{ description = "Build a cargo project while also compiling the standard library"; inputs = { nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable"; crane.url = "github:ipetkov/crane"; flake-utils.url = "github:numtide/flake-utils"; rust-overlay = { url = "github:oxalica/rust-overlay"; inputs.nixpkgs.follows = "nixpkgs"; }; }; outputs = { self, nixpkgs, crane, flake-utils, rust-overlay, ... }: flake-utils.lib.eachSystem [ "x86_64-linux" ] (system: let pkgs = import nixpkgs { inherit system; overlays = [ (import rust-overlay) ]; }; rustToolchainFor = p: p.rust-bin.selectLatestNightlyWith (toolchain: toolchain.default.override { extensions = [ "rust-src" ]; targets = [ "x86_64-unknown-linux-gnu" ]; }); rustToolchain = rustToolchainFor pkgs; # NB: we don't need to overlay our custom toolchain for the *entire* # pkgs (which would require rebuidling anything else which uses rust). # Instead, we just want to update the scope that crane will use by appending # our specific toolchain there. craneLib = (crane.mkLib pkgs).overrideToolchain rustToolchainFor; src = craneLib.cleanCargoSource ./.; my-crate = craneLib.buildPackage { inherit src; strictDeps = true; cargoVendorDir = craneLib.vendorMultipleCargoDeps { inherit (craneLib.findCargoFiles src) cargoConfigs; cargoLockList = [ ./Cargo.lock # Unfortunately this approach requires IFD (import-from-derivation) # otherwise Nix will refuse to read the Cargo.lock from our toolchain # (unless we build with `--impure`). # # Another way around this is to manually copy the rustlib `Cargo.lock` # to the repo and import it with `./path/to/rustlib/Cargo.lock` which # will avoid IFD entirely but will require manually keeping the file # up to date! "${rustToolchain.passthru.availableComponents.rust-src}/lib/rustlib/src/rust/library/Cargo.lock" ]; }; cargoExtraArgs = "-Z build-std --target x86_64-unknown-linux-gnu"; buildInputs = [ # Add additional build inputs here ]; }; in { checks = { inherit my-crate; }; packages.default = my-crate; devShells.default = craneLib.devShell { # Inherit inputs from checks. checks = self.checks.${system}; # Extra inputs can be added here; cargo and rustc are provided by default # from the toolchain that was specified earlier. packages = [ ]; }; }); }