cargoDeps = rustPlatform.importCargoLock {
    lockFile = ./Cargo.lock;
    outputHashes = {
      "rand-0.8.3" = "0ya2hia3cn31qa8894s3av2s8j5bjwb6yq92k0jsnlx7jid0jwqa";
    };
  };
}
```

If you do not specify an output hash for a git dependency, building
`cargoDeps` will fail and inform you of which crate needs to be
added. To find the correct hash, you can first use `lib.fakeSha256` or
`lib.fakeHash` as a stub hash. Building `cargoDeps` will then inform
you of the correct hash.

#### Hooks {#hooks}

`rustPlatform` provides the following hooks to automate Cargo builds:

* `cargoSetupHook`: configure Cargo to use dependencies vendored
  through `fetchCargoVendor` or `importCargoLock`. This hook uses the
  `cargoDeps` environment variable to find the vendored
  dependencies. If a project already vendors its dependencies, the
  variable `cargoVendorDir` can be used instead. When the
  `Cargo.toml`/`Cargo.lock` files are not in `sourceRoot`, then the
  optional `cargoRoot` is used to specify the Cargo root directory
  relative to `sourceRoot`.
* `cargoBuildHook`: use Cargo to build a crate. If the crate to be
  built is a crate in e.g. a Cargo workspace, the relative path to the
  crate to build can be set through the optional `buildAndTestSubdir`
  environment variable. Features can be specified with
  `cargoBuildNoDefaultFeatures` and `cargoBuildFeatures`. Additional
  Cargo build flags can be passed through `cargoBuildFlags`.
* `maturinBuildHook`: use [Maturin](https://github.com/PyO3/maturin)
  to build a Python wheel. Similar to `cargoBuildHook`, the optional
  variable `buildAndTestSubdir` can be used to build a crate in a
  Cargo workspace. Additional Maturin flags can be passed through
  `maturinBuildFlags`.
* `cargoCheckHook`: run tests using Cargo. The build type for checks
  can be set using `cargoCheckType`. Features can be specified with
  `cargoCheckNoDefaultFeatures` and `cargoCheckFeatures`. Additional
  flags can be passed to the tests using `checkFlags` and
  `checkFlagsArray`. By default, tests are run in parallel. This can
  be disabled by setting `dontUseCargoParallelTests`.
* `cargoNextestHook`: run tests using
  [cargo-nextest](https://github.com/nextest-rs/nextest). The same
  options for `cargoCheckHook` also applies to `cargoNextestHook`.
* `cargoInstallHook`: install binaries and static/shared libraries
  that were built using `cargoBuildHook`.
* `bindgenHook`: for crates which use `bindgen` as a build dependency, lets
  `bindgen` find `libclang` and `libclang` find the libraries in `buildInputs`.

#### Examples {#examples}

#### Python package using `setuptools-rust` {#python-package-using-setuptools-rust}

For Python packages using `setuptools-rust`, you can use
`fetchCargoVendor` and `cargoSetupHook` to retrieve and set up Cargo
dependencies. The build itself is then performed by
`buildPythonPackage`.

The following example outlines how the `tokenizers` Python package is
built. Since the Python package is in the `source/bindings/python`
directory of the `tokenizers` project's source archive, we use
`sourceRoot` to point the tooling to this directory:

```nix
{
  fetchFromGitHub,
  buildPythonPackage,
  cargo,
  rustPlatform,
  rustc,
  setuptools-rust,
}:

buildPythonPackage rec {
  pname = "tokenizers";
  version = "0.10.0";

  src = fetchFromGitHub {
    owner = "huggingface";
    repo = "tokenizers";
    tag = "python-v${version}";
    hash = "sha256-rQ2hRV52naEf6PvRsWVCTN7B1oXAQGmnpJw4iIdhamw=";
  };

  cargoDeps = rustPlatform.fetchCargoVendor {
    inherit
      pname
      version
      src
      sourceRoot
      ;
    hash = "sha256-RO1m8wEd5Ic2M9q+zFHeCJWhCr4Sv3CEWd08mkxsBec=";
  };

  sourceRoot = "${src.name}/bindings/python";

  nativeBuildInputs = [
    cargo
    rustPlatform.cargoSetupHook
    rustc
    setuptools-rust
  ];

  # ...
}
```

In some projects, the Rust crate is not in the main Python source
directory.  In such cases, the `cargoRoot` attribute can be used to
specify the crate's directory relative to `sourceRoot`. In the