[src] Enable nullability in a few files. (#18185)

src/Foundation/ConnectAttribute.cs

@@ -22,19 +22,21 @@
 //
 using System;
 
+#nullable enable
+
 namespace Foundation {
 
 	[AttributeUsage (AttributeTargets.Property)]
 	public sealed class ConnectAttribute : Attribute {
-		string name;
+		string? name;
 
 		public ConnectAttribute () { }
 		public ConnectAttribute (string name)
 		{
 			this.name = name;
 		}
 
-		public string Name {
+		public string? Name {
 			get { return this.name; }
 			set { this.name = value; }
 		}

src/Foundation/ExportAttribute.cs

@@ -34,28 +34,30 @@
 using ObjCRuntime;
 using Registrar;
 
+#nullable enable
+
 namespace Foundation {
 
 	[AttributeUsage (AttributeTargets.Method | AttributeTargets.Constructor | AttributeTargets.Property)]
 	public class ExportAttribute : Attribute {
-		string selector;
+		string? selector;
 		ArgumentSemantic semantic;
 
 		protected ExportAttribute () { }
 
-		public ExportAttribute (string selector)
+		public ExportAttribute (string? selector)
 		{
 			this.selector = selector;
 			this.semantic = ArgumentSemantic.None;
 		}
 
-		public ExportAttribute (string selector, ArgumentSemantic semantic)
+		public ExportAttribute (string? selector, ArgumentSemantic semantic)
 		{
 			this.selector = selector;
 			this.semantic = semantic;
 		}
 
-		public string Selector {
+		public string? Selector {
 			get { return this.selector; }
 			set { this.selector = value; }
 		}

src/ObjCRuntime/LinkWithAttribute.cs

@@ -26,6 +26,8 @@
 using System;
 using System.IO;
 
+#nullable enable
+
 namespace ObjCRuntime {
 	[Flags]
 	public enum LinkTarget : int {
@@ -74,19 +76,19 @@ public bool ForceLoad {
 			get; set;
 		}
 
-		public string Frameworks {
+		public string? Frameworks {
 			get; set;
 		}
 
-		public string WeakFrameworks {
+		public string? WeakFrameworks {
 			get; set;
 		}
 
-		public string LibraryName {
+		public string? LibraryName {
 			get; private set;
 		}
 
-		public string LinkerFlags {
+		public string? LinkerFlags {
 			get; set;
 		}
 

src/ObjCRuntime/Registrar.core.cs

@@ -1,10 +1,16 @@
 using System.Text;
 
+#nullable enable
+
 namespace Registrar {
 	abstract partial class Registrar {
-		internal static string CreateSetterSelector (string getterSelector)
+		internal static string? CreateSetterSelector (string? getterSelector)
 		{
+#if NET
 			if (string.IsNullOrEmpty (getterSelector))
+#else
+			if (getterSelector is null || string.IsNullOrEmpty (getterSelector))
+#endif
 				return getterSelector;
 
 			var first = (int) getterSelector [0];
@@ -16,7 +22,7 @@ internal static string CreateSetterSelector (string getterSelector)
 
 		public static string SanitizeObjectiveCName (string name)
 		{
-			StringBuilder sb = null;
+			StringBuilder? sb = null;
 
 			for (int i = 0; i < name.Length; i++) {
 				var ch = name [i];
@@ -30,18 +36,18 @@ public static string SanitizeObjectiveCName (string name)
 				case '>':
 				case '$':
 				case '-':
-					if (sb == null)
+					if (sb is null)
 						sb = new StringBuilder (name, 0, i, name.Length);
 					sb.Append ('_');
 					break;
 				default:
-					if (sb != null)
+					if (sb is not null)
 						sb.Append (ch);
 					break;
 				}
 			}
 
-			if (sb != null)
+			if (sb is not null)
 				return sb.ToString ();
 
 			return name;

src/ObjCRuntime/RuntimeOptions.cs

@@ -11,6 +11,8 @@
 using ObjCRuntime;
 #endif
 
+#nullable enable
+
 #if MMP || MMP_TEST || MTOUCH || BUNDLER
 namespace Xamarin.Bundler {
 #else
@@ -25,20 +27,20 @@ class RuntimeOptions {
 		const string CFNetworkHandlerValue = "CFNetworkHandler";
 		const string NSUrlSessionHandlerValue = "NSUrlSessionHandler";
 
-		string http_message_handler;
+		string? http_message_handler;
 
 #if MTOUCH || MMP || BUNDLER
 		/*
 		 * This section is only used by the tools
 		 */
-		internal static RuntimeOptions Create (Application app, string http_message_handler, string tls_provider)
+		internal static RuntimeOptions Create (Application app, string? http_message_handler, string? tls_provider)
 		{
 			var options = new RuntimeOptions ();
 			options.http_message_handler = ParseHttpMessageHandler (app, http_message_handler);
 			return options;
 		}
 
-		static string ParseHttpMessageHandler (Application app, string value)
+		static string ParseHttpMessageHandler (Application app, string? value)
 		{
 			switch (value) {
 			// default
@@ -89,11 +91,11 @@ internal void Write (string app_dir)
 		}
 
 		// Called from CoreHttpMessageHandler
-		internal static TypeDefinition GetHttpMessageHandler (Application app, RuntimeOptions options, ModuleDefinition httpModule, ModuleDefinition platformModule = null)
+		internal static TypeDefinition GetHttpMessageHandler (Application app, RuntimeOptions options, ModuleDefinition httpModule, ModuleDefinition? platformModule = null)
 		{
-			string handler;
+			string? handler;
 
-			if (options != null) {
+			if (options is not null) {
 				handler = options.http_message_handler;
 			} else if (app.Platform == Utils.ApplePlatform.WatchOS) {
 				handler = NSUrlSessionHandlerValue;
@@ -111,10 +113,10 @@ internal static TypeDefinition GetHttpMessageHandler (Application app, RuntimeOp
 				type = httpModule.GetType ("System.Net.Http", "HttpClientHandler");
 				break;
 			case CFNetworkHandlerValue:
-				type = platformModule.GetType ("System.Net.Http", "CFNetworkHandler");
+				type = platformModule!.GetType ("System.Net.Http", "CFNetworkHandler");
 				break;
 			case NSUrlSessionHandlerValue:
-				type = platformModule.GetType ("Foundation", "NSUrlSessionHandler");
+				type = platformModule!.GetType ("Foundation", "NSUrlSessionHandler");
 				break;
 #else
 #if NET
@@ -125,7 +127,7 @@ internal static TypeDefinition GetHttpMessageHandler (Application app, RuntimeOp
 			case HttpClientHandlerValue:
 				if (app.Platform == Utils.ApplePlatform.WatchOS) {
 					ErrorHelper.Warning (2015, Errors.MT2015, handler);
-					type = platformModule.GetType ("System.Net.Http", "NSUrlSessionHandler");
+					type = platformModule!.GetType ("System.Net.Http", "NSUrlSessionHandler");
 				} else {
 					type = httpModule.GetType ("System.Net.Http", "HttpClientHandler");
 				}
@@ -134,25 +136,25 @@ internal static TypeDefinition GetHttpMessageHandler (Application app, RuntimeOp
 			case CFNetworkHandlerValue:
 				if (app.Platform == Utils.ApplePlatform.WatchOS) {
 					ErrorHelper.Warning (2015, Errors.MT2015, handler);
-					type = platformModule.GetType ("System.Net.Http", "NSUrlSessionHandler");
+					type = platformModule!.GetType ("System.Net.Http", "NSUrlSessionHandler");
 				} else {
-					type = platformModule.GetType ("System.Net.Http", "CFNetworkHandler");
+					type = platformModule!.GetType ("System.Net.Http", "CFNetworkHandler");
 				}
 				break;
 			case NSUrlSessionHandlerValue:
-				type = platformModule.GetType ("System.Net.Http", "NSUrlSessionHandler");
+				type = platformModule!.GetType ("System.Net.Http", "NSUrlSessionHandler");
 				break;
 #endif
 			default:
 				throw new InvalidOperationException (string.Format ("Unknown HttpMessageHandler `{0}`.", handler));
 			}
-			if (type == null)
+			if (type is null)
 				throw new InvalidOperationException (string.Format ("Cannot load HttpMessageHandler `{0}`.", handler));
 			return type;
 		}
 #else
 
-		internal static RuntimeOptions Read ()
+		internal static RuntimeOptions? Read ()
 		{
 			// for iOS NSBundle.ResourcePath returns the path to the root of the app bundle
 			// for macOS apps NSBundle.ResourcePath returns foo.app/Contents/Resources
@@ -185,12 +187,12 @@ internal static HttpMessageHandler GetHttpMessageHandler ()
 			case CFNetworkHandlerValue:
 				return new CFNetworkHandler ();
 			default:
-				if (handler_name != null && handler_name != NSUrlSessionHandlerValue)
+				if (handler_name is not null && handler_name != NSUrlSessionHandlerValue)
 					Runtime.NSLog ($"{handler_name} is not a valid HttpMessageHandler, defaulting to System.Net.Http.NSUrlSessionHandlerValue");
 				return new NSUrlSessionHandler ();
 			}
 #elif __WATCHOS__
-			if (handler_name != null && handler_name != NSUrlSessionHandlerValue)
+			if (handler_name is not null && handler_name != NSUrlSessionHandlerValue)
 				Runtime.NSLog ($"{handler_name} is not a valid HttpMessageHandler, defaulting to NSUrlSessionHandler");
 			return new NSUrlSessionHandler ();
 #else
@@ -200,7 +202,7 @@ internal static HttpMessageHandler GetHttpMessageHandler ()
 			case NSUrlSessionHandlerValue:
 				return new NSUrlSessionHandler ();
 			default:
-				if (handler_name != null && handler_name != HttpClientHandlerValue)
+				if (handler_name is not null && handler_name != HttpClientHandlerValue)
 					Runtime.NSLog ($"{handler_name} is not a valid HttpMessageHandler, defaulting to System.Net.Http.HttpClientHandler");
 				return new HttpClientHandler ();
 			}