CodeBehindGenerator has improper pipeline

[Youssef1313]

maui/src/Controls/src/SourceGen/CodeBehindGenerator.cs

Lines 64 to 67 in 83c3ac9

	var sourceProvider = projectItemProvider
	.Combine(xmlnsDefinitionsProvider)
	.Combine(initContext.CompilationProvider)
	.Select(static (t, _) => (t.Left.Left, t.Left.Right, t.Right));

This won't work well. Combining CompilationProvider and having Compilation as part of the pipeline will cause the generator to re-run on every change. So, it's not incremental at all. Note that sourceProvider is the last step.

This also roots Compilation objects in memory. See dotnet/roslyn-analyzers#6352 (Edit: I don't think there is a memory leak concern in this case)

[ghost]

We've moved this issue to the Backlog milestone. This means that it is not going to be worked on for the coming release. We will reassess the backlog following the current release and consider this item at that time. To learn more about our issue management process and to have better expectation regarding different types of issues you can read our Triage Process.

[Youssef1313]

Note: I think this needs a second look from Roslyn team.

[StephaneDelcroix]

@jonathanpeppers thoughts ?

[jonathanpeppers]

I asked in Teams (private link), where some of the Roslyn folks are.

[jfversluis]

@Youssef1313 @jonathanpeppers @StephaneDelcroix any updates on this?

[jonathanpeppers]

The points in teams are:

1. The MAUI source generator is currently not incremental at all. It reruns on every keystroke.
2. This is likely not an easy thing to solve at all.

You can define any type in XAML and then give it a x:Name. But it really needs to rerun if types or their namespaces change?
So, if you added a method, maybe we wouldn't need to run the source generator in that case.

One comment from the Roslyn team:

One possible approach here is to extract type/namespace names from source and metadata, and refresh that index when it changes.
It's unfortunate that somewhat requires reiventing our decltrees.

[homeyf]

Verified this issue with Visual Studio Enterprise 17.9.0 Preview 1.0. Can repro on android platform.

[mgoertz-msft]

Completed with PR #20524. Not sure why it didn't auto-complete this item.

[akoeplinger]

Not sure why it didn't auto-complete this item.

Because the PR had Fixes Issue #12978 but it needs to be Fixes #12978 for GitHub to recognize it.