Enable implicit RID with `--sc`

[richlander]

The new --sc syntax works for self-contained apps, per #19681.

It still requires a RID. Let's enable it to work with the implicit SDK RID so that we don't create a breaking change in .NET 7. This argument is new. It also will enable users to get around the new warning with -r.

This change is some really nice fit-and-finish for .NET 6. This behavior is the original intent of #19576.

This is the behavior with RC2.

rich@MacBook-Air-M1-2020 app % dotnet build --sc
Microsoft (R) Build Engine version 17.0.0-preview-21470-01+cb055d28f for .NET
Copyright (C) Microsoft Corporation. All rights reserved.

  Determining projects to restore...
  All projects are up-to-date for restore.
/usr/local/share/dotnet/sdk/6.0.100-rc.2.21473.35/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.RuntimeIdentifierInference.targets(150,5): error NETSDK1031: It is not supported to build or publish a self-contained application without specifying a RuntimeIdentifier. You must either specify a RuntimeIdentifier or set SelfContained to false. [/Users/rich/app/app.csproj]

Build FAILED.

/usr/local/share/dotnet/sdk/6.0.100-rc.2.21473.35/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.RuntimeIdentifierInference.targets(150,5): error NETSDK1031: It is not supported to build or publish a self-contained application without specifying a RuntimeIdentifier. You must either specify a RuntimeIdentifier or set SelfContained to false. [/Users/rich/app/app.csproj]
    0 Warning(s)
    1 Error(s)

Time Elapsed 00:00:02.03
rich@MacBook-Air-M1-2020 app % dotnet build --sc -r osx-arm64
Microsoft (R) Build Engine version 17.0.0-preview-21470-01+cb055d28f for .NET
Copyright (C) Microsoft Corporation. All rights reserved.

  Determining projects to restore...
  Restored /Users/rich/app/app.csproj (in 180 ms).
  You are using a preview version of .NET. See: https://aka.ms/dotnet-core-preview
  app -> /Users/rich/app/bin/Debug/net6.0/osx-arm64/app.dll

Build succeeded.
    0 Warning(s)
    0 Error(s)

Time Elapsed 00:00:06.09

[marcpopMSFT]

@richlander I moved this to 6.0.2xx since we're closing down on 1xx. I don't see it as a breaking change to enable this in 2xx since it's loosening the limitations of the CLI. Let me know if you disagree.

[richlander]

It'd be really nice to get this in .100 to make it easier for folks to deal with NETSDK1179. They go together very nicely.

We're also not done with NET1179 #21560

That said, if we cannot make it, .200 is fine. Yes, you are right. It isn't breaking. I was wrong about that.

[sfoslund]

@richlander looking at this more closely, the error you're seeing here is NETSDK1031, not NETSDK1179.

We plan on enabling implicit RIDs for the --self-contained option in .NET 7 anyway, right? So this issue is asking to enable it in 6.0.2xx for only the shorthand version of the option (--sc) and not the longhand (--self-contained)? I think this would be very confusing behavior, since it would be the only option in our entire CLI for which we have different behavior depending on if the short or longhand version of the option is used.

Further, the actual change to enable implicit RIDs will be simple if we're not differentiating between the long and shorthand options, but it would get significantly more complex to only have this behavior for the shorthand option.

[richlander]

Fair enough. Let's make the change in .NET 7 as you say. I changed the milestone.