How to get cargo miri as a check

[TheNeikos]

I've looked at the cargoFmt command, but I am not sure how to get it to run.

Did someone get it to work yet? I understand its a bit more 'difficult' because of the extra toolchain because miri is nightly only?

[ipetkov]

I haven't used cargo miri as of yet, so pardon the light speculation here, but I think as long as the toolchain contains the miri component and as long as cargo miri can safely run from inside of the Nix sandbox it should be as simple as:

1. Add the toolchain derivation as a nativeBuildInput for the crate's derivation
2. Call cargo miri in a test phase

I did notice that the miri README mentioned:

The first time you run Miri, it will perform some extra setup and install some dependencies. It will ask you for confirmation before installing anything.

Not sure if this means miri needs to install its own additional components from the network the first time it runs. It would be interesting if they could be packaged up for general Nix consumption if that's the case...

[ipetkov]

Okay, judging from the output of cargo +nightly miri setup we need:

• A recent build of xargo. This is something that can be packaged since it's a cargo project
• The stdlib source, which needs to come from the rust-src component of the toolchain

[TheNeikos]

Alright! I got it working with the following steps:

• Acquire an unstable rust toolchain (I am using oxalicas rust overlay):

          unstableRustTarget = pkgs.rust-bin.selectLatestNightlyWith (toolchain: toolchain.default.override {
            extensions = [ "rust-src" "miri" ];
          });

• build the latest xargo (I am not show how miri checks what the 'latest' is, but it is needed or it will try downloading?)

         xargo = pkgs.rustPlatform.buildRustPackage
            rec {
              pname = "xargo";
              version = "0.3.26";

              src = pkgs.fetchFromGitHub {
                owner = "japaric";
                repo = pname;
                rev = "v${version}";
                hash = "sha256-MPopR58EIPiLg79wxf3nDy6SitdsmuUCjOLut8+fFJ4=";
              };

              cargoHash = "sha256-LmOu7Ni6TkACHy/ZG8ASG/P2UWEs3Qljz4RGSW1i3zk=";

              doCheck = false;

              buildInputs = [ ];
              nativeBuildInputs = [ ];
            };

• set the XARGO_RUST_SRC env variable to ${unstableRustTarget}/lib/rustlib/src/rust/library
• Run cargo miri test !
• Enjoy!

[TheNeikos]

Now, the last step is to get lib.cargoBuild to work together with it.

The only thing I think can be problematic, is that the xargo version and the miri version need to match up somehow. I am not sure how this can be automated...

[ipetkov]

I'd be open to packaging up xargo locally within crane, I'd anticipate that as long as we have a recent xargo version miri should just work

[ipetkov]

I tried out adding a wrapper which pulls in xargo, but the problem I ran into is that xargo does not play nicely with Nix's sandbox. it appears to insist on grabbing a lock in the sysroot which crashes on any invocation

[JeremiahSecrist]

maybe a temp directory could be used in which the sysroot data is copied over to satisfy this constraint? I recently got interested in miri for extra testing for my projects and found this thread. I hope raising a 2 year old conversation isn't an issue.

[tjjfvi]

For anyone looking to do this now that miri no longer uses xargo, I was able to get it working with the following:

checks.miri = craneLib.mkCargoDerivation (
  craneConfig # base config, with `src`, `cargoArtifacts`, etc.
  // {
    name = "miri-tests";
    buildPhaseCargoCommand = ''
      # test with miri
      cargo miri run ...
    '';
    doInstallCargoArtifacts = false;
    MIRI_SYSROOT = craneLib.mkCargoDerivation {
      pname = "miri-sysroot";
      version = "0.0.0";
      dontUnpack = true;
      buildPhaseCargoCommand = ''
        MIRI_SYSROOT=$out cargo miri setup
      '';
      dontFixup = true;
      cargoLock =
        pkgs.runCommand "sysroot-cargoLock"
          { nativeBuildInputs = [ rustToolchain ]; }
          ''
            cp `rustc --print sysroot`/lib/rustlib/src/rust/library/Cargo.lock $out
          '';
      cargoArtifacts = null;
    };
  }
);