On Mon, Feb 3, 2025 at 3:52 PM Thiago Macieira wrote:
>
> A <containerfwd> header would be very helpful.



If we have the power to change the Standard so that there's a way of
forward-declaring standard library classes, then perhaps make it so
that we can do the following:

    declare std::vector;

    extern std::vector<int> &Func(void); // defined in another
translation unit

    int main(void)
   {
        std::vector<int> &my_container = Func();
   }

The new core language feature, "declare", must always be followed by
the name of a standard library class (or template class).

When a compiler encounters "declare", it basically just copy-pastes a
declaration in place. So the first time the following is encountered
in a translation unit:

    declare std::vector;

it simply gets replaced with:

    namespace std {
        template<class T> class less;
        template<class T> class allocator;
        template< class Key, class Compare = less<Key>, class
Allocator = allocator<Key> > class set;
    }