Merge pull request #202394 from figsoda/remove-carnix

}

```

## `buildRustCrate`: Compiling Rust crates using Nix instead of Cargo {#compiling-rust-crates-using-nix-instead-of-cargo}

### Simple operation {#simple-operation}

When run, `cargo build` produces a file called `Cargo.lock`,

containing pinned versions of all dependencies. Nixpkgs contains a

tool called `carnix` (`nix-env -iA nixos.carnix`), which can be used

to turn a `Cargo.lock` into a Nix expression.

That Nix expression calls `rustc` directly (hence bypassing Cargo),

and can be used to compile a crate and all its dependencies. Here is

an example for a minimal `hello` crate:

```ShellSession

$ cargo new hello

$ cd hello

$ cargo build

     Compiling hello v0.1.0 (file:///tmp/hello)

     Finished dev [unoptimized + debuginfo] target(s) in 0.20 secs

$ carnix -o hello.nix --src ./. Cargo.lock --standalone

$ nix-build hello.nix -A hello_0_1_0

```

Now, the file produced by the call to `carnix`, called `hello.nix`, looks like:

```nix

# Generated by carnix 0.6.5: carnix -o hello.nix --src ./. Cargo.lock --standalone

{ stdenv, buildRustCrate, fetchgit }:

let kernel = stdenv.buildPlatform.parsed.kernel.name;

    # ... (content skipped)

in

rec {

  hello = f: hello_0_1_0 { features = hello_0_1_0_features { hello_0_1_0 = f; }; };

  hello_0_1_0_ = { dependencies?[], buildDependencies?[], features?[] }: buildRustCrate {

    crateName = "hello";

    version = "0.1.0";

    authors = [ "pe@pijul.org <pe@pijul.org>" ];

    src = ./.;

    inherit dependencies buildDependencies features;

  };

  hello_0_1_0 = { features?(hello_0_1_0_features {}) }: hello_0_1_0_ {};

  hello_0_1_0_features = f: updateFeatures f (rec {

        hello_0_1_0.default = (f.hello_0_1_0.default or true);

    }) [ ];

}

```

In particular, note that the argument given as `--src` is copied

verbatim to the source. If we look at a more complicated

dependencies, for instance by adding a single line `libc="*"` to our

`Cargo.toml`, we first need to run `cargo build` to update the

`Cargo.lock`. Then, `carnix` needs to be run again, and produces the

following nix file:

```nix

# Generated by carnix 0.6.5: carnix -o hello.nix --src ./. Cargo.lock --standalone

{ stdenv, buildRustCrate, fetchgit }:

let kernel = stdenv.buildPlatform.parsed.kernel.name;

    # ... (content skipped)

in

rec {

  hello = f: hello_0_1_0 { features = hello_0_1_0_features { hello_0_1_0 = f; }; };

  hello_0_1_0_ = { dependencies?[], buildDependencies?[], features?[] }: buildRustCrate {

    crateName = "hello";

    version = "0.1.0";

    authors = [ "pe@pijul.org <pe@pijul.org>" ];

    src = ./.;

    inherit dependencies buildDependencies features;

  };

  libc_0_2_36_ = { dependencies?[], buildDependencies?[], features?[] }: buildRustCrate {

    crateName = "libc";

    version = "0.2.36";

    authors = [ "The Rust Project Developers" ];

    sha256 = "01633h4yfqm0s302fm0dlba469bx8y6cs4nqc8bqrmjqxfxn515l";

    inherit dependencies buildDependencies features;

  };

  hello_0_1_0 = { features?(hello_0_1_0_features {}) }: hello_0_1_0_ {

    dependencies = mapFeatures features ([ libc_0_2_36 ]);

  };

  hello_0_1_0_features = f: updateFeatures f (rec {

    hello_0_1_0.default = (f.hello_0_1_0.default or true);

    libc_0_2_36.default = true;

  }) [ libc_0_2_36_features ];

  libc_0_2_36 = { features?(libc_0_2_36_features {}) }: libc_0_2_36_ {

    features = mkFeatures (features.libc_0_2_36 or {});

  };

  libc_0_2_36_features = f: updateFeatures f (rec {

    libc_0_2_36.default = (f.libc_0_2_36.default or true);

    libc_0_2_36.use_std =

      (f.libc_0_2_36.use_std or false) ||

      (f.libc_0_2_36.default or false) ||

      (libc_0_2_36.default or false);

  }) [];

}

```

Here, the `libc` crate has no `src` attribute, so `buildRustCrate`

will fetch it from [crates.io](https://crates.io). A `sha256`

attribute is still needed for Nix purity.

### Handling external dependencies {#handling-external-dependencies}

Some crates require external libraries. For crates from

[crates.io](https://crates.io), such libraries can be specified in

`defaultCrateOverrides` package in nixpkgs itself.

Starting from that file, one can add more overrides, to add features

or build inputs by overriding the hello crate in a separate file.

```nix

with import <nixpkgs> {};

((import ./hello.nix).hello {}).override {

  crateOverrides = defaultCrateOverrides // {

    hello = attrs: { buildInputs = [ openssl ]; };

  };

}

```

Here, `crateOverrides` is expected to be a attribute set, where the

key is the crate name without version number and the value a function.

The function gets all attributes passed to `buildRustCrate` as first

argument and returns a set that contains all attribute that should be

overwritten.

For more complicated cases, such as when parts of the crate's

derivation depend on the crate's version, the `attrs` argument of

the override above can be read, as in the following example, which

patches the derivation:

```nix

with import <nixpkgs> {};

((import ./hello.nix).hello {}).override {

  crateOverrides = defaultCrateOverrides // {

    hello = attrs: lib.optionalAttrs (lib.versionAtLeast attrs.version "1.0")  {

      postPatch = ''

        substituteInPlace lib/zoneinfo.rs \

          --replace "/usr/share/zoneinfo" "${tzdata}/share/zoneinfo"

      '';

    };

  };

}

```

Another situation is when we want to override a nested

dependency. This actually works in the exact same way, since the

`crateOverrides` parameter is forwarded to the crate's

dependencies. For instance, to override the build inputs for crate

`libc` in the example above, where `libc` is a dependency of the main

crate, we could do:

```nix

with import <nixpkgs> {};

((import hello.nix).hello {}).override {

  crateOverrides = defaultCrateOverrides // {

    libc = attrs: { buildInputs = []; };

  };

}

```

### Options and phases configuration {#options-and-phases-configuration}

Actually, the overrides introduced in the previous section are more

general. A number of other parameters can be overridden:

- The version of `rustc` used to compile the crate:

  ```nix

  (hello {}).override { rust = pkgs.rust; };

  ```

- Whether to build in release mode or debug mode (release mode by

  default):

  ```nix

  (hello {}).override { release = false; };

  ```

- Whether to print the commands sent to `rustc` when building

  (equivalent to `--verbose` in cargo:

  ```nix

  (hello {}).override { verbose = false; };

  ```

- Extra arguments to be passed to `rustc`:

  ```nix

  (hello {}).override { extraRustcOpts = "-Z debuginfo=2"; };

  ```

- Phases, just like in any other derivation, can be specified using

  the following attributes: `preUnpack`, `postUnpack`, `prePatch`,

  `patches`, `postPatch`, `preConfigure` (in the case of a Rust crate,

  this is run before calling the "build" script), `postConfigure`

  (after the "build" script),`preBuild`, `postBuild`, `preInstall` and

  `postInstall`. As an example, here is how to create a new module

  before running the build script:

  ```nix

  (hello {}).override {

    preConfigure = ''

       echo "pub const PATH=\"${hi.out}\";" >> src/path.rs"

    '';

  };

  ```

### Features {#features}

One can also supply features switches. For example, if we want to

compile `diesel_cli` only with the `postgres` feature, and no default

features, we would write:

```nix

(callPackage ./diesel.nix {}).diesel {

  default = false;

  postgres = true;

}

```

Where `diesel.nix` is the file generated by Carnix, as explained above.

## Setting Up `nix-shell` {#setting-up-nix-shell}

Oftentimes you want to develop code from within `nix-shell`. Unfortunately

    <itemizedlist spacing="compact">

      <listitem>

        <para>

          Create the first release note entry in this section!

          <literal>carnix</literal> and <literal>cratesIO</literal> has

          been removed due to being unmaintained, use alternatives such

          as

          <link xlink:href="https://github.com/nix-community/naersk">naersk</link>

          and

          <link xlink:href="https://github.com/kolloch/crate2nix">crate2nix</link>

          instead.

        </para>

      </listitem>

    </itemizedlist>

<!-- To avoid merge conflicts, consider adding your item at an arbitrary place in the list instead. -->

- Create the first release note entry in this section!

- `carnix` and `cratesIO` has been removed due to being unmaintained, use alternatives such as [naersk](https://github.com/nix-community/naersk) and [crate2nix](https://github.com/kolloch/crate2nix) instead.

## Other Notable Changes {#sec-release-23.05-notable-changes}

# Generated by carnix 0.9.10: carnix generate-nix

{ lib, buildPlatform, buildRustCrate, buildRustCrateHelpers, cratesIO, fetchgit }:

with buildRustCrateHelpers;

let inherit (lib.lists) fold;

    inherit (lib.attrsets) recursiveUpdate;

in

rec {

  crates = cratesIO;

  carnix = crates.crates.carnix."0.10.0" deps;

  __all = [ (carnix {}) ];

  deps.aho_corasick."0.6.10" = {

    memchr = "2.2.0";

  };

  deps.ansi_term."0.11.0" = {

    winapi = "0.3.6";

  };

  deps.argon2rs."0.2.5" = {

    blake2_rfc = "0.2.18";

    scoped_threadpool = "0.1.9";

  };

  deps.arrayvec."0.4.10" = {

    nodrop = "0.1.13";

  };

  deps.atty."0.2.11" = {

    termion = "1.5.1";

    libc = "0.2.50";

    winapi = "0.3.6";

  };

  deps.autocfg."0.1.2" = {};

  deps.backtrace."0.3.14" = {

    cfg_if = "0.1.7";

    rustc_demangle = "0.1.13";

    autocfg = "0.1.2";

    backtrace_sys = "0.1.28";

    libc = "0.2.50";

    winapi = "0.3.6";

  };

  deps.backtrace_sys."0.1.28" = {

    libc = "0.2.50";

    cc = "1.0.32";

  };

  deps.bitflags."1.0.4" = {};

  deps.blake2_rfc."0.2.18" = {

    arrayvec = "0.4.10";

    constant_time_eq = "0.1.3";

  };

  deps.carnix."0.10.0" = {

    clap = "2.32.0";

    dirs = "1.0.5";

    env_logger = "0.6.1";

    failure = "0.1.5";

    failure_derive = "0.1.5";

    itertools = "0.8.0";

    log = "0.4.6";

    nom = "3.2.1";

    regex = "1.1.2";

    serde = "1.0.89";

    serde_derive = "1.0.89";

    serde_json = "1.0.39";

    tempdir = "0.3.7";

    toml = "0.5.0";

    url = "1.7.2";

  };

  deps.cc."1.0.32" = {};

  deps.cfg_if."0.1.7" = {};

  deps.clap."2.32.0" = {

    atty = "0.2.11";

    bitflags = "1.0.4";

    strsim = "0.7.0";

    textwrap = "0.10.0";

    unicode_width = "0.1.5";

    vec_map = "0.8.1";

    ansi_term = "0.11.0";

  };

  deps.cloudabi."0.0.3" = {

    bitflags = "1.0.4";

  };

  deps.constant_time_eq."0.1.3" = {};

  deps.dirs."1.0.5" = {

    redox_users = "0.3.0";

    libc = "0.2.50";

    winapi = "0.3.6";

  };

  deps.either."1.5.1" = {};

  deps.env_logger."0.6.1" = {

    atty = "0.2.11";

    humantime = "1.2.0";

    log = "0.4.6";

    regex = "1.1.2";

    termcolor = "1.0.4";

  };

  deps.failure."0.1.5" = {

    backtrace = "0.3.14";

    failure_derive = "0.1.5";

  };

  deps.failure_derive."0.1.5" = {

    proc_macro2 = "0.4.27";

    quote = "0.6.11";

    syn = "0.15.29";

    synstructure = "0.10.1";

  };

  deps.fuchsia_cprng."0.1.1" = {};

  deps.humantime."1.2.0" = {

    quick_error = "1.2.2";

  };

  deps.idna."0.1.5" = {

    matches = "0.1.8";

    unicode_bidi = "0.3.4";

    unicode_normalization = "0.1.8";

  };

  deps.itertools."0.8.0" = {

    either = "1.5.1";

  };

  deps.itoa."0.4.3" = {};

  deps.lazy_static."1.3.0" = {};

  deps.libc."0.2.50" = {};

  deps.log."0.4.6" = {

    cfg_if = "0.1.7";

  };

  deps.matches."0.1.8" = {};

  deps.memchr."1.0.2" = {

    libc = "0.2.50";

  };

  deps.memchr."2.2.0" = {};

  deps.nodrop."0.1.13" = {};

  deps.nom."3.2.1" = {

    memchr = "1.0.2";

  };

  deps.percent_encoding."1.0.1" = {};

  deps.proc_macro2."0.4.27" = {

    unicode_xid = "0.1.0";

  };

  deps.quick_error."1.2.2" = {};

  deps.quote."0.6.11" = {

    proc_macro2 = "0.4.27";

  };

  deps.rand."0.4.6" = {

    rand_core = "0.3.1";

    rdrand = "0.4.0";

    fuchsia_cprng = "0.1.1";

    libc = "0.2.50";

    winapi = "0.3.6";

  };

  deps.rand_core."0.3.1" = {

    rand_core = "0.4.0";

  };

  deps.rand_core."0.4.0" = {};

  deps.rand_os."0.1.3" = {

    rand_core = "0.4.0";

    rdrand = "0.4.0";

    cloudabi = "0.0.3";

    fuchsia_cprng = "0.1.1";

    libc = "0.2.50";

    winapi = "0.3.6";

  };

  deps.rdrand."0.4.0" = {

    rand_core = "0.3.1";

  };

  deps.redox_syscall."0.1.51" = {};

  deps.redox_termios."0.1.1" = {

    redox_syscall = "0.1.51";

  };

  deps.redox_users."0.3.0" = {

    argon2rs = "0.2.5";

    failure = "0.1.5";

    rand_os = "0.1.3";

    redox_syscall = "0.1.51";

  };

  deps.regex."1.1.2" = {

    aho_corasick = "0.6.10";

    memchr = "2.2.0";

    regex_syntax = "0.6.5";

    thread_local = "0.3.6";

    utf8_ranges = "1.0.2";

  };

  deps.regex_syntax."0.6.5" = {

    ucd_util = "0.1.3";

  };

  deps.remove_dir_all."0.5.1" = {

    winapi = "0.3.6";

  };

  deps.rustc_demangle."0.1.13" = {};

  deps.ryu."0.2.7" = {};

  deps.scoped_threadpool."0.1.9" = {};

  deps.serde."1.0.89" = {};

  deps.serde_derive."1.0.89" = {

    proc_macro2 = "0.4.27";

    quote = "0.6.11";

    syn = "0.15.29";

  };

  deps.serde_json."1.0.39" = {

    itoa = "0.4.3";

    ryu = "0.2.7";

    serde = "1.0.89";

  };

  deps.smallvec."0.6.9" = {};

  deps.strsim."0.7.0" = {};

  deps.syn."0.15.29" = {

    proc_macro2 = "0.4.27";

    quote = "0.6.11";

    unicode_xid = "0.1.0";

  };

  deps.synstructure."0.10.1" = {

    proc_macro2 = "0.4.27";

    quote = "0.6.11";

    syn = "0.15.29";

    unicode_xid = "0.1.0";

  };

  deps.tempdir."0.3.7" = {

    rand = "0.4.6";

    remove_dir_all = "0.5.1";

  };

  deps.termcolor."1.0.4" = {

    wincolor = "1.0.1";

  };

  deps.termion."1.5.1" = {

    libc = "0.2.50";

    redox_syscall = "0.1.51";

    redox_termios = "0.1.1";

  };

  deps.textwrap."0.10.0" = {

    unicode_width = "0.1.5";

  };

  deps.thread_local."0.3.6" = {

    lazy_static = "1.3.0";

  };

  deps.toml."0.5.0" = {

    serde = "1.0.89";

  };

  deps.ucd_util."0.1.3" = {};

  deps.unicode_bidi."0.3.4" = {

    matches = "0.1.8";

  };

  deps.unicode_normalization."0.1.8" = {

    smallvec = "0.6.9";

  };

  deps.unicode_width."0.1.5" = {};

  deps.unicode_xid."0.1.0" = {};

  deps.url."1.7.2" = {

    idna = "0.1.5";

    matches = "0.1.8";

    percent_encoding = "1.0.1";

  };

  deps.utf8_ranges."1.0.2" = {};

  deps.vec_map."0.8.1" = {};

  deps.winapi."0.3.6" = {

    winapi_i686_pc_windows_gnu = "0.4.0";

    winapi_x86_64_pc_windows_gnu = "0.4.0";

  };

  deps.winapi_i686_pc_windows_gnu."0.4.0" = {};

  deps.winapi_util."0.1.2" = {

    winapi = "0.3.6";

  };

  deps.winapi_x86_64_pc_windows_gnu."0.4.0" = {};

  deps.wincolor."1.0.1" = {

    winapi = "0.3.6";

    winapi_util = "0.1.2";

  };

}