Add test/value_init_test3

test/Jamfile.v2

@@ -37,6 +37,7 @@ run string_view_test_io.cpp ;
 
 run value_init_test.cpp ;
 run value_init_test2.cpp ;
+run value_init_test3.cpp ;
 run value_init_workaround_test.cpp ;
 run initialized_test.cpp ;
 compile-fail value_init_test_fail1.cpp ;

test/value_init_test3.cpp

@@ -0,0 +1,40 @@
+// Copyright 2020 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt)
+
+#include <boost/utility/value_init.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <boost/config.hpp>
+#include <boost/config/pragma_message.hpp>
+
+#if __cplusplus >= 201103L || ( defined(BOOST_MSVC) && BOOST_MSVC >= 1900 )
+
+struct X
+{
+    int a;
+    char b;
+};
+
+struct Y: boost::value_initialized<X>
+{
+    char c = 42;
+};
+
+int main()
+{
+    Y y;
+
+    BOOST_TEST_EQ( y.data().a, 0 );
+    BOOST_TEST_EQ( y.data().b, 0 );
+    BOOST_TEST_EQ( y.c, 42 );
+
+    return boost::report_errors();
+}
+
+#else
+
+BOOST_PRAGMA_MESSAGE( "Skipping test because compiler doesn't support in-class member initializers" )
+
+int main() {}
+
+#endif