Discussion: Rvalue refs and a Move construtor for D

[Les De Ridder]

On Saturday, 31 August 2019 at 20:15:22 UTC, Suleyman wrote:
> I made a POC for the implementation without rvalue ref.
> Here it is: https://github.com/dlang/dmd/pull/10383.
>
> It compiles. And works just like the rvalue ref implementation 
> would.

I realise you need to differentiate between copy constructors and 
move
constructors somehow, but I'm not sure calling move constructors
`__move_ctor` is the right solution. The average user of D should
neverhave to use a `__` symbol, but it's not unlikely they might 
want to
write a struct with move semantics.  Maybe a solution with a UDA 
is
possible?

> I also added a `cast(rvalue)` which does the same as the 
> `(T&&)` in C++ but returns an rvalue. And an intrinsic 
> `__move()` and a `__traits(getRvalue)` which are simply 
> syntactic flavors of `cast(rvalue)`.

I'm not sure why there are three different ways to 'cast to an 
rvalue'?
Is there a technical reason?

I also noticed you're casting lvalues to 'rvalues' and then 
binding them
to a `ref` param. Is that not an rvalue reference? Why can't we 
have
generalised rvalue references instead?