crates-lsp

Language Server implementation targeted specifically towards the Cargo.toml file of Rust projects, providing auto-completion for crate versions and in-editor hints when the selected crate versions are out of date.

Project is heavily inspired by the crates plugin for VSCode.

Usage

In order to use crates-lsp, you must:

1. Install the crates-lsp binary somewhere on your machine.
2. Configure your editor to use the crates-lsp binary as a Language Server.

1. Installing crates-lsp

You can either download the pre-built crates-lsp binary from a release, or if you have Cargo (the Rust build tool) installed, you can build and install it yourself directly from crates.io:

cargo install --locked crates-lsp

2. Configuring your editor

This step is highly dependent on which editor you are using, see the guides below for known example configurations.

In most cases, these require crates-lsp to be available in your $PATH, or for you to specify the full path to it.

Neovim

vim.lsp.config['crates'] = {
  cmd = { 'crates-lsp' },
  filetypes = { 'toml' },
  root_markers = { 'Cargo.toml', '.git' },
  init_options = {
    -- Configuration options go here
  }
}

Helix

[language-servers.crates-lsp]
except-features = ["format"]
# config = {} # Configuration options go here

[[language]]
name = "toml"
language-servers = [ "crates-lsp", "taplo" ]
formatter = { command = "taplo", args = ["fmt", "-"] }

See the Languages section of the Helix wiki, if you're unsure of where to put this.

See Lsp section of the Neovim wiki, if you're unsure of where to put this.

Configuration

crates-lsp has the following configuration options, which can be passed in from your editor (See Usage section above):

Option	Type	Default	Description
cache_directory	string/path	OS-specific crates-lsp cache directory	Directory in which to cache information about available crate versions, to avoid constantly querying crates.io. Uses the OS-specific cache directory. See directories-rs
files	[string]	["Cargo.toml"]	List of exact filenames for which crates-lsp should provide feedback. Avoids crates-lsp throwing errors if you happen to open a toml file with a [dependencies] section, which does not contain Rust package names.
use_api	bool	false	If true, uses the Crates API instead of the Crate Index. There are almost no reasons to ever enable this, and doing so puts a lot more strain on the services provided by crates.io. Please don't!
inlay_hints	bool	true	If false, disables inlay hints.
up_to_date_hint	string	✓	Text of inlay hint to show, when package is up to date.
needs_update_hint	string	 {}	Text of inlay hint to show next to packages which should be updated. Any appearance of {} within the string, will be replaced by the newer version, which the package should be updated to.
diagnostics	bool	true	If false, disables diagnostics.
unknown_dep_severity	int	2 (WARNING)	Sets severity of diagnostics indicating that a package could not be looked up. See Diagnostic Severity
needs_update_severity	int	3 (INFO)	Sets severity of diagnostics indicating that a package needs to be updated. See Diagnostic Severity
up_to_date_severity	int	4 (HINT)	Sets severity of diagnostics indicating that a package is up to date. See Diagnostic Severity

Diagnostic Severity

Integer indicating the severity to use when crates-lsp conveys a diagnostic about packages, such as: Needs Update, Unknown Package, or Up To Date. The following severities are available:

• 1 ERROR
• 2 WARNING
• 3 INFORMATION
• 4 HINT

Examples

These examples only showcase configuration options, and are not complete examples!

Neovim

The init_options field contains the crates-lsp configuration options.

vim.lsp.config['crates'] = {
  init_options = {
    inlay_hints = false,      -- Disable inlay hints entirely
    needs_update_severity = 1 -- Report necessary updates as ERRORs
  }
}

Helix

[language-server.crates-lsp]
# Disable inlay hints, Report necessary updates as ERRORs
config = { inlay_hints = false, needs_update_severity = 1 }