[Bug] Unable to compile latest version from source for unix systems.

[xiangzhi]

I was trying to compile the source code from scratch when I ran into the following build error:

Welcome to .NET Core 3.1!
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SDK Version: 3.1.410

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  Determining projects to restore...
  Restored /home/xiangzht/Dev/csharp/psi/Sources/Runtime/Microsoft.Psi/Microsoft.Psi.csproj (in 1.28 sec).
  Assembling 'IL/MemoryAccess.il' , no listing file, to dll --> 'bin/Debug/netstandard2.0/Microsoft.Psi.IL.dll'

  Operation completed successfully
Data/Importer.cs(111,68): error CS8652: The feature 'not pattern' is currently in Preview and *unsupported*. To use Preview features, use the 'preview' language version. [/home/xiangzht/Dev/csharp/psi/Sources/Runtime/Microsoft.Psi/Microsoft.Psi.csproj]
Data/Importer.cs(273,72): error CS8652: The feature 'not pattern' is currently in Preview and *unsupported*. To use Preview features, use the 'preview' language version. [/home/xiangzht/Dev/csharp/psi/Sources/Runtime/Microsoft.Psi/Microsoft.Psi.csproj]
Data/Importer.cs(369,42): error CS8652: The feature 'not pattern' is currently in Preview and *unsupported*. To use Preview features, use the 'preview' language version. [/home/xiangzht/Dev/csharp/psi/Sources/Runtime/Microsoft.Psi/Microsoft.Psi.csproj]
Data/Importer.cs(386,42): error CS8652: The feature 'not pattern' is currently in Preview and *unsupported*. To use Preview features, use the 'preview' language version. [/home/xiangzht/Dev/csharp/psi/Sources/Runtime/Microsoft.Psi/Microsoft.Psi.csproj]

Build FAILED.

Data/Importer.cs(111,68): error CS8652: The feature 'not pattern' is currently in Preview and *unsupported*. To use Preview features, use the 'preview' language version. [/home/xiangzht/Dev/csharp/psi/Sources/Runtime/Microsoft.Psi/Microsoft.Psi.csproj]
Data/Importer.cs(273,72): error CS8652: The feature 'not pattern' is currently in Preview and *unsupported*. To use Preview features, use the 'preview' language version. [/home/xiangzht/Dev/csharp/psi/Sources/Runtime/Microsoft.Psi/Microsoft.Psi.csproj]
Data/Importer.cs(369,42): error CS8652: The feature 'not pattern' is currently in Preview and *unsupported*. To use Preview features, use the 'preview' language version. [/home/xiangzht/Dev/csharp/psi/Sources/Runtime/Microsoft.Psi/Microsoft.Psi.csproj]
Data/Importer.cs(386,42): error CS8652: The feature 'not pattern' is currently in Preview and *unsupported*. To use Preview features, use the 'preview' language version. [/home/xiangzht/Dev/csharp/psi/Sources/Runtime/Microsoft.Psi/Microsoft.Psi.csproj]
    0 Warning(s)
    4 Error(s)

Time Elapsed 00:00:02.45

I actually started on a Mac system but the print out above came from a 20.04 Ubuntu System. The error seemed to be coming from the usage is not pattern in Microsoft.Psi.Data.Importer.cs that was added in the latest version.

if (this.streamReader.GetStreamMetadata(streamName) is not PsiStreamMetadata psiStreamMetadata)

As far as I can tell the is not pattern was only included in C# 9.0 which is not part of .NET standard 2.0. I'm not sure why it didn't throw an error on Windows machines.

[xiangzhi]

Upon more testing, the compiling would work if I have the dotnet-sdk-5.0 sdk installed. I'm still puzzled by the fact that we can set a package as netstandard2.0 but use C# 9 features.

[chitsaw]

Ah, that's because C# 9 is a language (compiler) feature which you get when you install the new .NET5 SDK, but that is independent of the framework you're targeting (e.g. netstandard2.0).

[xiangzhi]

Make sense! I guess we should edit the wiki/readme to change it to .NET5 SDK :)

[chitsaw]

Make sense! I guess we should edit the wiki/readme to change it to .NET5 SDK :)

Done!