Remove deprecated DUNE_UNUSED

CHANGELOG.md

@@ -36,6 +36,11 @@
   that it is no drop-in replacement, as it must be sometimes placed at
   different position in the code.
 
+- The macros `DUNE_UNUSED` is removed Use C++17's attribute
+  `[[maybe_unused]]` instead, but be aware that it is no drop-in
+  replacement, as it must be sometimes placed at a different position
+  in the code.
+
 # Release 2.8
 
 - Set minimal required CMake version in cmake to >= 3.13.

cmake/modules/CheckCXXFeatures.cmake

@@ -10,9 +10,6 @@
 #    This module internally sets the following variables, which are then
 #    exported into the config.h of the current dune module.
 #
-#    :code:`HAS_ATTRIBUTE_UNUSED`
-#       True if attribute unused is supported
-#
 # .. cmake_variable:: DISABLE_CXX_VERSION_CHECK
 #
 #    You may set this variable to TRUE to disable checking for
@@ -180,18 +177,6 @@ endif()
 # make sure we have at least C++17
 dune_require_cxx_standard(MODULE "DUNE" VERSION 17)
 
-# perform tests
-
-# __attribute__((unused))
-check_cxx_source_compiles("
-   int main(void)
-   {
-     int __attribute__((unused)) foo;
-     return 0;
-   };
-"  HAS_ATTRIBUTE_UNUSED
-)
-
 # ******************************************************************************
 #
 # Checks for standard library features

config.h.cmake

@@ -20,9 +20,6 @@
 /* Standard debug streams with a level below will collapse to doing nothing */
 #define DUNE_MINIMAL_DEBUG_LEVEL ${DUNE_MINIMAL_DEBUG_LEVEL}
 
-/* does the compiler support __attribute__((unused))? */
-#cmakedefine HAS_ATTRIBUTE_UNUSED 1
-
 /* does the standard library provide experimental::make_array() ? */
 #cmakedefine DUNE_HAVE_CXX_EXPERIMENTAL_MAKE_ARRAY 1
 
@@ -97,6 +94,7 @@
 /* old feature support macros which were tested until 2.8, kept around for one more release */
 #define HAS_ATTRIBUTE_DEPRECATED 0
 #define HAS_ATTRIBUTE_DEPRECATED_MSG 0
+#define HAS_ATTRIBUTE_UNUSED 0
 
 /* Define to ENABLE_UMFPACK if the UMFPack library is available */
 #cmakedefine HAVE_UMFPACK ENABLE_SUITESPARSE

dune/common/unused.hh

@@ -4,27 +4,9 @@
 #define DUNE_COMMON_UNUSED_HH
 
 /** \file
- * \brief Definition of the DUNE_UNUSED macro for the case that config.h
- *      is not available
+ * \brief Definition of the `DUNE_UNUSED_PARAMETER` macro.
  */
 
-#ifndef HAS_ATTRIBUTE_UNUSED
-//! A macro for marking variables that the compiler mistakenly flags as unused, which sometimes happens due to templates.
-/**
- * \ingroup CxxUtilities
- * \deprecated Use C++17's \code[[maybe_unused]]\endcode instead. This
- * macro will be removed after Dune 2.8. Be aware that it must be
- * sometimes placed at a different position in the code.
- */
-#define DUNE_UNUSED
-#else
-#ifdef __GNUC__
-#  define DUNE_UNUSED _Pragma("GCC warning \"DUNE_UNUSED is deprecated\"") __attribute__((unused))
-#else
-#  define DUNE_UNUSED _Pragma("message \"DUNE_UNUSED is deprecated\"") __attribute__((unused))
-#endif
-#endif
-
 /**
  * A macro to mark intentionally unused function parameters with.
  *