libsForQt5 = prev.libsForQt5 // {
                qtdeclarative = prev.libsForQt5.qtdeclarative.overrideAttrs (_: {
                  version = "5.15-e203a18";
                  src = prev.fetchFromGitHub {
                    owner = "qt";
                    repo = "qtdeclarative";
                    rev = "5.15";
                    sha256 = "hjR7baOeFihEzH7ABk77YjaLKvBArPvYKyTmShnZvCk=";
                  };
                });
                full = with final.libsForQt5; env "qt-full-${qtbase.version}" ([
                  qtcharts qtconnectivity qtdeclarative qtdoc qtgraphicaleffects
                  qtimageformats qtlocation qtmultimedia qtquickcontrols qtquickcontrols2
                  qtscript qtsensors qtserialport qtsvg qttools qttranslations
                  qtvirtualkeyboard qtwebchannel qtwebengine qtwebkit qtwebsockets
                  qtwebview qtx11extras qtxmlpatterns
                ] ++ prev.lib.optional (!prev.stdenv.isDarwin) qtwayland
                  ++ prev.lib.optional (prev.stdenv.isDarwin) qtmacextras);
              };

error: attribute 'override' missing, at /nix/var/nix/profiles/per-user/root/channels/nixos/nixos/modules/programs/ccache.nix:53:54