Description
I am not completely sure if this is related to Nullable. Nullable could be special if there was boxing, but this is just a local variable losing its value after Yield. No boxing is involved in this case.
Possibly it is a more general issue with liveness/storing/restoring of mixed value/ref fields of a struct, just a repro happened to involve nullable.
== To repro:
In shared-generics.cs uncomment 2 scenarios marked with
// TODO: uncomment to repro https://github.com/dotnet/runtimelab/issues/3043 and run the test.
The test will fail. It looks like we lose the value here:
public static async2 Task<T> StaticReturnClassType(T value)
{
// value != null
await Task.Yield();
// value == null
return value;
}Also, I think, while modifying the test with Console.WriteLine(value) in various places to see where exactly the value is lost, I think I have seen the scenario to pass, but lost track to what shape the test was and can't make it pass again. There is a thought that we may be dealing with uninitialized data, maybe...