Add the macro CGAL_USE_TYPE(), and a test for <CGAL/use.h>

Installation/include/CGAL/use.h

@@ -25,10 +25,15 @@ namespace CGAL { namespace internal {
 template < typename T > inline
 void use(const T&) {}
 
+template<typename> void use_type() {}
+
 } }
 
-// CGAL_USE() is a macro which aims at removing "variable is unused" warnings.
-
+/// CGAL_USE() is a macro which aims at removing "variable is unused" warnings.
 #define CGAL_USE(x) ::CGAL::internal::use(x)
 
+/// CGAL_USE_TYPE() is a macro which aims at removing "typedef locally
+/// defined but not used" warnings.
+#define CGAL_USE_TYPE(T) ::CGAL::internal::use_type<T>()
+
 #endif // CGAL_USE_H

Installation/test/Installation/CMakeLists.txt

@@ -42,6 +42,8 @@ if ( CGAL_FOUND )
 
   create_single_source_cgal_program( "deprecation_warning.cpp" )
 
+  create_single_source_cgal_program( "test_use_h.cpp" )
+
   create_link_to_program(CGAL)
  
   if ( WITH_CGAL_Core )

Installation/test/Installation/test_use_h.cpp

@@ -0,0 +1,33 @@
+#include <CGAL/use.h>
+
+template <typename T>
+struct Foo {
+  typedef typename T::fake fake; 
+  // Fake typedef to check that Foo<double> is not instantiated.
+};
+
+int test_use_type()
+{
+  typedef Foo<double> type;
+
+  // If the following line is commented, g++-4.8 -Wall displays that
+  // warning:
+  //   typedef ‘type’ locally defined but not used [-Wunused-local-typedefs]
+  CGAL_USE_TYPE(type);
+
+  return 0;
+}
+
+int test_use() {
+  int unused;
+
+  // If the following line is commented, g++-4.8 -Wall displays that
+  // warning:
+  //   unused variable ‘unused’ [-Wunused-variable]
+  CGAL_USE(unused);
+  return 0;
+}
+
+int main() {
+  return test_use_type() + test_use();
+}