Handle plugins when background indexing is disabled

[yikesboy]

Problem
SourceKit-LSP fails to index Swift source code that is generated by build tool plugins during compilation, which results in:

• No type information for generated code in the main application under Sources
• Unable to jump to definitions of generated code
• Missing autocompletion for symbols from generated code
• etc...

Environment
Editor: Neovim
Swift: 6.1
Platform: Arch Linux
Build Tool: SPM

Context
The VSCode extension handles this correctly by default, so I think it would make sense to at least optionally support it within SourceKit-LSP.
Generated files are located in .build
Issue affects just LSP; compilation works correctly.

[bnbarham]

Plugins not running should have been fixed by #665. Could you enable extended logging (*) and include a sourcekit-lsp diagnose?

Also, could you expand on:

The VSCode extension handles this correctly by default, so I think it would make sense to at least optionally support it within SourceKit-LSP.

? Are you saying your project works in VS Code and not Neovim? The Swift VS Code extension uses sourcekit-lsp, so if this is the case then that narrows things down a lot.

(*) https://github.com/swiftlang/sourcekit-lsp/blob/main/Documentation/Enable%20Extended%20Logging.md note that this will include file paths and source of opened files

[yikesboy]

The extended logs, where i try to "go-to-definition" of a struct, that was generated with a build tool plugin and is located in .build/...

extended-logs.zip

? Are you saying your project works in VS Code and not Neovim? The Swift VS Code extension uses sourcekit-lsp, so if this is the case then that narrows things down a lot.

It works to "go-to-defintion" or retrieve type information in VSCode, yes!

[bnbarham]

Looks like background indexing is disabled. Getting the correct arguments for plugins depends on this being enabled, so that explains the behavior you're seeing.

Since it's not in the initialization options and VS Code is working, my guess would be that you have a ~/.sourcekit-lsp/config.json with "backgroundIndexing": false. Could you check if that's the case? If not, please also check .sourcekit-lsp/config.json within your workspace (I had thought these override initialization options, but that might not be the case).

[yikesboy]

Background indexing fixed it, thank you!

Does this mean it is not possible whatsoever to pick up code generated by plugins without BI being enabled?

Otherwise, closed from my end.

[bnbarham]

Plugins run during creation of the build plan, so running them in LSP without background indexing (which creates a separate build arena) can then conflict with the regular build itself.

I'll leave this open and re-title to re-visit once SwiftPM is swapped over to swift-build. That won't automatically fix this, but maybe we have more options then.