How to pass two generics types into an extension method

In case you are wondering why this is just not possible, I'd think the problem lies with ambiguity:

public static T Map<TEntity,T>(this TEntity entity) where TEntity : IEntity
{
    return Mapper.Map<TEntity, T>(entity);        
}

public static T Map<T>(this ExchangeSet set)
{
    // ...
}

So, which method gets called? Keep in mind this is just a simple example. It's very well possible that there could be a future implementation of partial type inference, but I'd imagine it would be too confusing when it comes to overload resolution and the cost/benefit would be completely out of control. Then again, that's just speculation.