jiebi/CodeConvo huggingface dataset:
I agree with and The currently design involves: start with a reference to a value not in the vec, use its PartialEq impl to do a linear scan, remove the first found, shift everything after the removed element. To generalize almost all of the discussion above, people are questioning whether the conjunction of all 5 of these decisions is really as common as a name like removeitem would suggest, whether a different permutation of choices might be more widely applicable, and how to adjust naming to leave room for all the other equally or more common permutations: ones where the ref we want to remove is a ref to a vec element, or we want to remove by FnMut instead of PartialEq, or we want a binary search, or we want to remove the last, or all matches, or we want the more efficient swapremove behavior. Fortunately Vec already supports all permutations of these use cases equally well, with nice independent APIs for searching and removing. Many people have voiced opinions equivalent to "removing an item from a vec is so common that there absolutely must be a function for it". I think what they mean is that the union of all permutations of the above 5 choices is common, which is true; they don't necessarily mean the specific choices that go into removeitem as it exists would justify a method specific to those choices. points out that satisfying the set of use cases which all together are common would take a much larger number of new methods.
Per , I think we should go ahead and remove . fcp close
That is not what I meant. When I said that I need in my code, I meant exactly that: that I could take my existing code and replace it with and it would have exactly the same behavior, because I really do need specifically, not the other fancier methods. I'm perfectly fine with changing the name so that we can accommodate other fancier methods in the future, but why would that mean that we shouldn't have at all?
fcp cancel
proposal cancelled.
Per , I think we should go ahead and remove . fcp close
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Checking KodrAus’ checkbox per
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Since we've merged the deprecation would we like to close this tracking issue now? Or keep it open until the unstable deprecated method is removed entirely?
I think keeping this open until we removed the method is a good idea. How long do we want to wait with that by the way? I guess a couple of cycles is sufficient?
Before closing, it would be great if someone could suggest a "one clean and obvious" way to remove the first/last occurance of an item from a Vector. Irrespective of the arguments made here, a method removing the first/last occurance of an item is provided across all major programming languages, and is to be "expected" Anyone new to rust is bound to google "remove from vec rust" and end up on this discussion which would only leave them more confused.
should answer those questions. But here is a copy of my answer for convenience: You can of course handle the case however you like (panic and ignoring are not the only possibilities). Like the first element, but replace with . Remember that has a runtime of O(n) as all elements after the index need to be shifted. has a runtime of O(1) as it swaps the to-be-removed element with the last one. If the order of elements is not important in your case, use instead of !
It might be worth adding more examples (maybe all of the ones above) to the docs.
I'd like to add those to the docs, should they go along the example that we currently have?
What examples are you referring to? I could imagine those "remove examples" either going on the type (as a new section "Removing elements" or something like that) or directly on the method (below the existing docs). And by the way, feel free to add (parts of) my text/examples verbatim.
Thank you.
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Also ICEs on beta. label regression-from-stable-to-beta
Interesting, this is rustc now, right? There has been as similar rustdoc ice:
Yes, this can be hit with or for example. I tried running the code in , but it seems to have been fixed by now.
claim I'll try to take a look at this.
Steps to reproduce: The output of is: does as suggested by the message, but that fails too (as expected): Proposed fix: in the beta and stable channels (i.e. whenever is forbidden), the message that suggests adding should not be shown. (Clean up the test case with .) CC
Gonna milestone this real quick, as it seems quite important.
I might be able to whip up a quick fix, though I'm not 100% sure about testing it properly ... (I've never actually tried building something for a non-dev release channel before...)
after chatting with it seems like I have a patch, building it now
gonna leave to it
Hello good Rust folks :smile: Before the beta, I used which is in . Is there any way to use this trait during the beta ? I'm not sure how I can get the code to compile. Thanks for any tip / hints you can offer :+1:
Hi Commenting on random unrelated issues is usually not the right thing to do. You should rather open a new issue, or ask on . But to answer your question anyway, that trait only has : … and is stable and can be used on beta. So I’d recommend you copy/paste the trait into your code, or make a function.
Thanks for taking the time to answer. I appreciate it. I don't see how this is unrelated. This is related, since the code I'm talking about used to compile with and the compiler suggests to do that, during the beta period. Thanks for your tip on copying the function :+1: I guess I'll just do that if nothing better is available and change this again when the trait is stable.
This specific issue is about fixing one of the compiler’s error message, not about fixing code that triggers that error. It really helps everyone to keep discussions on topic.
Alright. I understand. I'll make sure to open a new issue or go on StackOverflow next time if appropriate. Thanks again :+1:
This doesn't seem to be properly fixed in the beta channel. I'm still being recommended to add in the errors, and then told it's not available in the beta channel. Rust version: The code I used (snappy example in the docs with the extra addition on the first line:
This happened after Beta release.
We'll see the effect of this patch in 1.0 and afterwards Beta, etc.
Whoops, I thought this made it in before beta. Thanks!
are there plans to release updates to the beta channel within a given 6 weeks cycle? Either this one or in the future.
I'm certain there will be updates; see discussion from last night here:
So how does one fix this error? I'm a new user of the rust library and I can't seem to use the collections library during the beta due to this problem. Given this git issue is a top google result, it would be nice if there were a solution here. Edit: Looks like the solution is to switch to the rust nightly. Is the entire collections library off-limits in the beta?
by design, you have access to the parts of that are re-exported from (and are stable).
Rust compiler (rustc 1.1.0-nightly ( 2015-05-14) (built 2015-05-14) fails to compile this source: With the error: I can reproduce this ICE also on
Reduced it a bit:
The broken IR:
Looking through it quickly, it seems like the order of the cleanups is messed up? If is then from the switch we go to the label which just jumps to where we memcpy the value for into the alloca and then continue to the label. This is where the problem is since it tries to call on the value returned from . But that's the thing, we wouldn't have called in that arm of the branch and hence shouldn't need to call free either.
Adding a block around suppresses the error. I feel like we had a similar problem not too long ago.
This is "caused" by the micro optimization for dereferencing owned pointer rvalues in . Since is the "trailing" expression for the arm its cleanup will be scheduled in the same scope as the match expression. cc
Either way, this is a dupe of I believe had an idea for a fix.
it's simple, we remove the micro-optimization and always return an datum from . The possibility of returning datum also caused issues with field accesses - see for that fix. We have a static type system and the / marker types are there for a reason. If there is no answer to "how is an rvalue dereference or field meaningful?", then the return type for both of those should be .
Original testcase by (reduced from ): The debug log reveals that a (shallow free) cleanup of the rvalue is scheduled in the scope of AST node , while the dereference expression itself has id : reveals that id refers to the entire function's block: This means the cleanup of a value valid only within a match arm is scheduled outside the arm. cc
Dupe of Leaving open for now but we can close either.
This is caused by a micro-optimization specific to dereferences of rvalues. Is this used oftenly enough to justify its existence in the first place? Even if it is, I guess we can disable it in problematic cases like this, where the temporary scope of the match arm's RHS is outside the arm.
I think we can probably remove it, in general removing special treatment of seems like a Good Thing
Triage: this still ICEs.
can you point me/us at the micro-optimization that you mentioned above, so that I (we) can try removing it ourselves and measure the impact?
I only vaguely recall this issue, but I'm pretty sure I was talking about .
triage: still ICEs.
Indeed, it doesn't even need : Does this at least continue to ICE even if LLVM is compiled without assertions? If not, we may want to up the priority on this ticket.
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this probably crashes since but I haven't verified that yet
smaller
even smaller
Rustdoc on [nightly documents][1] methods have signature of as while it only has to document it as . ! On [rustdoc stable][2], things are normal: ! : Version 1.49.0 ( 2020-12-29) [1]: [2]:
I'd like to investigate this :)
searched nightlies: from nightly-2020-12-29 to nightly-2021-01-22 regressed nightly: nightly-2021-01-09 searched commits: from to regressed commit: This regressed in , so this is probably caused by
This also affects Where will generate:
So a few observations: which displays mutability in patterns, causing to be displayed the mechanism for detecting and eliding works by , but as returns instead of , the comparison fails and displays the type.
I see two path to solving this bug: an option for to not display the mutability in patterns revert cc what do you think?
I would prefer to go for 1, there's no reason to have two completely different functions for pretty-printing.
Assigning and removing as in the prioritization working group.
(now a beta regression)
New contributors haven't use before, so there's no reason for them to read the changelog: nothing has changed.
I can tackle this.
that would be great! To get started, take a look at . In addition to adding , also add . You'll have to move from to so you can access it in . You should also double check that the changelog warning isn't printed during the command itself. I'm not sure exactly how to do that without reading the code, but I expect it to be a simple or something like that.
is unacceptably slow. Consider this code: When trying this code, make sure you have enabled release mode. On my local machine I see this output: So is 15x slower than . My rustc version is . My OS is Debian Stretch x86_64
label +A-process +I-slow
On windows they are both equally fast, so it seems to be a unix-specific thing. Also note that these two programs are not equivalent, as also reads , while you don't (this probably introduces some overhead). Still seems worth at least investigating.
What's the magnitude of slowness here? and what's the time taken on windows? Here's it on my computer, built with release mode My computer : Apple M1 Mac Mini, 16gb RAM and 8 CPU Cores
. I just compared old rustc () and new one, with this fix (). I see that the bug is actually fixed, thanks a lot! Moreover, both benchmarks became faster
For this code: You get the following error message: The suggestion may be excused to be not 100% perfect, but here it suggests to add an use statement despite that same item being imported already. What I want is this exactly: that it removes stuff from the suggestion list that is already being imported. Note that changing the glob import to a non glob one doesn't change anything.
cc
Why is that even an error?
tuple structs have private fields by default, you can't construct instances of B outside of the foo module.
oh ^^ maybe we should simply modify this error message then to say that the "function" is private?
It already says "constructor is not visible here due to private fields". That's okay, but maybe you might have meant another B from another module or something. However, the candidate offered is not any better as its the same one you are attempting to use.
Reopening to track "removal of suggestion" work for pub tuple structs with private fields.
<!-- Thank you for finding an Internal Compiler Error! If possible, try to provide a minimal verifiable example. You can read "Rust Bug Minimization Patterns" for how to create smaller examples. --<!-- If you're using the stable version of the compiler, you should also check if the bug also exists in the beta or nightly versions. --: Not posting the entire 1.7K lines backtrace :upsidedownface: <!-- Include a backtrace in the code block by setting in your environment. E.g. . --<details<summary<strongBacktrace</strong</summary<p</p</details
You can also reproduce this in the rustc repo itself where will encounter the error with
Reduced: label F-typealiasimpl_trait
Found another repro I think: this one bisects to
`
prioritize
going to also link and as other reports of the same issue
WG-prioritization assigning priority (). label -I-prioritize +P-medium
Ok, after a bit more back ond forth , I'm tentatively bumping this issue to P-critical and raise these questions (echoing the comments from the discussion): would it make sense to revert ? cc or would it make sense to revert (which IIUC leaked in the std library an unstable nightly only feature) ? cc Next week Rust 1.72 will be released, artifacts are going to be build real soon, I think. Thanks for additional comments to help improve my understanding of the context here. label -P-medium +P-critical
The underlying issue here is an issue with TAIT. was an implementation-only change simplifying some backtrace code in that was made under the assumption that TAIT was reliable enough to be used inside . As it is not user-facing it should be easily revertible. So the question here is whether it is safer to get TAIT working (potentially by reverting ?) so it can be used internally or to just hold off on using it until the issue has been resolved, reapplying once that happens. I have no compiler experience, but my initial hunch would be that the library change is preferable for now. I'll get a PR ready until tomorrow, unless someone beats me to it.
should not be reverted.
All it does is cause us to now eagerly reveal opaques that were being skipped over during normalization, which means that we're just not hitting this code anymore: It does not introduce a bug, it just reveals one that already existed. I'm gonna use the minimized example () here. What's happening here is that we're generating a drop shim for that looks like: which then tries to validate that . However, it has type , where is a , which does not hit the code I linked above. Before , we'd emit something that looks like: which is a field that is incompletely normalized, but does* hit the code above.
Submitted the PR reverting : .
fixes this issue by not considering mir validity on shims until they have been optimized, which uses the reveal-all param-env for that shim. This ICE shouldn't be possible to trigger without , since it has to do with one of the intra-pass mir validations that are only done when that flag is active: I don't personally think that needs to be reverted, either.
This was also possible to trigger even before using an associated type. The test in exercises this too.
The expansion of and both currently cause code to fail the stability check because they expand to reveal unstable implementation details. A seemingly reasonable solution to this would be to just not run the analysis on any code that has been macro-expanded. cc
I definitely agree with this approach: we should be able to annotate a macro with a stability level, and that's what should count for its users. Do we have a way of telling what part of an AST was generated via macro expansion by the time we get to linting?
Mostly; there's the field of a : for normal code, for macro generated code (basically containing the backtrace of macro invocations that led to that point).
OK, that makes this sound like a pretty easy fix. I'll take a quick look at it tomorrow (unless wants to?)
Hm, this seems slightly subtle, since the contents of a macro would then never be checked for stability. This differs to a conventional function, e.g. given , won't warn, but the contents of is still checked, while where is just never checked. (Of course, macros and phasing are both feature gated so you have to opt-in to instability to use non-standard macros anyway.)
Good point. Also, it looks tricky with the current infrastructure to even lint on the macro invocation -- the backtrace of macro expansion does not appear to link to the def_id of the macro (or give any other way of getting at the macro's stability). Nevertheless, I think we should bail out of the lint when we hit the results of expansion; those should be checked, if anywhere, at the site of macro definition. One other question: do syntax extensions also produce the span information you mentioned above? I ask because original problematic cases are written syntax extensions. If not, is there some other way of telling that an expansion happened?
I have a patch ready that bails of out the lint on expanded code. This also seems to mask uses of . If y'all are ok with this strategy for now, I'll file a PR.
Sounds good to me. Thanks!
cc
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Slightly minimized:
I understand the issue here, and have a solution but it might not be optimal. claim
Following , we realized that rustdoc users would prefer to have a syntax extension rather than using plain HTML to have warning blocks. suggested the following: suggested: What do you think? cc
Personal Opinions: The first style will look fine for short forms, but I'm not sure for longer text. A possible syntax: Which to me pushes the text too far right. Not having any spacing, but just separating with newlines, seems hard to parse at a glance what is part of the WARNING, and prevents multiple line breaks inside the warning. Also, it's not as extensible. INFO can be , but if we ever want more extensions, they would increasingly possibly conflict with other things. The second style makes it immediately clear what is part of the block, and is unlikely to accidentally conflict if we ever want to add more block styles. It also supports multiple lines or inner blocks trivially. A final advantage is that it may support nested blocks, in case those ever come to be useful. Overall: I prefer the second form, both aesthetically and for future-proofing
I think I agree with in preferring the second form. I like the first form's simplicity, but it also seems surprising that is treated as a 'keyword' and will change the formatting of the docs.
That's why we have this debate. :stuckouttongue:
I personally actually prefer stabilizing a CSS class, I think we should do more of that, just because parsing can get annoying. But this is not that hard to parse anyway. The problem with is precisely that you can't scope it easily: what if you want to add code blocks? bullet points?
The problem with this is it ties rustdoc to the HTML backend; like I said nothing rustdoc currently does guarentees that it will generate HTML from the markdown. Changing that means that to make the JSON backend have the same info, we'd have to add a full HTML parser to rustdoc just to read the HTML in the markdown, because pulldown does not parse HTML for us. I really think we should avoid making the JSON backend a second-class citizen.
Also there's not much point to this if it's just a little CSS IMO, you can add that yourself with and it will look just as good and be more flexible since you can control the styles yourself.