Intellisense broken in VisualFSharp solution in VS

[0101]

Please provide a succinct description of the issue.

Repro steps

Provide the steps required to reproduce the problem:

1. Open VisualFSharp solution in VS
2. Go to any file in FSharp.Editor project (always seems to happen there but usually also other projects)

Expected behavior

We semantic coloring, type hints, tooltips, F12 works, etc.

Actual behavior

None of that works

Known workarounds

Edit all .fsproj files (e.g. add a whitespace character anywhere).

touch-projects.fsx

(Thanks copilot!)

open System
open System.IO

let addWhitespaceToFsprojFiles (directory: string) =
    let fsprojFiles = Directory.GetFiles(directory, "*.fsproj", SearchOption.AllDirectories)
    for file in fsprojFiles do
        let content = File.ReadAllText(file)
        printfn "Modifying %s..." file
        File.WriteAllText(file, content + " ")
        
printfn "Enter the directory to crawl:"
let directoryToCrawl = Console.ReadLine()
addWhitespaceToFsprojFiles(directoryToCrawl)

Related information

VS 17.12 p2, but likely also other versions.

[0101]

This seems to be happening since we started using SDK9 preview 7 in the repo.

The cause is that we don't get command line arguments from CPS for a few of the loaded projects. Therefore we cannot create FSharp options for them, or any that depend on them.

Digging further, CPS doesn't send us the command line args, because they are not populated into FscCommandLineArgs variable during design time build.

This happens in CoreCompile target.

Here we see that for FSharp.Core netstandard2.0 this target was skipped. Reason being outputs are up to date.

These are the outputs

        Outputs="@(DocFileItem);
                 @(IntermediateAssembly);
                 @(IntermediateRefAssembly);
                 @(_DebugSymbolsIntermediatePath);
                 $(NonExistentFile);
                 @(CustomAdditionalCompileOutputs)"

One of them is NonExistentFile which depends on _ComputeNonExistentFileProperty

And we can see that one is skipped for the projects where we get the issue:

 Target "_ComputeNonExistentFileProperty" skipped, due to false condition; (('$(BuildingInsideVisualStudio)' == 'true') and ('$(BuildingOutOfProcess)' != 'true') and (('$(BuildingProject)' == 'false') or ('$(UseHostCompilerIfAvailable)' == 'true'))) was evaluated as (('true' == 'true') and ('' != 'true') and (('true' == 'false') or ('' == 'true'))).

Condition Analyzer:
❌ '$(BuildingProject)'=='false' ➔ 'true'=='false'
❌ '$(UseHostCompilerIfAvailable)'=='true' ➔ ''=='true'

BuildingProject should be false but it's true. And it's set via an unrelated project:

[majocha]

This is still a thing unfortunately.
Less invasive workaround is to touch just the top level Directory.Build.targets.

[xperiandri]

@T-Gro, is this planned as a separate work, or will some other large feature fix this automatically when completed?

[T-Gro]

The biggest work item we have for this year is replacement of FSharp.Editor (this is what is added to VisualFsharp.sln when compared with the small solutions like FSharp.sln).

You are correct = this will both change composition of projects in our solution, as well as how F# in general (for any solution) behaves in VS.