HIE fails in multi-folder project

[ismailmustafa]

If a haskell stack project is inside a sub folder when opened with vscode, it fails to start HIE. For example, my project is structured like so:

.
├── backend
│   ├── LICENSE
│   ├── README.md
│   ├── Setup.hs
│   ├── haskellProject.cabal
│   ├── resources
│   ├── src
│   └── stack.yaml
└── frontend
    └── ... js files ...

To fix the issue, I have to cd into backend and then open that specific folder within vscode.

[ismailmustafa]

Couple of ways I'm thinking about approaching this:

1. This function could recursively look for stack.yaml and use the first one it finds. This could be problematic if you have multiple folders each containing a different stack.yaml (though I'm unsure that this would ever be an issue/use-case):
   

   haskell-ide-engine/src/Haskell/Ide/Engine/Plugin/Base.hs

   Line 107 in 01189cf

   getProjectGhcVersion :: IO String

2. the LSP client could pass a stack.yaml filepath to hie on start, however this would involve stack.yaml search logic on the client side which I'm not a big fan of. If it's possible to just get the filepath of the file being worked on, then logic could remain in hie. This approach would fix the issue mentioned in 1.

[Anrock]

@ismailmustafa dunno about LSP client for VSCode but neovim LanguageClient implemented option 2 and it works pretty much ok.