Question

Converting a project from Codeblocks to Visual Studio I encountered this puzzling error from the compiler:

Error   4   error C2228: left of '.swap' must have class/struct/union
shared_ptr.hpp

Error   3   error C2440: '<function-style-cast>' : cannot convert from
'boost::shared_ptr<T>' to 'boost::shared_ptr<T>' shared_ptr.hpp 384

Here’s the code in question in boost’s shared_ptr.hpp

template<class Y>
shared_ptr & operator=( shared_ptr<Y> && r ) // never throws
{
    this_type( static_cast< shared_ptr<Y> && >( r ) ).swap( *this );
    return *this;
}

I set up a similar but less complicated project and did not get the same error.

Answer 1

You probably try to swap two shared_ptr of incompatible types. Make sure that the two shared_ptr point to objects of the same/convertible type.