Stabilize `const_waker`
Closes: https://github.com/rust-lang/rust/issues/102012.
For `local_waker` and `context_ext` related things, I just ~~moved them to dedicated feature gates and reused their own tracking issue (maybe it's better to open a new one later, but at least they should not be tracked under https://github.com/rust-lang/rust/issues/102012 from the beginning IMO.)~~ reused their own feature gates as suggested by ``@tgross35.``
``@rustbot`` label: +T-libs-api
r? libs-api
Fix doc nits
Many tiny changes to stdlib doc comments to make them consistent (for example "Returns foo", rather than "Return foo"), adding missing periods, paragraph breaks, backticks for monospace style, and other minor nits.
from_ref, from_mut: clarify documentation
This was brought up [here](https://github.com/rust-lang/rust/issues/56604#issuecomment-2143193486). The domain of quantification is generally always constrained by the type in the type signature, and I am not sure it's always worth spelling that out explicitly as that makes things exceedingly verbose. But since this was explicitly brought up, let's clarify.
Gate `AsyncFn*` under `async_closure` feature
T-lang has not come to a consensus on the naming of async closure callable bounds, and as part of allowing the async closures RFC merge, we agreed to place `AsyncFn` under the same gate as `async Fn` so that these syntaxes can be evaluated in parallel.
See https://github.com/rust-lang/rfcs/pull/3668#issuecomment-2246435537
r? oli-obk
Replace some `mem::forget`'s with `ManuallyDrop`
> but I would like to see a larger effort to replace all uses of `mem::forget`.
_Originally posted by `@saethlin` in https://github.com/rust-lang/rust/issues/127584#issuecomment-2226087767_
So,
r? `@saethlin`
Sorry, I have finished writing all of this before I got your response.
Remove generic lifetime parameter of trait `Pattern`
Use a GAT for `Searcher` associated type because this trait is always implemented for every lifetime anyway.
cc #27721
Update tracking issue for `const_binary_heap_new_in`
This PR updates the tracking issue of `const_binary_heap_new_in` feature:
- Old issue: #112353
- New issue: #125961
Add missing try_new_uninit_slice_in and try_new_zeroed_slice_in
The methods for fallible slice allocation in a given allocator were missing from `Box`, which was an oversight according to https://github.com/rust-lang/wg-allocators/issues/130
This PR adds them as `try_new_uninit_slice_in` and `try_new_zeroed_slice_in`. I simply copy-pasted the implementations of `try_new_uninit_slice` and `try_new_zeroed_slice` and adusted doc comment, typings, and the allocator it uses internally.
Also adds missing punctuation to the doc comments of `try_new_uninit_slice` and `try_new_zeroed_slice`.
Related issue is https://github.com/rust-lang/rust/issues/32838 (Allocator traits and std::heap) *I think*. Also relevant is https://github.com/rust-lang/rust/issues/63291, but I did not add the corresponding `#[unstable]` proc macro, since `try_new_uninit_slice` and `try_new_zeroed_slice` are also not annotated with it.
When we do the big `use` reformatting there are a tiny number of cases
where rustfmt moves a comment from one `use` item to another in an
undesirable way. This commit pre-emptively rearranges things to prevent
this from happening.
Remove memory leaks in doctests in `core`, `alloc`, and `std`
cc `@RalfJung` https://github.com/rust-lang/rust/issues/126067https://github.com/rust-lang/miri/issues/3670
Should be no actual *documentation* changes[^1], all added/modified lines in the doctests are hidden with `#`,
This PR splits the existing memory leaks in doctests in `core`, `alloc`, and `std` into two general categories:
1. "Non-focused" memory leaks that are incidental to the thing being documented, and/or are easy to remove, i.e. they are only there because preventing the leak would make the doctest less clear and/or concise.
- These doctests simply have a comment like `# // Prevent leaks for Miri.` above the added line that removes the memory leak.
- [^2]Some of these would perhaps be better as part of the public documentation part of the doctest, to clarify that a memory leak can happen if it is not otherwise mentioned explicitly in the documentation (specifically the ones in `(A)Rc::increment_strong_count(_in)`).
2. "Focused" memory leaks that are intentional and documented, and/or are possibly fragile to remove.
- These doctests have a `# // FIXME` comment above the line that removes the memory leak, with a note that once `-Zmiri-disable-leak-check` can be applied at test granularity, these tests should be "un-unleakified" and have `-Zmiri-disable-leak-check` enabled.
- Some of these are possibly fragile (e.g. unleaking the result of `Vec::leak`) and thus should definitely not be made part of the documentation.
This should be all of the leaks currently in `core` and `alloc`. I only found one leak in `std`, and it was in the first category (excluding the modules `@RalfJung` mentioned in https://github.com/rust-lang/rust/issues/126067 , and reducing the number of iterations of [one test](https://github.com/rust-lang/rust/blob/master/library/std/src/sync/once_lock.rs#L49-L94) from 1000 to 10)
[^1]: assuming [^2] is not added
[^2]: backlink
Generalize `fn allocator` for Rc/Arc.
Split out from #119761
- For `Rc`/`Arc`, the existing associated `fn`s are changed to allow unsized pointees.
- For `Weak`s, new methods are added.
`````@rustbot````` label +A-allocators
Mark format! with must_use hint
Uses unstable feature https://github.com/rust-lang/rust/issues/94745
Part of #126475
First contribution to rust, please let me know if the blessing of tests is correct
Thanks `@bjorn3` for the help
Make casts of pointers to trait objects stricter
This is an attempt to `fix` https://github.com/rust-lang/rust/issues/120222 and https://github.com/rust-lang/rust/issues/120217.
This is done by adding restrictions on casting pointers to trait objects.
Before this PR the rules were as follows:
> When casting `*const X<dyn A>` -> `*const Y<dyn B>`, principal traits in `A` and `B` must refer to the same trait definition (or no trait).
With this PR the rules are changed to
> When casting `*const X<dyn Src>` -> `*const Y<dyn Dst>`
> - if `Dst` has a principal trait `DstP`,
> - `Src` must have a principal trait `SrcP`
> - `dyn SrcP` and `dyn DstP` must be the same type (modulo the trait object lifetime, `dyn T+'a` -> `dyn T+'b` is allowed)
> - Auto traits in `Dst` must be a subset of auto traits in `Src`
> - Not adhering to this is currently a FCW (warn-by-default + `FutureReleaseErrorReportInDeps`), instead of an error
> - if `Src` has a principal trait `Dst` must as well
> - this restriction will be removed in a follow up PR
This ensures that
1. Principal trait's generic arguments match (no `*const dyn Tr<A>` -> `*const dyn Tr<B>` casts, which are a problem for [#120222](https://github.com/rust-lang/rust/issues/120222))
2. Principal trait's lifetime arguments match (no `*const dyn Tr<'a>` -> `*const dyn Tr<'b>` casts, which are a problem for [#120217](https://github.com/rust-lang/rust/issues/120217))
3. No auto traits can be _added_ (this is a problem for arbitrary self types, see [this comment](https://github.com/rust-lang/rust/pull/120248#discussion_r1463835350))
Some notes:
- We only care about the metadata/last field, so you can still cast `*const dyn T` to `*const WithHeader<dyn T>`, etc
- The lifetime of the trait object itself (`dyn A + 'lt`) is not checked, so you can still cast `*mut FnOnce() + '_` to `*mut FnOnce() + 'static`, etc
- This feels fishy, but I couldn't come up with a reason it must be checked
The diagnostics are currently not great, to say the least, but as far as I can tell this correctly fixes the issues.
cc `@oli-obk` `@compiler-errors` `@lcnr`
Run alloc sync tests
I was browsing the code and this struck me as weird. We're not running some doc tests because, the comment says, Windows builders deadlock. That should absolutely not happen, at least with our current implementation. And if it does happen I'd like to know.
Just to be sure though I'll do some try builds.
try-job: x86_64-msvc
try-job: i686-msvc
try-job: i686-mingw
try-job: x86_64-mingw
Rollup of 8 pull requests
Successful merges:
- #127179 (Print `TypeId` as hex for debugging)
- #127189 (LinkedList's Cursor: method to get a ref to the cursor's list)
- #127236 (doc: update config file path in platform-support/wasm32-wasip1-threads.md)
- #127297 (Improve std::Path's Hash quality by avoiding prefix collisions)
- #127308 (Attribute cleanups)
- #127354 (Describe Sized requirements for mem::offset_of)
- #127409 (Emit a wrap expr span_bug only if context is not tainted)
- #127447 (once_lock: make test not take as long in Miri)
r? `@ghost`
`@rustbot` modify labels: rollup
LinkedList's Cursor: method to get a ref to the cursor's list
We're already providing `.back()` & `.front()`, for which we hold onto a reference to the parent list, so why not share it? Useful for when you got `LinkedList` -> `CursorMut` -> `Cursor` and cannot take another ref to the list, even though you should be able to. This seems to be completely safe & sound.
The name is, of course, bikesheddable.
Don't check the capacity every time (and also for `Extend` for tuples, as this is how `unzip()` is implemented).
I did this with an unsafe method on `Extend` that doesn't check for growth (`extend_one_unchecked()`). I've marked it as perma-unstable currently, although we may want to expose it in the future so collections outside of std can benefit from it. Then specialize `Extend for (A, B)` for `TrustedLen` to call it.
It may seem that an alternative way of implementing this is to have a semi-public trait (`#[doc(hidden)]` public, so collections outside of core can implement it) for `extend()` inside tuples, and specialize it from collections. However, it is impossible due to limitations of `min_specialization`.
A concern that may arise with the current approach is that implementing `extend_one_unchecked()` correctly must also incur implementing `extend_reserve()`, otherwise you can have UB. This is a somewhat non-local safety invariant. However, I believe this is fine, since to have actual UB you must have unsafe code inside your `extend_one_unchecked()` that makes incorrect assumption, *and* not implement `extend_reserve()`. I've also documented this requirement.
Apologies for the many attempts, my dev loop for this consists of editing on github, committing, and then waiting for the CI failure log to yell at me.
The methods for fallible slice allocation in a given allocator were missing, which was an oversight according to https://github.com/rust-lang/wg-allocators/issues/130
This PR adds them as `try_new_uninit_slice_in` and `try_new_zeroed_slice_in`.
Also adds missing punctuation to the doc comments of ` try_new_uninit_slice` and `try_new_zeroed_slice`
The rules for casting `*mut X<dyn A>` -> `*mut Y<dyn B>` are as follows:
- If `B` has a principal
- `A` must have exactly the same principal (including generics)
- Auto traits of `B` must be a subset of autotraits in `A`
Note that `X<_>` and `Y<_>` can be identity, or arbitrary structs with last field being the dyn type.
The lifetime of the trait object itself (`dyn ... + 'a`) is not checked.
This prevents a few soundness issues with `#![feature(arbitrary_self_types)]` and trait upcasting.
Namely, these checks make sure that vtable is always valid for the pointee.
In 126578 we ended up with more binary size increases than expected.
This change attempts to avoid inlining large things into small things, to avoid that kind of increase, in cases when top-down inlining will still be able to do that inlining later.
Cleanup bootstrap check-cfg
This PR cleanup many custom `check-cfg` in bootstrap that have been accumulated over the years.
As well as updating some outdated comments.
Remove `__rust_force_expr`.
This was added (with a different name) to improve an error message. It is no longer needed -- removing it changes the error message, but overall I think the new message is no worse:
- the mention of `#` in the first line is a little worse,
- but the extra context makes it very clear what the problem is, perhaps even clearer than the old message,
- and the removal of the note about the `expr` fragment (an internal detail of `__rust_force_expr`) is an improvement.
Overall I think the error is quite clear and still far better than the old message that prompted #61933, which didn't even mention patterns.
The motivation for this is #124141, which will cause pasted metavariables to be tokenized and reparsed instead of the AST node being cached. This change in behaviour occasionally has a non-zero perf cost, and `__rust_force_expr` causes the tokenize/reparse step to occur twice. Removing `__rust_force_expr` greatly reduces the extra overhead for the `deep-vector` benchmark.
r? ```@oli-obk```
Detect unused structs which derived Default
<!--
If this PR is related to an unstable feature or an otherwise tracked effort,
please link to the relevant tracking issue here. If you don't know of a related
tracking issue or there are none, feel free to ignore this.
This PR will get automatically assigned to a reviewer. In case you would like
a specific user to review your work, you can assign it to them by using
r? <reviewer name>
-->
Fixes#98871
This was added (with a different name) to improve an error message. It
is no longer needed -- removing it changes the error message, but overall
I think the new message is no worse:
- the mention of `#` in the first line is a little worse,
- but the extra context makes it very clear what the problem is, perhaps
even clearer than the old message,
- and the removal of the note about the `expr` fragment (an internal
detail of `__rust_force_expr`) is an improvement.
Overall I think the error is quite clear and still far better than the
old message that prompted #61933, which didn't even mention patterns.
The motivation for this is #124141, which will cause pasted
metavariables to be tokenized and reparsed instead of the AST node being
cached. This change in behaviour occasionally has a non-zero perf cost,
and `__rust_force_expr` causes the tokenize/reparse step to occur twice.
Removing `__rust_force_expr` greatly reduces the extra overhead for the
`deep-vector` benchmark.
