Add fixers project and implement a fixer for FieldReferenceForObservablePropertyFieldAnalyzer

[333fred]

This adds a fixer for MVVMTK0034, that simply swaps the field reference for what will be generated for the property. It leaves the qualification intact, basically just doing a text swap. Because it's a very very simple fixer, the built-in batch fixall provider works just fine and does not need special handling.

While I implemented the fixer and added some tests, I did not actually set up all the msbuild goop for properly packaging this as part of the existing packages (as, frankly, the multi-targeting and msbuild setup in this repo is very complicated and I didn't feel like trying to grok exactly how to add it given the setup). The fixer assembly needs to be put next to the analyzer assemblies. This PR will be editable by maintainers, so feel free to implement this in-place in the PR itself.

Fixes #577.

[Sergio0694]

Now for the fun part, making this thing actually work with multi-targeted packaging 🤣

[Sergio0694]

FYI @Arlodotexe you might also want to take a look if you want to learn something new 😄
This still might also potentially be useful for you folks in Labs.

[333fred]

I'm assuming you've tested the package in VS and seen the analyzers (and fix all) working?

[Sergio0694]

Not yet. I've just marked this as ready to review as it's not clearly still work in progress, is all 😄

[Sergio0694]

Mmmh trying this out, I get this:

System.InvalidOperationException : The solution does not contain the specified document.
   at Microsoft.CodeAnalysis.Solution.CheckContainsDocument(DocumentId documentId)
   at Microsoft.CodeAnalysis.Solution.WithDocumentSyntaxRoot(DocumentId documentId,SyntaxNode root,PreservationMode mode)
   at async Microsoft.CodeAnalysis.IntroduceVariable.AbstractIntroduceParameterService`4.IntroduceParameterAsync[TExpressionSyntax,TInvocationExpressionSyntax,TObjectCreationExpressionSyntax,TIdentifierNameSyntax](<Unknown Parameters>)
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at async Microsoft.CodeAnalysis.CodeActions.CodeAction.ComputeOperationsAsync(<Unknown Parameters>)
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at async Microsoft.CodeAnalysis.CodeActions.CodeAction.GetPreviewOperationsAsync(<Unknown Parameters>)
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at async Microsoft.CodeAnalysis.Editor.Implementation.Suggestions.SuggestedAction.GetPreviewResultAsync(<Unknown Parameters>)
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at async Microsoft.CodeAnalysis.Editor.Implementation.Suggestions.SuggestedActionWithNestedFlavors.PreviewChangesSuggestedAction.CreateAsync(<Unknown Parameters>)
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at async Microsoft.CodeAnalysis.Editor.Implementation.Suggestions.SuggestedActionWithNestedFlavors.GetPreviewChangesFlavorAsync(<Unknown Parameters>)
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at async Microsoft.CodeAnalysis.Editor.Implementation.Suggestions.SuggestedActionWithNestedFlavors.CreateAllFlavorsAsync(<Unknown Parameters>)
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at async Microsoft.CodeAnalysis.Extensions.IExtensionManagerExtensions.PerformFunctionAsync[T](<Unknown Parameters>)

Kinda seems unrelated. Not sure why the code fix isn't showing up though. Let me try in a different project as well.

[Sergio0694]

It works!! 🚀🚀🚀

Also validated batch fixer, works perfectly too. The fixer seems to be busted with a shared project, but that would seem to just be Roslyn choking up for whatever reason. It works perfectly fine in a standalone project, as in the picture above.

[Sergio0694]

Hey @333fred are you able to run the unit tests locally? They're failing for me with some packing error, but they run fine in the CI, so I'm not entirely sure I understand what's going on with them. Can you try on your end as well as a sanity check?

[Youssef1313]

Hey @333fred are you able to run the unit tests locally? They're failing for me with some packing error, but they run fine in the CI, so I'm not entirely sure I understand what's going on with them. Can you try on your end as well as a sanity check?

What is the error?

[Sergio0694]

Message: 

Test method CommunityToolkit.Mvvm.SourceGenerators.Roslyn401.UnitTests.Test_FieldReferenceForObservablePropertyFieldCodeFixer.ExternalConditionalMemberAccess threw exception:
NuGet.Packaging.Core.PackagingException: The package is missing the required nuspec file. Path: C:\Users\sergiopedri\AppData\Local\Temp\test-packages\Microsoft.NETCore.App.Ref.6.0.0

Stack Trace: 

PackageFolderReader.GetNuspecFile()
PackageReaderBase.GetNuspec()
PackageReaderBase.get_NuspecReader()
PackageReaderBase.GetFrameworkItems()
PackageReaderBase.GetFrameworkItemsAsync(CancellationToken cancellationToken)
<ResolveCoreAsync>d__50.MoveNext() line 365
--- End of stack trace from previous location where exception was thrown ---
ExceptionDispatchInfo.Throw()
TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
TaskAwaiter`1.GetResult()
<44 more frames...>
TaskAwaiter.GetResult()
<RunAsync>d__62.MoveNext() line 181
--- End of stack trace from previous location where exception was thrown ---
ExceptionDispatchInfo.Throw()
TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
TaskAwaiter.GetResult()
<ExternalConditionalMemberAccess>d__3.MoveNext() line 284
--- End of stack trace from previous location where exception was thrown ---
ExceptionDispatchInfo.Throw()
TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)

I get a total of 114 failing unit tests across all source generator tests on all targets 🥲

[Youssef1313]

@Sergio0694 Does deleting %TEMP%\test-packages help?

[Sergio0694]

Oh, cool, that worked, thank you! 😄

[Sergio0694]

LGTM, thank you!

[333fred]

It's my pr so I can't mark it approved, but your changes lgtm

[Sergio0694]

Thank you @333fred! And @Youssef1313 for the review 😄