This year's WWDC 2021 session on ARC optimization was focused on handling lifetime bugs caused by misuse of weak and owned references, alongside compiler optimizations that ellide retain/release calls.

https://developer.apple.com/videos/play/wwdc2021/10216/

Maybe consider if this is the future the anti-GC folks want to have in D.

It is nice to throw ARC around when unaware of the details how it actually works, possible bugs or crashes.

On Saturday, 12 June 2021 at 11:44:11 UTC, Paulo Pinto wrote:

D is a system level language where the default pointer cast is equivalent to C++ reinterpret_cast. D is not a higher level language like Swift.

I think most D programmers have no problem using good old reference counting. Understanding how to use weak references is a pretty insignificant issue compared to all the other things that can go wrong when using a system level language like D.

On Saturday, 12 June 2021 at 11:44:11 UTC, Paulo Pinto wrote:

Interesting, but it doesn't really apply to D as we only use shared reference counting as library feature, so we probably won't profit of such optimizations.

However, I would favor the route the nim language does take and annotate certain parts of GC code as acyclic either proved or assumed, so these GC pointers can be excluded from cycle detection.

On Saturday, 12 June 2021 at 11:56:45 UTC, Ola Fosheim Grøstad wrote:

Nim doesn't use weak references but has cyclic reference detection instead.

https://nim-lang.org/blog/2020/10/15/introduction-to-arc-orc-in-nim.html

One of the strengths of Nim is that you can just plug and play a different GC and this also means badging the code with weak references doesn't play well with that versatility.

Also, weak references means that we now have manual memory management again and if not used properly then the program will leak memory. Automatic memory management is no longer automatic with weak pointers.

If D is going to implement ARC, then I suggest as automatic as possible with cycle detection.

On Saturday, 12 June 2021 at 16:56:54 UTC, IGotD- wrote:

All programmers should create a model before they program. You only need to use weak-references if you pull down a datastructure in a disorderly fashion.

Which basically is combining RC and tracing GC like Python.

Then you might as well just use GC.

On Saturday, 12 June 2021 at 16:56:54 UTC, IGotD- wrote:

Leaks will usually be detected during testing. Just make the runtime such that it tells you where the memory was allocated that wasn't freed when the program terminates. It isn't really all that complicated.