How to resolve this "cast to pointer from type of different size" warning?

I have two programs that communicate over the D-Bus. In one of the there is a function that takes two parameters namely const char* data and int size and in another one I have a function that returns a value of the type unsigned char. I place a function call in the first program like this function((char*)program2->function().value(), 1) but i get the warning cast to pointer from integer of different size [-Wint-to-pointer-cast]. how should i resolve this warning? also I'm using Qt libraries.

EDIT:

actually in the function that takes the const char* and int I append the data to a QByteArray which accepts const char* and a size of type int in it's constructor as provided by Qt and the other program is supposed to return a number in the range 0-255 hence the unsinged char. If what I'm doing is wrong what's the best way to obtain the desired result?

Also call to program2->function invokes the following:

inline QDBusPendingReply<uchar> type()
    {
        QList<QVariant> argumentList;
        return asyncCallWithArgumentList(QLatin1String("type"), argumentList);
    }

this class has a function called value() which invokes:

inline typename Select<0>::Type value() const
    {
        return argumentAt<0>();
    }

NOTE: my main purpose of this question was to find out a way to create a reference to the returned result of calling a function defined within the proxy class not how to convert it to something acceptable for creation of a QByteArray so please stop adding unrelated tags like QByteArray or QtCore etc.

What you need is the address of the data... which would look like

function2(& program2->function().value(), 1);

and would be perfectly safe, since the lifetime of the temporary variable is until the end of the complete expression, which is long enough¹ for function2 to use it.

Unfortunately, you can't use the & address-of operator on an rvalue. But there is a workaround, since you can bind a const lvalue reference to an rvalue, and you want a pointer to const data anyway:

template<T>
const T* get_addr(const T& v) { return &v; }

function2( get_addr(program2->function().value()), 1 );

If you get a signed-vs-unsigned, mismatch, try

function2( get_addr<char>(program2->function().value()), 1 );

Of course this is a lot of work just to avoid giving the variable a name, as Captain Obvlious has done.

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¹ Unless function2 saves that pointer for later, but if it does then you shouldn't be using a local variable to hold the value either, but pay very close attention to object lifetime.