[generator] Ensure non-constant static interface fields are generated as interface properties.

tests/generator-Tests/Unit-Tests/CodeGeneratorExpectedResults/JavaInterop1/ObsoleteInterfaceAlternativeClass.txt

@@ -72,6 +72,18 @@ public partial interface IParent : IJavaObject, IJavaPeerable {
 	[Obsolete ("deprecated")]
 	public const string AlreadyObsolete = (string) "android.permission.ACCEPT_HANDOVER";
 
+
+	// Metadata.xml XPath field reference: path="/api/package[@name='com.xamarin.android']/interface[@name='Parent']/field[@name='API_NAME']"
+	[Register ("API_NAME")]
+	public static string ApiName {
+		get {
+			const string __id = "API_NAME.Ljava/lang/String;";
+
+			var __v = _members.StaticFields.GetObjectValue (__id);
+			return JNIEnv.GetString (__v.Handle, JniHandleOwnership.TransferLocalRef);
+		}
+	}
+
 	// Metadata.xml XPath method reference: path="/api/package[@name='com.xamarin.android']/interface[@name='Parent']/method[@name='comparing' and count(parameter)=0]"
 	[Register ("comparing", "()I", "")]
 	public static unsafe int Comparing ()

tests/generator-Tests/Unit-Tests/CodeGeneratorExpectedResults/JavaInterop1/WriteInterfaceFieldAsDimProperty.txt

@@ -0,0 +1,126 @@
+[Register ("com/xamarin/android/MyInterface", DoNotGenerateAcw=true)]
+public abstract class MyInterface : Java.Lang.Object {
+	internal MyInterface ()
+	{
+	}
+
+	// Metadata.xml XPath field reference: path="/api/package[@name='com.xamarin.android']/interface[@name='MyInterface']/field[@name='EGL_NATIVE_VISUAL_ID']"
+	[Register ("EGL_NATIVE_VISUAL_ID")]
+	public const int EglNativeVisualId = (int) 12334;
+
+
+	// Metadata.xml XPath field reference: path="/api/package[@name='com.xamarin.android']/interface[@name='MyInterface']/field[@name='EGL_NO_SURFACE']"
+	[Register ("EGL_NO_SURFACE")]
+	public static int EglNoSurface {
+		get {
+			const string __id = "EGL_NO_SURFACE.I";
+
+			var __v = _members.StaticFields.GetInt32Value (__id);
+			return __v;
+		}
+		set {
+			const string __id = "EGL_NO_SURFACE.I";
+
+			try {
+				_members.StaticFields.SetValue (__id, value);
+			} finally {
+			}
+		}
+	}
+
+	static readonly JniPeerMembers _members = new JniPeerMembers ("com/xamarin/android/MyInterface", typeof (MyInterface));
+
+}
+
+[Register ("com/xamarin/android/MyInterface", DoNotGenerateAcw=true)]
+[global::System.Obsolete ("Use the 'MyInterface' type. This type will be removed in a future release.", error: true)]
+public abstract class MyInterfaceConsts : MyInterface {
+	private MyInterfaceConsts ()
+	{
+	}
+
+}
+
+// Metadata.xml XPath interface reference: path="/api/package[@name='com.xamarin.android']/interface[@name='MyInterface']"
+[Register ("com/xamarin/android/MyInterface", "", "Com.Xamarin.Android.IMyInterfaceInvoker")]
+public partial interface IMyInterface : IJavaObject, IJavaPeerable {
+	private static readonly JniPeerMembers _members = new JniPeerMembers ("com/xamarin/android/MyInterface", typeof (IMyInterface), isInterface: true);
+
+
+	// Metadata.xml XPath field reference: path="/api/package[@name='com.xamarin.android']/interface[@name='MyInterface']/field[@name='EGL_NO_SURFACE']"
+	[Register ("EGL_NO_SURFACE")]
+	public static int EglNoSurface {
+		get {
+			const string __id = "EGL_NO_SURFACE.I";
+
+			var __v = _members.StaticFields.GetInt32Value (__id);
+			return __v;
+		}
+		set {
+			const string __id = "EGL_NO_SURFACE.I";
+
+			try {
+				_members.StaticFields.SetValue (__id, value);
+			} finally {
+			}
+		}
+	}
+
+}
+
+[global::Android.Runtime.Register ("com/xamarin/android/MyInterface", DoNotGenerateAcw=true)]
+internal partial class IMyInterfaceInvoker : global::Java.Lang.Object, IMyInterface {
+	static readonly JniPeerMembers _members = new JniPeerMembers ("com/xamarin/android/MyInterface", typeof (IMyInterfaceInvoker));
+
+	static IntPtr java_class_ref {
+		get { return _members.JniPeerType.PeerReference.Handle; }
+	}
+
+	[global::System.Diagnostics.DebuggerBrowsable (global::System.Diagnostics.DebuggerBrowsableState.Never)]
+	[global::System.ComponentModel.EditorBrowsable (global::System.ComponentModel.EditorBrowsableState.Never)]
+	public override global::Java.Interop.JniPeerMembers JniPeerMembers {
+		get { return _members; }
+	}
+
+	[global::System.Diagnostics.DebuggerBrowsable (global::System.Diagnostics.DebuggerBrowsableState.Never)]
+	[global::System.ComponentModel.EditorBrowsable (global::System.ComponentModel.EditorBrowsableState.Never)]
+	protected override IntPtr ThresholdClass {
+		get { return class_ref; }
+	}
+
+	[global::System.Diagnostics.DebuggerBrowsable (global::System.Diagnostics.DebuggerBrowsableState.Never)]
+	[global::System.ComponentModel.EditorBrowsable (global::System.ComponentModel.EditorBrowsableState.Never)]
+	protected override global::System.Type ThresholdType {
+		get { return _members.ManagedPeerType; }
+	}
+
+	IntPtr class_ref;
+
+	public static IMyInterface GetObject (IntPtr handle, JniHandleOwnership transfer)
+	{
+		return global::Java.Lang.Object.GetObject<IMyInterface> (handle, transfer);
+	}
+
+	static IntPtr Validate (IntPtr handle)
+	{
+		if (!JNIEnv.IsInstanceOf (handle, java_class_ref))
+			throw new InvalidCastException ($"Unable to convert instance of type '{JNIEnv.GetClassNameFromInstance (handle)}' to type 'com.xamarin.android.MyInterface'.");
+		return handle;
+	}
+
+	protected override void Dispose (bool disposing)
+	{
+		if (this.class_ref != IntPtr.Zero)
+			JNIEnv.DeleteGlobalRef (this.class_ref);
+		this.class_ref = IntPtr.Zero;
+		base.Dispose (disposing);
+	}
+
+	public IMyInterfaceInvoker (IntPtr handle, JniHandleOwnership transfer) : base (Validate (handle), transfer)
+	{
+		IntPtr local_ref = JNIEnv.GetObjectClass (((global::Java.Lang.Object) this).Handle);
+		this.class_ref = JNIEnv.NewGlobalRef (local_ref);
+		JNIEnv.DeleteLocalRef (local_ref);
+	}
+
+}

tests/generator-Tests/Unit-Tests/CodeGeneratorExpectedResults/XAJavaInterop1/ObsoleteInterfaceAlternativeClass.txt

@@ -72,6 +72,18 @@ public partial interface IParent : IJavaObject, IJavaPeerable {
 	[Obsolete ("deprecated")]
 	public const string AlreadyObsolete = (string) "android.permission.ACCEPT_HANDOVER";
 
+
+	// Metadata.xml XPath field reference: path="/api/package[@name='com.xamarin.android']/interface[@name='Parent']/field[@name='API_NAME']"
+	[Register ("API_NAME")]
+	public static string ApiName {
+		get {
+			const string __id = "API_NAME.Ljava/lang/String;";
+
+			var __v = _members.StaticFields.GetObjectValue (__id);
+			return JNIEnv.GetString (__v.Handle, JniHandleOwnership.TransferLocalRef);
+		}
+	}
+
 	// Metadata.xml XPath method reference: path="/api/package[@name='com.xamarin.android']/interface[@name='Parent']/method[@name='comparing' and count(parameter)=0]"
 	[Register ("comparing", "()I", "")]
 	public static unsafe int Comparing ()

tests/generator-Tests/Unit-Tests/CodeGeneratorExpectedResults/XAJavaInterop1/WriteInterfaceFieldAsDimProperty.txt

@@ -0,0 +1,126 @@
+[Register ("com/xamarin/android/MyInterface", DoNotGenerateAcw=true)]
+public abstract class MyInterface : Java.Lang.Object {
+	internal MyInterface ()
+	{
+	}
+
+	// Metadata.xml XPath field reference: path="/api/package[@name='com.xamarin.android']/interface[@name='MyInterface']/field[@name='EGL_NATIVE_VISUAL_ID']"
+	[Register ("EGL_NATIVE_VISUAL_ID")]
+	public const int EglNativeVisualId = (int) 12334;
+
+
+	// Metadata.xml XPath field reference: path="/api/package[@name='com.xamarin.android']/interface[@name='MyInterface']/field[@name='EGL_NO_SURFACE']"
+	[Register ("EGL_NO_SURFACE")]
+	public static int EglNoSurface {
+		get {
+			const string __id = "EGL_NO_SURFACE.I";
+
+			var __v = _members.StaticFields.GetInt32Value (__id);
+			return __v;
+		}
+		set {
+			const string __id = "EGL_NO_SURFACE.I";
+
+			try {
+				_members.StaticFields.SetValue (__id, value);
+			} finally {
+			}
+		}
+	}
+
+	static readonly JniPeerMembers _members = new XAPeerMembers ("com/xamarin/android/MyInterface", typeof (MyInterface));
+
+}
+
+[Register ("com/xamarin/android/MyInterface", DoNotGenerateAcw=true)]
+[global::System.Obsolete ("Use the 'MyInterface' type. This type will be removed in a future release.", error: true)]
+public abstract class MyInterfaceConsts : MyInterface {
+	private MyInterfaceConsts ()
+	{
+	}
+
+}
+
+// Metadata.xml XPath interface reference: path="/api/package[@name='com.xamarin.android']/interface[@name='MyInterface']"
+[Register ("com/xamarin/android/MyInterface", "", "Com.Xamarin.Android.IMyInterfaceInvoker")]
+public partial interface IMyInterface : IJavaObject, IJavaPeerable {
+	private static readonly JniPeerMembers _members = new XAPeerMembers ("com/xamarin/android/MyInterface", typeof (IMyInterface), isInterface: true);
+
+
+	// Metadata.xml XPath field reference: path="/api/package[@name='com.xamarin.android']/interface[@name='MyInterface']/field[@name='EGL_NO_SURFACE']"
+	[Register ("EGL_NO_SURFACE")]
+	public static int EglNoSurface {
+		get {
+			const string __id = "EGL_NO_SURFACE.I";
+
+			var __v = _members.StaticFields.GetInt32Value (__id);
+			return __v;
+		}
+		set {
+			const string __id = "EGL_NO_SURFACE.I";
+
+			try {
+				_members.StaticFields.SetValue (__id, value);
+			} finally {
+			}
+		}
+	}
+
+}
+
+[global::Android.Runtime.Register ("com/xamarin/android/MyInterface", DoNotGenerateAcw=true)]
+internal partial class IMyInterfaceInvoker : global::Java.Lang.Object, IMyInterface {
+	static readonly JniPeerMembers _members = new XAPeerMembers ("com/xamarin/android/MyInterface", typeof (IMyInterfaceInvoker));
+
+	static IntPtr java_class_ref {
+		get { return _members.JniPeerType.PeerReference.Handle; }
+	}
+
+	[global::System.Diagnostics.DebuggerBrowsable (global::System.Diagnostics.DebuggerBrowsableState.Never)]
+	[global::System.ComponentModel.EditorBrowsable (global::System.ComponentModel.EditorBrowsableState.Never)]
+	public override global::Java.Interop.JniPeerMembers JniPeerMembers {
+		get { return _members; }
+	}
+
+	[global::System.Diagnostics.DebuggerBrowsable (global::System.Diagnostics.DebuggerBrowsableState.Never)]
+	[global::System.ComponentModel.EditorBrowsable (global::System.ComponentModel.EditorBrowsableState.Never)]
+	protected override IntPtr ThresholdClass {
+		get { return class_ref; }
+	}
+
+	[global::System.Diagnostics.DebuggerBrowsable (global::System.Diagnostics.DebuggerBrowsableState.Never)]
+	[global::System.ComponentModel.EditorBrowsable (global::System.ComponentModel.EditorBrowsableState.Never)]
+	protected override global::System.Type ThresholdType {
+		get { return _members.ManagedPeerType; }
+	}
+
+	IntPtr class_ref;
+
+	public static IMyInterface GetObject (IntPtr handle, JniHandleOwnership transfer)
+	{
+		return global::Java.Lang.Object.GetObject<IMyInterface> (handle, transfer);
+	}
+
+	static IntPtr Validate (IntPtr handle)
+	{
+		if (!JNIEnv.IsInstanceOf (handle, java_class_ref))
+			throw new InvalidCastException ($"Unable to convert instance of type '{JNIEnv.GetClassNameFromInstance (handle)}' to type 'com.xamarin.android.MyInterface'.");
+		return handle;
+	}
+
+	protected override void Dispose (bool disposing)
+	{
+		if (this.class_ref != IntPtr.Zero)
+			JNIEnv.DeleteGlobalRef (this.class_ref);
+		this.class_ref = IntPtr.Zero;
+		base.Dispose (disposing);
+	}
+
+	public IMyInterfaceInvoker (IntPtr handle, JniHandleOwnership transfer) : base (Validate (handle), transfer)
+	{
+		IntPtr local_ref = JNIEnv.GetObjectClass (((global::Java.Lang.Object) this).Handle);
+		this.class_ref = JNIEnv.NewGlobalRef (local_ref);
+		JNIEnv.DeleteLocalRef (local_ref);
+	}
+
+}

tests/generator-Tests/Unit-Tests/DefaultInterfaceMethodsTests.cs

@@ -462,5 +462,31 @@ public void GenerateProperNestedInterfaceSignatures ()
 			Assert.True (generated.Contains ("GetOnActivityDestroyed_IHandler:Com.Xamarin.Android.Application/IActivityLifecycleInterface, MyAssembly"));
 			Assert.False (generated.Contains ("GetOnActivityDestroyed_IHandler:Com.Xamarin.Android.Application.IActivityLifecycleInterface, MyAssembly"));
 		}
+
+		[Test]
+		public void WriteInterfaceFieldAsDimProperty ()
+		{
+			// Ensure we write interface fields that are not constant, and thus must be written as properties
+			var xml = @"<api>
+			  <package name='com.xamarin.android' jni-name='com/xamarin/android'>
+			    <interface abstract='true' deprecated='not deprecated' final='false' name='MyInterface' static='false' visibility='public' jni-signature='Lcom/xamarin/android/MyInterface;'>
+			      <field deprecated='not deprecated' final='true' name='EGL_NATIVE_VISUAL_ID' jni-signature='I' static='true' transient='false' type='int' type-generic-aware='int' value='12334' visibility='public' volatile='false'></field>
+			      <field deprecated='not deprecated' final='false' name='EGL_NO_SURFACE' jni-signature='I' static='true' transient='false' type='int' type-generic-aware='int' visibility='public' volatile='false'></field>
+			    </interface>
+			  </package>
+			</api>";
+
+			var gens = ParseApiDefinition (xml);
+			var iface = gens.OfType<InterfaceGen> ().Single ();
+
+			var result = iface.Validate (options, new GenericParameterDefinitionList (), new CodeGeneratorContext ());
+			Assert.True (result);
+
+			generator.WriteType (iface, string.Empty, new GenerationInfo (string.Empty, string.Empty, "MyAssembly"));
+
+			var generated = writer.ToString ();
+
+			Assert.AreEqual (GetTargetedExpected (nameof (WriteInterfaceFieldAsDimProperty)), writer.ToString ().NormalizeLineEndings ());
+		}
 	}
 }

tools/generator/Java.Interop.Tools.Generator.ObjectModel/InterfaceGen.cs

@@ -149,14 +149,23 @@ internal string GetEventDelegateName (Method m)
 		// These are fields that we currently support generating on the interface with DIM
 		public IEnumerable<Field> GetGeneratableFields (CodeGenerationOptions options)
 		{
-			if (!options.SupportInterfaceConstants)
-				return Enumerable.Empty<Field> ();
+			var fields = new List<Field> ();
 
-			return Fields.Where (f => !f.NeedsProperty && !(f.DeprecatedComment?.Contains ("constant will be removed") == true));
+			// Constant fields
+			if (options.SupportInterfaceConstants)
+				fields.AddRange (Fields.Where (f => !f.NeedsProperty && !(f.DeprecatedComment?.Contains ("constant will be removed") == true)));
+
+			// Invoked fields exposed as properties
+			if (options.SupportDefaultInterfaceMethods)
+				fields.AddRange (Fields.Where (f => f.NeedsProperty && !(f.DeprecatedComment?.Contains ("constant will be removed") == true)));
+
+			return fields;
 		}
 
 		public bool HasDefaultMethods => GetAllMethods ().Any (m => m.IsInterfaceDefaultMethod);
 
+		public bool HasFieldsAsProperties => Fields.Any (f => f.NeedsProperty);
+
 		public bool HasStaticMethods => GetAllMethods ().Any (m => m.IsStatic);
 
 		public bool IsConstSugar (CodeGenerationOptions options)

tools/generator/SourceWriters/BoundInterface.cs

@@ -153,14 +153,14 @@ void AddInheritedInterfaces (InterfaceGen iface, CodeGenerationOptions opt)
 
 		void AddClassHandle (InterfaceGen iface, CodeGenerationOptions opt)
 		{
-			if (opt.SupportDefaultInterfaceMethods && (iface.HasDefaultMethods || iface.HasStaticMethods))
+			if (opt.SupportDefaultInterfaceMethods && (iface.HasDefaultMethods || iface.HasStaticMethods || iface.HasFieldsAsProperties))
 				Fields.Add (new PeerMembersField (opt, iface.RawJniName, iface.Name, true));
 		}
 
 		void AddFields (InterfaceGen iface, CodeGenerationOptions opt, CodeGeneratorContext context)
 		{
 			// Interface fields are only supported with DIM
-			if (!opt.SupportInterfaceConstants)
+			if (!opt.SupportInterfaceConstants && !opt.SupportDefaultInterfaceMethods)
 				return;
 
 			var seen = new HashSet<string> ();