libsForQt5.pix: fix build

pkgs/applications/maui/pix.nix

@@ -17,8 +17,17 @@
   qtlocation,
   exiv2,
   kquickimageedit,
+  fetchFromGitHub,
 }:
 
+let
+  src-kdtree = fetchFromGitHub {
+    owner = "cdalitz";
+    repo = "kdtree-cpp";
+    rev = "refs/tags/v1.3";
+    hash = "sha256-h3cmndvjMlp/MTk/Ve3R183BLrE7VbL7GQx8YkOHEgU=";
+  };
+in
 mkDerivation {
   pname = "pix";
 
@@ -27,6 +36,18 @@ mkDerivation {
     extra-cmake-modules
   ];
 
+  postPatch = ''
+    cp ${src-kdtree}/kdtree.cpp src/
+    substituteInPlace src/CMakeLists.txt \
+      --replace-fail "main.cpp" "main.cpp kdtree.cpp"
+  '';
+
+  env = {
+    NIX_CFLAGS_COMPILE = toString [
+      "-I${src-kdtree}"
+    ];
+  };
+
   buildInputs = [
     applet-window-buttons
     karchive
@@ -44,11 +65,11 @@ mkDerivation {
     kquickimageedit
   ];
 
-  meta = with lib; {
+  meta = {
     description = "Image gallery application";
     mainProgram = "pix";
     homepage = "https://invent.kde.org/maui/pix";
-    license = licenses.gpl3Plus;
-    maintainers = with maintainers; [ onny ];
+    license = lib.licenses.gpl3Plus;
+    maintainers = with lib.maintainers; [ onny ];
   };
 }