Can variadic expansions be used as a chain of comma-operator calls?

Question

I was looking at \"How to properly use references with variadic templates,\" and wondered how far comma expansion can go.

Here\'s a variant of the answer:

Answer 1

Unpacking is only allowed in certain contexts, and comma separated statements doesn't belong to them. Using your words: The expansion is semantically and not lexically. However, it doesn't matter because there are several other ways of doing it. There are already some kind of patterns/idioms to write simple variadic functions. One way of doing it:

Use a helper template function, that does nothing at all:

template <typename ...Args>
void pass(Args&&...) { }

Instead of using the comma operator, pass the expressions to this function:

template <typename ...Args>
void inc(Args&&... args)
{
    pass(++std::forward<Args>(args)...);
}

You can use the comma operator within the expansion, if the expressions have to be more complex. This might be useful in your case, if some operator++ have return type void:

    pass((++std::forward<Args>(args), 0)...);