From a569142769bfe32f37c9c1418d40f2c49524b34c Mon Sep 17 00:00:00 2001
From: Pablo Deymonnaz <pdeymon@fi.uba.ar>
Date: Wed, 18 Feb 2026 19:32:23 -0300
Subject: [PATCH] Add nix flake with dev shell and package build

  Provides a nix flake using crane + rust-overlay for building ethlambda
  and a development shell with Rust 1.92.0, clippy, rustfmt, and system
  dependencies (libclang, pkg-config). Includes direnv integration via
  .envrc and handles vergen-git2 env var fallback for nix builds where
  .git is absent.
---
 .envrc     |  1 +
 flake.lock | 64 ++++++++++++++++++++++++++++++++++++
 flake.nix  | 96 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 161 insertions(+)
 create mode 100644 .envrc
 create mode 100644 flake.lock
 create mode 100644 flake.nix

diff --git a/.envrc b/.envrc
new file mode 100644
index 0000000..3550a30
--- /dev/null
+++ b/.envrc
@@ -0,0 +1 @@
+use flake
diff --git a/flake.lock b/flake.lock
new file mode 100644
index 0000000..fb30092
--- /dev/null
+++ b/flake.lock
@@ -0,0 +1,64 @@
+{
+  "nodes": {
+    "crane": {
+      "locked": {
+        "lastModified": 1771438068,
+        "narHash": "sha256-nGBbXvEZVe/egCPVPFcu89RFtd8Rf6J+4RFoVCFec0A=",
+        "owner": "ipetkov",
+        "repo": "crane",
+        "rev": "b5090e53e9d68c523a4bb9ad42b4737ee6747597",
+        "type": "github"
+      },
+      "original": {
+        "owner": "ipetkov",
+        "repo": "crane",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1771177547,
+        "narHash": "sha256-trTtk3WTOHz7hSw89xIIvahkgoFJYQ0G43IlqprFoMA=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "ac055f38c798b0d87695240c7b761b82fc7e5bc2",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "crane": "crane",
+        "nixpkgs": "nixpkgs",
+        "rust-overlay": "rust-overlay"
+      }
+    },
+    "rust-overlay": {
+      "inputs": {
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1771384185,
+        "narHash": "sha256-KvmjUeA7uODwzbcQoN/B8DCZIbhT/Q/uErF1BBMcYnw=",
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "rev": "23dd7fa91602a68bd04847ac41bc10af1e6e2fd2",
+        "type": "github"
+      },
+      "original": {
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}
diff --git a/flake.nix b/flake.nix
new file mode 100644
index 0000000..84b0139
--- /dev/null
+++ b/flake.nix
@@ -0,0 +1,96 @@
+{
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+
+    rust-overlay = {
+      url = "github:oxalica/rust-overlay";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+
+    crane.url = "github:ipetkov/crane";
+  };
+
+  outputs = { self, nixpkgs, rust-overlay, crane }:
+    let
+      supportedSystems = [ "x86_64-linux" "aarch64-linux" "x86_64-darwin" "aarch64-darwin" ];
+      forAllSystems = nixpkgs.lib.genAttrs supportedSystems;
+
+      mkPkgs = system: import nixpkgs {
+        inherit system;
+        overlays = [ rust-overlay.overlays.default ];
+      };
+
+      rustToolchain = pkgs: pkgs.rust-bin.stable."1.92.0".default.override {
+        extensions = [ "clippy" "rustfmt" ];
+      };
+
+      mkCraneLib = pkgs: (crane.mkLib pkgs).overrideToolchain (rustToolchain pkgs);
+    in
+    {
+      packages = forAllSystems (system:
+        let
+          pkgs = mkPkgs system;
+          craneLib = mkCraneLib pkgs;
+
+          commonArgs = {
+            pname = "ethlambda";
+            src = craneLib.cleanCargoSource ./.;
+            strictDeps = true;
+
+            nativeBuildInputs = with pkgs; [
+              pkg-config
+            ];
+
+            buildInputs = with pkgs; [
+              llvmPackages.libclang
+            ] ++ pkgs.lib.optionals pkgs.stdenv.hostPlatform.isDarwin (with pkgs; [
+              libiconv
+              apple-sdk_15
+            ]);
+
+            LIBCLANG_PATH = "${pkgs.llvmPackages.libclang.lib}/lib";
+
+            # vergen-git2 falls back to env vars when .git is absent
+            VERGEN_GIT_SHA = self.shortRev or self.dirtyShortRev or "unknown";
+            VERGEN_GIT_BRANCH = "nix";
+          };
+
+          cargoArtifacts = craneLib.buildDepsOnly commonArgs;
+
+          ethlambda = craneLib.buildPackage (commonArgs // {
+            inherit cargoArtifacts;
+            # Only install the main binary
+            cargoExtraArgs = "--bin ethlambda";
+          });
+        in
+        {
+          default = ethlambda;
+          inherit ethlambda;
+        }
+      );
+
+      devShells = forAllSystems (system:
+        let
+          pkgs = mkPkgs system;
+        in
+        {
+          default = pkgs.mkShell {
+            nativeBuildInputs = with pkgs; [
+              (rustToolchain pkgs)
+              pkg-config
+              cargo-watch
+            ];
+
+            buildInputs = with pkgs; [
+              llvmPackages.libclang
+            ] ++ pkgs.lib.optionals pkgs.stdenv.hostPlatform.isDarwin (with pkgs; [
+              libiconv
+              apple-sdk_15
+            ]);
+
+            LIBCLANG_PATH = "${pkgs.llvmPackages.libclang.lib}/lib";
+          };
+        }
+      );
+    };
+}