Ionide-vscode-fsharp: Stringinterpolation requires langVersion in .NET 5

[NicoVIII]

Describe the bug
If I want to use string interpolation from F# 5 in a new .NET 5 project, I get an error in the editor that tells me, that string interpolation is not available in F# 4.7. As far as I know, F# 5 is now the default language version and dotnet build runs successfully without this error.

To Reproduce
Steps to reproduce the behaviour:

1. Use string interpolation in an net5.0 project without LangVersion

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net5.0</TargetFramework>
    <RootNamespace>test</RootNamespace>
  </PropertyGroup>

let test = "test"
$"%s{test}"

Expected behaviour
I would expect that the language version is the same for editor and compiler.

Screenshots

Environment (please complete the following information):

• OS: Windows (but inside of a mcr.microsoft.com/dotnet/sdk:5.0-focal dev container)
• Ionide version: 4.17.0
• VSCode version: Version: 1.51.0 (user setup)
• dotnet SDK version: 5.0.100
• mono / .Net Framework version: -

Additional context
I created a reproduction repo here: https://github.com/NicoVIII/repro-bug

I don't rule out that I do something wrong. If this is the case: Sorry!

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[baronfel]

We're actively working on this, you can follow the status here: https://github.com/fsharp/FsAutoComplete/pull/656

[NicoVIII]

Thank you! I wasn't sure, if this is another thing, which belongs to FsAutoComplete and not directly to Ionide, so I opened the bug here :)

[Krzysztof-Cieslak]

This is fixed in Ionide 5.0 preview

[jkone27]

is this fixed also for linux/ubuntu ? have v.5.5.4 installed running ubuntu on windows in this case (net 5 sdk)

removing the string interpolation sign makes the error disappear

[NicoVIII]

Works for me with 5.5.5 and on Manjaro with target framework net5.0.

[baronfel]

That's correct, this is implemented in all ionide 5.x versions.

[jkone27]

it worked after uninstall of vscode and ionide as well and clean re'install, not sure what was causing it