[common][typetraits] add noop function

dumux/experimental/common/CMakeLists.txt

 # SPDX-FileCopyrightInfo: Copyright © DuMux Project contributors, see AUTHORS.md in root folder
 # SPDX-License-Identifier: GPL-3.0-or-later
 
+add_subdirectory(typetraits)
 file(GLOB DUMUX_EXPERIMENTAL_COMMON_HEADERS *.hh *.inc)
 install(FILES ${DUMUX_EXPERIMENTAL_COMMON_HEADERS}
         DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/dumux/experimental/common)

dumux/experimental/common/typetraits/CMakeLists.txt

+# SPDX-FileCopyrightInfo: Copyright © DuMux Project contributors, see AUTHORS.md in root folder
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+file(GLOB DUMUX_EXPERIMENTAL_COMMON_TYPETRAITS_HEADERS *.hh *.inc)
+install(FILES ${DUMUX_EXPERIMENTAL_COMMON_TYPETRAITS_HEADERS}
+        DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/dumux/experimental/common/typetraits)

dumux/experimental/common/typetraits/typetraits.hh

+// -*- mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+// vi: set et ts=4 sw=4 sts=4:
+//
+// SPDX-FileCopyrightInfo: Copyright © DuMux Project contributors, see AUTHORS.md in root folder
+// SPDX-License-Identifier: GPL-3.0-or-later
+//
+/*!
+ * \file
+ * \ingroup Typetraits
+ * \brief Type traits.
+ */
+#ifndef DUMUX_EXPERIMENTAL_TYPE_TRAITS_HH
+#define DUMUX_EXPERIMENTAL_TYPE_TRAITS_HH
+
+#include <type_traits>
+
+namespace Dumux {
+
+/*!
+ * \brief Function that performs no operation.
+ */
+inline constexpr auto noop = [] (auto...) {};
+using Noop = decltype(noop);
+
+
+} // end namespace Dumux
+#endif