[Generator] Move GeneratedType out and enable nullability. (#17434)

Co-authored-by: GitHub Actions Autoformatter <github-actions-autoformatter@xamarin.com>

src/bgen/GeneratedType.cs

@@ -0,0 +1,52 @@
+using System;
+using System.Collections.Generic;
+using System.Reflection;
+
+#nullable enable
+
+//
+// This class is used to generate a graph of the type hierarchy of the
+// generated types and required by the UIApperance support to determine
+// which types need to have Appearance methods created
+//
+public class GeneratedType {
+	public GeneratedType (Type t, GeneratedTypes root)
+	{
+		Root = root;
+		Type = t;
+		var generator = root.Generator;
+		foreach (var iface in Type.GetInterfaces ()) {
+			if (iface.Name == "UIAppearance" || iface.Name == "IUIAppearance")
+				ImplementsAppearance = true;
+		}
+		var btype = ReflectionExtensions.GetBaseType (Type, generator);
+		if (btype != generator.TypeManager.System_Object) {
+			Parent = btype;
+			// protected against a StackOverflowException - bug #19751
+			// it does not protect against large cycles (but good against copy/paste errors)
+			if (Parent == Type)
+				throw new BindingException (1030, true, Type, Parent);
+			ParentGenerated = Root.Lookup (Parent);
+
+			// If our parent had UIAppearance, we flag this class as well
+			if (ParentGenerated.ImplementsAppearance)
+				ImplementsAppearance = true;
+			ParentGenerated.Children.Add (this);
+		}
+
+		if (generator.AttributeManager.HasAttribute<CategoryAttribute> (t))
+			ImplementsAppearance = false;
+	}
+	public GeneratedTypes Root;
+	public Type Type;
+	public List<GeneratedType> Children = new (1);
+	public Type? Parent;
+	public GeneratedType? ParentGenerated;
+	public bool ImplementsAppearance;
+
+	List<MemberInfo>? appearance_selectors;
+
+	public List<MemberInfo> AppearanceSelectors {
+		get { return appearance_selectors ??= new (); }
+	}
+}

src/bgen/Generator.cs

@@ -54,57 +54,6 @@ using ObjCRuntime;
 using Foundation;
 using Xamarin.Utils;
 
-//
-// This class is used to generate a graph of the type hierarchy of the
-// generated types and required by the UIApperance support to determine
-// which types need to have Appearance methods created
-//
-public class GeneratedType {
-	public GeneratedType (Type t, GeneratedTypes root)
-	{
-		Root = root;
-		Type = t;
-		var generator = root.Generator;
-		foreach (var iface in Type.GetInterfaces ()) {
-			if (iface.Name == "UIAppearance" || iface.Name == "IUIAppearance")
-				ImplementsAppearance = true;
-		}
-		var btype = ReflectionExtensions.GetBaseType (Type, generator);
-		if (btype != generator.TypeManager.System_Object) {
-			Parent = btype;
-			// protected against a StackOverflowException - bug #19751
-			// it does not protect against large cycles (but good against copy/paste errors)
-			if (Parent == Type)
-				throw new BindingException (1030, true, Type, Parent);
-			ParentGenerated = Root.Lookup (Parent);
-
-			// If our parent had UIAppearance, we flag this class as well
-			if (ParentGenerated.ImplementsAppearance)
-				ImplementsAppearance = true;
-			ParentGenerated.Children.Add (this);
-		}
-
-		if (generator.AttributeManager.HasAttribute<CategoryAttribute> (t))
-			ImplementsAppearance = false;
-	}
-	public GeneratedTypes Root;
-	public Type Type;
-	public List<GeneratedType> Children = new List<GeneratedType> (1);
-	public Type Parent;
-	public GeneratedType ParentGenerated;
-	public bool ImplementsAppearance;
-
-	List<MemberInfo> appearance_selectors;
-
-	public List<MemberInfo> AppearanceSelectors {
-		get {
-			if (appearance_selectors == null)
-				appearance_selectors = new List<MemberInfo> ();
-			return appearance_selectors;
-		}
-	}
-}
-
 public class GeneratedTypes {
 	public Generator Generator;
 

src/bgen/TrampolineInfo.cs

@@ -24,9 +24,9 @@ public class TrampolineInfo {
 	public string DelegateReturnType;
 	public string ReturnFormat;
 	public string Clear;
-	public string OutReturnType;
+	public string? OutReturnType;
 	public string PostConvert;
-	public string UserDelegateTypeAttribute;
+	public string? UserDelegateTypeAttribute;
 	public Type Type;
 
 	public TrampolineInfo (string userDelegate, string delegateName, string trampolineName, string pars,

src/generator.csproj

@@ -100,6 +100,7 @@
     <Compile Include="..\src\bgen\Enums.cs" />
     <Compile Include="..\src\bgen\ExtensionMethods.cs" />
     <Compile Include="..\src\bgen\Filters.cs" />
+    <Compile Include="..\src\bgen\GeneratedType.cs" />
     <Compile Include="..\src\bgen\Generator.cs" />
     <Compile Include="..\src\bgen\MarshalInfo.cs" />
     <Compile Include="..\src\bgen\NamespaceManager.cs" />