rust-orphan-rules VS compiler-team

Well, unless someone comes up with better, compatible rules, the orpan rules are gonna stick around.

Additionally there are other issues with rust currently. Compile time code (ala constexpr) is not up to par with C++20 (not really close). The const generic aren't as powerful as C++20 which added non primitive non type template parameters (though with you stuck with C++14, it actually is significantly better than what you have, again, if you're going to use C++, just use 20). Generics accepting closures is a bit more of an ordeal in rust, compared to C++. Also C++'s Duck Typed templates allow for some uncharacteristically strong typing compared to what is expressible in Rust generics currently. Now, duck typed templates do have major downsides, for example the entire feature of concepts is completely irrelevant in rust, but required for sane DTT type bounds, but they also have major upsides. Rust currently doesn't have "negative trait bounds", basically "This objected does not implement this trait, or std::enable_if> or the equivalent concepts implementation. Rust also doesn't have trait specializations, basically template specialization. Do note all features I've talked about to this point have nightly options, they just are at various stages of being stable/complete. Another issue is the orphan rule, though this is kind of a problem in C++ too in some respects, and that's unlikely to change drastically, since there are legitimate reasons for it's existence. For a lot of code none of these things are big deals, others they are, which is why you find inconsistent feed back on these issues.

Not that simple... hence why Orphan rule is still in-place. The struct wrapper was implemented in Rust as a temporary safe work-around. However, they are making progress on a solution: https://github.com/Ixrec/rust-orphan-rules/issues/1

That's still not an entirely complete explanation because there's more nuanced situations which aren't completely foreign but are foreign enough that if allowed, two crates could write the same impls. Some of the definitions are still unofficial as far as am I'm aware. For the best reference I’ve seen so far see this for more details.

In our crate the compiler doesn't know when calling MyTrait methods on MyStruct whether to use the implementation defined in crate 3 or crate 4! Rust has a set of orphan rules to prevent this situation from happening.

Sadly because of the rusts orphan rule you cannot implement a Trait on a Type where you do not own one or the other. So, apart from upstream contributions your only options are either a new Trait or a new Type.

If anyone is looking for additional background about orphan rules, check out https://github.com/Ixrec/rust-orphan-rules

> Also, why aren't we size-sorting fields already?

We are for struct/enum fields. https://camlorn.net/posts/April%202017/rust-struct-field-reo...

There's even an unstable flag to help catch incorrect assumptions about struct layout. https://github.com/rust-lang/compiler-team/issues/457

Are you talking about https://github.com/rust-lang/compiler-team/issues/688 ? I think that issue provides a lot of interesting context for this specific improvement.

And mips64, which rustc recently dumped support for after their attempt to extort funding/resources from Loongson failed:

https://github.com/rust-lang/compiler-team/issues/648

This is the biggest problem with the LLVM mentality: they use architecture support as a means to extract support (i.e. salaried dev positions) from hardware companies.

GNU may have annoyingly-higher standards for merging changes, but once it's in there and supported they will keep it for the long haul.

See https://github.com/rust-lang/compiler-team/issues/688

The work has been going on for some time now and it seems we are quite close to it being enabled as a default for nightly builds, I am super thrilled upwards of 20% faster clean builds and possibly more are on the horizon. Hope everything works out without triggering some unseen ICE. https://github.com/rust-lang/compiler-team/issues/681 Edit: If you want to discuss this feature reach out on Zulip

I'd recommend reading the MCP[1] they linked regarding the decision as well as their target tier policy [2].

They are dropping tier 1 support for Win 7 and Win 8. That means they are no longer going to guarantee that the project builds on those platforms and passes all tests via CI.

As long as it is feasible they will probably keep CI runs for those platforms and if interested parties step up and provide sufficient maintenance support, it will remain tier 2. i.e a guarantee that it builds on those platforms via CI but not necessarily that all features are supported and guaranteed via passing tests.

If interested parties can provide sufficient maintenance that all tests continue passing, it will be tier 1 in all but name. However the rest of the development community won't waste their time with issues like Win 7 and 8's partial support for UTF-8.

And once CI stops being feasible for the compiler team to host, it'll drop down to tier 3. If there's sufficient interest from the community towards maintaining these targets, in practice you should see comparable support to with tiers 1 or 2 however now any CI will be managed externally by the community and the compiler team will stop worrying about changes that could break compilation on those targets.

TLDR: They aren't saying "it'll no longer work" but rather "if you want it to stay maintained for these targets, you have to pitch in dev hours to maintain it and eventually support the infrastructure to do this because we don't see a reason to continue doing this". So if you care for these targets, you'll have to contribute to keep it maintained.

[1]: https://github.com/rust-lang/compiler-team/issues/651

(The already broken) XP support was removed almost 3 years ago: https://github.com/rust-lang/compiler-team/issues/378