Fix test for GCC 4.7 and 4.6

test/no_rvalue_to_nonconst_visitation.cpp

@@ -1,4 +1,4 @@
-// Copyright (c) 2017 Antony Polukhin
+// Copyright (c) 2017-2018 Antony Polukhin
 //
 // Distributed under the Boost Software License, Version 1.0. (See
 // accompanying file LICENSE_1_0.txt or copy at
@@ -6,22 +6,27 @@
 
 #include "boost/config.hpp"
 #include "boost/variant.hpp"
-#include <string>
+
+struct foo {};
 
 struct some_user_provided_visitor_for_lvalues: boost::static_visitor<void> {
-    void operator()(std::string& ) const {}
+    void operator()(foo& ) const {}
     void operator()(int ) const {}
 };
 
 int main() {
     boost::apply_visitor(
         some_user_provided_visitor_for_lvalues(),
-        boost::variant<int, std::string>("Hello")
+        boost::variant<int, foo>(foo())
     );
 
+#ifdef __GNUC__
+#   if __GNUC__ < 5 && __GNUC_MINOR__ < 8
+#       error This test does not pass on GCC < 4.8 because of the incomplete C++11 support
+#   endif
+#endif
+
 #ifdef BOOST_MSVC
 #   error Temporaries/rvalues could bind to non-const lvalues on MSVC compilers
 #endif
-
-    return 0;
 }