Language support not available on Windows

[JoaoVictorVP]

Describe the bug
Basically, no completion, intellisense, errors, etc. Nothing kinda works.

To Reproduce
Be on windows
Install swift with winget (6.1.0)
Install vscode
Install swift extension for vscode
Create a project (either with swift vscode commands or the CLI)
Open a .swift file
done, nothing works

Expected behavior
Having basic code completion, type inference and error reporting

Environment

• OS: Windows 11 23H2
• Swift version: Swift version 6.1 (swift-6.1-RELEASE)
  Target: x86_64-unknown-windows-msvc
• Visual Studio Code version: 1.100.3
• vscode-swift version: 2.3.20250521

Additional context

and code is working with cli:

till now, I was only able to "reliably" use swift with a proper lsp support was in an wsl ubuntu, and it was getting heavier and heavier (too much) with each line of code
maybe this all is related to the constant CPU hogging problem , but either way

[plemarquand]

Thanks for the report, could you run the Swift > Capture Diagnostic Bundle command and zip/attach the resulting files? This will help us diagnose.

[JoaoVictorVP]

right away
vscode-diagnostics-2025-06-05T16-54-48-03-00 (swift).zip

for additional info:
I tested in vs-codium as well, same results (downloaded the VSIX for it and LLDB)
when I enabled the logs for lsp the only one it emitted was: [Trace - 4:54:17 PM] Sending request 'initialize - (0)'.

[award999]

@JoaoVictorVP nothing in the diagnostic bundle immediately stands out to me. Can you check for this SourceKit-LSP: Indexing output channel? Is it churning away? I've seen it get stuck in a never ending loop of build commands

[JoaoVictorVP]

@award999 (I forgot to quote you before)
The strange thing to me is that this channel does not exist, it only has 'SourceKit Language Server (6.1.0)' and 'Swift'

in the first it says ->

[Trace - 9:22:19 AM] Sending request 'initialize - (0)'.

and in the second ->

09:22:15: Activating Swift for Visual Studio Code...
09:22:19: raylib-thingie: workspaceStateUpdated: c:\dev\swift\other-test\raylib-thingie
09:22:19: SourceKit-LSP setup
09:22:19: raylib-thingie: add: c:\dev\swift\other-test\raylib-thingie
09:22:19: raylib-thingie: Resolving Dependencies: starting ... 
09:22:19: Exec Task: (raylib-thingie) swift package resolve
09:22:19: raylib-thingie: focus: c:\dev\swift\other-test\raylib-thingie
09:22:22: raylib-thingie: Resolving Dependencies: ... done.
09:22:23: raylib-thingie: pluginsUpdated: c:\dev\swift\other-test\raylib-thingie

It seems that there is no error, which is very strange. Was you able to code in swift on windows using this extension before without problems?

[award999]

Ya even trying now, no issues. Umm so if that channel does not exist then background indexing is not on or at least running which could explain no code completion. First can you execute Tasks: Run Build Task command and select the Build All one. Reload the window, does that solve the issue? If not can you uninstall the pre-release version of the extension and install the stable release? I made some changes that touch some LSP code so it is possible that there is some weird timing issue I introduced

[JoaoVictorVP]

yeah, it's a bit weird, I just restarted my computer thinking it could be some configuration or PATH issue but it's the same outcome
as for your questions:

1. I can execute it, yes. It runs on the bottom-left of the screen, it goes "preparing" then I think [1/5] and goes from each one then ends, and it says this
   

2. I tried reloading the extensions multiple times, and even using it on vscodium. Now I tried reloading window (with the command pallete) and the same outcome.

3. I also tried the non-pre-release version a bit earlier today (it's my current one) because I thought it was something related to that as well
   
   but the same outcome happens with it

As for your trying, how'd you did it?
My steps are:

1. using winget to install (as swift docs state to do)
2. installing the extension on vscode

I don't know if I'm missing something that is crucial here, supposedly not as in linux I did it and it worked.

Currently, I can build and run swift normally in the terminal, create new projects, etc (I can also create projects with the extension).

[award999]

Only other thought right now is to setup a SourceKit-LSP configuration file and disable the backgroundIndexing setting. Let me know if that helps but I think we'll likely have to move this issue over to sourcekit-lsp

[JoaoVictorVP]

yeah, no results with backgroundIndexing false
well, that's sad, I can also wait for the new version (6.2) and try it out when it releases, or something like that
given the nature of this problem, I'm in doubt if the problem is my computer setup, because you can use the language on windows. So maybe I'll also try to use it in a VM whenever possible to check it out, and I report back with the results

[rbenegal]

One more thing you could possibly try if you have the chance @JoaoVictorVP - could you please set swift.sourcekit-lsp.trace.server to verbose and then check the output from the SourceKit Language Server (6.1.0) window?
So like:

There should be some more info now indicating what is happening with SourceKit, perhaps it's not able to send any responses for some reason. For example:

I'm wondering if there is some other process (antivirus/firewall or similar) that blocks communication between SourceKit and VS Code which prevents things from working? The sourcekit-lsp process should be running in the background, and you should get a notification if something happens to it, but perhaps there is something else going on.

[award999]

And you did mention using winget to install swift, but do you have the Visual Studio and SDK dependencies mentioned in the windows instructions?