Struct inside template class is not recognized by Visual Studio

Question

I am trying to re-implement a singly-linked list class with templates. Below is the code that has troubles.

template<typename T>
class list
{
private:
    struct node
    {
        node* next;
        T data;

        node( T d ) : next( nullptr ), data( d ) {}
    };
    node* first_node;
    size_t m_size;
public:
    list() : first_node( nullptr ), size( 0 ) {}
    // ...
};

Everything is ok, until I try to use (i.e in a method push_back()) members of a node* type variable. Example:

void push_back( const T& data ) 
{
    node* temp = first_node;
    while( temp->next )
    {
        temp = temp->next;
    }
    // ...
}

While I am typing temp->, Visual Studio's IntelliSense should bring up a context menu to show the members of the node structure. It is not doing this. Also, when I hover the next word in my code, the tooltip looks like this:

Let me say it clear: I don't get any debugging error, but my question is: Why isn't Visual Studio 2013 able to compute those things?

Answer 1

This is not unexpected and is not an error. You are writing a template, the IntelliSense parser doesn't know what concrete type the next member belongs to. That cannot be known until later in your code you instantiate, say, a list<int>. So it gives you what it knows, it certainly does know that temp->next is a list<T>::node and tells you so, just not for which particular kind of list. So it prefixes <unknown>.

You could certainly argue that it should display template class<T> list<T>::node::next instead. Not so sure that spins everybody's propeller, or if this is at all capability of the EDG parser (doubtful), you can make your case at Connect and file a bug report.