Merge pull request #35 from very-cool-name/fix_joint_view

Fix joint view

include/boost/variant/variant.hpp

@@ -71,10 +71,12 @@
 #include <boost/mpl/front.hpp>
 #include <boost/mpl/identity.hpp>
 #include <boost/mpl/if.hpp>
+#include <boost/mpl/insert_range.hpp>
 #include <boost/mpl/int.hpp>
 #include <boost/mpl/is_sequence.hpp>
 #include <boost/mpl/iterator_range.hpp>
 #include <boost/mpl/iter_fold_if.hpp>
+#include <boost/mpl/list.hpp>
 #include <boost/mpl/logical.hpp>
 #include <boost/mpl/max_element.hpp>
 #include <boost/mpl/next.hpp>
@@ -2452,16 +2454,20 @@ struct make_variant_over
 private: // precondition assertions
 
     BOOST_STATIC_ASSERT(( ::boost::mpl::is_sequence<Types>::value ));
+    typedef typename boost::mpl::insert_range<
+      boost::mpl::list<>
+    , boost::mpl::end< boost::mpl::list<> >::type
+    , Types
+    >::type copied_sequence_t;
 
 public: // metafunction result
 
     typedef variant<
-          detail::variant::over_sequence< Types >
+          detail::variant::over_sequence<copied_sequence_t>
         > type;
 
 };
 
-
 ///////////////////////////////////////////////////////////////////////////////
 // function template swap
 //

test/Jamfile.v2

@@ -52,6 +52,7 @@ test-suite variant
     [ run auto_visitors.cpp ]
     [ run overload_selection.cpp ]
     [ run recursive_wrapper_move_test.cpp ]
-   ;
+    [ run variant_over_joint_view_test.cpp ]
+   ; 
 
 

test/variant_over_joint_view_test.cpp

@@ -0,0 +1,64 @@
+// Copyright (c) 2017
+// Mikhail Maximov
+//
+// Distributed under the Boost Software License, Version 1.0. (See
+// accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+// The test is base on https://svn.boost.org/trac/boost/ticket/8554 
+// variant was not able to extract types from mpl::joint_view
+
+#include <string>
+
+#include "boost/config.hpp"
+#include "boost/test/minimal.hpp"
+
+#include "boost/variant.hpp"
+#include "boost/mpl/joint_view.hpp"
+#include "boost/mpl/insert_range.hpp"
+#include "boost/mpl/set.hpp"
+
+template<class T, class Variant>
+void check_exception_on_get(Variant& v) {
+    try {
+        boost::get<T>(v);
+        BOOST_FAIL("Expected exception boost::bad_get, but got nothing.");
+    } catch (boost::bad_get&) { //okay it is expected behaviour
+    } catch (...) { BOOST_FAIL("Expected exception boost::bad_get, but got something else."); }
+}
+
+void test_joint_view() {
+    typedef boost::variant<int> v1;
+    typedef boost::variant<std::string> v2;
+    typedef boost::make_variant_over<boost::mpl::joint_view<v1::types, v2::types>::type>::type v3;
+
+    v1 a = 1;
+    v2 b = "2";
+    v3 c = a;
+    BOOST_CHECK(boost::get<int>(c) == 1);
+    BOOST_CHECK(c.which() == 0);
+    v3 d = b;
+    BOOST_CHECK(boost::get<std::string>(d) == "2");
+    BOOST_CHECK(d.which() == 1);
+    check_exception_on_get<std::string>(c);
+    check_exception_on_get<int>(d);
+}
+
+void test_set() {
+    typedef boost::mpl::set2< std::string, int > types;
+    typedef boost::make_variant_over< types >::type v;
+
+    v a = 1;
+    BOOST_CHECK(boost::get<int>(a) == 1);
+    check_exception_on_get<std::string>(a);
+    a = "2";
+    BOOST_CHECK(boost::get<std::string>(a) == "2");
+    check_exception_on_get<int>(a);
+}
+
+int test_main(int , char* [])
+{
+    test_joint_view();
+    test_set();
+    return 0;
+}