rust-analyzer: specify binary relative to zed workspace dir / allow environment variables

[pavelzw]

looking at https://zed.dev/docs/languages/rust#binary, it says

If you want to use a binary in a custom location, you can specify a path and optional arguments:

{
  "lsp": {
    "rust-analyzer": {
     "binary": {
        "path": "/Users/example/bin/rust-analyzer",
        "arguments": []
      }
    }
  }
}

This "path" has to be an absolute path.

I am using rust together with pixi. pixi installs the rust-analyzer to $ZED_WORKTREE_ROOT/.pixi/envs/default/bin/rust-analyzer. I would like to add this to my project config s.t. every zed user automatically uses the correct rust-analyzer binary.

Currently, zed doesn't allow passing $ZED_WORKTREE_ROOT to the path.

Something like

{
  "lsp": {
    "rust-analyzer": {
      "binary": {
        "path": "$ZED_WORKTREE_ROOT/.pixi/envs/default/bin/rust-analyzer",
        "arguments": []
      }
    }
  }
}

would solve my issue.

VSCode's .vscode/settings.json supports this as well:

{
  "rust-analyzer.server.path": "${workspaceFolder}/.pixi/envs/default/bin/rust-analyzer"
}

[SomeoneToIgnore]

#41214

#42135

[pavelzw]

awesome, thanks!