[WASM][.NET 7] AOT crashes on startup

[DierkDroth]

Current behavior

I'm experiencing a crash when tring to start the WASM AOT version of my app (logs and image below). Interpreter works no problem.
As per the app's trace output it definitely starts working, but then suddenly crashes.

I would think creating a repo would be close to impossible other than trying 'the real thing'. This is latest UNO dev bits

I don't even know where to start looking...

stage.unusual-suite.com-1669702268500.zip

Expected behavior

AOT should not crash

How to reproduce it (as minimally and precisely as possible)

No response

Workaround

No response

Works on UWP/WinUI

Yes

Environment

Uno.UI / Uno.UI.WebAssembly / Uno.UI.Skia

NuGet package version(s)

No response

Affected platforms

WebAssembly

IDE

No response

IDE version

No response

Relevant plugins

No response

Anything else we need to know?

No response

[jeromelaban]

Thanks for the report.

This is a .NET runtime error that we cannot fix ourselves.

In order to open an issue there, you'll need to create a trimmed down repro and to help determine the source, you can enable the profiling information with WasmShellEnableEmccProfiling to show more of the stack trace.

[DierkDroth]

@jeromelaban thanks. Oh boy, this worries me a lot.

Is there a way to actually debug an uploaded AOT build?
Other than that I conly could apply 'printfs', wait for the next build (> 45 mins) and see what happens... not fun

[jeromelaban]

There isn't anything other than WasmShellEnableEmccProfiling and Console.WriteLine at this time.

[DierkDroth]

@jeromelaban I'm trying to nail it down by a series of adding 'printfs' + rebuild + test.

I'm close to a point where I believe it's related to threading. I recall UNO recently announced threading support for WASM.

Is there a way I could turn WASM threading support on/off to further isolate the issue?

[jeromelaban]

If you have a stack trace with WasmShellEnableEmccProfiling please post it here. About threading, it's not enabled by default.

[DierkDroth]

@jeromelaban ok, I'm now sure it has to do with thread handling. The statement where is crashes basically looks like this:
(string, object) result = await TaskCompletionSource<(string, object)>.Task;

I'll get you the traces as I'm able to produce them...

[jeromelaban]

Neither await nor TaskCompletionSource have a direct link to threading being enabled in the runtime. It may simply be an issue with templates.

Make sure to post the stack trace of the crash.

[DierkDroth]

@jeromelaban I don't think this worked as you expected it, since it didn't even make is that far with a new build + switches from above.

Nevertheless here are the logs
stage.unusual-suite.com-1669751868374.zip

[jeromelaban]

Thanks. It looks like switches were not enabled properly. You need to set:

<PropertyGroup>
   <WasmShellEnableEmccProfiling>true</WasmShellEnableEmccProfiling>
</PropertyGroup>

to get a meaningful trace. You'll otherwise get traces with at dotnet.wasm:0xbc030 that can't be analyzed.

[DierkDroth]

Thanks @jeromelaban. Here are new logs

stage.unusual-suite.com-1669785525984.zip

[jeromelaban]

Thanks. This looks like this is indeed related to generics. Which version of the uno.wasm.bootstrapper package are you using?

[DierkDroth]

Thanks for looking into, @jeromelaban. Please see screenshot below