseType, out impl))
 				{
 					impl = CreateProxy(baseType, true, nonTrivialAdapter);
-					Impls.Add(baseType, impl);
+					Impls.Add(baseType, impl!);
 				}
 			}
 
-			if (!impl.IsMonitored)
+			if (!(impl!.IsMonitored))
 			{
 				throw new InvalidOperationException("Class was previously proxied without a monitor!");
 			}
@@ -197,7 +197,7 @@ namespace BizHawk.BizInvoke
 
 			foreach (var mi in baseMethods)
 			{
-				var entryPointName = mi.Attr.EntryPoint ?? mi.Info.Name;
+				var entryPointName = mi.Attr!.EntryPoint ?? mi.Info.Name;
 
 				var hook = mi.Attr.Compatibility
 					? ImplementMethodDelegate(type, mi.Info, mi.Attr.CallingConvention, entryPointName, monitorField, nonTrivialAdapter)
@@ -208,9 +208,9 @@ namespace BizHawk.BizInvoke
 
 			return new(
 				postCreateHooks,
-				type.CreateType(),
+				type.CreateType()!,
 				connectMonitor: monitor
-					? (o, m) => o.GetType().GetField(monitorField.Name).SetValue(o, m)
+					? (o, m) => o.GetType().GetField(monitorField!.Name).SetValue(o, m)
 					: null,
 				connectCallingConventionAdapter: (o, a) => o.GetType().GetField(adapterField.Name).SetValue(o, a));
 		}
@@ -219,7 +219,11 @@ namespace BizHawk.BizInvoke
 		/// create a method implementation that uses GetDelegateForFunctionPointer internally
 		/// </summary>
 		private static Action<object, IImportResolver, ICallingConventionAdapter> ImplementMethodDelegate(
-			TypeBuilder type, MethodInfo baseMethod, CallingConvention nativeCall, string entryPointName, FieldInfo monitorField,
+			TypeBuilder type,
+			MethodInfo baseMethod,
+			CallingConvention nativeCall,
+			string entryPointName,
+			FieldInfo? monitorField,
 			bool nonTrivialAdapter)
 		{
 			// create the delegate type
@@ -260,7 +264,7 @@ namespace BizHawk.BizInvoke
 			{
 				il.Emit(OpCodes.Ldarg_0);
 				il.Emit(OpCodes.Ldfld, monitorField);
-				il.Emit(OpCodes.Callvirt, typeof(IMonitor).GetMethod("Enter"));
+				il.Emit(OpCodes.Callvirt, typeof(IMonitor).GetMethod("Enter")!);
 				exc = il.BeginExceptionBlock();
 			}
 
@@ -275,7 +279,7 @@ namespace BizHawk.BizInvoke
 
 			if (monitorField != null) // monitor: finally exit
 			{
-				LocalBuilder loc = null;
+				LocalBuilder? loc = null;
 				if (returnType != typeof(void))
 				{
 					loc = il.DeclareLocal(returnType);
@@ -286,12 +290,12 @@ namespace BizHawk.BizInvoke
 				il.BeginFinallyBlock();
 				il.Emit(OpCodes.Ldarg_0);
 				il.Emit(OpCodes.Ldfld, monitorField);
-				il.Emit(OpCodes.Callvirt, typeof(IMonitor).GetMethod("Exit"));
+				il.Emit(OpCodes.Callvirt, typeof(IMonitor).GetMethod("Exit")!);
 				il.EndExceptionBlock();
 
 				if (returnType != typeof(void))
 				{
-					il.Emit(OpCodes.Ldloc, loc);
+					il.Emit(OpCodes.Ldloc, loc!);
 				}
 			}
 
@@ -331,8 +335,12 @@ namespace BizHawk.BizInvoke
 		/// create a method implementation that uses calli internally
 		/// </summary>
 		private static Action<object, IImportResolver, ICallingConventionAdapter> ImplementMethodCalli(
-			TypeBuilder type, MethodInfo baseMethod,
+			TypeBuilder type,
-			CallingConvention nativeCall, string entryPointName, FieldInfo monitorField, FieldInfo adapterField)
+			MethodInfo baseMethod,
+			CallingConvention nativeCall,
+			string entryPointName,
+			FieldInfo? monitorField,
+			FieldInfo adapterField)
 		{
 			var paramInfos = baseMethod.GetParameters();
 			var paramTypes = paramInfos.Select(p => p.ParameterType).ToArray();
@@ -363,7 +371,7 @@ namespace BizHawk.BizInvoke
 			{
 				il.Emit(OpCodes.Ldarg_0);
 				il.Emit(OpCodes.Ldfld, monitorField);
-				il.Emit(OpCodes.Callvirt, typeof(IMonitor).GetMethod("Enter"));
+				il.Emit(OpCodes.Callvirt, typeof(IMonitor).GetMethod("Enter")!);
 				exc = il.BeginExceptionBlock();
 			}
 
@@ -388,7 +396,7 @@ namespace BizHawk.BizInvoke
 
 			if (monitorField != null) // monitor: finally exit
 			{
-				LocalBuilder loc = null;
+				LocalBuilder? loc = null;
 				if (returnType != typeof(void))
 				{
 					loc = il.DeclareLocal(returnType);
@@ -399,12 +407,12 @@ namespace BizHawk.BizInvoke
 				il.BeginFinallyBlock();
 				il.Emit(OpCodes.Ldarg_0);
 				il.Emit(OpCodes.Ldfld, monitorField);
-				il.Emit(OpCodes.Callvirt, typeof(IMonitor).GetMethod("Exit"));
+				il.Emit(OpCodes.Callvirt, typeof(IMonitor).GetMethod("Exit")!);
 				il.EndExceptionBlock();
 
 				if (returnType != typeof(void))
 				{
-					il.Emit(OpCodes.Ldloc, loc);
+					il.Emit(OpCodes.Ldloc, loc!);
 				}
 			}
 
@@ -477,7 +485,7 @@ namespace BizHawk.BizInvoke
 
 			if (type.IsByRef)
 			{
-				var et = type.GetElementType();
+				var et = type.GetElementType()!;
 				if (!et.IsPrimitive && !et.IsEnum)
 				{
 					throw new NotImplementedException("Only refs of primitive or enum types are supported!");
@@ -496,7 +504,7 @@ namespace BizHawk.BizInvoke
 
 			if (type.IsArray)
 			{
-				var et = type.GetElementType();
+				var et = type.GetElementType()!;
 				if (!et.IsValueType)
 				{
 					throw new NotImplementedException("Only arrays of value types are supported!");
@@ -545,7 +553,7 @@ namespace BizHawk.BizInvoke
 					typeof(IntPtr),
 					() =>
 					{
-						var mi = typeof(ICallingConventionAdapter).GetMethod("GetFunctionPointerForDelegate");
+						var mi = typeof(ICallingConventionAdapter).GetMethod("GetFunctionPointerForDelegate")!;
 						var end = il.DefineLabel();
 						var isNull = il.DefineLabel();
 
@@ -573,13 +581,13 @@ namespace BizHawk.BizInvoke
 				il.Emit(OpCodes.Brfalse, isNull);
 
 				var encoding = il.DeclareLocal(typeof(Encoding), false);
-				il.EmitCall(OpCodes.Call, typeof(Encoding).GetProperty("UTF8").GetGetMethod(), Type.EmptyTypes);
+				il.EmitCall(OpCodes.Call, typeof(Encoding).GetProperty("UTF8")!.GetGetMethod(), Type.EmptyTypes);
 				il.Emit(OpCodes.Stloc, encoding);
 
 				var strlenbytes = il.DeclareLocal(typeof(int), false);
 				il.Emit(OpCodes.Ldloc, encoding);
 				il.Emit(OpCodes.Ldarg, (short)idx);
-				il.EmitCall(OpCodes.Callvirt, typeof(Encoding).GetMethod("GetByteCount", new[] { typeof(string) }), Type.EmptyTypes);
+				il.EmitCall(OpCodes.Callvirt, typeof(Encoding).GetMethod("GetByteCount", new[] { typeof(string) })!, Type.EmptyTypes);
 				il.Emit(OpCodes.Stloc, strlenbytes);
 
 				var strval = il.DeclareLocal(typeof(string), true); // pin!
@@ -605,13 +613,13 @@ namespace BizHawk.BizInvoke
 				il.Emit(OpCodes.Add);
 				// charcount
 				il.Emit(OpCodes.Ldloc, strval);
-				il.Emit(OpCodes.Call, typeof(string).GetProperty("Length").GetGetMethod());
+				il.Emit(OpCodes.Call, typeof(string).GetProperty("Length")!.GetGetMethod());
 				// bytes
 				il.Emit(OpCodes.Ldloc, bytes);
 				// bytelength
 				il.Emit(OpCodes.Ldloc, strlenbytes);
 				// call
-				il.EmitCall(OpCodes.Callvirt, typeof(Encoding).GetMethod("GetBytes", new[] { typeof(char*), typeof(int), typeof(byte*), typeof(int) }), Type.EmptyTypes);
+				il.EmitCall(OpCodes.Callvirt, typeof(Encoding).GetMethod("GetBytes", new[] { typeof(char*), typeof(int), typeof(byte*), typeof(int) })!, Type.EmptyTypes);
 				// unused ret
 				il.Emit(OpCodes.Pop);
 
@@ -681,7 +689,7 @@ namespace BizHawk.BizInvoke
 		public CallingConvention CallingConvention { get; }
 
 		/// <remarks>The annotated method's name is used iff <see langword="null"/>.</remarks>
-		public string EntryPoint { get; set; }
+		public string? EntryPoint { get; set; } = null;
 
 		/// <summary><see langword="true"/> iff a compatibility interop should be used, which is slower but supports more argument types.</summary>
 		public bool Compatibility { get; set; }

src/BizHawk.BizInvoke/BizInvokerUtilities.cs

@@ -5,6 +5,7 @@ namespace BizHawk.BizInvoke
 {
 	public static unsafe class BizInvokerUtilities
 	{
+#nullable disable //TODO If U1 and U2 were structs, this wouldn't be a problem. Would changing them to structs break this helper's functionality? --yoshi
 		[StructLayout(LayoutKind.Explicit)]
 		private class U
 		{
@@ -13,6 +14,7 @@ namespace BizHawk.BizInvoke
 			[FieldOffset(0)]
 			public U2 Second;
 		}
+#nullable restore
 		[StructLayout(LayoutKind.Explicit)]
 		private class U1
 		{
@@ -24,6 +26,8 @@ namespace BizHawk.BizInvoke
 		{
 			[FieldOffset(0)]
 			public object Target;
+
+			public U2(object target) => Target = target;
 		}
 		private class CF
 		{
@@ -39,7 +43,7 @@ namespace BizHawk.BizInvoke
 			int ret;
 			fixed(int* fx = &c.FirstField)
 			{
-				var u = new U { Second = new U2 { Target = c }};
+				var u = new U { Second = new U2(c) };
 				ret = (int)((ulong)(UIntPtr)fx - (ulong)u.First.P);
 			}
 			return ret;
@@ -50,7 +54,7 @@ namespace BizHawk.BizInvoke
 			int ret;
 			fixed(char* fx = s)
 			{
-				var u = new U { Second = new U2 { Target = s }};
+				var u = new U { Second = new U2(s) };
 				ret = (int)((ulong)(UIntPtr)fx - (ulong)u.First.P);
 			}
 			return ret;

src/BizHawk.BizInvoke/CallingConventionAdapter.cs

@@ -68,7 +68,7 @@ namespace BizHawk.BizInvoke
 		{
 			if (!typeof(Delegate).IsAssignableFrom(delegateType))
 				throw new InvalidOperationException("Must be a delegate type!");
-			var invoke = delegateType.GetMethod("Invoke");
+			var invoke = delegateType.GetMethod("Invoke")!;
 			ReturnType = invoke.ReturnType;
 			ParameterTypes = invoke.GetParameters().Select(p => p.ParameterType).ToList().AsReadOnly();
 		}
@@ -170,10 +170,10 @@ namespace BizHawk.BizInvoke
 					: (ICallingConventionAdapter)new MsHostSysVGuest();
 			}
 
-			private readonly Dictionary<Delegate, int> _slots;
+			private readonly Dictionary<Delegate, int>? _slots;
 			private readonly ICallbackAdjuster _waterboxHost;
 
-			public WaterboxAdapter(IEnumerable<Delegate> slots, ICallbackAdjuster waterboxHost)
+			public WaterboxAdapter(IEnumerable<Delegate>? slots, ICallbackAdjuster waterboxHost)
 			{
 				if (slots != null)
 				{
@@ -246,7 +246,7 @@ namespace BizHawk.BizInvoke
 
 			private readonly MemoryBlock _memory;
 			private readonly object _sync = new object();
-			private readonly WeakReference[] _refs;
+			private readonly WeakReference?[] _refs;
 
 			public MsHostSysVGuest()
 			{
@@ -259,8 +259,7 @@ namespace BizHawk.BizInvoke
 			{
 				for (int i = 0; i < _refs.Length; i++)
 				{
-					if (_refs[i] == null || !_refs[i].IsAlive)
+					if (_refs[i] is not { IsAlive: true }) return i; // return index of first null or dead
-						return i;
 				}
 				throw new InvalidOperationException("Out of Thunk memory");
 			}
@@ -331,10 +330,8 @@ namespace BizHawk.BizInvoke
 
 			private void SetLifetime(int index, object lifetime)
 			{
-				if (_refs[index] == null)
+				_refs[index] ??= new(null);
-					_refs[index] = new WeakReference(lifetime);
+				_refs[index]!.Target = lifetime;
-				else
-					_refs[index].Target = lifetime;
 			}
 
 			public IntPtr GetFunctionPointerForDelegate(Delegate d)

src/BizHawk.BizInvoke/MemoryBlock.cs

@@ -21,11 +21,11 @@ namespace BizHawk.BizInvoke
 			_pal = OSTailoredCode.IsUnixHost
 				? (IMemoryBlockPal)new MemoryBlockLinuxPal(Size)
 				: new MemoryBlockWindowsPal(Size);
-			Start = _pal.Start;
+			Start = _pal!.Start;
 			EndExclusive = Start + Size;
 		}
 
-		private IMemoryBlockPal _pal;
+		private IMemoryBlockPal? _pal;
 
 		/// <summary>
 		/// end address of the memory block (not part of the block; class invariant: equal to <see cref="Start"/> + <see cref="Size"/>)