[generator] Add support for skipInterfaceMethods (#1265)

Context: #1264
Context: 73ebad2
Context: a7e09b7
Context: dotnet/android@00256b6

Consider [`java.util.List<E>`][0], which implements
[`java.util.SequencedCollection<E>`][1] and provides an interface
default method to implement `SequencedCollection<E>.reversed()`:

	// Java
	package java.util;
	public /* partial */ interface SequencedCollection<E> implements Collection<E> {
	  SequencedCollection<E> reverse ();
	}
	public /* partial */ interface List<E> implements SequencedCollection<E> {
	  default List<E> reversed() { … }
	}

We then *bind* the above, along with some manual fixups in
dotnet/android@00256b69:

	// C# bindings
	public partial interface ISequencedCollection {
	  [Register ("reversed", "()Ljava/util/SequencedCollection;", "GetReversedHandler:Java.Util.ISequencedCollectionInvoker, Mono.Android, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null", ApiSince = 35)]
	  ISequencedCollection? Reversed ();
	}

	public partial interface IList : ISequencedCollection {
	  [Register ("reversed", "()Ljava/util/List;", "GetReversedHandler:Java.Util.IList, Mono.Android, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null", ApiSince = 35)]
	  unsafe Java.Util.ISequencedCollection Java.Util.ISequencedCollection.Reversed () => …
	}

Next, we try to bind [`androidx.paging:paging-common-android`][2].
[`androidx.paging.ItemSnapshotList`][3] inherits from
[`kotlin.collections.AbstractList`][4]:

	// Kotlin
	package kotlin.collections;
	public abstract /* partial */ class AbstractList<out E> protected constructor() :
	    kotlin.collections.AbstractCollection<E>(), java.util.List<E> {
	}

In a scenario that rhymes with 73ebad2, `generator` with
`Mono.Android.dll` (bindings for `Java.Util.IList`) cannot determine
that the `Kotlin.Collections.AbstractList` type has a `Reversed()`
method (via `Java.Util.IList`), and so re-declares it:

	// C#
	public partial class AbstractList : Kotlin.Collections.AbstractCollection, Java.Util.IList {
	  public abstract ISequencedCollection Reversed ();
	}

We fear that a complete fix for this may be complicated, as we would
have to determine if each interface method has a compatible default
interface method on any other interface in scope.

Introduce new `skipInterfaceMethods` metadata, with identical
semantics to `skipInvokerMethods` (73ebad2), to allow specifying
`interface`-derived methods which should be *skipped* when generating
bindings:

	<attr
	    path="/api/package[@name='kotlin.collections']/class[@name='AbstractList']"
	    name="skipInterfaceMethods">
	  java/util/SequencedCollection.reversed()Ljava/util/SequencedCollection;
	</attr>

The above fragment would prevent `Reversed()` from being declared in
the binding for `Kotlin.Collections.AbstractList`.

[0]: https://developer.android.com/reference/java/util/List
[1]: https://developer.android.com/reference/java/util/SequencedCollection
[2]: https://maven.google.com/web/index.html?q=paging#androidx.paging:paging-common-android
[3]: https://developer.android.com/reference/androidx/paging/ItemSnapshotList
[4]: https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.collections/-abstract-list/

Author: jpobst

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

@@ -379,6 +379,34 @@ public void SkipInterfaceInvokerMethodsMetadata ()
 			Assert.False (writer.ToString ().Contains ("InvokeAbstractInt32Method"), $"was: `{writer}`");
 		}
 
+		[Test]
+		public void SkipInterfaceMethodsMetadata ()
+		{
+			var xml = @"<api>
+			  <package name='java.lang' jni-name='java/lang'>
+			    <class abstract='false' deprecated='not deprecated' final='false' name='Object' static='false' visibility='public' jni-signature='Ljava/lang/Object;' />
+			  </package>
+			  <package name='com.xamarin.android' jni-name='com/xamarin/android'>
+			    <interface abstract='true' deprecated='not deprecated' extends='java.lang.Object' extends-generic-aware='java.lang.Object' jni-extends='Ljava/lang/Object;' final='false' name='MyInterface' static='false' visibility='public' jni-signature='Lcom/xamarin/android/MyInterface;'>
+			      <method abstract='true' deprecated='not deprecated' final='false' name='countAffectedRows' jni-signature='()I' bridge='false' native='false' return='int' jni-return='I' static='false' synchronized='false' synthetic='false' visibility='public'></method>
+			    </interface>
+			    <class abstract='true' deprecated='not deprecated' extends='java.lang.Object' extends-generic-aware='java.lang.Object' jni-extends='Ljava/lang/Object;' final='false' name='MyBaseClass' static='false' visibility='public' jni-signature='Lcom/xamarin/android/MyBaseClass;' skipInterfaceMethods='com/xamarin/android/MyInterface.countAffectedRows()I'>
+			      <implements name='com.xamarin.android.MyInterface' name-generic-aware='com.xamarin.android.MyInterface' jni-type='Lcom/xamarin/android/MyInterface;'></implements>
+			    </class>
+			  </package>
+			</api>";
+
+			var gens = ParseApiDefinition (xml);
+			var klass = gens.Single (g => g.Name == "MyBaseClass");
+
+			generator.Context.ContextTypes.Push (klass);
+			generator.WriteType (klass, string.Empty, new GenerationInfo ("", "", "MyAssembly"));
+			generator.Context.ContextTypes.Pop ();
+
+			// The abstract method should not get generated because we are suppressing it with 'skipInterfaceMethods'
+			Assert.False (writer.ToString ().Contains ("public abstract int CountAffectedRows ();"), $"was: `{writer}`");
+		}
+
 		[Test]
 		public void CompatVirtualMethod_Class ()
 		{

tools/generator/Java.Interop.Tools.Generator.Importers/XmlApiImporter.cs

@@ -147,6 +147,10 @@ public static ClassGen CreateClass (XElement pkg, XElement elem, CodeGenerationO
 				}
 			}
 
+			if (elem.Attribute ("skipInterfaceMethods")?.Value is string skip)
+				foreach (var m in skip.Split (new char [] { ',', ' ', '\n', '\r' }, StringSplitOptions.RemoveEmptyEntries))
+					klass.SkippedInterfaceMethods.Add (m);
+
 			return klass;
 		}
 

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

@@ -11,6 +11,7 @@ namespace MonoDroid.Generation
 	public class ClassGen : GenBase
 	{
 		bool fill_explicit_implementation_started;
+		HashSet<string> skipped_interface_methods;
 
 		public List<Ctor> Ctors { get; private set; } = new List<Ctor> ();
 
@@ -355,6 +356,8 @@ public override void ResetValidation ()
 			base.ResetValidation ();
 		}
 
+		public HashSet<string> SkippedInterfaceMethods => skipped_interface_methods ??= new HashSet<string> ();
+
 		public override string ToNative (CodeGenerationOptions opt, string varname, Dictionary<string, string> mappings = null)
 		{
 			if (opt.CodeGenerationTarget == CodeGenerationTarget.JavaInterop1) {

tools/generator/SourceWriters/BoundClass.cs

@@ -221,6 +221,8 @@ void AddInterfaceAbstractMembers (ClassGen klass, InterfaceGen iface, CodeGenera
 
 				if (context.ContextGeneratedMethods.Any (_ => _.Name == method.Name && _.JniSignature == method.JniSignature))
 					continue;
+				if (klass.SkippedInterfaceMethods.Contains (method.GetSkipInvokerSignature ()))
+					continue;
 
 				for (var cls = klass; cls != null; cls = cls.BaseGen)
 					if (cls.ContainsMethod (method, false) || cls != klass && klass.ExplicitlyImplementedInterfaceMethods.Contains (sig)) {