move the Unused.hpp file from opm-material to here

CMakeLists_files.cmake

@@ -54,6 +54,7 @@ list (APPEND PROGRAM_SOURCE_FILES
 list( APPEND PUBLIC_HEADER_FILES
       opm/common/ErrorMacros.hpp
       opm/common/Exceptions.hpp
+      opm/common/Unused.hpp
       opm/common/data/SimulationDataContainer.hpp
       opm/common/OpmLog/CounterLog.hpp
       opm/common/OpmLog/EclipsePRTLog.hpp

cmake/Modules/opm-common-prereqs.cmake

@@ -3,7 +3,7 @@
 
 # defines that must be present in config.h for our headers
 set (opm-common_CONFIG_VAR
-	)
+	"HAS_ATTRIBUTE_UNUSED")
 
 # dependencies
 set (opm-common_DEPS

opm/common/Unused.hpp

@@ -0,0 +1,43 @@
+// -*- mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+// vi: set et ts=4 sw=4 sts=4:
+/*
+  This file is part of the Open Porous Media project (OPM).
+
+  OPM is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  OPM is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with OPM.  If not, see <http://www.gnu.org/licenses/>.
+*/
+/*!
+ * \file
+ * \brief Provides the OPM_UNUSED macro
+ *
+ * This macro can be used to mark variables as "potentially unused" which suppresses some
+ * bogus compiler warnings. If the compiler does not support this, the macro is a no-op.
+ */
+#ifndef OPM_UNUSED_HH
+#define OPM_UNUSED_HH
+
+#ifndef HAS_ATTRIBUTE_UNUSED
+#define OPM_UNUSED
+#else
+#define OPM_UNUSED __attribute__((unused))
+#endif
+
+#ifdef NDEBUG
+#define OPM_DEBUG_UNUSED
+#define OPM_OPTIM_UNUSED OPM_UNUSED
+#else
+#define OPM_DEBUG_UNUSED OPM_UNUSED
+#define OPM_OPTIM_UNUSED
+#endif
+
+#endif