Changes to TypeScript definition files in linked modules not detected by Language Server

[jstarmx]

Describe the bug
Svelte Language Server does not pick up changes to TypeScript definition files in linked modules without being restarted.

To Reproduce

1. Clone this repo: https://github.com/jstarmx/svelte-typescript-test
2. Follow setup instructions
3. Open /app/src/App.svelte
4. Open /package/src/Alert.d.ts
5. Change the type of text on line 4 from string to something else, e.g. number
6. Observe that the problems panel in VS Code does not show any errors
7. Restart Svelte Language Server
8. Observe that the problems panel now shows an error in App.svelte

Expected behavior
Problems panel to display the error without needing to restart Svelte Language Server

System (please complete the following information):

• OS: macOS Big Sur 11.3.1
• IDE: VSCode
• Plugin/Package: Svelte for VSCode

Additional context
Happy to try to contribute a fix if you think it's do-able/worthwhile/actually an issue...

[dummdidumm]

There are two problems to this:

• File paths are not the same (case-sensitivity-wise), we need to normalize them
• If the service for a TS file is searched, it doesn't take into account existing services where the file is already present but where the file is not the child of that tsconfig. This means that package/src/Alert.d.ts is moved to another TS service. I think we need to change the update logic there to go through all existing services, too, and update them accordingly (99% of the time there will be only one).

[jstarmx]

@dummdidumm thanks for looking into this so quickly, that's fantastic 👍

[fkling]

Just wanted to note that I experienced the same problem in neovim (it works fine in VSCode). I was able to get it to work by configuring the lsp client to use the repo root as root directory. Something like

    require('lspconfig').svelte.setup {
      capabilities = capabilities,
      on_attach = on_attach,
      settings = servers.svelte,
      root_dir = require('lspconfig').util.find_git_ancestor
    }

I'm not familiar with all the lsp stuff to know why it works for other clients (e.g. tsserver) and other environments (e.g. vscode) but not in this case by default 🤷🏻‍♂️

[jasonlyu123]

That's tracked in #1415. And the reason is that we only have a directory file watcher, and the tsserver has watchers for individual files. It might consume more system resources, so I am hesitant if we should add that. As for VSCode, the LSP process starts in the workspace root. It doesn't open two processes because there are two package.json.

[fkling]

Thank you @jasonlyu123, I didn't find that issue!