A spell-checker for Rust code.
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A public API spell-checker plugin for the rustc Rust compiler. It finds spelling errors in the names and documentation of most exported things like mods, fns, structs and their fields, enums and their variants.

Identifiers like foo_bar and FooBar are broken into foo and bar, with numbers/non-alphabetic characters acting as separators. It acts in a very naive way: just comparing the words with a dictionary.

The dictionary format is just a listing of words, one per line. src/stdlib.txt is the words/abbreviations/sequences of letters from the Rust standard library that are correct, but are not in my /usr/share/dict/words.

Known to work with Rust commit e09d98603 2014-11-18 23:51:43.


This is Cargo-enabled, and can be used as a normal Cargo dependency. Both the library/compiler plugin and the standalone executable are built with cargo build.


The checker comes as compiler plugin that enables it to run during the normal compilation process, it is used by simply loading the crate as a plugin. This causes the compiler to emit warnings (by default) for incorrect words via the misspellings lint; one can use #[deny(misspellings)] to make mistakes errors, and #[allow(misspellings)] to stop the warnings, like with other lints.

# Cargo.toml
name = "spellck_example"
version = "0.0.0"
authors = []

git = "https://github.com/huonw/spellck"

name = "spellck_example"
path = "spellck_example.rs"
crate_type = ["lib"]
// spellck_example.rs

#[phase(plugin)] extern crate spellck;

/// Bad dok coment
pub fn mispelled() {}

/// This is public, but poor speeling won't get a warning.
pub struct Notaword {
    pub madeuptext: uint

Any uses of the plugin must have the SPELLCK_LINT_DICT environment variable specified, pointing at the dictionary files to be used (compiler plugins cannot take any arguments yet). Multiple can be specified, in the same format as the platform's PATH variable.

$ SPELLCK_LINT_DICT=/usr/share/dict/words cargo build
       Fresh spellck v0.2.0 (https://github.com/huonw/spellck)
   Compiling spellck_example v0.0.0 (file:...)
spellck_example.rs:6:1: 6:19 warning: misspelled words: dok, coment, #[warn(misspellings)] on by default
spellck_example.rs:6 /// Bad dok coment
spellck_example.rs:7:1: 7:22 warning: misspelled word: mispelled, #[warn(misspellings)] on by default
spellck_example.rs:7 pub fn mispelled() {}

Words can also be added to the list of valid words using an attribute containing a string of space separated words in the crate root like so:

// lib.rs -- the crate root
#![spellck_extra_words="these are not in word list but are now"]

#[phase(plugin)] extern crate spellck;

At the moment, the explicit extern crate is required as there is no other way to load plugins (#15446). The extern crate declaration could have a #[cfg(check_spelling)] attribute, so that the lint is only loaded and run when compiled with --cfg check_spelling is specified.


The standalone binary spellck_standalone does not require loading a compiler plugin, it is used like spellck_standalone crate_file.rs. This defaults to using /usr/share/dict/words as the dictionary. (A default cargo build will output the resulting binary as target/spellck_standalone.)


  • -d, --dict: supply an extra dictionary, one word per line (can be listed multiple times)
  • -n, --no-def-dict: don't load /usr/share/dict/words by default