UnmanagedCallersOnly test failing in the outerloop during compilation

[janvorli]

The issue seems to be due to some C# compiler update - the failures seem to be at places of negative testing that expects runtime failures, but we started to get compilation failures instead.

/__w/1/s/src/tests/Interop/UnmanagedCallersOnly/UnmanagedCallersOnlyTest.cs(341,6): error CS8896: 'UnmanagedCallersOnly' can only be applied to ordinary static methods or static local functions. [/__w/1/s/src/tests/Interop/UnmanagedCallersOnly/UnmanagedCallersOnlyTest.csproj]
##[error]src/tests/Interop/UnmanagedCallersOnly/UnmanagedCallersOnlyTest.cs(341,6): error CS8896: 'UnmanagedCallersOnly' can only be applied to ordinary static methods or static local functions.
/__w/1/s/src/tests/Interop/UnmanagedCallersOnly/UnmanagedCallersOnlyTest.cs(439,6): error CS8895: Methods attributed with 'UnmanagedCallersOnly' cannot have generic type parameters and cannot be declared in a generic type. [/__w/1/s/src/tests/Interop/UnmanagedCallersOnly/UnmanagedCallersOnlyTest.csproj]
##[error]src/tests/Interop/UnmanagedCallersOnly/UnmanagedCallersOnlyTest.cs(439,6): error CS8895: Methods attributed with 'UnmanagedCallersOnly' cannot have generic type parameters and cannot be declared in a generic type.
/__w/1/s/src/tests/Interop/UnmanagedCallersOnly/UnmanagedCallersOnlyTest.cs(440,48): error CS8894: Cannot use 'T' as a parameter type on a method attributed with 'UnmanagedCallersOnly'. [/__w/1/s/src/tests/Interop/UnmanagedCallersOnly/UnmanagedCallersOnlyTest.csproj]
##[error]src/tests/Interop/UnmanagedCallersOnly/UnmanagedCallersOnlyTest.cs(440,48): error CS8894: Cannot use 'T' as a parameter type on a method attributed with 'UnmanagedCallersOnly'.
/__w/1/s/src/tests/Interop/UnmanagedCallersOnly/UnmanagedCallersOnlyTest.cs(520,10): error CS8895: Methods attributed with 'UnmanagedCallersOnly' cannot have generic type parameters and cannot be declared in a generic type. [/__w/1/s/src/tests/Interop/UnmanagedCallersOnly/UnmanagedCallersOnlyTest.csproj]
##[error]src/tests/Interop/UnmanagedCallersOnly/UnmanagedCallersOnlyTest.cs(520,10): error CS8895: Methods attributed with 'UnmanagedCallersOnly' cannot have generic type parameters and cannot be declared in a generic type.

Log here:
https://dev.azure.com/dnceng/public/_build/results?buildId=811186&view=logs&j=db768a9e-3325-5ce3-2d52-896c40bee68a&t=59112ad9-fe58-56ee-6943-84df6f0e3f8e&l=13792

[am11]

It would probably save some time if outerloop legs are auto triggered in the PR, which is changing global.json.

csc(1) errors out in this case since dotnet/roslyn#47008, maybe we can convert these (now)invalid methods into IL and continue to test the scenario.

[jkoritzinsky]

I’m going to bring this up in the interop sync today so we can decide what we want to do.

[jkoritzinsky]

cc: @AaronRobinsonMSFT @elinor-fung

[AaronRobinsonMSFT]

Boo, but yay? Proves that the compiler is doing its job. I should be able to push up a PR later today with this fixed in the main branch. The plan of record is to move the non-C# friendly code to IL so the failure cases can be tested.