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Track variant selectively so reused values round-trip #360

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Merged
gennaroprota merged 1 commit into from
Jul 30, 2026
+34 −2
Merged

Track variant selectively so reused values round-trip #360

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4 changes: 2 additions & 2 deletions include/boost/serialization/variant.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -294,7 +294,7 @@ struct tracking_level<
variant<BOOST_VARIANT_ENUM_PARAMS(T)>
>{
typedef mpl::integral_c_tag tag;
typedef mpl::int_< ::boost::serialization::track_always> type;
typedef mpl::int_< ::boost::serialization::track_selectively> type;
BOOST_STATIC_CONSTANT(int, value = type::value);
};

Expand All @@ -304,7 +304,7 @@ struct tracking_level<
std::variant<Types...>
>{
typedef mpl::integral_c_tag tag;
typedef mpl::int_< ::boost::serialization::track_always> type;
typedef mpl::int_< ::boost::serialization::track_selectively> type;
BOOST_STATIC_CONSTANT(int, value = type::value);
};
#endif
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32 changes: 32 additions & 0 deletions test/test_variant.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -194,13 +194,41 @@ void test(Variant & v)
test_type(v);
}

// Serializing the same variant twice by value must store two independent
// values, not an object reference the loader cannot resolve into a separate
// destination object. Regression test for issue #203.
template<class Variant>
void test_reuse(const Variant & v){
const char * testfile = boost::archive::tmpnam(NULL);
BOOST_REQUIRE(testfile != NULL);
{
test_ostream os(testfile, TEST_STREAM_FLAGS);
test_oarchive oa(os, TEST_ARCHIVE_FLAGS);
oa << boost::serialization::make_nvp("first", v);
oa << boost::serialization::make_nvp("second", v);
}
Variant v1;
Variant v2;
{
test_istream is(testfile, TEST_STREAM_FLAGS);
test_iarchive ia(is, TEST_ARCHIVE_FLAGS);
ia >> boost::serialization::make_nvp("first", v1);
ia >> boost::serialization::make_nvp("second", v2);
}
BOOST_CHECK(are_equal(v, v1));
BOOST_CHECK(are_equal(v, v2));
std::remove(testfile);
}

int test_boost_variant(){
std::cerr << "Testing boost_variant\n";
boost::variant<bool, int, float, double, A, std::string> v;
test(v);
const A a;
boost::variant<bool, int, float, double, const A *, std::string> v1 = & a;
test_type(v1);
v = 1;
test_reuse(v);
return EXIT_SUCCESS;
}

Expand All @@ -214,6 +242,8 @@ int test_boost_variant2(){
const A a;
boost::variant2::variant<bool, int, float, double, const A *, std::string> v1 = & a;
test_type(v1);
v = 1;
test_reuse(v);
return EXIT_SUCCESS;
}
#endif
Expand All @@ -228,6 +258,8 @@ int test_std_variant(){
const A a;
std::variant<bool, int, float, double, const A *, std::string> v1 = & a;
test_type(v1);
v = 1;
test_reuse(v);
return EXIT_SUCCESS;
}
#endif
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