Visual Studio 17.5.1 broke F# intellisense

[vsfeedback]

This issue has been moved from a ticket on Developer Community.

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[severity:It's more difficult to complete my work] [regression] [worked-in:17.5]
After upgrading to Visual studio 17.5.1 (from 17.5), Intellisense in F# source files doesn't work properly anymore. The most visible effect is that no errors are shown and I need to build to see errors in Error List pane

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Original Comments

Feedback Bot on 3/6/2023, 01:50 AM:

(private comment, text removed)

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Original Solutions

(no solutions)

[vzarytovskii]

I saw once this but couldn't reproduce. I wonder if it's a result of the incremental builder issue, or vallinkage issue.

[MaxWilson]

I have also had this issue. Sometimes even building does not make the errors show up in the error pane or inline in the code, only in the Output window. Known workaround: closing Visual Studio and re-opening it fixes it for a while.

For a while I thought it might be because I had Text Macro extensions installed, or Github Copilot, but I've reproed the issue without them.

If I find a screenshot I will post it but for now I can merely confirm that the issue is still active in VS Version 17.6.0 Preview 2.0.

[MaxWilson]

Solved for now by rolling back to VS 2022 Version 17.4.2. Edit: switching errors to "Build Only" instead of "Build + Intellisense" tentatively seems to be a viable workaround too--after Control + Shift + B, build errors show up correctly in Intellisense. Never mind, it eventually recurred even with "Build Only".

My current workaround to is jump back and forth between VS 2022 and VS Code.

[ghostinside]

just updated today to 17.7, F# intellisense stopped recognizing c# references despite the solution being built successfully

[vzarytovskii]

just updated today to 17.7, F# intellisense stopped recognizing c# references despite the solution being built successfully

We'll need a bit more info here.

Is it new style or old style project?
Does it work in 17.8 preview?

[ghostinside]

it does not work in preview,

C# project (.net 4.8): {3A499F41-1A5A-46A1-BF01-8ECADB9C4223}
F# project (.net 4.8, fsharp.core 7 ): {50b30417-ae00-46c5-9fd1-f5094510cf4d}

[ghostinside]

[ghostinside]

it recognizes System namespace, but not any "custom"

[vzarytovskii]

@0101 it looks like the same issue we had with old projects, do you remember where the link for vsix is?

[0101]

Yeah, here's a VSIX that fixes the issue with old-style projects. You can install it and see if it helps.

[ghostinside]

live is getting better

[ghostinside]

@0101 what do you mean by old-style projects? where I can read about old vs new, should I upgrade existing projects?

[MaxWilson]

Solved for now by rolling back to VS 2022 Version 17.4.2. Edit: switching errors to "Build Only" instead of "Build + Intellisense" tentatively seems to be a viable workaround too--after Control + Shift + B, build errors show up correctly in Intellisense. Never mind, it eventually recurred even with "Build Only".

My current workaround to is jump back and forth between VS 2022 and VS Code.

Follow-up: this issue does not currently repro for me in Version 17.8.0 Preview 1.0. Intellisense is a bit slow because I'm using a weak computer, but it does eventually update and remove errors after 5-6 seconds, whereas previously the errors would remain indefinitely.

[0101]

@0101 what do you mean by old-style projects? where I can read about old vs new, should I upgrade existing projects?

Can't really find any good docs about this. But with .NET Core came a new format for csproj/fsproj files. It starts with:

<Project Sdk="Microsoft.NET.Sdk">

Whereas the old format starts with

<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="15.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">

And they are handled differently by VS.

If you can it's probably a good idea to upgrade to the new format, but I don't know if there's an easy automatic way to do that.

Here's an article to possibly get you started: https://www.hanselman.com/blog/upgrading-an-existing-net-project-files-to-the-lean-new-csproj-format-from-net-core

[vzarytovskii]

There's a tool for migrating them:
https://github.com/dotnet/try-convert

I haven't tried it personally, but it should "just work" for typical projects..

[T-Gro]

Closing as the issue does not repro anymore (see comments above), can be reopened if it happens on latest tooling again.