Perfect forwarding

[Adam D. Ruppe]

On Sunday, 26 July 2020 at 10:51:44 UTC, Mathias LANG wrote:
> How do you forward this:
> ```
> class Foo
> {
>     void set (time_t value = time()) {}
> }
> ```

The same as the others wrt the default argument. The fact it is 
in a class complicates things a little since `this` is not 
propagated through... but if I remove it from there it still 
works.

Here's my solution as a link so people can look at it (and prolly 
destroy holes i missed lol) if you want but not click if you 
still wanna play with the challenge.

http://arsdnet.net/dcode/forward.d

The 8 lines at top are the forward, then the rest are the test 
conditions.

BTW I'd note that just doing a speculative forward is a bit 
simpler than this - you can just do (Args...)(auto ref Args args) 
- but the linked technique does it ahead-of-time, as if you wrote 
it by hand, meaning reflection still works on the forwarded 
definitions too.