On 2/3/25 15:28, Avi Kivity via Std-Proposals wrote:

On Mon, 2025-02-03 at 13:05 +0100, Marcin Jaczewski via Std-Proposals wrote:

pon., 3 lut 2025 o 12:50 Frederick Virchanza Gotham via Std-Proposals

<std-proposals@lists.isocpp.org <mailto:std-

proposals@lists.isocpp.org>> napisał(a):

On Mon, Feb 3, 2025 at 11:14 AM Andrey Semashev wrote:

It is not. A forward declaration would suffice.

But I'll be need forward declarations for other stuff like "std::less"

and "std::allocator":

    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;

    }

    typedef std::set<unsigned> IndexSet;

Then problem is not that you need "aliases" but that std types are a

pain to forward declare.

Because the code you show here is invalid as for most standard libs

this is not a declaration of  `set`.

Question is could standard fix it and allow users to have a way to

forward declare standard classes

without including whole implementation?

We already have `<iosfwd>` could standard mandate a similar header for

the rest of stdlib?

import std;

Modules don't exist.