Add Nix flake: crane + fenix build, treefmt-nix formatting

Uses flake-parts to organize outputs, with nix/rust.nix defining a single craneLib/toolchain/commonArgs environment shared by the package build (nix/rust.nix) and the dev shell (nix/devshell.nix), so both stay close to identical. Deps are cached separately from the crate itself via crane's buildDepsOnly, giving incremental rebuilds. Checks cover clippy, rustfmt, cargo-doc, cargo-audit, and nextest; treefmt-nix wires up `nix fmt` for Rust/Nix/TOML files. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_018ALEXkc7pTro7tF1WcUuKb
2026-08-10 23:58:00 +08:00
parent 979e77571f
commit 840cea1f10
6 changed files with 393 additions and 0 deletions
@@ -0,0 +1,38 @@
+# Dev shell built from the same craneLib/toolchain as the package build
+# (nix/rust.nix), so the environment developers see locally matches what
+# `nix build` uses as closely as possible.
+{
+  pkgs,
+  lib,
+  rust,
+}:
+rust.craneLib.devShell {
+  inherit (rust) checks;
+
+  packages =
+    with pkgs;
+    [
+      cargo-nextest
+      cargo-criterion
+      cargo-audit
+      cargo-expand
+      taplo
+      bacon
+    ]
+    ++ lib.optionals pkgs.stdenv.isLinux [ mold ]
+    ++ lib.optionals pkgs.stdenv.isDarwin [
+      libiconv
+      darwin.apple_sdk.frameworks.Security
+      darwin.apple_sdk.frameworks.SystemConfiguration
+    ];
+
+  shellHook = ''
+    export RUST_SRC_PATH="${rust.rustToolchain}/lib/rustlib/src/rust/library"
+  ''
+  + lib.optionalString pkgs.stdenv.isLinux ''
+    export CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_LINKER="clang"
+    export CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_RUSTFLAGS="-C link-arg=-fuse-ld=mold"
+    export CARGO_TARGET_AARCH64_UNKNOWN_LINUX_GNU_LINKER="clang"
+    export CARGO_TARGET_AARCH64_UNKNOWN_LINUX_GNU_RUSTFLAGS="-C link-arg=-fuse-ld=mold"
+  '';
+}
@@ -0,0 +1,103 @@
+# Shared Rust build environment: toolchain, craneLib, source filtering,
+# and cached dependency artifacts. Consumed by both the package build
+# (nix/package.nix, implicit below) and the dev shell (nix/devshell.nix)
+# so the two stay close to identical.
+{
+  inputs,
+  pkgs,
+  system,
+  lib,
+}:
+let
+  fenixPkgs = inputs.fenix.packages.${system};
+
+  rustToolchain = fenixPkgs.stable.withComponents [
+    "cargo"
+    "clippy"
+    "llvm-tools"
+    "rust-analyzer"
+    "rust-src"
+    "rustc"
+    "rustfmt"
+  ];
+
+  craneLib = (inputs.crane.mkLib pkgs).overrideToolchain (_: rustToolchain);
+
+  src = craneLib.cleanCargoSource ./..;
+
+  commonArgs = {
+    inherit src;
+    strictDeps = true;
+
+    nativeBuildInputs = [
+      pkgs.pkg-config
+    ]
+    ++ lib.optionals pkgs.stdenv.isLinux [
+      pkgs.clang
+      pkgs.mold
+    ];
+
+    buildInputs = lib.optionals pkgs.stdenv.isDarwin [
+      pkgs.libiconv
+      pkgs.darwin.apple_sdk.frameworks.Security
+      pkgs.darwin.apple_sdk.frameworks.SystemConfiguration
+    ];
+  };
+
+  # Built once, reused by the package build, clippy, doc, and nextest —
+  # this is what makes incremental rebuilds fast under crane.
+  cargoArtifacts = craneLib.buildDepsOnly commonArgs;
+
+  package = craneLib.buildPackage (
+    commonArgs
+    // {
+      inherit cargoArtifacts;
+      pname = "rust_template";
+      doCheck = false; # exercised separately via checks.nextest
+    }
+  );
+
+  checks = {
+    clippy = craneLib.cargoClippy (
+      commonArgs
+      // {
+        inherit cargoArtifacts;
+        cargoClippyExtraArgs = "--all-targets -- --deny warnings";
+      }
+    );
+
+    doc = craneLib.cargoDoc (
+      commonArgs
+      // {
+        inherit cargoArtifacts;
+        env.RUSTDOCFLAGS = "--deny warnings";
+      }
+    );
+
+    fmt = craneLib.cargoFmt { inherit src; };
+
+    audit = craneLib.cargoAudit {
+      inherit src;
+      inherit (inputs) advisory-db;
+    };
+
+    nextest = craneLib.cargoNextest (
+      commonArgs
+      // {
+        inherit cargoArtifacts;
+        partitions = 1;
+        partitionType = "count";
+      }
+    );
+  };
+in
+{
+  inherit
+    craneLib
+    commonArgs
+    cargoArtifacts
+    package
+    checks
+    rustToolchain
+    ;
+}
@@ -0,0 +1,14 @@
+# treefmt-nix module: wires up `nix fmt` and the `formatting` check.
+_: {
+  perSystem = _: {
+    treefmt = {
+      projectRootFile = "flake.nix";
+
+      programs.rustfmt.enable = true;
+      programs.nixfmt.enable = true;
+      programs.deadnix.enable = true;
+      programs.statix.enable = true;
+      programs.taplo.enable = true;
+    };
+  };
+}