Blazor - Build vs Build + Intellisense errors count after build differs (144 vs 38)

[janseris]

Describe the bug:
Build shows 144 errors
Build + Intellisense shows 38 errors
Sample project:
Ordinace.zip

blazor.build.+.intellisense.error.count.doesnt.work.mp4

Version used:
e.g. VS2022 17.3.3

To reproduce:

Try build project. For detailed reproduction, see attached video.

Expected behavior:
Number of Build + Intellisense errors is greater or equal than number of Build errors

Actual behavior:
Number of Build + Intellisense errors is much less than number of Build errors

Additional context:
Another example:
Ordinace2.zip

[davidwengier]

@dibarbet @mavasani Do you have any more context on this? Is this expected?

It seems like FSA has something to do with this, because I get 38 errors as per the repro video, but if I open another file that has errors, that numbers goes to 76, and doesn't go down when I close the document. I remember seeing some commenta bout a known issue with LSP and FSA recently, maybe?

[dibarbet]

@davidwengier the expectation is that build + intellisense will show you all errors from the build + intellisense errors, so there's definitely a problem here as it isn't showing all the build errors. Note that its totally possible for the intellisense only column to show less errors - for example missing closed docs or compilation end diagnostics when FSA is off.

After playing around with it for a few minutes, I can repro this when FSA is off and C# LSP pull diagnostics is off. What I did

1. Add errors in two different blazor files
2. Add an error in a CS file.
3. Close everything except 1 blazor file, then restart VS (just to get to a clean state).
4. Open the sln, note the initial error in the open blazor file in the error list.
5. Build the solution and note the following behavior.
   

This does not repro when C# LSP pull diagnostics is on, so I'm guessing its undefined behavior due to Razor being on LSP and Roslyn not.

but if I open another file that has errors, that numbers goes to 76, and doesn't go down when I close the document

This appears to be a bug in C# projects as well. I will take a look as once the document is closed the intellisense errors should go away.

[DustinCampbell]

@dibarbet -- Were you planning to follow up on this? Do you have a bug tracking this on the C# side?