Add a nix flake for people on nixos

This is also very nice since it always supplies a known working version of the deps (xmake)

flake.nix

@@ -0,0 +1,44 @@
+{
+  description = "Tilted C++ development environment";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, flake-utils }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = import nixpkgs {
+          inherit system;
+        };
+      in
+      {
+        devShells.default = pkgs.mkShell {
+          buildInputs = with pkgs; [
+            gcc14
+            gdb
+            libclang
+            cmake
+            xmake
+            gnumake
+          ];
+
+          shellHook = ''
+            # Unset environment variables, required for xmake to find
+            # the linker/compiler that we provide here
+            unset CC
+            unset CXX
+            unset LD
+            unset AR
+            unset AS
+            unset RANLIB
+            unset STRIP
+            unset CFLAGS
+            unset CXXFLAGS
+            unset LDFLAGS
+            echo "C++ development environment loaded"
+          '';
+        };
+      });
+}