# Rust

Rust support is available natively in Zed.

- Tree-sitter: [tree-sitter/tree-sitter-rust](https://github.com/tree-sitter/tree-sitter-rust)
- Language Server: [rust-lang/rust-analyzer](https://github.com/rust-lang/rust-analyzer)

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## Inlay Hints

The following configuration can be used to change the inlay hint settings for `rust-analyzer` in Rust:

```json
{
  "lsp": {
    "rust-analyzer": {
      "initialization_options": {
        "inlayHints": {
          "maxLength": null,
          "lifetimeElisionHints": {
            "enable": "skip_trivial",
            "useParameterNames": true
          },
          "closureReturnTypeHints": {
            "enable": "always"
          }
        }
      }
    }
  }
}
```

See [Inlay Hints](https://rust-analyzer.github.io/book/features.html#inlay-hints) in the Rust Analyzer Manual for more information.

## Target directory

The `rust-analyzer` target directory can be set in `initialization_options`:

```json
{
  "lsp": {
    "rust-analyzer": {
      "initialization_options": {
        "rust": {
          "analyzerTargetDir": true
        }
      }
    }
  }
}
```

A `true` setting will set the target directory to `target/rust-analyzer`. You can set a custom directory with a string like `"target/analyzer"` instead of `true`.

## Binary

You can configure which `rust-analyzer` binary Zed should use.

By default, Zed will try to find a `rust-analyzer` in your `$PATH` and try to use that. If that binary successfully executes `rust-analyzer --help`, it's used. Otherwise, Zed will fall back to installing its own `rust-analyzer` version and using that.

If you want to disable Zed looking for a `rust-analyzer` binary, you can set `ignore_system_version` to `true` in your `settings.json`:

```json
{
  "lsp": {
    "rust-analyzer": {
      "binary": {
        "ignore_system_version": true
      }
    }
  }
}
```

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

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

This `"path"` has to be an absolute path.

## Alternate Targets

If want rust-analyzer to provide diagnostics for a target other than you current platform (e.g. for windows when running on macOS) you can use the following Zed lsp settings:

```json
{
  "lsp": {
    "rust-analyzer": {
      "initialization_options": {
        "cargo": {
          "target": "x86_64-pc-windows-msvc"
        }
      }
    }
  }
}
```

If you are using `rustup` and you can find a list of available target triples (`aarch64-apple-darwin`, `x86_64-unknown-linux-gnu`, etc) by running:

```sh
rustup target list --installed
```

## LSP tasks

Zed provides tasks using tree-sitter, but rust-analyzer has an LSP extension method for querying file-related tasks via LSP.
This is enabled by default and can be configured as

```json
"lsp": {
  "rust-analyzer": {
    "enable_lsp_tasks": true,
  }
}
```

## Manual Cargo Diagnostics fetch

By default, rust-analyzer has `checkOnSave: true` enabled, which causes every buffer save to trigger a `cargo check --workspace --all-targets` command.
For lager projects this might introduce excessive wait times, so a more fine-grained triggering could be enabled by altering the

```json
"diagnostics": {
  "cargo": {
    // When enabled, Zed disables rust-analyzer's check on save and starts to query
    // Cargo diagnostics separately.
    "fetch_cargo_diagnostics": false
  }
}
```

default settings.

This will stop rust-analyzer from running `cargo check ...` on save, yet still allow to run
`editor: run/clear/cancel flycheck` commands in Rust files to refresh cargo diagnostics; the project diagnostics editor will also refresh cargo diagnostics with `editor: run flycheck` command when the setting is enabled.