Add janky development shell

flake.lock

@@ -0,0 +1,48 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1733024928,
+        "narHash": "sha256-n/DOfpKH1vkukuBnach91QBQId2dr5tkE7/7UrkV2zw=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "2c27ab2e60502d1ebb7cf38909de38663f762a79",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs",
+        "rust-overlay": "rust-overlay"
+      }
+    },
+    "rust-overlay": {
+      "inputs": {
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1733020719,
+        "narHash": "sha256-Chv9+3zrf1DhdB9JyskjoV0vJbCQEgkVqrU3p4RPLv8=",
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "rev": "8e18f10703112e6c33e1c0d8b93e8305f6f0a75c",
+        "type": "github"
+      },
+      "original": {
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,43 @@
+{
+    description = "Advent of Code";
+
+    inputs = {
+        nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+        rust-overlay = {
+            url = "github:oxalica/rust-overlay";
+            inputs.nixpkgs.follows = "nixpkgs";
+        };
+    };
+
+    outputs = { nixpkgs, rust-overlay, ... }:
+    let
+        lib = nixpkgs.lib;
+        systems = ["x86_64-linux"];
+
+        forEachSystem = fn: lib.genAttrs systems (system:
+        let
+            overlays = [ (import rust-overlay) ];
+            pkgs = import nixpkgs { inherit system overlays; };
+        in fn { inherit pkgs; } );
+
+        mkRustToolchain = pkgs: pkgs.rust-bin.fromRustupToolchainFile ./rust-toolchain.toml;
+    in {
+        devShells = forEachSystem ({ pkgs }: let
+            rustToolchain = mkRustToolchain pkgs;
+            rustNightlyToolchain = pkgs.rust-bin.selectLatestNightlyWith (t: t.minimal.override {
+                extensions = [ "rustfmt" ];
+            });
+
+        rustShell = pkgs.mkShell {
+                name = "AoC";
+
+                nativeBuildInputs = [
+                    rustToolchain
+                    rustNightlyToolchain
+                ];
+            };
+        in {
+            default = rustShell;
+        });
+    };
+}

rust-toolchain.toml

@@ -0,0 +1,5 @@
+[toolchain]
+channel = "stable"
+components = ["clippy", "rust-analyzer", "rust-src"]
+targets = ["x86_64-unknown-linux-gnu"]
+profile = "minimal" # includes rustc, cargo, and rust-std

rustfmt.toml

@@ -0,0 +1,18 @@
+edition = "2021"
+
+# Just enforce it here as well instead of relying on editorconfig alone
+hard_tabs = false
+tab_spaces = 4
+newline_style = "Unix"
+
+imports_granularity = "Module"
+group_imports = "StdExternalCrate"
+
+force_multiline_blocks = false
+fn_single_line = false
+comment_width = 100
+wrap_comments = true
+hex_literal_case = "Upper"
+blank_lines_upper_bound = 2
+overflow_delimited_expr = true
+reorder_impl_items = true