[Media3] Attempting to create ExoPlayer instance crashes

[tipa]

Android framework version

net9.0-android

Affected platform version

.NET 9

Description

The code throw an exception when trying to create an instance of ExoPlayer

System.ArgumentException: Could not determine Java type corresponding to AndroidX.Media3.ExoPlayer.IExoPlayerInvoker, Xamarin.AndroidX.Media3.ExoPlayer, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null. (Parameter 'targetType')

Steps to Reproduce

var builder = new AndroidX.Media3.ExoPlayer.ExoPlayerBuilder(this);
var player = builder.Build();

Example project: media3.zip

Given other developers seem to already be using the media3 bindings, I wonder if I am doing anything wrong...?

Did you find any workaround?

No response

Relevant log output

No response

[bmaluijb]

I have the exact same issue. I've tried many variations, including a clean MAUI project running .NET 9 (full version, not pre-release).

[moljac]

Repro Exception

System.ArgumentException: Could not determine Java type corresponding to `AndroidX.Media3.ExoPlayer.IExoPlayerInvoker, Xamarin.AndroidX.Media3.ExoPlayer, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null`. (Parameter 'targetType')
   at Java.Interop.TypeManager.CreateInstance(IntPtr handle, JniHandleOwnership transfer, Type targetType) in /Users/runner/work/1/s/xamarin-android/src/Mono.Android/Java.Interop/TypeManager.cs:line 323
   at Java.Lang.Object.GetObject(IntPtr handle, JniHandleOwnership transfer, Type type) in /Users/runner/work/1/s/xamarin-android/src/Mono.Android/Java.Lang/Object.cs:line 302
   at Java.Lang.Object._GetObject[IExoPlayer](IntPtr handle, JniHandleOwnership transfer) in /Users/runner/work/1/s/xamarin-android/src/Mono.Android/Java.Lang/Object.cs:line 288
   at Java.Lang.Object.GetObject[IExoPlayer](IntPtr handle, JniHandleOwnership transfer) in /Users/runner/work/1/s/xamarin-android/src/Mono.Android/Java.Lang/Object.cs:line 280
   at AndroidX.Media3.ExoPlayer.ExoPlayerBuilder.Build() in D:\a\_work\1\s\generated\androidx.media3.media3-exoplayer\obj\Release\net8.0-android\generated\src\AndroidX.Media3.ExoPlayer.IExoPlayer.cs:line 749
   at media3.MainActivity.OnCreate(Bundle savedInstanceState) in /Users/moljac/Downloads/1036/media3/MainActivity.cs:line 16
   at Android.App.Activity.n_OnCreate_Landroid_os_Bundle_(IntPtr jnienv, IntPtr native__this, IntPtr native_savedInstanceState) in /Users/runner/work/1/s/xamarin-android/src/Mono.Android/obj/Release/net9.0/android-35/mcw/Android.App.Activity.cs:line 3196
   at Android.Runtime.JNINativeWrapper.Wrap_JniMarshal_PPL_V(_JniMarshal_PPL_V callback, IntPtr jnienv, IntPtr klazz, IntPtr p0) in /Users/runner/work/1/s/xamarin-android/src/Mono.Android/Android.Runtime/JNINativeWrapper.g.cs:line 121

[ne0rrmatrix]

Here is an example of how to use media 3 with Maui. https://github.com/CommunityToolkit/Maui/pull/2076

var Player = new ExoPlayerBuilder(Platform.AppContext).Build() ?? throw new InvalidOperationException("Player cannot be null");

Above is how you create an new instance of the player

[bmaluijb]

@ne0rrmatrix Have you tested this with .NET 9? I cannot get it working, just get the exception.

[ne0rrmatrix]

I have tested against dotnet 8 over the last few months. I am currently unable to test using either dotnet 8 or 9 and can't provide any feedback. After updating to dotnet 9 I cannot build anything. Once I get my mac's and pc's working with new dotnet I will see if any changes are needed.

[moljac]

Let me create repro sample for both net9.0 and net8.0, so we can narrow it down.

[moljac]

Archive.zip

Repro:

dotnet build net8.0/media3/media3.csproj -t:run -f:net8.0-android

OK!

dotnet build net9.0/media3/media3.csproj -t:run -f:net9.0-android

Crashes!!!

[ne0rrmatrix]

SDK version needs to be set for dotnet 9. Example:

{
    "sdk": 
    {
        "version": "9.0.100",
        "rollForward": "patch"
    },
    "msbuild-sdks": 
    {
        "MSBuild.Sdk.Extras": "3.0.44",
        "Microsoft.Build.Traversal": "4.1.0",
        "Microsoft.Build.NoTargets": "3.7.56",
        "Xamarin.Legacy.Sdk": "0.2.0-alpha4"
    }
}

Sample builds fine in Debug or Release mode when using current 9.0 version of dotnet from VS 2022 install.

edit: Sample build fine but does crash when app loads.

[moljac]

Sample builds fine in Debug or Release mode when using current 9.0 version of dotnet from VS 2022 install.

Yes. Builds fine, but crashes during running.

[jonpryor]

I believe that this was broken by: https://github.com/dotnet/android/commit/35f41dcc7cf5eb65dc12d7c0a3421e67c2bdb6d6

What I don't understand is why this wasn't caught by existing unit tests, e.g. https://github.com/dotnet/android/blob/70948d5eaa72091389940fdd5a0eb828c85bdd60/tests/Mono.Android-Tests/Java.Interop/JavaObjectExtensionsTests.cs#L38

[moljac]

@ne0rrmatrix

Does your app crash during running [loading]?

Just to be certain

[ne0rrmatrix]

App crashes after launching activity. It also only crashes when exoplayer build() instruction is executed

[ne0rrmatrix]

To be specific it crashes only when executing Build(). If I run

var player = new ExoplayerBuilder(); // App does not crash. Return type is `ExoplayerBuilder`
player.Build(); // App crashes on this line. Return type is `IExoPlayer`

[moljac]

@ne0rrmatrix

Thanks a lot. Did you use repro sample provided in this issue?

Just asking, so other can use it for debugging.

thx

[ne0rrmatrix]

Yes I tried the sample app. It has exact same behavior. I also tested by modifying it like above to try and test if ExoPlayerBuilder was working. It is working for that class. It is only the Build() method that causes the crash.

[jpobst]

Moving this to dotnet/android for better visibility/tracking, as initial investigation appears to be a .NET 9 regression in Java.Interop.

[jonpryor]

@jonpryor wrote:

What I don't understand is why this wasn't caught by existing unit tests, e.g. https://github.com/dotnet/android/blob/70948d5eaa72091389940fdd5a0eb828c85bdd60/tests/Mono.Android-Tests/Java.Interop/JavaObjectExtensionsTests.cs#L38

The answer is that before we try to do anything with *Invoker types, we first try to use an existing binding for the runtime type: https://github.com/dotnet/android/blob/4559426e2ab367e6b153363e0059f128e225f70d/src/Mono.Android/Java.Interop/TypeManager.cs#L246-L264

Because the runtime type is java.lang.Integer, which is bound, we never actually hit the *Invoker codepath.

(The test wasn't testing what I thought it was testing!)

[jonpryor]

For me, media3.zip works on .NET 9 when you build in Release configuration.

[ne0rrmatrix]

I can confirm it works in Release mode in .NET 9. It does not work in Debug mode though.

[jonpryor]

…which brings us to the question: What's Happening™?

Answer: type maps. (Borderline "duh.") Which differ in structure and content between Debug and Release builds.

For reasons I'm still digging into, the Debug config type maps also differ between Mono.Android.dll and other assemblies. The type map for Mono.Android.dll contains duplicate entries for *Invoker types, e.g. from obj/Debug/net9.0-android/android/typemaps.arm64-v8a.ll:

@.TypeMapEntry.17434_from = private unnamed_addr constant [47 x i8] c"Java.Util.Functions.IIntSupplier, Mono.Android\00", align 1
@.TypeMapEntry.17435_to = private unnamed_addr constant [31 x i8] c"java/util/function/IntSupplier\00", align 1
@.TypeMapEntry.17436_from = private unnamed_addr constant [54 x i8] c"Java.Util.Functions.IIntSupplierInvoker, Mono.Android\00", align 1
…
  %struct.TypeMapEntry {
    ptr @.TypeMapEntry.17434_from, ; char* from
    ptr @.TypeMapEntry.17435_to; char* to
  }, ; 9766
  %struct.TypeMapEntry {
    ptr @.TypeMapEntry.17436_from, ; char* from
    ptr @.TypeMapEntry.17435_to; char* to
  }, ; 9767

It does not contain *Invoker entries for other assemblies:

@.TypeMapEntry.13525_from = private unnamed_addr constant [72 x i8] c"AndroidX.Media3.ExoPlayer.IExoPlayer, Xamarin.AndroidX.Media3.ExoPlayer\00", align 1
@.TypeMapEntry.13526_to = private unnamed_addr constant [36 x i8] c"androidx/media3/exoplayer/ExoPlayer\00", align 1
# no entry for IExoPlayerInvoker

though oddly the TypeMapEntry array does have a duplicate! With the same from and to values:

  %struct.TypeMapEntry {                                                        
    ptr @.TypeMapEntry.13525_from, ; char* from
    ptr @.TypeMapEntry.13526_to; char* to
  }, ; 7491
  %struct.TypeMapEntry {
    ptr @.TypeMapEntry.13525_from, ; char* from
    ptr @.TypeMapEntry.13526_to; char* to
  }, ; 7492

Open Questions:

1. What's going on with Release builds that it works?
2. Why does Mono.Android.dll get "duplicates" for *Invoker types while non-Mono.Android.dll assemblies don't?
3. Should the type maps be updated to not contain the duplicates? (Impacts?)

4. (Building upon (2) and (3)): what's the correct fix?

   1. Update type maps so that we reliably have duplicates?

   2. Update type maps so they reliably don't have duplicates, update TypeManager.CreateInstance() to appropriately deal with this (do type map lookup before determining Invoker type)

   3. Leave type maps alone, update TypeManager.CreateInstance() to appropriately deal with this (do type map lookup before determining Invoker type)

[jonpryor]

Still digging, but this appears to be an ordering issue: duplicate detection appears to want the abstract class/interface declaration to appear before the Invoker definition, e.g.:

% monodis --typedef obj/Debug/net9.0-android/android/assets/arm64-v8a/Mono.Android.dll
…
7676: Java.Util.Functions.IIntSupplier (flist=57464, mlist=135763, flags=0x1000a1, extends=0x0)
7677: Java.Util.Functions.IIntSupplierInvoker (flist=57464, mlist=135764, flags=0x100000, extends=0x7d58)

This isn't the case with IExoPlayer:

% monodis --typedef obj/Debug/net9.0-android/android/assets/arm64-v8a/Xamarin.AndroidX.Media3.ExoPlayer.dll | grep IExoPlayer
139: AndroidX.Media3.ExoPlayer.IExoPlayerInvoker (flist=20, mlist=567, flags=0x100000, extends=0x85)
…
166: AndroidX.Media3.ExoPlayer.IExoPlayer (flist=598, mlist=1671, flags=0x1000a1, extends=0x0)

Note that the type definition for IExoPlayerInvoker comes before the definition for IExoPlayer.

This presumably happens because there is an in-tree (non-generated) partial class definition of IExoPlayerInvoker: https://github.com/dotnet/android-libraries/blob/3c21f4643c5dfe74e64fec54e3679baf4dc8d067/source/androidx.media3/media3-exoplayer/Additions/AndroidX.Media3.ExoPlayer.IExoPlayer.cs#L10

(Aside: why is all this generated code checked in?)

The cause of the bug is somewhere within TypeMapGenerator: with tons of extra logging, compare "normal" IIntSupplier (Invoker follows interface):

# jonp: TypeMapGenerator.GenerateDebugNativeAssembly: entry={JavaName=java/util/function/IntSupplier, ManagedName=Java.Util.Functions.IIntSupplier, Mono.Android, SkipInJavaToManaged=True}
# jonp: TypeMapGenerator.GenerateDebugNativeAssembly: entry={JavaName=java/util/function/IntSupplier, ManagedName=Java.Util.Functions.IIntSupplierInvoker, Mono.Android, SkipInJavaToManaged=False}
# jonp: TypeMapGenerator.GenerateDebugNativeAssembly:   java/util/function/IntSupplier:
# jonp: TypeMapGenerator.GenerateDebugNativeAssembly:     TypeMapDebugEntry{JavaName=java/util/function/IntSupplier, ManagedName=Java.Util.Functions.IIntSupplier, Mono.Android, JavaIndex=0, ManagedIndex=0, SkipInJavaToManaged=True, DuplicateForJavaToManaged=}
# jonp: TypeMapGenerator.GenerateDebugNativeAssembly:     TypeMapDebugEntry{JavaName=java/util/function/IntSupplier, ManagedName=Java.Util.Functions.IIntSupplierInvoker, Mono.Android, JavaIndex=0, ManagedIndex=0, SkipInJavaToManaged=False, DuplicateForJavaToManaged=TypeMapDebugEntry{JavaName=java/util/function/IntSupplier, ManagedName=Java.Util.Functions.IIntSupplier, Mono.Android, JavaIndex=0, ManagedIndex=0, SkipInJavaToManaged=True, DuplicateForJavaToManaged=}}

to IExoPlayer:

# jonp: TypeMapGenerator.GenerateDebugNativeAssembly: entry={JavaName=androidx/media3/exoplayer/ExoPlayer, ManagedName=AndroidX.Media3.ExoPlayer.IExoPlayerInvoker, Xamarin.AndroidX.Media3.ExoPlayer, SkipInJavaToManaged=False}
# jonp: TypeMapGenerator.GenerateDebugNativeAssembly: entry={JavaName=androidx/media3/exoplayer/ExoPlayer, ManagedName=AndroidX.Media3.ExoPlayer.IExoPlayer, Xamarin.AndroidX.Media3.ExoPlayer, SkipInJavaToManaged=True}
# jonp: TypeMapGenerator.GenerateDebugNativeAssembly:   androidx/media3/exoplayer/ExoPlayer:
# jonp: TypeMapGenerator.GenerateDebugNativeAssembly:     TypeMapDebugEntry{JavaName=androidx/media3/exoplayer/ExoPlayer, ManagedName=AndroidX.Media3.ExoPlayer.IExoPlayer, Xamarin.AndroidX.Media3.ExoPlayer, JavaIndex=0, ManagedIndex=0, SkipInJavaToManaged=False, DuplicateForJavaToManaged=}
# jonp: TypeMapGenerator.GenerateDebugNativeAssembly:     TypeMapDebugEntry{JavaName=androidx/media3/exoplayer/ExoPlayer, ManagedName=AndroidX.Media3.ExoPlayer.IExoPlayer, Xamarin.AndroidX.Media3.ExoPlayer, JavaIndex=0, ManagedIndex=0, SkipInJavaToManaged=True, DuplicateForJavaToManaged=TypeMapDebugEntry{JavaName=androidx/media3/exoplayer/ExoPlayer, ManagedName=AndroidX.Media3.ExoPlayer.IExoPlayer, Xamarin.AndroidX.Media3.ExoPlayer, JavaIndex=0, ManagedIndex=0, SkipInJavaToManaged=False, DuplicateForJavaToManaged=}}

Note in particular the last two lines, which come from javaDuplicates after the SyncDebugDuplicates(javaDuplicates) call: https://github.com/dotnet/android/blob/78f88633baf99211a2157efbadf072d4981de1b0/src/Xamarin.Android.Build.Tasks/Utilities/TypeMapGenerator.cs#L267

With IExoPlayer, IExoPlayerInvoker isn't mentioned at all within javaDuplicates. Why?

[jonpryor]

The bug appears to be within HandleDuplicates(): https://github.com/dotnet/android/blob/78f88633baf99211a2157efbadf072d4981de1b0/src/Xamarin.Android.Build.Tasks/Utilities/TypeMapGenerator.cs#L301-L317

@@ -309,8 +335,11 @@ namespace Xamarin.Android.Tasks
                                TypeMapDebugEntry oldEntry = duplicates[0];
                                if (td.IsAbstract || td.IsInterface || oldEntry.TypeDefinition.IsAbstract || oldEntry.TypeDefinition.IsInterface) {
                                        if (td.IsAssignableFrom (oldEntry.TypeDefinition, cache)) {
+                                               log.LogDebugMessage ($"# jonp: !!! {td.FullName} IsAssignableFrom {oldEntry.TypeDefinition.FullName}");
+                                               log.LogDebugMessage ($"# jonp: !!! entry={oldEntry}");
                                                oldEntry.TypeDefinition = td;
                                                oldEntry.ManagedName = GetManagedTypeName (td);
+                                               log.LogDebugMessage ($"# jonp: !!! updated entry={oldEntry}");
                                        }
                                }
                        }

prints the following log messages:

# jonp: !!! AndroidX.Media3.ExoPlayer.IExoPlayer IsAssignableFrom AndroidX.Media3.ExoPlayer.IExoPlayerInvoker
# jonp: !!! entry=TypeMapDebugEntry{JavaName=androidx/media3/exoplayer/ExoPlayer, ManagedName=AndroidX.Media3.ExoPlayer.IExoPlayerInvoker, Xamarin.AndroidX.Media3.ExoPlayer, JavaIndex=0, ManagedIndex=0, SkipInJavaToManaged=False, DuplicateForJavaToManaged=}
# jonp: !!! updated entry=TypeMapDebugEntry{JavaName=androidx/media3/exoplayer/ExoPlayer, ManagedName=AndroidX.Media3.ExoPlayer.IExoPlayer, Xamarin.AndroidX.Media3.ExoPlayer, JavaIndex=0, ManagedIndex=0, SkipInJavaToManaged=False, DuplicateForJavaToManaged=}

IExoPlayerInvoker is "'removed".

Within the repro, there are two other types that trigger the above message::

# jonp: !!! Kotlin.Collections.AbstractList IsAssignableFrom Kotlin.Collections.AbstractListInvoker
# jonp: !!! Kotlin.Collections.AbstractSet IsAssignableFrom Kotlin.Collections.AbstractSetInvoker

Unsurprisingly, those also have partial class declarations within dotnet/android-libraries…

[jonpryor]

@grendello: what's the rationale for this code?

https://github.com/dotnet/android/blob/78f88633baf99211a2157efbadf072d4981de1b0/src/Xamarin.Android.Build.Tasks/Utilities/TypeMapGenerator.cs#L309-L315

If I remove that code -- such that the else block is just duplicates.Add(entry) -- then the app builds and runs without a crash.

[jonpryor]

Commit a017561b1e44c51a9af79fae0baaa50fe01c4123 appears to have added the HandleDebugDuplicates() logic. I think this is the explanation:

Update typemap generation code in Xamarin.Android.Build.Tasks.dll so that all the duplicate Java type names will point to the same managed type name. Additionally, make sure we select the managed type in the same fashion the old typemap generator in Java.Interop worked: prefer base types to the derived ones if the type is an interface or an abstract class. The effect of this change is that no matter which entry EmbeddedAssemblies::binary_search() ends up selecting it will always return the same managed type name for all aliased Java types.

[jonpryor]

@jonpryor wrote:

If I remove that code -- such that the else block is just duplicates.Add(entry) -- then the app builds and runs without a crash.

It might not crash, but it's also not right either. From obj/Debug/net9.0-android/android/typemaps.arm64-v8a.ll:

@map_java_to_managed = internal dso_local constant [12070 x %struct.TypeMapEntry] [
    …
    %struct.TypeMapEntry {
        ptr @.TypeMapEntry.13528_to, ; char* from
        ptr @.TypeMapEntry.13540_from; char* to
    }, ; 6921
    %struct.TypeMapEntry {
        ptr @.TypeMapEntry.13528_to, ; char* from
        ptr @.TypeMapEntry.13540_from; char* to
    }, ; 6922
…
@.TypeMapEntry.13527_from = private unnamed_addr constant [72 x i8] c"AndroidX.Media3.ExoPlayer.IExoPlayer, Xamarin.AndroidX.Media3.ExoPlayer\00", align 1
@.TypeMapEntry.13528_to = private unnamed_addr constant [36 x i8] c"androidx/media3/exoplayer/ExoPlayer\00", align 1
…
@.TypeMapEntry.13540_from = private unnamed_addr constant [79 x i8] c"AndroidX.Media3.ExoPlayer.IExoPlayerInvoker, Xamarin.AndroidX.Media3.ExoPlayer\00", align 1

The first entry should be 13527_from, not 13540_from. As-is, there is no entry for IExoPlayer!

[jonpryor]

@grendello: my current attempted fix is:

diff --git a/src/Xamarin.Android.Build.Tasks/Utilities/TypeMapGenerator.cs b/src/Xamarin.Android.Build.Tasks/Utilities/TypeMapGenerator.cs
index a6dbce277..91b552af3 100644
--- a/src/Xamarin.Android.Build.Tasks/Utilities/TypeMapGenerator.cs
+++ b/src/Xamarin.Android.Build.Tasks/Utilities/TypeMapGenerator.cs
@@ -77,6 +77,11 @@ namespace Xamarin.Android.Tasks
            public TypeDefinition TypeDefinition;
            public bool SkipInJavaToManaged;
            public TypeMapDebugEntry DuplicateForJavaToManaged;
+
+           public override string ToString ()
+           {
+               return $"TypeMapDebugEntry{{JavaName={JavaName}, ManagedName={ManagedName}, JavaIndex={JavaIndex}, ManagedIndex={ManagedIndex}, SkipInJavaToManaged={SkipInJavaToManaged}, DuplicateForJavaToManaged={DuplicateForJavaToManaged}}}";
+           }
        }

        // Widths include the terminating nul character but not the padding!
@@ -170,6 +175,7 @@ namespace Xamarin.Android.Tasks

        bool GenerateDebug (bool skipJniAddNativeMethodRegistrationAttributeScan, string outputDirectory, bool generateNativeAssembly)
        {
+           log.LogDebugMessage ($"# jonp: TypeMapGenerator.GenerateDebug: generateNativeAssembly: {generateNativeAssembly}");
            if (generateNativeAssembly) {
                return GenerateDebugNativeAssembly (skipJniAddNativeMethodRegistrationAttributeScan, outputDirectory);
            }
@@ -192,11 +198,13 @@ namespace Xamarin.Android.Tasks

            var javaDuplicates = new Dictionary<string, List<TypeMapDebugEntry>> (StringComparer.Ordinal);
            foreach (TypeDefinition td in state.AllJavaTypes) {
+               log.LogDebugMessage ($"# jonp: TypeMapGenerator.GenerateDebugFiles: td={td.FullName}");
                UpdateApplicationConfig (td);
                string moduleName = td.Module.Assembly.Name.Name;
                ModuleDebugData module;

                if (!modules.TryGetValue (moduleName, out module)) {
+                   log.LogDebugMessage ($"# jonp: TypeMapGenerator.GenerateDebugFiles: adding new module: {moduleName}");
                    string outputFileName = $"{moduleName}{TypemapExtension}";
                    module = new ModuleDebugData {
                        EntryCount = 0,
@@ -219,6 +227,8 @@ namespace Xamarin.Android.Tasks
                }

                TypeMapDebugEntry entry = GetDebugEntry (td, state.TypeCache);
+               log.LogDebugMessage ($"# jonp: TypeMapGenerator.GenerateDebugFiles: entry={{JavaName={entry.JavaName}, ManagedName={entry.ManagedName}, SkipInJavaToManaged={entry.SkipInJavaToManaged}}}");
+
                HandleDebugDuplicates (javaDuplicates, entry, td, state.TypeCache);
                if (entry.JavaName.Length > module.JavaNameWidth)
                    module.JavaNameWidth = (uint)entry.JavaName.Length + 1;
@@ -230,6 +240,13 @@ namespace Xamarin.Android.Tasks
                module.ManagedToJavaMap.Add (entry);
            }
            SyncDebugDuplicates (javaDuplicates);
+           log.LogDebugMessage ($"# jonp: TypeMapGenerator.GenerateDebugFiles: javaDuplicates:");
+           foreach (var e in javaDuplicates) {
+               log.LogDebugMessage ($"# jonp: TypeMapGenerator.GenerateDebugFiles:   {e.Key}:");
+               foreach (var entry in e.Value) {
+                   log.LogDebugMessage ($"# jonp: TypeMapGenerator.GenerateDebugFiles:     {entry}");
+               }
+           }

            foreach (ModuleDebugData module in modules.Values) {
                PrepareDebugMaps (module);
@@ -251,6 +268,7 @@ namespace Xamarin.Android.Tasks

        bool GenerateDebugNativeAssembly (bool skipJniAddNativeMethodRegistrationAttributeScan, string outputDirectory)
        {
+           log.LogDebugMessage ($"# jonp: TypeMapGenerator.GenerateDebugNativeAssembly");
            var javaToManaged = new List<TypeMapDebugEntry> ();
            var managedToJava = new List<TypeMapDebugEntry> ();

@@ -259,12 +277,20 @@ namespace Xamarin.Android.Tasks
                UpdateApplicationConfig (td);

                TypeMapDebugEntry entry = GetDebugEntry (td, state.TypeCache);
+               log.LogDebugMessage ($"# jonp: TypeMapGenerator.GenerateDebugNativeAssembly: entry={{JavaName={entry.JavaName}, ManagedName={entry.ManagedName}, SkipInJavaToManaged={entry.SkipInJavaToManaged}}}");
                HandleDebugDuplicates (javaDuplicates, entry, td, state.TypeCache);

                javaToManaged.Add (entry);
                managedToJava.Add (entry);
            }
            SyncDebugDuplicates (javaDuplicates);
+           log.LogDebugMessage ($"# jonp: TypeMapGenerator.GenerateDebugNativeAssembly: javaDuplicates:");
+           foreach (var e in javaDuplicates) {
+               log.LogDebugMessage ($"# jonp: TypeMapGenerator.GenerateDebugNativeAssembly:   Java type: {e.Key}:");
+               foreach (var entry in e.Value) {
+                   log.LogDebugMessage ($"# jonp: TypeMapGenerator.GenerateDebugNativeAssembly:     {entry}");
+               }
+           }

            var data = new ModuleDebugData {
                EntryCount = (uint)javaToManaged.Count,
@@ -305,14 +331,30 @@ namespace Xamarin.Android.Tasks
            if (!javaDuplicates.TryGetValue (entry.JavaName, out duplicates)) {
                javaDuplicates.Add (entry.JavaName, new List<TypeMapDebugEntry> { entry });
            } else {
-               duplicates.Add (entry);
                TypeMapDebugEntry oldEntry = duplicates[0];
+               if ((td.IsAbstract || td.IsInterface) &&
+                       !oldEntry.TypeDefinition.IsAbstract &&
+                       !oldEntry.TypeDefinition.IsInterface &&
+                       td.IsAssignableFrom (oldEntry.TypeDefinition, cache)) {
+                   // We found the `Invoker` type *before* the declared type
+                   // Fix things up so the abstract type is first, and the `Invoker` is considered a duplicate.
+                   duplicates.Insert (0, entry);
+                   oldEntry.SkipInJavaToManaged = false;
+               } else {
+                   // ¯\_(ツ)_/¯
+                   duplicates.Add (entry);
+               }
+               #if false
                if (td.IsAbstract || td.IsInterface || oldEntry.TypeDefinition.IsAbstract || oldEntry.TypeDefinition.IsInterface) {
                    if (td.IsAssignableFrom (oldEntry.TypeDefinition, cache)) {
+                       log.LogDebugMessage ($"# jonp: !!! {td.FullName} IsAssignableFrom {oldEntry.TypeDefinition.FullName}");
+                       log.LogDebugMessage ($"# jonp: !!! entry={oldEntry}");
                        oldEntry.TypeDefinition = td;
                        oldEntry.ManagedName = GetManagedTypeName (td);
+                       log.LogDebugMessage ($"# jonp: !!! updated entry={oldEntry}");
                    }
                }
+               #endif
            }
        }

The good news is that this appears to work.

The bad news is that despite working, the resulting typemaps.arm64-v8a.ll doesn't look right at all:

@map_managed_to_java = internal dso_local constant [12070 x %struct.TypeMapEntry] [
    …
    %struct.TypeMapEntry {
        ptr @.TypeMapEntry.13527_from, ; char* from
        ptr @.TypeMapEntry.13528_to; char* to
    }, ; 7491
    …
    %struct.TypeMapEntry {
        ptr @.TypeMapEntry.13540_from, ; char* from
        ptr @.TypeMapEntry.13528_to; char* to
    }, ; 7499
    …
], align 8

@map_java_to_managed = internal dso_local constant [12070 x %struct.TypeMapEntry] [
    …
    %struct.TypeMapEntry {
        ptr @.TypeMapEntry.13528_to, ; char* from
        ptr null; char* to
    }, ; 6921
    %struct.TypeMapEntry {
        ptr @.TypeMapEntry.13528_to, ; char* from
        ptr null; char* to
    }, ; 6922
    …
], align 8

@.TypeMapEntry.13527_from = private unnamed_addr constant [72 x i8] c"AndroidX.Media3.ExoPlayer.IExoPlayer, Xamarin.AndroidX.Media3.ExoPlayer\00", align 1
@.TypeMapEntry.13528_to = private unnamed_addr constant [36 x i8] c"androidx/media3/exoplayer/ExoPlayer\00", align 1
…
@.TypeMapEntry.13540_from = private unnamed_addr constant [79 x i8] c"AndroidX.Media3.ExoPlayer.IExoPlayerInvoker, Xamarin.AndroidX.Media3.ExoPlayer\00", align 1

The map_managed_to_java entries look correct.

The map_java_to_managed entries confuse me, mapping 13528_to (androidx/media3/exoplayer/ExoPlayer) to null?!

But this appears to be what .NET 9 GA does with IIntSupplier, so maybe that's fine?