nix-build: + xo-alloc2 working

default.nix

@@ -142,6 +142,7 @@ let
             xo-facet          = self.callPackage pkgs/xo-facet.nix          {};
             xo-allocutil      = self.callPackage pkgs/xo-allocutil.nix      {};
             xo-alloc          = self.callPackage pkgs/xo-alloc.nix          {}; # buildDocs = true;
+            xo-alloc2         = self.callPackage pkgs/xo-alloc2.nix         { buildDocs = true; };
             xo-refcnt         = self.callPackage pkgs/xo-refcnt.nix         {};
             xo-ordinaltree    = self.callPackage pkgs/xo-ordinaltree.nix    {};
             xo-flatstring     = self.callPackage pkgs/xo-flatstring.nix     { buildDocs = true; buildExamples = true; };
@@ -489,6 +490,7 @@ in
     facet          = pkgs.xo-facet;
     allocutil      = pkgs.xo-allocutil;
     alloc          = pkgs.xo-alloc;
+    alloc2         = pkgs.xo-alloc2;
     ordinaltree    = pkgs.xo-ordinaltree;
     flatstring     = pkgs.xo-flatstring;
     pyutil         = pkgs.xo-pyutil;

pkgs/xo-alloc2.nix

@@ -0,0 +1,69 @@
+{
+  # nixpkgs dependencies
+  lib, stdenv, cmake, catch2,
+  doxygen,
+
+  python3Packages,
+
+  sphinx, graphviz,
+
+  # xo dependencies
+  xo-facet,
+  xo-randomgen,
+  xo-subsys,
+#  xo-callback,
+#  xo-unit,
+#  xo-reflect,
+#  xo-randomgen,
+#  xo-reflectutil,
+#  xo-indentlog,
+#  xo-allocutil,
+  xo-cmake,
+
+  buildDocs ? false,
+  doCheck ? true,
+} :
+
+stdenv.mkDerivation (finalattrs:
+  {
+    name = "xo-alloc2";
+
+    src = ../xo-alloc2;
+
+    cmakeFlags = ["-DCMAKE_MODULE_PATH=${xo-cmake}/share/cmake"]
+                  ++ lib.optionals buildDocs ["-DXO_ENABLE_DOCS=on"]
+                  ++ lib.optionals doCheck ["-DENABLE_TESTING=1"];
+
+    inherit buildDocs;
+    inherit doCheck;
+
+    postBuild = lib.optionalString buildDocs ''
+      cmake --build . -- docs
+    '';
+
+    nativeBuildInputs = [
+      cmake
+      catch2
+      xo-randomgen
+      xo-cmake
+    ] ++ lib.optionals buildDocs [
+      doxygen
+      sphinx
+      graphviz
+      python3Packages.sphinx-rtd-theme
+      python3Packages.breathe
+      python3Packages.sphinxcontrib-ditaa
+      python3Packages.sphinxcontrib-plantuml
+      python3Packages.pillow
+    ];
+    propagatedBuildInputs = [
+      xo-facet
+      xo-subsys
+#      xo-callback
+#      xo-unit
+#      xo-reflect
+#      xo-allocutil
+#      xo-reflectutil
+#      xo-indentlog
+    ];
+  })