Building a 5.0 app with 6.0 SDK in VS 2019 causes analyzers to fail to load

[pranavkm]

MVC and StartupAnalyzer are shipped as part of the SDK and target every version of .NET 3.1 onwards. These analyzers have been updated to reference Microsoft.CodeAnalysis versions 4.0.0.0 which isn't available on VS 2019. Consequently opening a 5.0 project with a 6.0 SDK results in a bunch of warnings:

1>CSC : warning CS8032: An instance of analyzer Microsoft.AspNetCore.Analyzers.StartupAnalyzer cannot be created from C:\Program Files\dotnet\sdk\6.0.100-rc.2.21464.10\Sdks\Microsoft.NET.Sdk.Web\analyzers\cs\Microsoft.AspNetCore.Analyzers.dll : Could not load file or assembly 'Microsoft.CodeAnalysis, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified..
1>CSC : warning CS8032: An instance of analyzer Microsoft.AspNetCore.Mvc.Analyzers.AttributesShouldNotBeAppliedToPageModelAnalyzer cannot be created from C:\Program Files\dotnet\sdk\6.0.100-rc.2.21464.10\Sdks\Microsoft.NET.Sdk.Web\analyzers\cs\Microsoft.AspNetCore.Mvc.Analyzers.dll : Could not load file or assembly 'Microsoft.CodeAnalysis, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified..
1>CSC : warning CS8032: An instance of analyzer Microsoft.AspNetCore.Mvc.Analyzers.AvoidHtmlPartialAnalyzer cannot be created from C:\Program Files\dotnet\sdk\6.0.100-rc.2.21464.10\Sdks\Microsoft.NET.Sdk.Web\analyzers\cs\Microsoft.AspNetCore.Mvc.Analyzers.dll : Could not load file or assembly 'Microsoft.CodeAnalysis, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified..
1>CSC : warning CS8032: An instance of analyzer Microsoft.AspNetCore.Mvc.Analyzers.TagHelpersInCodeBlocksAnalyzer cannot be created from C:\Program Files\dotnet\sdk\6.0.100-rc.2.21464.10\Sdks\Microsoft.NET.Sdk.Web\analyzers\cs\Microsoft.AspNetCore.Mvc.Analyzers.dll : Could not load file or assembly 'Microsoft.CodeAnalysis, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified..
1>CSC : warning CS8032: An instance of analyzer Microsoft.AspNetCore.Mvc.Analyzers.TopLevelParameterNameAnalyzer cannot be created from C:\Program Files\dotnet\sdk\6.0.100-rc.2.21464.10\Sdks\Microsoft.NET.Sdk.Web\analyzers\cs\Microsoft.AspNetCore.Mvc.Analyzers.dll : Could not load file or assembly 'Microsoft.CodeAnalysis, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified..
1>CSC : warning CS8032: An instance of analyzer Microsoft.AspNetCore.Components.Analyzers.ComponentParameterAnalyzer cannot be created from C:\Program Files\dotnet\sdk\6.0.100-rc.2.21464.10\Sdks\Microsoft.NET.Sdk.Web\analyzers\cs\Microsoft.AspNetCore.Components.Analyzers.dll : Could not load file or assembly 'Microsoft.CodeAnalysis, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified..
1>CSC : warning CS8032: An instance of analyzer Microsoft.AspNetCore.Components.Analyzers.ComponentParameterUsageAnalyzer cannot be created from C:\Program Files\dotnet\sdk\6.0.100-rc.2.21464.10\Sdks\Microsoft.NET.Sdk.Web\analyzers\cs\Microsoft.AspNetCore.Components.Analyzers.dll : Could not load file or assembly 'Microsoft.CodeAnalysis, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified..
1>CSC : warning CS8032: An instance of analyzer Microsoft.Extensions.Internal.ComponentInternalUsageDiagnosticAnalyzer cannot be created from C:\Program Files\dotnet\sdk\6.0.100-rc.2.21464.10\Sdks\Microsoft.NET.Sdk.Web\analyzers\cs\Microsoft.AspNetCore.Components.Analyzers.dll : Could not load file or assembly 'Microsoft.CodeAnalysis, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified..
1>CSC : warning CS8032: An instance of analyzer Microsoft.AspNetCore.Analyzers.StartupAnalyzer cannot be created from C:\Program Files\dotnet\sdk\6.0.100-rc.2.21464.10\Sdks\Microsoft.NET.Sdk.Web\analyzers\cs\Microsoft.AspNetCore.Analyzers.dll : Could not load file or assembly 'Microsoft.CodeAnalysis, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified..
1>CSC : warning CS8032: An instance of analyzer Microsoft.AspNetCore.Mvc.Analyzers.AttributesShouldNotBeAppliedToPageModelAnalyzer cannot be created from C:\Program Files\dotnet\sdk\6.0.100-rc.2.21464.10\Sdks\Microsoft.NET.Sdk.Web\analyzers\cs\Microsoft.AspNetCore.Mvc.Analyzers.dll : Could not load file or assembly 'Microsoft.CodeAnalysis, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified..
1>CSC : warning CS8032: An instance of analyzer Microsoft.AspNetCore.Mvc.Analyzers.AvoidHtmlPartialAnalyzer cannot be created from C:\Program Files\dotnet\sdk\6.0.100-rc.2.21464.10\Sdks\Microsoft.NET.Sdk.Web\analyzers\cs\Microsoft.AspNetCore.Mvc.Analyzers.dll : Could not load file or assembly 'Microsoft.CodeAnalysis, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified..
1>CSC : warning CS8032: An instance of analyzer Microsoft.AspNetCore.Mvc.Analyzers.TagHelpersInCodeBlocksAnalyzer cannot be created from C:\Program Files\dotnet\sdk\6.0.100-rc.2.21464.10\Sdks\Microsoft.NET.Sdk.Web\analyzers\cs\Microsoft.AspNetCore.Mvc.Analyzers.dll : Could not load file or assembly 'Microsoft.CodeAnalysis, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified..
1>CSC : warning CS8032: An instance of analyzer Microsoft.AspNetCore.Mvc.Analyzers.TopLevelParameterNameAnalyzer cannot be created from C:\Program Files\dotnet\sdk\6.0.100-rc.2.21464.10\Sdks\Microsoft.NET.Sdk.Web\analyzers\cs\Microsoft.AspNetCore.Mvc.Analyzers.dll : Could not load file or assembly 'Microsoft.CodeAnalysis, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified..
1>CSC : warning CS8032: An instance of analyzer Microsoft.AspNetCore.Components.Analyzers.ComponentParameterAnalyzer cannot be created from C:\Program Files\dotnet\sdk\6.0.100-rc.2.21464.10\Sdks\Microsoft.NET.Sdk.Web\analyzers\cs\Microsoft.AspNetCore.Components.Analyzers.dll : Could not load file or assembly 'Microsoft.CodeAnalysis, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified..
1>CSC : warning CS8032: An instance of analyzer Microsoft.AspNetCore.Components.Analyzers.ComponentParameterUsageAnalyzer cannot be created from C:\Program Files\dotnet\sdk\6.0.100-rc.2.21464.10\Sdks\Microsoft.NET.Sdk.Web\analyzers\cs\Microsoft.AspNetCore.Components.Analyzers.dll : Could not load file or assembly 'Microsoft.CodeAnalysis, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified..
1>CSC : warning CS8032: An instance of analyzer Microsoft.Extensions.Internal.ComponentInternalUsageDiagnosticAnalyzer cannot be created from C:\Program Files\dotnet\sdk\6.0.100-rc.2.21464.10\Sdks\Microsoft.NET.Sdk.Web\analyzers\cs\Microsoft.AspNetCore.Components.Analyzers.dll : Could not load file or assembly 'Microsoft.CodeAnalysis, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified..

We should pin these to the the most recent version supported by VS2019.

[martincostello]

Something similar to this case up when I raised a PR to file the logging source generator (dotnet/runtime#57894 (comment)) because it was using the old version, which made the type needed to understand file-scoped namespaces unavailable. I believe the folks over in runtime are/were looking into a multi-targeting solution to make both versions of VS happy.

[christiansparre]

This took me a bit to track down 😒

We have TreatWarningsAsErrors enabled so had to add NoWarn CS8032 to be able to build the solution in VS after installing rc1 yesterday...