Did Safe C++ ever have a full, correct, fully compliant, reference implementation, or was there only (closed-source) Circle as some kind of reference implementation? Circle, as far as I know, is closed-source.
> Did Safe C++ ever have a full, correct, fully compliant, reference implementation, or was there only (closed-source) Circle as some kind of reference implementation?
Technically speaking the clauses on either side of the "or" aren't mutually exclusive. You can have a "full, correct, fully compliant, reference implementation" that is also a closed-source implementation!
Well, unless the implication that Circle isn't "full, correct, [and] fully compliant", in which case I feel I should ask "with respect to what?" and "why do you need those requirements?"
But Safe C++ and Circle are different languages, right? And Circle is not the same as the Safe C++ proposal that was submitted, right? There are presumably differences between them, and I do not know what those differences are, and I do not know if those differences were documented somewhere. I cannot find any occurrences of "reference implementation" in the Safe C++ draft.
> But Safe C++ and Circle are different languages, right?
Eh, bit of a mixed bag, I think, depending on the context in which the words are used. "Circle" can refer to the compiler/toolchain or the set of C++ extensions the compiler implements, whereas Safe C++ is either the proposal or the extensions the proposal describe. As a result, you can say that you can compile Safe C++ using Circle, and you can also describe Safe C++ as a subset of the Circle extensions. I wouldn't exactly describe the lines as well-defined, for what it's worth.
> There are presumably differences between them, and I do not know what those differences are, and I do not know if those differences were documented somewhere.
They're sort of documented indirectly, as far as I can tell. Compare the features in the Safe C++ proposal and the features described in the Circle readme [0]. That'll get you an approximation at least, albeit somewhat shaded by the old docs (understandable given the one-man show).
> I cannot find any occurrences of "reference implementation" in the Safe C++ draft.
The exact words "reference implementation" may not show up, but I think this bit qualifies (emphasis added):
> Everything in this proposal took about 18 months to design and implement in Circle.
If they're the same language, then I think it's a fair objection that it's closed-source, as some people might find using a closed-source compiler to be unsuitable as a replacement for the existing open source C++ ones. If it's not the same language, then it's not clear that Safe C++ actually exists today, so it also seems fair that people might be interested in alternatives that they expect might be available sooner.
I don't think the objection in the first sentence makes sense because I don't think replacing the existing C++ compilers was ever in the cards. If anything, the fact that the Safe C++ proposal has a section titled "Implementation Guidance" seems to point to precisely the opposite - that the intent was for existing C++ compilers to be updated to add the new features, not that Circle was to replace them.
I'm not sure about the second sentence either? Circle (supposedly?) implements everything in the Safe C++ proposal, so in that respect Safe C++ exists. Alternatively, you can say Safe C++ doesn't exist because major compilers don't implement it, but that's kind of the point of the Safe C++ proposal (and many (most?) other C++ language proposals, for that matter) - it's describing new features that don't currently exist but might be worth adding to the standard.
> people might be interested in alternatives that they expect might be available sooner.
This is also a bit funny because this was one of the more contentious points of debate in the Safe C++ vs. profiles discussion, and the impression I got is that between the two Safe C++ was generally considered to be closer to "might be available sooner" than profiles.
It sounds like the difference of opinion here is around how soon we expect that the major compilers will actually implement the safe features. I tend not to be optimistic that these sorts of changes will be available anytime soon, and I think it would be fair to consider alternatives at this point, but that's obviously a judgment call and not everyone will agree on that.
As far as Safe C++ vs. profiles specifically, I don't think the conversation really ever got to the point of serious discussions of how soon the features could be implemented. My understanding is that there were bigger hangups about what direction to go in the first place as well as what "profiles" even meant.
> and I think it would be fair to consider alternatives at this point
I would assume those who could consider alternatives already have, and that those (still) interested in safe(r) C++ do so because the alternatives are insufficient for one reason or another.
But standardization also matters for avoiding vendor lock-in, right?
Like, Python and Javascript both have many "implementations", and those are some of the most popular languages. Python does not have an ISO specification. But Javascript does have an Ecma standard, ECMAScript.
> It's not possible to port a millions line C++ code base, like Chrome, to another language so large C++ projects are stuck with objectively pretty bad language and are forced to continue to use C++ even though a better language might exist.
One good aspect about C++ is its backwards compatibility or stability. Also a drawback, but companies not having to spend huge amounts of time, expertise and money rewriting their whole codebases all the time is something they appreciate.
Might worth noting that this change technically doesn't violate Rust's stability guarantees since type inference changes and/or adding new impls are exempt. Of course, that doesn't really help with the question of whether this change should have been made in the given timeframe (as opposed to the socket struct change IIRC?), but that ship has long sailed.
They could be amended, but I suspect they will not be. There's a reason those exemptions were added in the first place, and the impression I get is that the 1.80 issues were more of a social problem that doesn't significantly change the reasons the exemptions were added in the first place.
In addition, as I mentioned I don't think this is the first time Rust has had to navigate this kind of wide-ranging technically-allowed-but-still-breaking change. The Rust devs first created a PR to change its internal representation for IP addresses in November 2020 [0], but multiple major libraries (including mio, which tokio depends on) incorrectly assumed that the representation for Rust's IP address type was the same as libc's representation and basically type punned between the two, so the change would result in UB. The Rust devs could have pushed out the change anyways, as the change didn't violate the backwards compatibility guarantee due to just being an internal implementation detail change, but the PR didn't actually land until July 2022 [1] because the Rust devs wanted to give the ecosystem time to migrate.
Yes, this was a social issue more than a technical one.
At the same time, I was affected by this breakage, and it took me all of ten minutes to fix. So I both understand the outrage, and agree with it in general, but also, it was a tad overblown, I think.
Should they have done a slower rollout, like the IpAddr change? Probably. Is it the end of the world that they made a mistake? Nah. But if it happens more often, that's cause for concern.
> If WG21 were handling Rust instead f64 would implement Ord, and people would just write unsafe blocks with no explanation in the implementation of supposedly "safe" functions. Rust's technology doesn't care but their culture does.
I'm sure you think this was somehow succinctly making your point, but I can't see any connection at all, so if you did have an actual point you're going to need to explain it.
OK? I don't see how that's connected? It's not controversial that f32 and f64 are partially ordered, the problem in C++ is that the difference between "Partially Ordered" and "Totally Ordered" is semantic not syntactic in their language and all semantic mistakes are just IFNDR so it's a footgun.
The nightly release of the Carbon compiler can be used via https://carbon.compiler-explorer.com/ . Note that it is definitely a work in progress, it hasn't even reached our v0.1 goals yet, but a good chunk of important functionality is working.
Printing as in the example from Carbon's Github repository, does not work. 'Print("Test");' gives a complaint about not finding 'Print'.