add python dependency sphinx-sitemap

flake.nix

@@ -9,12 +9,17 @@
       let
         pkgs = import nixpkgs {
           inherit system;
+          overlays = [
+            # Add sphinx-sitemap from an overlay until
+            # it becomes available from nixpkgs-unstable
+            (import ./overlay.nix)
+          ];
         };
       in {
         packages.default = pkgs.stdenv.mkDerivation {
           name = "nix-dev";
           src = self;
-          buildInputs = with pkgs.python310Packages; [
+          buildInputs = with pkgs.python310.pkgs; [
             livereload
             linkify-it-py
             myst-parser
@@ -23,6 +28,7 @@
             sphinx-copybutton
             sphinx-design
             sphinx-notfound-page
+            sphinx-sitemap
             black
           ];
           buildPhase = ''

overlay.nix

@@ -0,0 +1,50 @@
+final: prev: let
+  python-module-sphinx-sitemap = {
+    lib,
+    buildPythonPackage,
+    fetchPypi,
+    sphinx,
+    pytest,
+  }: let
+    pname = "sphinx-sitemap";
+    version = "2.5.1";
+  in
+    buildPythonPackage {
+      inherit pname version;
+
+      src = fetchPypi {
+        inherit pname version;
+        sha256 = "sha256-mEvvBou9vCbPriCai2E5LpaBq8kZG0d80w2kBuOmDuU=";
+      };
+
+      propagatedBuildInputs = [
+        sphinx
+      ];
+
+      nativeCheckInputs = [
+        pytest
+      ];
+
+      doCheck = true;
+      checkPhase = ''
+        pytest --fixtures tests
+      '';
+
+      meta = with lib; {
+        description = "Sitemap generator for Sphinx";
+        homepage = "https://github.com/jdillard/sphinx-sitemap";
+        maintainers = with maintainers; [ ];
+        license = licenses.mit;
+      };
+    };
+in {
+  python310 = prev.python310.override {
+    packageOverrides = python-final: python-prev: {
+      sphinx-sitemap = python-module-sphinx-sitemap {
+        inherit (prev) lib;
+        inherit (python-prev) buildPythonPackage fetchPypi pytest;
+        inherit (python-prev.pkgs) sphinx;
+      };
+    };
+  };
+}