[xtro] Enable nullability and fix any issues.

tests/xtro-sharpie/xtro-report/xtro-report.csproj

@@ -5,6 +5,9 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
     <AppendTargetFrameworkToOutputPath>false</AppendTargetFrameworkToOutputPath>
+
+    <WarningsAsErrors>Nullable</WarningsAsErrors>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="../xtro-sharpie/Filter.cs">

tests/xtro-sharpie/xtro-sanity/Sanitizer.cs

@@ -374,7 +374,7 @@ static List<Frameworks> GetAllFrameworks ()
 
 		static Frameworks GetFrameworks (string platform)
 		{
-			return Frameworks.GetFrameworks (ApplePlatformExtensions.Parse (platform), false);
+			return Frameworks.GetFrameworks (ApplePlatformExtensions.Parse (platform), false)!;
 		}
 
 		static List<Frameworks> GetFrameworks (IEnumerable<string> platforms)

tests/xtro-sharpie/xtro-sanity/xtro-sanity.csproj

@@ -5,6 +5,9 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
     <AppendTargetFrameworkToOutputPath>false</AppendTargetFrameworkToOutputPath>
+
+    <WarningsAsErrors>Nullable</WarningsAsErrors>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="..\..\..\tools\common\Frameworks.cs">

tests/xtro-sharpie/xtro-sharpie/AttributeHelpers.cs

@@ -1,3 +1,4 @@
+using System.Diagnostics.CodeAnalysis;
 using Sharpie.Bind;
 
 namespace Extrospection {
@@ -10,7 +11,7 @@ static bool Skip (ICustomAttributeProvider item)
 		}
 
 		// These both return out Version and bool as you can have an an attribute with no version (null) which is different no matching attribute at all
-		public static bool FindDeprecated (ICustomAttributeProvider item, out Version version)
+		public static bool FindDeprecated (ICustomAttributeProvider item, [NotNullWhen (true)] out Version? version)
 		{
 			version = null;
 
@@ -23,7 +24,7 @@ public static bool FindDeprecated (ICustomAttributeProvider item, out Version ve
 			return false;
 		}
 
-		public static bool FindObsolete (ICustomAttributeProvider item, out Version version)
+		public static bool FindObsolete (ICustomAttributeProvider item, [NotNullWhen (true)] out Version? version)
 		{
 			version = null;
 
@@ -70,7 +71,7 @@ public static bool HasObsolete (CustomAttribute attribute, Platforms platform)
 			return attribute.Constructor.DeclaringType.Name == "ObsoleteAttribute";
 		}
 
-		static bool GetPlatformVersion (CustomAttribute attribute, out Version version)
+		static bool GetPlatformVersion (CustomAttribute attribute, out Version? version)
 		{
 			// Three different Attribute flavors
 			// (PlatformName platform, PlatformArchitecture architecture = PlatformArchitecture.None, string message = null)
@@ -95,7 +96,7 @@ public static bool FindObjcDeprecated (IEnumerable<Attr> attrs, out VersionTuple
 		{
 			var attr = attrs.GetAvailabilityAttributes ().FirstOrDefault (x => x.AvailabilityAttributeDeprecated.HasValue && !x.AvailabilityAttributeDeprecated.Value.IsEmptyVersionTuple && x.AvailabilityAttributePlatformIdentifierName == Helpers.ClangPlatformName);
 			if (attr is not null) {
-				version = attr.AvailabilityAttributeDeprecated.Value;
+				version = attr.AvailabilityAttributeDeprecated!.Value;
 				return true;
 			} else {
 				version = VersionTuple.Empty;
@@ -111,7 +112,7 @@ public static bool HasAnyDeprecationForCurrentPlatform (ICustomAttributeProvider
 			// Properties are a special case  as it is generated on the property itself and not the individual get_ \ set_ methods
 			// Cecil does not have a link between the MethodDefinition we have and the hosting PropertyDefinition, so we have to dig to find the match
 			if (item is MethodDefinition method) {
-				PropertyDefinition property = method.DeclaringType.Properties.FirstOrDefault (p => p.GetMethod == method || p.SetMethod == method);
+				var property = method.DeclaringType.Properties.FirstOrDefault (p => p.GetMethod == method || p.SetMethod == method);
 				if (property is not null && HasAnyDeprecationForCurrentPlatform (property)) {
 					return true;
 				}
@@ -159,7 +160,7 @@ public static bool HasAnyAdvice (ICustomAttributeProvider item)
 			// Properties are a special case for [Advice], as it is generated on the property itself and not the individual get_ \ set_ methods
 			// Cecil does not have a link between the MethodDefinition we have and the hosting PropertyDefinition, so we have to dig to find the match
 			if (item is MethodDefinition method) {
-				PropertyDefinition property = method.DeclaringType.Properties.FirstOrDefault (p => p.GetMethod == method || p.SetMethod == method);
+				var property = method.DeclaringType.Properties.FirstOrDefault (p => p.GetMethod == method || p.SetMethod == method);
 				if (property is not null && HasAdviced (property.CustomAttributes))
 					return true;
 			}

tests/xtro-sharpie/xtro-sharpie/DeprecatedCheck.cs

@@ -45,7 +45,7 @@ public override void EndVisit ()
 
 		void ProcessObjcEntry (string objcClassName, VersionTuple objcVersion)
 		{
-			TypeDefinition managedType = ManagedTypes.FirstOrDefault (x => Helpers.GetName (x) == objcClassName && x.IsPublic);
+			var managedType = ManagedTypes.FirstOrDefault (x => Helpers.GetName (x) == objcClassName && x.IsPublic);
 			if (managedType is not null) {
 				var framework = Helpers.GetFramework (managedType);
 				if (framework is not null)
@@ -60,7 +60,7 @@ void ProcessObjcSelector (string fullname, VersionTuple objcVersion)
 			string objcClassName = fullname.Substring (class_method ? 1 : 0, n);
 			string selector = fullname.Substring (n + 2);
 
-			TypeDefinition managedType = ManagedTypes.FirstOrDefault (x => Helpers.GetName (x) == objcClassName);
+			var managedType = ManagedTypes.FirstOrDefault (x => Helpers.GetName (x) == objcClassName);
 			if (managedType is not null) {
 				var framework = Helpers.GetFramework (managedType);
 				if (framework is null)
@@ -92,7 +92,7 @@ void ProcessCFunction (string fullname, VersionTuple objcVersion)
 			}
 		}
 
-		public void ProcessItem (ICustomAttributeProvider item, string itemName, VersionTuple objcVersion, string framework)
+		public void ProcessItem (ICustomAttributeProvider item, string? itemName, VersionTuple objcVersion, string framework)
 		{
 			// Our bindings do not need have [Deprecated] for ancient versions we don't support anymore
 			if (VersionHelpers.VersionTooOldToCare (objcVersion))
@@ -114,8 +114,7 @@ public void ProcessItem (ICustomAttributeProvider item, string itemName, Version
 			}
 
 			// Some APIs have both a [Deprecated] and [Obsoleted]. Bias towards [Obsoleted].
-			Version managedVersion;
-			bool foundObsoleted = AttributeHelpers.FindObsolete (item, out managedVersion);
+			bool foundObsoleted = AttributeHelpers.FindObsolete (item, out var managedVersion);
 			if (foundObsoleted) {
 				if (managedVersion is not null && !ManagedBeforeOrEqualToObjcVersion (objcVersion, managedVersion))
 					Log.On (framework).Add ($"!deprecated-attribute-wrong! {itemName} has {managedVersion} not {objcVersion} on [Obsoleted] attribute");

tests/xtro-sharpie/xtro-sharpie/DesignatedInitializerCheck.cs

@@ -24,13 +24,13 @@ public DesignatedInitializerCheck (BindingResult bindingResult)
 		static Dictionary<string, TypeDefinition> types = new Dictionary<string, TypeDefinition> ();
 		static Dictionary<string, MethodDefinition> methods = new Dictionary<string, MethodDefinition> ();
 
-		static TypeDefinition GetType (ObjCInterfaceDecl decl)
+		static TypeDefinition? GetType (ObjCInterfaceDecl decl)
 		{
 			types.TryGetValue (decl.Name, out var td);
 			return td;
 		}
 
-		static MethodDefinition GetMethod (ObjCMethodDecl decl)
+		static MethodDefinition? GetMethod (ObjCMethodDecl decl)
 		{
 			methods.TryGetValue (decl.GetName (), out var md);
 			return md;
@@ -51,7 +51,7 @@ public override void VisitManagedMethod (MethodDefinition method)
 		public override void VisitObjCMethodDecl (ObjCMethodDecl decl)
 		{
 			// don't process methods (or types) that are unavailable for the current platform
-			if (!decl.IsAvailable () || !(decl.DeclContext as Decl).IsAvailable ())
+			if (!decl.IsAvailable () || !(((Decl) decl.DeclContext!).IsAvailable ()))
 				return;
 
 			var method = GetMethod (decl);

tests/xtro-sharpie/xtro-sharpie/EnumCheck.cs

@@ -2,8 +2,8 @@ namespace Extrospection {
 
 	class EnumCheck : BaseVisitor {
 		class ManagedValue {
-			public FieldDefinition Field;
-			public EnumConstantDecl Decl;
+			public required FieldDefinition Field;
+			public EnumConstantDecl? Decl;
 		}
 
 		Dictionary<string, TypeDefinition> enums = new Dictionary<string, TypeDefinition> (StringComparer.InvariantCultureIgnoreCase);

tests/xtro-sharpie/xtro-sharpie/FieldCheck.cs

@@ -57,10 +57,10 @@ void CheckAttributes (string memberName, ICustomAttributeProvider p)
 					&& ca.Constructor.DeclaringType.Name != "FieldAttribute`1")
 					continue;
 
-				var name = ca.ConstructorArguments [0].Value as string;
+				var name = (string) ca.ConstructorArguments [0].Value!;
 
 				if (!fields.TryGetValue (name, out var mr))
-					fields.Add (name, p as MemberReference);
+					fields.Add (name, (MemberReference) p);
 				else {
 					// not critical and quite noisy with current API profile
 					// Console.WriteLine ("!duplicate-field-name! {0} [Field] exists as both {1} and {2}", name, memberName, mr.FullName);

tests/xtro-sharpie/xtro-sharpie/Helpers.cs

@@ -1,3 +1,5 @@
+using System.Diagnostics.CodeAnalysis;
+
 namespace Extrospection {
 
 	public enum Platforms {
@@ -252,7 +254,9 @@ static bool IsStatic (this TypeDefinition self)
 			return (self.IsSealed && self.IsAbstract);
 		}
 
-		public static string GetName (this ObjCMethodDecl self)
+
+		[return: NotNullIfNotNull (nameof (self))]
+		public static string? GetName (this ObjCMethodDecl? self)
 		{
 			if (self is null)
 				return null;
@@ -263,15 +267,15 @@ public static string GetName (this ObjCMethodDecl self)
 			if (self.DeclContext is ObjCCategoryDecl category) {
 				sb.Append (category.ClassInterface.Name);
 			} else {
-				sb.Append ((self.DeclContext as NamedDecl).Name);
+				sb.Append (((NamedDecl) self.DeclContext!).Name);
 			}
 			sb.Append ("::");
 			var sel = self.Selector.ToString ();
 			sb.Append (string.IsNullOrEmpty (sel) ? self.Name : sel);
 			return sb.ToString ();
 		}
 
-		public static string GetName (this TypeDefinition self)
+		public static string? GetName (this TypeDefinition? self)
 		{
 			if ((self is null) || !self.HasCustomAttributes)
 				return null;
@@ -309,13 +313,13 @@ public static string GetName (this TypeDefinition self)
 			return null;
 		}
 
-		public static string GetName (this MethodDefinition self)
+		public static string? GetName (this MethodDefinition? self)
 		{
 			if (self is null)
 				return null;
 
 			var type = self.DeclaringType;
-			string tname = self.DeclaringType.GetName ();
+			string? tname = self.DeclaringType.GetName ();
 			// a static type is not used for static selectors
 			bool is_static = !type.IsStatic () && self.IsStatic;
 
@@ -340,7 +344,7 @@ public static string GetName (this MethodDefinition self)
 			return sb.ToString ();
 		}
 
-		public static string GetSelector (this MethodDefinition self)
+		public static string? GetSelector (this MethodDefinition self)
 		{
 			if ((self is null) || !self.HasCustomAttributes)
 				return null;
@@ -375,9 +379,12 @@ public static bool IsObsolete (this ICustomAttributeProvider provider)
 			return false;
 		}
 
-		public static PropertyDefinition FindProperty (this MethodReference method)
+		public static PropertyDefinition? FindProperty (this MethodReference? method)
 		{
-			var def = method?.Resolve ();
+			if (method is null)
+				return null;
+
+			var def = method.Resolve ();
 			if (def is null)
 				return null;
 
@@ -409,7 +416,7 @@ public static string GetFramework (TypeReference type)
 
 		public static string GetFramework (MethodDefinition method)
 		{
-			string framework = null;
+			string? framework = null;
 			if (method.HasPInvokeInfo)
 				framework = Path.GetFileNameWithoutExtension (method.PInvokeInfo.Module.Name);
 			else
@@ -423,7 +430,7 @@ public static string GetFramework (MemberReference member)
 			return MapFramework (framework);
 		}
 
-		public static string GetFramework (Decl decl)
+		public static string? GetFramework (Decl decl)
 		{
 			var header_file = decl.PresumedLoc?.FileName;
 			if (header_file is null)
@@ -469,7 +476,7 @@ public static string MapFramework (string candidate)
 			}
 		}
 
-		public static (T, T) Sort<T> (T o1, T o2)
+		public static (T, T) Sort<T> (T o1, T o2) where T : notnull
 		{
 			if (StringComparer.Ordinal.Compare (o1.ToString (), o2.ToString ()) < 0)
 				return (o2, o1);

tests/xtro-sharpie/xtro-sharpie/Log.cs

@@ -1,12 +1,11 @@
 namespace Extrospection {
 
 	static class Log {
-		static Dictionary<string, List<string>> lists = new Dictionary<string, List<string>> (StringComparer.OrdinalIgnoreCase);
+		static Dictionary<string, List<string>> lists = new (StringComparer.OrdinalIgnoreCase);
 
 		public static IList<string> On (string fx)
 		{
-			List<string> list;
-			if (!lists.TryGetValue (fx, out list)) {
+			if (!lists.TryGetValue (fx, out var list)) {
 				list = new List<string> ();
 				lists.Add (fx, list);
 			}

tests/xtro-sharpie/xtro-sharpie/NullabilityCheck.cs

@@ -27,13 +27,13 @@ public NullabilityCheck (BindingResult bindingResult)
 		{
 		}
 
-		static TypeDefinition GetType (ObjCInterfaceDecl decl)
+		static TypeDefinition? GetType (ObjCInterfaceDecl decl)
 		{
 			types.TryGetValue (decl.Name, out var td);
 			return td;
 		}
 
-		static MethodDefinition GetMethod (ObjCMethodDecl decl)
+		static MethodDefinition? GetMethod (ObjCMethodDecl decl)
 		{
 			methods.TryGetValue (decl.GetName (), out var md);
 			return md;
@@ -91,7 +91,7 @@ static Null [] GetNullable (ICustomAttributeProvider cap)
 					// Type is `System.Byte[]` and value is a `CustomAttributeArgument[]`
 					// each with a `Type` of `System.Byte` and where value is a `byte`
 					case "System.Byte[]":
-						var caa = first.Value as CustomAttributeArgument [];
+						var caa = (CustomAttributeArgument []) first.Value;
 						var length = caa.Length;
 						var values = new Null [length];
 						for (int i = 0; i < length; i++)
@@ -106,11 +106,11 @@ static Null [] GetNullable (ICustomAttributeProvider cap)
 		public override void VisitObjCMethodDecl (ObjCMethodDecl decl)
 		{
 			// don't process methods (or types) that are unavailable for the current platform
-			if (!decl.IsAvailable () || !(decl.DeclContext as Decl).IsAvailable ())
+			if (!decl.IsAvailable () || !(((Decl) decl.DeclContext!).IsAvailable ()))
 				return;
 
 			// don't process deprecated methods (or types)
-			if (decl.IsDeprecated () || (decl.DeclContext as Decl).IsDeprecated ())
+			if (decl.IsDeprecated () || (((Decl) decl.DeclContext!).IsDeprecated ()))
 				return;
 
 			var method = GetMethod (decl);
@@ -203,7 +203,7 @@ public override void VisitObjCMethodDecl (ObjCMethodDecl decl)
 				ICustomAttributeProvider cap;
 				// the managed attributes are on the property, not the special methods
 				if (method.IsGetter) {
-					var property = method.FindProperty ();
+					var property = method.FindProperty ()!;
 					// also `null_resettable` will only show something (natively) on the setter (since it does not return null, but accept it)
 					// in this case we'll trust xtro checking the setter only (if it exists, if not then it can't be `null_resettable`)
 					if (property.SetMethod is not null)

tests/xtro-sharpie/xtro-sharpie/ObjCInterfaceCheck.cs

@@ -15,7 +15,7 @@ public override void VisitManagedType (TypeDefinition type)
 			if (!type.HasCustomAttributes)
 				return;
 
-			string rname = null;
+			string? rname = null;
 			bool wrapper = true;
 			bool skip = false;
 
@@ -24,7 +24,7 @@ public override void VisitManagedType (TypeDefinition type)
 				case "RegisterAttribute":
 					rname = type.Name;
 					if (ca.HasConstructorArguments) {
-						rname = (ca.ConstructorArguments [0].Value as string);
+						rname = (string?) ca.ConstructorArguments [0].Value;
 						if (ca.ConstructorArguments.Count > 1)
 							wrapper = (bool) ca.ConstructorArguments [1].Value;
 					}
@@ -47,8 +47,7 @@ public override void VisitManagedType (TypeDefinition type)
 				}
 			}
 			if (!skip && wrapper && !String.IsNullOrEmpty (rname)) {
-				TypeDefinition td;
-				if (!type_map.TryGetValue (rname, out td)) {
+				if (!type_map.TryGetValue (rname, out var td)) {
 					type_map.Add (rname, type);
 					type_map_copy.Add (rname, type);
 				} else {
@@ -149,22 +148,22 @@ public override void EndVisit ()
 		}
 
 		// - version check
-		bool ImplementProtocol (string protocol, TypeDefinition td)
+		bool ImplementProtocol (string protocol, TypeDefinition? td)
 		{
 			if (td is null)
 				return false;
 			if (td.HasInterfaces) {
 				foreach (var intf in td.Interfaces) {
 					TypeReference ifaceType;
-					ifaceType = intf?.InterfaceType;
-					if (protocol == GetProtocolName (ifaceType?.Resolve ()))
+					ifaceType = intf.InterfaceType;
+					if (protocol == GetProtocolName (ifaceType.Resolve ()))
 						return true;
 				}
 			}
 			return ImplementProtocol (protocol, td.BaseType?.Resolve ());
 		}
 
-		public static string GetProtocolName (TypeDefinition td)
+		public static string? GetProtocolName (TypeDefinition td)
 		{
 			if (!td.HasCustomAttributes)
 				return null;