One LSP instance per workspace

[Leandros]

Checked other resources

• This is not a bug report or a question (Please use issues for those).
• I have searched existing discussions.
• I have searched existing issues.
• This cannot be implemented in rust-analyzer.
• I have added a very descriptive title to this feature request.

Feature description

When using a single instance of neovim to work on more than one workspace, with different workspace configurations, the config is overwritten.

The following repository has this workspace setup:

workspace/
├── .vscode/
│   └── settings.json
├── cross/
│   ├── .cargo/
│   │   └── config.toml
│   ├── crate1/
│   │   ├── src/
│   │   │   └── lib.rs
│   │   └── Cargo.toml
│   ├── crate2/
│   │   ├── src/
│   │   │   └── main.rs
│   │   └── Cargo.toml
│   └── Cargo.toml
├── crate3/
│   ├── src/
│   │   └── lib.rs
│   └── Cargo.toml
└── Cargo.toml

(https://github.com/Leandros/nvim-lsp-test)

The root workspace is configured to build on the host architecture, and the cross workspace is configured to compile for a foreign architecture (eg. thumbv7m-non-eabi, for embedded work).

Both workspaces have different architectures configured through .vscode/settings.json. However, depending on which workspace is opened last in neovim, the settings of the first workspace are overwritten and the single rust-analyzer instance is now using an invalid architecture (and therefore, diagnostics break).

The repository linked can be used to easily reproduce the issue by opening it and editing cross/cross-crate/src/main.rs and host/host-crate/src/main.rs in any order. The settings from the first opened workspace are not present in the config for rust-analyzer.

This severely inhibits a good working experience for embedded projects.

A "quick" solution would be to spawn (with a configuration) a single rust-analyzer instance for each workspace.

[Leandros]

The idea would be that I could make rustaceanvim spawn multiple servers by specifying a different root_dir, for example, like so:

root_dir = function(filename, default)
  local clients = vim.lsp.get_clients({ name = 'rust-analyzer' })
  local found_dirs = vim.fs.find({ '.vscode' }, { upward = true, path = vim.fs.dirname(filename), type = 'directory' })
  if #found_dirs == 0 then
    return default(filename)
  end
  return vim.fs.dirname(found_dirs[1])
end,

I got this to work with a very minor patch to rustaceanvim; However, despite multiple instances of rust-analyzer, they use the same config (the config from the last opened workspace).

[mrcjkb]

I suppose this is now a duplicate of #869?

[Leandros]

Yes!