Assert that Block is the same type as AllocatorOrContainer::value_type

Reason: That's required both when AllocatorOrContainer is an allocator
type and when it's a container type. Now, when it is an allocator type,
the assert is usually in the implementation of std::vector, which we
use. But, when it's a container type, we need to assert that on our own.

include/boost/dynamic_bitset/dynamic_bitset.hpp

@@ -26,6 +26,7 @@
 #include "boost/static_assert.hpp"
 #include <iosfwd>
 #include <string>
+#include <type_traits>
 #include <vector>
 
 #if defined( BOOST_DYNAMIC_BITSET_SPECIALIZE_STD_HASH )
@@ -81,6 +82,7 @@ template< typename Block, typename AllocatorOrContainer >
 class dynamic_bitset
 {
     BOOST_STATIC_ASSERT( (bool)detail::dynamic_bitset_impl::allowed_block_type< Block >::value );
+    BOOST_STATIC_ASSERT( std::is_same< Block, typename AllocatorOrContainer::value_type >::value );
 
 public:
     //!     The same type as `Block`.