On Fri, Jan 15, 2021 at 7:49 AM Jean-Baptiste Vallon Hoarau via Std-Proposals <std-proposals@lists.isocpp.org> wrote:

Hello everyone,

I think you are all aware how verbose perfect forwarding is. I haven't seen any proposal that could tackle this (admittedly minor) issue so far, except the one on hygienic macros.
So what if we had an operator for casting to a reference?
For example, given a value x, than the following could be equivalent :
x& -> static_cast<decltype(x)&>(x)
x&& -> static_cast<decltype(x)&&>(x)

This would make forwarding a lot less cumbersome to write/read (goodbye decltype(x)(x), hello x&&). However, I don't see many use cases for explicit lvalue cast, and this would be at odd with lambda capture syntax.

Let me know what you think.
-Jean-Baptiste

I'd written this a while ago (http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0644r1.html), which would be a prefix operator >> for forwarding. This got rejected in 2017, >> is just a bad choice in the context of templates which are already using a lot of angle brackets.

Prefix && is a gcc extension so isn't an option. Postfix && looks like it's starting the beginning of a logical conjunction.

In discussion of my paper, the possibility of a good-but-nonconflicting keyword was brought up and people suggested declfwd (vote was 0-10) and fwdexpr (vote was 7-5). The best option here seems to be to add some kind of hygienic macro language feature such that we can introduce std::fwd(x) to actually be a function that does forwarding.

Barring that, I don't know if we can just by fiat say that std::fwd is a magic thing that is not addressable (we do already say that in general for standard library functions) that Just Works because of Compiler Magic.

Barry