feat: add nix flake (try 1)

Author: dsully

flake.lock

@@ -0,0 +1,55 @@
+{
+  description = "Devmoji git log";
+
+  inputs = {
+    nixpkgs.url = "https://flakehub.com/f/NixOS/nixpkgs/0.1.*.tar.gz";
+    rust-overlay = {
+      url = "github:oxalica/rust-overlay";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+  };
+
+  outputs = {
+    self,
+    nixpkgs,
+    rust-overlay,
+  }: let
+    supportedSystems = ["x86_64-linux" "aarch64-linux" "x86_64-darwin" "aarch64-darwin"];
+    forEachSupportedSystem = f:
+      nixpkgs.lib.genAttrs supportedSystems (system:
+        f {
+          pkgs = import nixpkgs {
+            inherit system;
+            overlays = [rust-overlay.overlays.default self.overlays.default];
+          };
+        });
+  in {
+    overlays.default = final: prev: {
+      rustToolchain = let
+        rust = prev.rust-bin;
+      in
+        if builtins.pathExists ./rust-toolchain.toml
+        then rust.fromRustupToolchainFile ./rust-toolchain.toml
+        else if builtins.pathExists ./rust-toolchain
+        then rust.fromRustupToolchainFile ./rust-toolchain
+        else
+          rust.stable.latest.default.override {
+            extensions = ["rust-src" "rustfmt"];
+          };
+    };
+
+    devShells = forEachSupportedSystem ({pkgs}: {
+      default = pkgs.mkShell {
+        packages = with pkgs; [
+          rustToolchain
+          rust-analyzer
+        ];
+
+        env = {
+          # Required by rust-analyzer
+          RUST_SRC_PATH = "${pkgs.rustToolchain}/lib/rustlib/src/rust/library";
+        };
+      };
+    });
+  };
+}

flake.nix

@@ -0,0 +1,3 @@
+[toolchain]
+channel = "stable"
+components = [ "rust-analyzer" ]