jiebi/CodeConvo huggingface dataset:
Code change:
pub use self::scoped_tls::ScopedKey; #[doc(hidden)] pub use self::local::__KeyInner as __LocalKeyInner; <ins> #[doc(hidden)] pub use self::scoped_tls::__KeyInner as __ScopedKeyInner; </ins> //////////////////////////////////////////////////////////////////////////////// // Builder

Related discussion:
text: Then the actual borrow of a static is an implementation detail and happens on the thread where the key is used, not where it was itself borrowed.
"I believe the only way #[threadlocal] statics can be safe is by requiring the absence of ." This is wrong, I think. For example, one might use thread local data for intrusive linked lists of hazard pointers. They would be thread local but might still be (one can guarantee existence with scoped threads or in certain circumstances where threads are bound to cores). That said you can obviously come up with other representations. In any case, I've mostly come around to believing that we need a separate lifetime (not just for this, but for things like ensuring that can't catch an error in a thread that changes thread local data, violating exception safety).
Based on what wrote, it seems like the TLS interface requires a that only allows non- data and is still accessible like one. One idea I had of how to enable this in todays Rust is to make generate a unit like struct instead of a . That struct would be and have a impl: According to this could also help with , but I'm not familiar enough with the TLS API in general to really reason about this.
I was expecting the impl to target an intermediary type, not the contents themselves. and have their own APIs to deal with. You would still be about to use the TLS API provided by libstd with thread-safe data, it's just the low-level which would have the requirement. Ideas of thread-local lifetimes predate the removal of from , and I'm not sure how relevant they are anymore. I'm also conflating thread-safe data access and thread lifetime... but how long does a thread live? What would unify with? Actually, there's an... easy solution for this. Somehow we were blinded by language semantics, but their details are fluid. It is trivial to make borrows of behave like borrows of an arbitrary rvalue, allowing the resulting reference to be passed down, but not returned. That would ensure that the the thread is just as alive for such borrows as it is for stack ones. would still require a like has, because it may not be when native TLS is supported. But both their APIs are compatible with such a change.
Wouldn't that limit the usability of thread locals in some cases, though?
Code change:
pub use self::scoped_tls::ScopedKey; #[doc(hidden)] pub use self::local::__KeyInner as __LocalKeyInner; <ins> #[doc(hidden)] pub use self::scoped_tls::__KeyInner as __ScopedKeyInner; </ins> //////////////////////////////////////////////////////////////////////////////// // Builder

Related discussion:
text: e.g., wouldn't that make it difficult to have a thread local point to another thread local? Maybe I just have to think about it. (BTW, I'm aware we're just talking about the low-level API :)).
in a , borrows are , I didn't even think of that. First off, a global static shouldn't be allowed to borrow a static. And in general, having borrows in a is going to be difficult to support, except for non- data, because they would be right now. We could disallow borrows or we could give some kind of scope to those borrows. Which makes me think, as a compromise between a lifetime and , there could be a pseudo-(rvalue)-scope. Combined with the ability to leave out in globals' type (or not having a type at all), the scope should bubble up into users of those statics. They would behave as if they were borrowed before everything else in the function where they're used, but still not (and they can't be returned from functions).
There's a few intertwined issues here at play, so I just want to quickly summarize the way I see things: This does not affect as it which has an , which while sound should be fixed, allowing removal of the block for . A borrow of a static should not yield something with the lifetime, as that is clearly not sound. I'm not sure I follow why we might require the types in a are not , I haven't quite followed that. Due the cross-platform requirements of std, however, I believe the best solution here is to use the same strategy as with an indirect accessor to ensure the semantics are the same across platforms that have and those that don't (where a normal is used).
triage: P-medium This is an unstable API so it's not super-high priority to fix, but we should defnitely fix!
requiring that a is not is an easy way to ensure that a borrow of it, while , cannot escape the current thread. I've changed my mind and prefer an rvalue borrow semantic for , but it still is the case that and use non- statics (ignoring the workarounds for ). If was supported everywhere, having rvalue borrow semantics wouldn't hurt the std TLS API (aside from stability issues with ), as the access patterns are already through anonymous lifetimes (references passed to closures).
Code change:
pub use self::scoped_tls::ScopedKey; #[doc(hidden)] pub use self::local::__KeyInner as __LocalKeyInner; <ins> #[doc(hidden)] pub use self::scoped_tls::__KeyInner as __ScopedKeyInner; </ins> //////////////////////////////////////////////////////////////////////////////// // Builder

Related discussion:
text: Maybe a combined strategy, where borrows of statics are iff the data is not (and rvalue-like otherwise), might work better and would require fewer changes to the std TLS implementation.
Right, but returning a borrow with a lifetime for a global is unsafe for other reasons (the lifetime of the thread is not ).
how can it be abused without sending it to a different thread?
The actual values themselves do not have a lifetime, so it can be a source of unsafety to advertise otherwise. For example you could stick a into a TLS value with a destructor, but when the destructor runs that pointer could be invalid.
Code change:
<ins> // run-rustfix // Regression test for #54505 - range borrowing suggestion had // incorrect syntax (missing parentheses). use std::ops::RangeBounds; // take a reference to any built-in range fn take_range(_r: &impl RangeBounds<i8>) {} fn main() { take_range(0..1); //~^ ERROR mismatched types [E0308] //~| HELP consider borrowing here //~| SUGGESTION &(0..1) take_range(1..); //~^ ERROR mismatched types [E0308] //~| HELP consider borrowing here //~| SUGGESTION &(1..) take_range(..); //~^ ERROR mismatched types [E0308] //~| HELP consider borrowing here //~| SUGGESTION &(..) take_range(0..=1); //~^ ERROR mismatched types [E0308] //~| HELP consider borrowing here //~| SUGGESTION &(0..=1) take_range(..5); //~^ ERROR mismatched types [E0308] //~| HELP consider borrowing here //~| SUGGESTION &(..5) take_range(..=42); //~^ ERROR mismatched types [E0308] //~| HELP consider borrowing here //~| SUGGESTION &(..=42) } </ins>

Related discussion:
text: is an incorrect suggestion because has higher precedence than . It should suggest .
If someone wants to tackle this issue, it should be straightforward to fix. In: there should be another branch for , where the path of the call is . This code is a good reference: This issue affects the other range syntaxes too, so those should also be fixed (although these are not — look at for clues).
Hi I'd like to tackle this and take the plunge into the Rust compiler code :)
great! Let me know if you hit any snags or need any more tips. You'll want to add tests for these (in ). The is a good place for general information about the compiler. When you're done, include in the pull request and I'll review it!
you've anticipated most of my newbie questions already :) Thanks for that info, very useful! I'm now in the process of stressing my PC with lots of compiling to actually get started. Skimming the test code I'm really impressed by how easy it is to add "UI" tests for these sorts of things (compile this, expect this error on this line). Snazzy! That's all great, but do you anticipate I should also add "deeper" tests? I guess I'm trying to understand if the scope of this is just pure UI or do I need to touch some syntax parsing/immediate representations, since you mentioned code in . Because the compiler is emitting a syntax suggestion, we might want to assert that the suggestion is correct syntax in the first place. I don't know if that's how deep the rabbit hole goes and if there's a facility to help out, but my hunch is that since we have all of the compiler at hand, why not use it to validate the suggestion syntax? EDIT: OK, reading up on adding new tests to the compiler I encountered mention of , and it seems to be sort-of what I was after.
The issue here is just a diagnostic issue, so checking that we're getting the updated hint is enough. The code in is just helpful to see what ranges like and are desugared into, so you can catch them in — you shouldn't need to modify anything (apart from the test) outside of . It would technically be possible to do something like this, but it would probably be more trouble than it's worth.
Code change:
<ins> // run-rustfix // Regression test for #54505 - range borrowing suggestion had // incorrect syntax (missing parentheses). use std::ops::RangeBounds; // take a reference to any built-in range fn take_range(_r: &impl RangeBounds<i8>) {} fn main() { take_range(0..1); //~^ ERROR mismatched types [E0308] //~| HELP consider borrowing here //~| SUGGESTION &(0..1) take_range(1..); //~^ ERROR mismatched types [E0308] //~| HELP consider borrowing here //~| SUGGESTION &(1..) take_range(..); //~^ ERROR mismatched types [E0308] //~| HELP consider borrowing here //~| SUGGESTION &(..) take_range(0..=1); //~^ ERROR mismatched types [E0308] //~| HELP consider borrowing here //~| SUGGESTION &(0..=1) take_range(..5); //~^ ERROR mismatched types [E0308] //~| HELP consider borrowing here //~| SUGGESTION &(..5) take_range(..=42); //~^ ERROR mismatched types [E0308] //~| HELP consider borrowing here //~| SUGGESTION &(..=42) } </ins>

Related discussion:
text: (I'm not aware of a facility to do this easily already.) I think manually going through the possible s and checking that the parenthesisation behaviour is correct in each case would be a lot simpler: if we handle the different s in an exhaustive now (it's likely that if the ranges were handled incorrectly, there could be some others that are also missed at the moment), then this should be a one-time fix and the tests should prevent it regressing. A simple UI test should be sufficient here: will generate the output files, which will include all the relevant notes.
There was a similar problem with the suggestions, and it was fixed in . Further use of the operator precedence list can be seen in (which introduced the error fixed in the other PR).
Thanks for your guidance and much appreciated. I have dug into HIR and built-in ranges a bit more. Decided to check all the built-in range types and concluded they are all indeed affected by this problem. The following test I came up with demonstrates my intended fix (fails with nightly as well as stage 1 compiled from master): None of the fix suggestions, when applied, constitute valid syntax. My test checks for syntax I believe should be suggested by the compiler. I'm keen to tackle all of the range types at once in the scope of this issue. The problem I see though is just how wildly different each of the range types is represented in HIR. Adding a call just above this line: Revealed the following: for isfor isfor isfor isfor isfor is I'm quite bewildered by this non-uniformity and I guess I need some help unifying all of these into a elegant condition to tell "is this a built-in range?". I could probably brute-force it in a with explicit checks for , but maybe we can do better. Thanks in advance! EDIT realized that this non-uniformity was actually mentioned in the second comment from , but my plea still stands. Thanks for your patience.
I think you can match on all of these with something along the lines of (pseudocode):
Right, that's what I had in mind, but was also wondering if something like a check for  trait would work better. I guess we want to match against built-in range literals though, and explicitly.
Code change:
<ins> // run-rustfix // Regression test for #54505 - range borrowing suggestion had // incorrect syntax (missing parentheses). use std::ops::RangeBounds; // take a reference to any built-in range fn take_range(_r: &impl RangeBounds<i8>) {} fn main() { take_range(0..1); //~^ ERROR mismatched types [E0308] //~| HELP consider borrowing here //~| SUGGESTION &(0..1) take_range(1..); //~^ ERROR mismatched types [E0308] //~| HELP consider borrowing here //~| SUGGESTION &(1..) take_range(..); //~^ ERROR mismatched types [E0308] //~| HELP consider borrowing here //~| SUGGESTION &(..) take_range(0..=1); //~^ ERROR mismatched types [E0308] //~| HELP consider borrowing here //~| SUGGESTION &(0..=1) take_range(..5); //~^ ERROR mismatched types [E0308] //~| HELP consider borrowing here //~| SUGGESTION &(..5) take_range(..=42); //~^ ERROR mismatched types [E0308] //~| HELP consider borrowing here //~| SUGGESTION &(..=42) } </ins>

Related discussion:
text: Here's how I rationalize it: because they are parsed and desugared by the compiler, the check needs to be explicit and hardcode all paths to builtin ranges. Handle a special case with a special case.
Yes, this is where the lowering code comes in handy, because you can see exactly how the different syntax is desugared differently, to make sure you really are catching all the cases. Yes, I agree. It'd be nice if there was a more uniform way to handle them, but it's not convenient at the moment. You could include a reference back to in a comment to where the desugaring takes place, which will provide some motivation for matching in .
All clear now, thanks. I have succeeded in matching all range types and getting the test to pass. Needs some cleanups, but hopefully should be ready for PR soon. I have a few more questions before that though :smile: I have noticed that most of my code would actually be irrelevant if I re-used functions and constants defined in , e.g.: Can't deny that I have used these as inspiration / guideline (albeit I did not do a stupid copy-paste). What's the policy on using clippy code (clippy is a submodule of main repo)? This is purely in the interest of pursuing . The diff is not that big (52 new lines to , fairly specific to matching paths) -- but still, my clean code sense tingles because of possible DRY violation. Another conundrum I have is whether we should address and paths (and if so, how to work out we're not using at compile time)?
Unfortunately, there's not much sharing from clippy to rustc. I wouldn't worry about it. If you can encapsulate it easily, it's possible that clippy could make use of the code in rustc instead. The function in picks the correct path for / — you should be able to use that.
Thanks for the suggestion for , unfortunately I can't really make the association of and . It seems to me they are disjoint -- in : lowering happens in , whereas typechecking happens in . in takes : The it uses needs an awful lot of things to be instantiated. Not sure if I can get the hold of it all in .
Code change:
<ins> // run-rustfix // Regression test for #54505 - range borrowing suggestion had // incorrect syntax (missing parentheses). use std::ops::RangeBounds; // take a reference to any built-in range fn take_range(_r: &impl RangeBounds<i8>) {} fn main() { take_range(0..1); //~^ ERROR mismatched types [E0308] //~| HELP consider borrowing here //~| SUGGESTION &(0..1) take_range(1..); //~^ ERROR mismatched types [E0308] //~| HELP consider borrowing here //~| SUGGESTION &(1..) take_range(..); //~^ ERROR mismatched types [E0308] //~| HELP consider borrowing here //~| SUGGESTION &(..) take_range(0..=1); //~^ ERROR mismatched types [E0308] //~| HELP consider borrowing here //~| SUGGESTION &(0..=1) take_range(..5); //~^ ERROR mismatched types [E0308] //~| HELP consider borrowing here //~| SUGGESTION &(..5) take_range(..=42); //~^ ERROR mismatched types [E0308] //~| HELP consider borrowing here //~| SUGGESTION &(..=42) } </ins>

Related discussion:
text: Another problem I encountered while writing tests is that the changes I have made will affect suggestions for code like this: With my changes, the suggestion would be . I believe the correct suggestion would not involve the needless parentheses. This is due to not differentiating between "de-sugared" form coming from and between these de-sugared forms being supplied explicitly as input source code. With this in mind, I think current code is not PR worthy just yet. If of interest, here's the branch:
Left a couple of comments on possible approaches on that commit. The code looks fine.
Code change:
<ins> // Verify that lifetime resolution correctly accounts for `Fn` bare trait objects. // check-pass #![allow(bare_trait_objects)] // This should work as: fn next_u32(fill_buf: &mut dyn FnMut(&mut [u8])) fn next_u32(fill_buf: &mut FnMut(&mut [u8])) { let mut buf: [u8; 4] = [0; 4]; fill_buf(&mut buf); } fn explicit(fill_buf: &mut dyn FnMut(&mut [u8])) { let mut buf: [u8; 4] = [0; 4]; fill_buf(&mut buf); } fn main() { let _: fn(&mut FnMut(&mut [u8])) = next_u32; let _: &dyn Fn(&mut FnMut(&mut [u8])) = &next_u32; let _: fn(&mut FnMut(&mut [u8])) = explicit; let _: &dyn Fn(&mut FnMut(&mut [u8])) = &explicit; let _: fn(&mut dyn FnMut(&mut [u8])) = next_u32; let _: &dyn Fn(&mut dyn FnMut(&mut [u8])) = &next_u32; let _: fn(&mut dyn FnMut(&mut [u8])) = explicit; let _: &dyn Fn(&mut dyn FnMut(&mut [u8])) = &explicit; } </ins>

Related discussion:
text: <!-- Thank you for filing a regression report! A regression is something that changed between versions of Rust but was not supposed to. Please provide a short summary of the regression, along with any information you feel is relevant to replicate it. --I tried this code with : I expected to see only warning without error, like this: Instead, this happened (extra error E0521 emitted, which is incorrect): If I add in line 3, it compiles without any error or warning: So the E0521 error emitted by the compiler is incorrect. The test code using should only produce warnings without an error. It most recently worked on: 1.63.0-nightly ( 2022-05-18) </p</details<!-- If you know when this regression occurred, please add a line like below, replacing with one of stable, beta, or nightly. modify labels: +regression-from-stable-to-{channel} -regression-untriaged --
labels:+T-compiler
label A-diagnostics
labels: +regression-from-stable-to-nightly
label -regression-untriaged Bisection: regressed nightly: nightly-2022-06-23 searched commit range: regressed commit: that’s , cc
Seems like, possibly, the code without the explicit (incorrectly) desugars to rather than Edit: Or perhaps it incorrectly desugars to
Here’s another kind of code example that reproduces the issue Which does confirm the idea that this appears to be interpreted like , rather than which would be correct.
WG-prioritization assigning priority (). label -I-prioritize +P-critical
Code change:
<ins> // Verify that lifetime resolution correctly accounts for `Fn` bare trait objects. // check-pass #![allow(bare_trait_objects)] // This should work as: fn next_u32(fill_buf: &mut dyn FnMut(&mut [u8])) fn next_u32(fill_buf: &mut FnMut(&mut [u8])) { let mut buf: [u8; 4] = [0; 4]; fill_buf(&mut buf); } fn explicit(fill_buf: &mut dyn FnMut(&mut [u8])) { let mut buf: [u8; 4] = [0; 4]; fill_buf(&mut buf); } fn main() { let _: fn(&mut FnMut(&mut [u8])) = next_u32; let _: &dyn Fn(&mut FnMut(&mut [u8])) = &next_u32; let _: fn(&mut FnMut(&mut [u8])) = explicit; let _: &dyn Fn(&mut FnMut(&mut [u8])) = &explicit; let _: fn(&mut dyn FnMut(&mut [u8])) = next_u32; let _: &dyn Fn(&mut dyn FnMut(&mut [u8])) = &next_u32; let _: fn(&mut dyn FnMut(&mut [u8])) = explicit; let _: &dyn Fn(&mut dyn FnMut(&mut [u8])) = &explicit; } </ins>

Related discussion:
text: ndarray 0.9.1 compiles with rustc 1.61.0 but not with rustc 1.64.0-nightly ( 2022-06-27). Put this into a of a new project: rustc stable <= 1.61.0 compiles the crate fine, rustc nightly gives the following error: modify labels: +regression-from-stable-to-nightly -regression-untriaged
Just adding a note. The issue seems to be an old version of that used to use back in v0.9.1 <details</detailsThe crate from v0.13.0 (released in sept. 2019) compiles fine also on latest Rust nightly
bisection seems to point to commit cc searched nightlies: from nightly-2022-04-01 to nightly-2022-06-28 regressed nightly: nightly-2022-06-23 searched commits: from to regressed commit: <details<summarybisected with <a href=''cargo-bisect-rustc</av0.6.0</summaryHost triple: x86_64-unknown-linux-gnu Reproduce with: </details(unsure if this regression may hit other more recent crates)
I've been suspecting this bug for a few days, but unable to reproduce it. I think I have a patch, will confirm once I manage to MCVE.
WG-prioritization assigning priority (). label -I-prioritize +P-high
Code change:
// components like the llvm tools and LLD. LLD is included below and // tools/LLDB come later, so let's just throw it in the rustc // component for now. <del> maybe_install_llvm_dylib(builder, host, image); </del> <ins> maybe_install_llvm_runtime(builder, host, image); </ins> // Copy over lld if it's there if builder.config.lld_enabled {

Related discussion:
text: Since , has been distributed in the component in two locations: (presumably as a runtime dependency of ) (not sure, maybe for linking custom drivers?) likely belongs in the component, if the duplication can't be avoided <hr/The difference can be seen in these consecutive nightlies' components: has just the second maybe it's used via relative by ? separate codegen backends are gone, maybe we should just try removing it? first nightly to include has both copies All 3 of those files are identical (even across nightlies, yay for deterministic builds): One fascinating aspect is that the size only increases from to , despite alone being uncompressed, so compression is really helping. Even the only goes from to . (I'm using archive sizes from the and directory listings in , FWIW) <hr/This part of the build system seems relevant, but I'm not sure which of the two this creates: cc
cc -- you've touched code related to this a bunch recently I think, so maybe would have some time to investigate fixing this. I suspect we want to only ship one LLVM per tarball, at least, though ideally we would only have just the one LLVM library total as well.
Half-way through writing up this issue I realized the connection. I'd suggest we try to get rid of the copy and see what breaks, it's possible it's been dead weight for a while now. And only if we have to keep both for some odd reason, we'd move it to .
The purposely orders the tarred files so that similar filenames are adjacent in the compression stream, especially in hope of helping with such duplicate files. I think we may still want the copy for the odd cross-compiled tool using , but that definitely belongs in .
Is that... even possible? Is a per-target component in the same way is?
Yes it is -- try -- but I don't know if anyone really needs that...
Actually, can you try something like cross-compiling a copy of to , after deleting the per-target ? I suspect that it would actually run just fine on a host, because 's s should only really contain the information and maybe some object code that is missing (which we could get rid of if we kept MIR for everything but idk how feasible that is). That is, the result of linking against should still use at runtime, so in is unnecessary. But maybe I'm missing something.