AOT+LLVM throws for `Enum.GetUnderlyingType()` on Android in .NET 7

[jonathanpeppers]

Description

Our Mono.Android-Tests project crashes on startup with:

05-05 15:19:34.429  4929  4929 F mono-rt : [ERROR] FATAL UNHANDLED EXCEPTION: System.ArgumentException: Type provided must be an Enum. Arg_ParamName_Name, enumType
05-05 15:19:34.429  4929  4929 F mono-rt :    at System.Enum.InternalGetUnderlyingType(RuntimeType enumType)
05-05 15:19:34.429  4929  4929 F mono-rt :    at System.RuntimeType.GetEnumUnderlyingType()
05-05 15:19:34.429  4929  4929 F mono-rt :    at System.Enum.GetUnderlyingType(Type enumType)
05-05 15:19:34.429  4929  4929 F mono-rt :    at Java.Interop.JniRuntime.JniTypeManager.GetUnderlyingType(Type , Int32& )
05-05 15:19:34.429  4929  4929 F mono-rt :    at Java.Interop.JniRuntime.JniTypeManager.GetTypeSignature(Type )
05-05 15:19:34.429  4929  4929 F mono-rt :    at Java.Interop.JniPeerMembers.JniInstanceMethods..ctor(Type )
05-05 15:19:34.429  4929  4929 F mono-rt :    at Java.Interop.JniPeerMembers.JniInstanceMethods.GetConstructorsForType(Type )
05-05 15:19:34.429  4929  4929 F mono-rt :    at Java.Interop.JniPeerMembers.JniInstanceMethods.StartCreateInstance(String , Type , JniArgumentValue* )
05-05 15:19:34.429  4929  4929 F mono-rt :    at Java.Lang.Error..ctor(String )
05-05 15:19:34.429  4929  4929 F mono-rt :    at Android.Runtime.JavaProxyThrowable..ctor(Exception )
05-05 15:19:34.429  4929  4929 F mono-rt :    at Java.Lang.Throwable.FromException(Exception )
05-05 15:19:34.429  4929  4929 F mono-rt :    at Android.Runtime.AndroidEnvironment.UnhandledException(Exception e)
05-05 15:19:34.429  4929  4929 F mono-rt :    at Android.Runtime.JNINativeWrapper.Wrap_JniMarshal_PPL_V(_JniMarshal_PPL_V , IntPtr , IntPtr , IntPtr )

This looks oddly familiar to a related issue in mono/mono: dotnet/android#1842

Looking at the underlying code, I think it throws here:

https://github.com/xamarin/java.interop/blob/61cdb40dcc8b33d400aef3fd12e0aeee72f71e35/src/Java.Interop/Java.Interop/JniRuntime.JniTypeManager.cs#L151-L152

Reproduction Steps

Build a .NET 7 Release app with -p:EnableLLVM=true.

Expected behavior

Use of -p:EnableLLVM=true on Android doesn't crash on startup.

Actual behavior

Use of -p:EnableLLVM=true crashes on startup on Android.

Regression?

This project appears to be working in .NET 6.

Known Workarounds

Disable LLVM.

Configuration

.NET 7.0.100-preview.4.22174.1 c7afae6936bf80239aa93bfd3b6f68513d9876d4
.NET runtime 7.0.0-preview.4.22172.7 c5d40c9

Other information

No response

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[steveisok]

/cc @SamMonoRT

[SamMonoRT]

cc @vargaz - please can you take a look.
@jonathanpeppers - do we need any related fix backported for MAUI release ?

[jonathanpeppers]

@SamMonoRT this issue is only happening in .NET 7.

It looks like the same test is passing in .NET 6.

[vargaz]

Which type is passed to the method ?

[jonpryor]

What's "odd" about this stack trace is that it makes no sense.

It starts with the JavaProxyThrowable constructor, which chains to the Java.Lang.Error constructor, which does:

var __r = _members.InstanceMethods.StartCreateInstance (__id, ((object) this).GetType (), __args);

i.e. the System.Type instance will be typeof(JavaProxyThrowable).

We then hit JniPeerMembers.JniInstanceMethods.StartCreateInstance(): https://github.com/xamarin/java.interop/blob/3fcce7466324c6564874fe275eac222a8970078c/src/Java.Interop/Java.Interop/JniPeerMembers.JniInstanceMethods.cs#L97-L112

which calls GetConstructorsForType(): https://github.com/xamarin/java.interop/blob/3fcce7466324c6564874fe275eac222a8970078c/src/Java.Interop/Java.Interop/JniPeerMembers.JniInstanceMethods.cs#L70-L82

• declaringType is typeof(JavaProxyThrowable).
• DeclaringType is typeof(Error)
• We thus hit new JniInstanceMethods(typeof(JavaProxyThrowable))

This brings us to the JniInstaceMethods(Type) constructor: https://github.com/xamarin/java.interop/blob/3fcce7466324c6564874fe275eac222a8970078c/src/Java.Interop/Java.Interop/JniPeerMembers.JniInstanceMethods.cs#L17-L29

Which calls GetTypeSignature(typeof(JavaProxyThrowable)): https://github.com/xamarin/java.interop/blob/3fcce7466324c6564874fe275eac222a8970078c/src/Java.Interop/Java.Interop/JniRuntime.JniTypeManager.cs#L51

Which calls GetUnderlyingType(typeof(JavaProxyThrowable), out int _): https://github.com/xamarin/java.interop/blob/3fcce7466324c6564874fe275eac222a8970078c/src/Java.Interop/Java.Interop/JniRuntime.JniTypeManager.cs#L140-L155

Which is where things make no sense: statically, we know type is typeof(JavaProxyThrowable), yet here:

https://github.com/xamarin/java.interop/blob/3fcce7466324c6564874fe275eac222a8970078c/src/Java.Interop/Java.Interop/JniRuntime.JniTypeManager.cs#L151-L152

typeof(JavaProxyThrowable).IsEnum must be true in order for us to hit Enum.GetUnderlyingType(typeof(JavaProxyThrowable)), but it shouldn't be true!

Thus, throwing the ArgumentException is correct behavior.

The bug is that typeof(JavaProxyThrowable).IsEnum is true when it should be false!

(Or AOT+LLVM inlining mumble something?)

[jonathanpeppers]

I made some smaller repros here, building xamarin-android/main. I used dotnet new android, and set -p:AndroidPackageFormat=apk, -p:AndroidUseAssemblyStore=false, and -p:AndroidEnableAssemblyCompression=false, to simplify things and make the IL readable if needed.

-p:EnableLLVM=false, these launch successfully:

• -r android-arm64: aot-nollvm-arm64.zip
• -r android-x64: aot-nollvm-x64.zip

-p:EnableLLVM=true, these fail:

• -r android-arm64: aot-llvm-arm64.zip

(this one might be a different issue, it has a different crash)

• -r android-x64: aot-llvm-x64.zip

I added more logging in xamarin-android to see the exception:

05-12 11:42:37.629  2490  2490 I MonoDroid: Android.Runtime.JavaProxyThrowable: Exception_WasThrown, Android.Runtime.JavaProxyThrowable
05-12 11:42:37.629  2490  2490 I MonoDroid:   --- End of managed Android.Runtime.JavaProxyThrowable stack trace ---
05-12 11:42:37.629  2490  2490 I MonoDroid: android.runtime.JavaProxyThrowable: System.NotSupportedException: Unable to activate instance of type foo.MainActivity from native handle 0x7ffd8e98a214 (key_handle 0x18e6dce).
05-12 11:42:37.629  2490  2490 I MonoDroid:  ---> System.MissingMethodException: No constructor found for foo.MainActivity::.ctor(System.IntPtr, Android.Runtime.JniHandleOwnership)
05-12 11:42:37.630  2490  2490 I MonoDroid:  ---> Java.Interop.JavaLocationException: Exception_WasThrown, Java.Interop.JavaLocationException

We believe that Type.IsInterface and Type.IsEnum might be returning values wrong for types.

[vargaz]

Which aotprofile file is used to AOT these apps ?

[jonathanpeppers]

It is this one, which was recorded using .NET 6:

https://github.com/xamarin/xamarin-android/blob/b250c04b09a2b725336ae6d6c5693e0b9f37e4cc/src/Xamarin.Android.Build.Tasks/dotnet.aotprofile

Working on another one, but it looks like I have to build a newer libmono-profiler-aot.so.