Add sp_type_with_alignment

Author: pdimov

include/boost/smart_ptr/detail/sp_type_traits.hpp

@@ -39,6 +39,16 @@ template<class T> struct sp_type_identity
     typedef T type;
 };
 
+// boost::type_with_alignment
+
+template<std::size_t A> struct sp_type_with_alignment
+{
+    struct alignas(A) type
+    {
+        unsigned char padding[ A ];
+    };
+};
+
 } // namespace detail
 } // namespace boost
 

test/Jamfile

@@ -428,3 +428,4 @@ run sp_move_only_deleter.cpp ;
 run sp_is_bounded_array_test.cpp ;
 run sp_is_unbounded_array_test.cpp ;
 run sp_type_identity_test.cpp ;
+run sp_type_with_alignment_test.cpp ;

test/sp_type_with_alignment_test.cpp

@@ -0,0 +1,18 @@
+// Copyright 2024 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/smart_ptr/detail/sp_type_traits.hpp>
+#include <boost/core/lightweight_test.hpp>
+
+int main()
+{
+    using boost::detail::sp_type_with_alignment;
+
+    BOOST_TEST_EQ( alignof( sp_type_with_alignment<1>::type ), 1 );
+    BOOST_TEST_EQ( alignof( sp_type_with_alignment<2>::type ), 2 );
+    BOOST_TEST_EQ( alignof( sp_type_with_alignment<4>::type ), 4 );
+    BOOST_TEST_EQ( alignof( sp_type_with_alignment<8>::type ), 8 );
+
+    return boost::report_errors();
+}