[generator] Unable to inherit reference interface with generic method parameters

[jpobst]

Context: dotnet/android#5027

Given this snippet:

package com.blah;

import android.database.Cursor;

public interface MyCursor extends Cursor { }

Compiling against API-29 succeeds, while API-30 fails with:

Error CS1026: ) expected
Error CS1056: Unexpected character '`'
Error CS1002: ; expected
Error CS1002: ; expected
Error CS1513: } expected

This is due to the interface invoker method for android.database.Cursor.setNotficationUris, added in API-30, which generates this code:

var uris = (global::System.Collections.Generic.IList`1)global::Java.Lang.Object.GetObject<global::System.Collections.Generic.IList`1> (native_uris, JniHandleOwnership.DoNotTransfer);

Using a type with an arity is not legal C# (IList`1). Instead we need to generate the full closed generic type like this:

global::System.Collections.Generic.IList<global::Android.Net.Uri>

When this is fixed, this PR can be reverted: dotnet/android#5124.

[awattar]

Hi. Any ETA for the potential fix?

[awattar]

@jpobst ?

[jpobst]

Nothing has changed since dotnet/android#5027 (comment).

[awattar]

Thanks. I was hoping it will get a new schedule since being moved to the new issue. No chances to be included in 8.8? 8.8 is still in the preview and this "quick fix" will make it more compatible with API-30 and will also unblock us.

[jpobst]

Unfortunately not. 8.8 is pretty locked down now and this isn't a quick-fix. I don't even know how to fix it yet.

[awattar]

@jpobst We have tested fix provided in #5124 and the original issue is gone as the setNotificationUris from Cursor interface was removed. Now it complains about the getter form AbstractCursor NotificationUris property:

obj/Release/generated/src/com.our.package.Database.Sqlite.AbstractWindowedCursor.cs(608,25,608,54): error CS0534: 'AbstractWindowedCursorInvoker' does not implement inherited abstract member 'AbstractCursor.NotificationUris.get'
obj/Release/generated/src/com.our.package.Database.Sqlite.AbstractCursor.cs(1621,25,1621,46): error CS0534: 'AbstractCursorInvoker' does not implement inherited abstract member 'AbstractCursor.NotificationUris.get'
obj/Release/generated/src/com.our.package.Database.Sqlite.MatrixCursor.cs(9,23,9,35): error CS0534: 'MatrixCursor' does not implement inherited abstract member 'AbstractCursor.NotificationUris.get'
obj/Release/generated/src/com.our.package.Database.Sqlite.MergeCursor.cs(9,23,9,34): error CS0534: 'MergeCursor' does not implement inherited abstract member 'AbstractCursor.NotificationUris.get'
obj/Release/generated/src/com.our.package.Database.Sqlite.SQLiteCursor.cs(9,23,9,35): error CS0534: 'SQLiteCursor' does not implement inherited abstract member 'AbstractCursor.NotificationUris.get'

so it was overridden in the partial class on the bindings level just copying NotificationUris from AbstractCursor for each of the above classes:

        internal partial class AbstractCursorInvoker
	{
		public override global::System.Collections.Generic.IList<global::Android.Net.Uri> NotificationUris
		{
			// Metadata.xml XPath method reference: path="/api/package[@name='com.our.package.database.sqlite']/class[@name='AbstractCursor']/method[@name='getNotificationUris' and count(parameter)=0]"
			[Register("getNotificationUris", "()Ljava/util/List;", "GetGetNotificationUrisHandler")]
			get;
		}
	}

	internal partial class AbstractWindowedCursorInvoker
	{
		public override global::System.Collections.Generic.IList<global::Android.Net.Uri> NotificationUris
		{
			// Metadata.xml XPath method reference: path="/api/package[@name='com.our.package.database.sqlite']/class[@name='AbstractCursor']/method[@name='getNotificationUris' and count(parameter)=0]"
			[Register("getNotificationUris", "()Ljava/util/List;", "GetGetNotificationUrisHandler")]
			get;
		}
	}

	public partial class MergeCursor
	{
		public override global::System.Collections.Generic.IList<global::Android.Net.Uri> NotificationUris
		{
			// Metadata.xml XPath method reference: path="/api/package[@name='com.our.package.database.sqlite']/class[@name='AbstractCursor']/method[@name='getNotificationUris' and count(parameter)=0]"
			[Register("getNotificationUris", "()Ljava/util/List;", "GetGetNotificationUrisHandler")]
			get;
		}
	}

	public partial class MatrixCursor
	{
		public override global::System.Collections.Generic.IList<global::Android.Net.Uri> NotificationUris
		{
			// Metadata.xml XPath method reference: path="/api/package[@name='com.our.package.database.sqlite']/class[@name='AbstractCursor']/method[@name='getNotificationUris' and count(parameter)=0]"
			[Register("getNotificationUris", "()Ljava/util/List;", "GetGetNotificationUrisHandler")]
			get;
		}
	}

	public partial class SQLiteCursor
	{
		public override global::System.Collections.Generic.IList<global::Android.Net.Uri> NotificationUris
		{
			// Metadata.xml XPath method reference: path="/api/package[@name='com.our.package.database.sqlite']/class[@name='AbstractCursor']/method[@name='getNotificationUris' and count(parameter)=0]"
			[Register("getNotificationUris", "()Ljava/util/List;", "GetGetNotificationUrisHandler")]
			get;
		}
	}

and now it complains about the generated code:

obj/Release/generated/src/com.our.package.Database.Sqlite.AbstractCursor.cs(1609,62,1609,85): error CS1503: Argument 1: cannot convert from 'System.Collections.Generic.IList<Android.Net.Uri>' to 'System.Collections.IList?'
obj/Release/generated/src/com.our.package.Database.Sqlite.ICrossProcessCursor.cs(411,62,411,85): error CS1503: Argument 1: cannot convert from 'System.Collections.Generic.IList<Android.Net.Uri>' to 'System.Collections.IList?'
obj/Release/generated/src/com.our.package.Database.Sqlite.ICrossProcessCursor.cs(420,12,420,188): error CS0266: Cannot implicitly convert type 'System.Collections.IList' to 'System.Collections.Generic.IList<Android.Net.Uri>'. An explicit conversion exists (are you missing a cast?)

In com.our.package.Database.Sqlite.AbstractCursor.cs:

		static IntPtr n_GetNotificationUris (IntPtr jnienv, IntPtr native__this)
		{
			var __this = global::Java.Lang.Object.GetObject<global::Com.Good.GD.Database.Sqlite.AbstractCursor> (jnienv, native__this, JniHandleOwnership.DoNotTransfer);
			HERE -> return global::Android.Runtime.JavaList.ToLocalJniHandle (__this.NotificationUris);
		}

In com.our.package.Database.Sqlite.ICrossProcessCursor.cs:

		static IntPtr n_GetNotificationUris (IntPtr jnienv, IntPtr native__this)
		{
			var __this = global::Java.Lang.Object.GetObject<global::Com.Good.GD.Database.Sqlite.ICrossProcessCursor> (jnienv, native__this, JniHandleOwnership.DoNotTransfer);
			HERE -> return global::Android.Runtime.JavaList.ToLocalJniHandle (__this.NotificationUris);
		}
#pragma warning restore 0169

		IntPtr id_getNotificationUris;
		public unsafe global::System.Collections.Generic.IList<global::Android.Net.Uri> NotificationUris {
			get {
				if (id_getNotificationUris == IntPtr.Zero)
					id_getNotificationUris = JNIEnv.GetMethodID (class_ref, "getNotificationUris", "()Ljava/util/List;");
				HERE -> return global::Android.Runtime.JavaList.FromJniHandle (JNIEnv.CallObjectMethod (((global::Java.Lang.Object) this).Handle, id_getNotificationUris), JniHandleOwnership.TransferLocalRef);
			}
		}

So it is still missing the cast as you have mentioned in
dotnet/android#5027 (comment)
as it tries to put global::System.Collections.Generic.IList<global::Android.Net.Uri> from NotificationUris to global::Android.Runtime.JavaList.ToLocalJniHandle that requires System.Collections.IList and vice versa.

[jpobst]

Removed Cursor.getNotificationUris as well: dotnet/android#5161.