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Add O(1) Vec -> VecDeque conversion guarantee #105128

Merged
merged 1 commit into from
Jan 8, 2023
Merged

Add O(1) Vec -> VecDeque conversion guarantee #105128

merged 1 commit into from
Jan 8, 2023

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Sp00ph
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@Sp00ph Sp00ph commented Dec 1, 2022

(See #105072)

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rustbot commented Dec 1, 2022

r? @joshtriplett

(rustbot has picked a reviewer for you, use r? to override)

@rustbot rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Dec 1, 2022
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rustbot commented Dec 1, 2022

Hey! It looks like you've submitted a new PR for the library teams!

If this PR contains changes to any rust-lang/rust public library APIs then please comment with @rustbot label +T-libs-api -T-libs to tag it appropriately. If this PR contains changes to any unstable APIs please edit the PR description to add a link to the relevant API Change Proposal or create one if you haven't already. If you're unsure where your change falls no worries, just leave it as is and the reviewer will take a look and make a decision to forward on if necessary.

Examples of T-libs-api changes:

  • Stabilizing library features
  • Introducing insta-stable changes such as new implementations of existing stable traits on existing stable types
  • Introducing new or changing existing unstable library APIs (excluding permanently unstable features / features without a tracking issue)
  • Changing public documentation in ways that create new stability guarantees
  • Changing observable runtime behavior of library APIs

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Sp00ph commented Dec 1, 2022

@rustbot label +T-libs-api -T-libs

@rustbot rustbot added T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. and removed T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Dec 1, 2022
@dtolnay dtolnay assigned dtolnay and unassigned joshtriplett Dec 1, 2022
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dtolnay commented Dec 1, 2022

@rust-lang/libs-api:
@rfcbot fcp merge

Can we guarantee that converting Vec to VecDeque (using From) is able to keep the original allocation, not dropping unused capacity or needing to snap to a particular element count, such as power-of-2?

rust-lang/libs-team#138 has the justifications. Here is what I found compelling:

By guaranteeing that this conversion be O(1), it allows users to freely convert between Vec<T> and VecDeque<T> without ever reallocating and makes it trivial to e.g. turn an existing Vec<T> into a FIFO queue.

As a bonus if the O(1) conversion happens, we could delegate VecDeque: FromIterator to Vec: FromIterator, getting a bunch of optimization for free (by not needing to reimplement them on VecDeque) and potentially saving a bunch of monomorphization work too (since collecting an iterator into either container type can reuse the same code).

(Could even spell it impl<I, T> FromIterator<I> for VecDeque<T> where Vec<T>: FromIterator<I> and never again worry about keeping them in sync.)

I'd love to have this. It'd be amazing to change the answer for "how do I remove a bunch of things from the front of a Vec?" to change from "well, let me tell you about a bunch options with into_iter and drain and ..." to "It's O(1) to convert it to a VecDeque, so just do that -- you can always convert it back again for just the unavoidable data movement cost anyway if you still need a Vec".

Be aware of the tradeoff that this complicates ever adopting a more sophisticated platform-specific deque internals, such as seen in https://crates.io/crates/slice-deque.

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rfcbot commented Dec 1, 2022 •
edited by joshtriplett
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Team member @dtolnay has proposed to merge this. The next step is review by the rest of the tagged team members:

No concerns currently listed.

Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

See this document for info about what commands tagged team members can give me.

@rfcbot rfcbot added proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. disposition-merge This issue / PR is in PFCP or FCP with a disposition to merge it. labels Dec 1, 2022
@dtolnay dtolnay mentioned this pull request Dec 1, 2022
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Sp00ph commented Dec 2, 2022

It's only about guaranteeing O(1) Vec -> VecDeque conversions, not the other way around. Converting VecDeque -> Vec may indeed have to rotate around memory and is therefore O(n), though it is already documented to not reallocate the buffer

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CryZe commented Dec 2, 2022

Yeah sorry I somehow got the direction of the impl wrong.

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bors commented Dec 5, 2022

☔ The latest upstream changes (presumably #105046) made this pull request unmergeable. Please resolve the merge conflicts.

@Sp00ph Sp00ph mentioned this pull request Dec 5, 2022
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If Rust had named it Deque, it may have made sense for it to not have an O(1) guaranteed conversion, but I think naming it VecDeque strongly recommends in favor of making this change.

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More fun stuff that such an implementation enables: O(1) vec::IntoIter → VecDeque conversions.

(Done as a non-guaranteed specialization in #105453.)

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dtolnay commented Dec 20, 2022

I'm marking @yaahc's box because she has stepped down from T-libs-api after the point that this feature got proposed for FCP.

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Be aware of the tradeoff that this complicates ever adopting a more sophisticated platform-specific deque internals, such as seen in https://crates.io/crates/slice-deque.

I will say that it is somewhat unfortunate that this API guarantee will prevent such a really cool trick like that, but I think the API guarantee here is probably worth it.

@rfcbot rfcbot added final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. and removed proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. labels Dec 28, 2022
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rfcbot commented Dec 28, 2022

🔔 This is now entering its final comment period, as per the review above. 🔔

@rfcbot rfcbot added finished-final-comment-period The final comment period is finished for this PR / Issue. and removed final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. labels Jan 7, 2023
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rfcbot commented Jan 7, 2023

The final comment period, with a disposition to merge, as per the review above, is now complete.

As the automated representative of the governance process, I would like to thank the author for their work and everyone else who contributed.

This will be merged soon.

@rfcbot rfcbot added the to-announce Announce this issue on triage meeting label Jan 7, 2023
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dtolnay commented Jan 7, 2023

@bors r+

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bors commented Jan 7, 2023

📌 Commit ac583f1 has been approved by dtolnay

It is now in the queue for this repository.

@bors bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jan 7, 2023
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dtolnay commented Jan 7, 2023

@bors rollup

@matthiaskrgr matthiaskrgr mentioned this pull request Jan 7, 2023
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bors added a commit to rust-lang-ci/rust that referenced this pull request Jan 7, 2023
@bors
Auto merge of rust-lang#106573 - matthiaskrgr:rollup-zkgfsta, r=matth…
e5d46a5 
…iaskrgr

Rollup of 10 pull requests

Successful merges:

 - rust-lang#101936 (Migrating rustc_infer to session diagnostics (part 3))
 - rust-lang#104081 (PhantomData layout guarantees)
 - rust-lang#104543 (Migrate `codegen_ssa` to diagnostics structs - [Part 3])
 - rust-lang#105128 (Add O(1) `Vec -> VecDeque` conversion guarantee)
 - rust-lang#105517 (Fix process-panic-after-fork.rs to pass on newer versions of Android.)
 - rust-lang#105859 (Point out span where we could introduce higher-ranked lifetime)
 - rust-lang#106509 (Detect closures assigned to binding in block)
 - rust-lang#106553 (docs: make `HashSet::retain` doctest more clear)
 - rust-lang#106556 (rustdoc: remove no-op mobile CSS `.content { margin-left: 0 }`)
 - rust-lang#106564 (Change to immutable borrow when cloning element of RepeatN)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit d7519c3 into rust-lang:master Jan 8, 2023
@rustbot rustbot added this to the 1.68.0 milestone Jan 8, 2023
@scottmcm scottmcm added the relnotes Marks issues that should be documented in the release notes of the next release. label Jan 9, 2023
@apiraino apiraino removed the to-announce Announce this issue on triage meeting label Jan 12, 2023
wip-sync pushed a commit to NetBSD/pkgsrc-wip that referenced this pull request Mar 20, 2023
@he32
rust: Upgrade to version 1.68.0.
f40cd06 
Pkgsrc changes:
 * Adjust patches and cargo checksums to new versions.

Upstream changes:

Version 1.68.0 (2023-03-09)
===========================

Language
--------

- [Stabilize default_alloc_error_handler]
  (rust-lang/rust#102318)
  This allows usage of `alloc` on stable without requiring the
  definition of a handler for allocation failure. Defining custom
  handlers is still unstable.
- [Stabilize `efiapi` calling convention.]
  (rust-lang/rust#105795)
- [Remove implicit promotion for types with drop glue]
  (rust-lang/rust#105085)

Compiler
--------

- [Change `bindings_with_variant_name` to deny-by-default]
  (rust-lang/rust#104154)
- [Allow .. to be parsed as let initializer]
  (rust-lang/rust#105701)
- [Add `armv7-sony-vita-newlibeabihf` as a tier 3 target]
  (rust-lang/rust#105712)
- [Always check alignment during compile-time const evaluation]
  (rust-lang/rust#104616)
- [Disable "split dwarf inlining" by default.]
  (rust-lang/rust#106709)
- [Add vendor to Fuchsia's target triple]
  (rust-lang/rust#106429)
- [Enable sanitizers for s390x-linux]
  (rust-lang/rust#107127)

Libraries
---------

- [Loosen the bound on the Debug implementation of Weak.]
  (rust-lang/rust#90291)
- [Make `std::task::Context` !Send and !Sync]
  (rust-lang/rust#95985)
- [PhantomData layout guarantees]
  (rust-lang/rust#104081)
- [Don't derive Debug for `OnceWith` & `RepeatWith`]
  (rust-lang/rust#104163)
- [Implement DerefMut for PathBuf]
  (rust-lang/rust#105018)
- [Add O(1) `Vec -> VecDeque` conversion guarantee]
  (rust-lang/rust#105128)
- [Leak amplification for peek_mut() to ensure BinaryHeap's invariant
  is always met]
  (rust-lang/rust#105851)

Stabilized APIs
---------------

- [`{core,std}::pin::pin!`]
  (https://doc.rust-lang.org/stable/std/pin/macro.pin.html)
- [`impl From<bool> for {f32,f64}`]
  (https://doc.rust-lang.org/stable/std/primitive.f32.html#impl-From%3Cbool%3E-for-f32)
- [`std::path::MAIN_SEPARATOR_STR`]
  (https://doc.rust-lang.org/stable/std/path/constant.MAIN_SEPARATOR_STR.html)
- [`impl DerefMut for PathBuf`]
  (https://doc.rust-lang.org/stable/std/path/struct.PathBuf.html#impl-DerefMut-for-PathBuf)

These APIs are now stable in const contexts:

- [`VecDeque::new`]
  (https://doc.rust-lang.org/stable/std/collections/struct.VecDeque.html#method.new)

Cargo
-----

- [Stabilize sparse registry support for crates.io]
  (rust-lang/cargo#11224)
- [`cargo build --verbose` tells you more about why it recompiles.]
  (rust-lang/cargo#11407)
- [Show progress of crates.io index update even `net.git-fetch-with-cli`
  option enabled]
  (rust-lang/cargo#11579)

Misc
----

Compatibility Notes
-------------------

- [Add `SEMICOLON_IN_EXPRESSIONS_FROM_MACROS` to future-incompat report]
  (rust-lang/rust#103418)
- [Only specify `--target` by default for `-Zgcc-ld=lld` on wasm]
  (rust-lang/rust#101792)
- [Bump `IMPLIED_BOUNDS_ENTAILMENT` to Deny + ReportNow]
  (rust-lang/rust#106465)
- [`std::task::Context` no longer implements Send and Sync]
  (rust-lang/rust#95985)

nternal Changes
----------------

These changes do not affect any public interfaces of Rust, but they represent
significant improvements to the performance or internals of rustc and related
tools.

- [Encode spans relative to the enclosing item]
  (rust-lang/rust#84762)
- [Don't normalize in AstConv]
  (rust-lang/rust#101947)
- [Find the right lower bound region in the scenario of partial order relations]
  (rust-lang/rust#104765)
- [Fix impl block in const expr]
  (rust-lang/rust#104889)
- [Check ADT fields for copy implementations considering regions]
  (rust-lang/rust#105102)
- [rustdoc: simplify JS search routine by not messing with lev distance]
  (rust-lang/rust#105796)
- [Enable ThinLTO for rustc on `x86_64-pc-windows-msvc`]
  (rust-lang/rust#103591)
- [Enable ThinLTO for rustc on `x86_64-apple-darwin`]
  (rust-lang/rust#103647)
netbsd-srcmastr pushed a commit to NetBSD/pkgsrc that referenced this pull request Apr 8, 2023
@he32
rust: Upgrade to version 1.68.2.
114ff56 
Pkgsrc changes:
 * Adjust patches (add & remove) and cargo checksums to new versions.
 * It's conceivable that the workaround for LLVM based NetBSD works
   even less in this version (ref. PKGSRC_HAVE_LIBCPP not having a
   corresponding patch anymore).

Upstream changes:

Version 1.68.2 (2023-03-28)
===========================

- [Update the GitHub RSA host key bundled within Cargo]
  (rust-lang/cargo#11883).
  The key was [rotated by GitHub]
  (https://github.blog/2023-03-23-we-updated-our-rsa-ssh-host-key/)
  on 2023-03-24 after the old one leaked.
- [Mark the old GitHub RSA host key as revoked]
  (rust-lang/cargo#11889).
  This will prevent Cargo from accepting the leaked key even when
  trusted by the system.
- [Add support for `@revoked` and a better error message for
  `@cert-authority` in Cargo's SSH host key verification]
  (rust-lang/cargo#11635)

Version 1.68.1 (2023-03-23)
===========================

- [Fix miscompilation in produced Windows MSVC artifacts]
  (rust-lang/rust#109094)
  This was introduced by enabling ThinLTO for the distributed rustc
  which led to miscompilations in the resulting binary. Currently
  this is believed to be limited to the -Zdylib-lto flag used for
  rustc compilation, rather than a general bug in ThinLTO, so only
  rustc artifacts should be affected.
- [Fix --enable-local-rust builds]
  (rust-lang/rust#109111)
- [Treat `$prefix-clang` as `clang` in linker detection code]
  (rust-lang/rust#109156)
- [Fix panic in compiler code]
  (rust-lang/rust#108162)

Version 1.68.0 (2023-03-09)
===========================

Language
--------

- [Stabilize default_alloc_error_handler]
  (rust-lang/rust#102318)
  This allows usage of `alloc` on stable without requiring the
  definition of a handler for allocation failure. Defining custom
  handlers is still unstable.
- [Stabilize `efiapi` calling convention.]
  (rust-lang/rust#105795)
- [Remove implicit promotion for types with drop glue]
  (rust-lang/rust#105085)

Compiler
--------

- [Change `bindings_with_variant_name` to deny-by-default]
  (rust-lang/rust#104154)
- [Allow .. to be parsed as let initializer]
  (rust-lang/rust#105701)
- [Add `armv7-sony-vita-newlibeabihf` as a tier 3 target]
  (rust-lang/rust#105712)
- [Always check alignment during compile-time const evaluation]
  (rust-lang/rust#104616)
- [Disable "split dwarf inlining" by default.]
  (rust-lang/rust#106709)
- [Add vendor to Fuchsia's target triple]
  (rust-lang/rust#106429)
- [Enable sanitizers for s390x-linux]
  (rust-lang/rust#107127)

Libraries
---------

- [Loosen the bound on the Debug implementation of Weak.]
  (rust-lang/rust#90291)
- [Make `std::task::Context` !Send and !Sync]
  (rust-lang/rust#95985)
- [PhantomData layout guarantees]
  (rust-lang/rust#104081)
- [Don't derive Debug for `OnceWith` & `RepeatWith`]
  (rust-lang/rust#104163)
- [Implement DerefMut for PathBuf]
  (rust-lang/rust#105018)
- [Add O(1) `Vec -> VecDeque` conversion guarantee]
  (rust-lang/rust#105128)
- [Leak amplification for peek_mut() to ensure BinaryHeap's invariant
  is always met]
  (rust-lang/rust#105851)

Stabilized APIs
---------------

- [`{core,std}::pin::pin!`]
  (https://doc.rust-lang.org/stable/std/pin/macro.pin.html)
- [`impl From<bool> for {f32,f64}`]
  (https://doc.rust-lang.org/stable/std/primitive.f32.html#impl-From%3Cbool%3E-for-f32)
- [`std::path::MAIN_SEPARATOR_STR`]
  (https://doc.rust-lang.org/stable/std/path/constant.MAIN_SEPARATOR_STR.html)
- [`impl DerefMut for PathBuf`]
  (https://doc.rust-lang.org/stable/std/path/struct.PathBuf.html#impl-DerefMut-for-PathBuf)

These APIs are now stable in const contexts:

- [`VecDeque::new`]
  (https://doc.rust-lang.org/stable/std/collections/struct.VecDeque.html#method.new)

Cargo
-----

- [Stabilize sparse registry support for crates.io]
  (rust-lang/cargo#11224)
- [`cargo build --verbose` tells you more about why it recompiles.]
  (rust-lang/cargo#11407)
- [Show progress of crates.io index update even `net.git-fetch-with-cli`
  option enabled]
  (rust-lang/cargo#11579)

Misc
----

Compatibility Notes
-------------------

- [Add `SEMICOLON_IN_EXPRESSIONS_FROM_MACROS` to future-incompat report]
  (rust-lang/rust#103418)
- [Only specify `--target` by default for `-Zgcc-ld=lld` on wasm]
  (rust-lang/rust#101792)
- [Bump `IMPLIED_BOUNDS_ENTAILMENT` to Deny + ReportNow]
  (rust-lang/rust#106465)
- [`std::task::Context` no longer implements Send and Sync]
  (rust-lang/rust#95985)

nternal Changes
----------------

These changes do not affect any public interfaces of Rust, but they represent
significant improvements to the performance or internals of rustc and related
tools.

- [Encode spans relative to the enclosing item]
  (rust-lang/rust#84762)
- [Don't normalize in AstConv]
  (rust-lang/rust#101947)
- [Find the right lower bound region in the scenario of partial order relations]
  (rust-lang/rust#104765)
- [Fix impl block in const expr]
  (rust-lang/rust#104889)
- [Check ADT fields for copy implementations considering regions]
  (rust-lang/rust#105102)
- [rustdoc: simplify JS search routine by not messing with lev distance]
  (rust-lang/rust#105796)
- [Enable ThinLTO for rustc on `x86_64-pc-windows-msvc`]
  (rust-lang/rust#103591)
- [Enable ThinLTO for rustc on `x86_64-apple-darwin`]
  (rust-lang/rust#103647)

Version 1.67.0 (2023-01-26)
==========================

Language
--------

- [Make `Sized` predicates coinductive, allowing cycles.]
  (rust-lang/rust#100386)
- [`#[must_use]` annotations on `async fn` also affect the
  `Future::Output`.] (rust-lang/rust#100633)
- [Elaborate supertrait obligations when deducing closure signatures.]
  (rust-lang/rust#101834)
- [Invalid literals are no longer an error under `cfg(FALSE)`.]
  (rust-lang/rust#102944)
- [Unreserve braced enum variants in value namespace.]
  (rust-lang/rust#103578)

Compiler
--------

- [Enable varargs support for calling conventions other than `C`
  or `cdecl`.] (rust-lang/rust#97971)
- [Add new MIR constant propagation based on dataflow analysis.]
  (rust-lang/rust#101168)
- [Optimize field ordering by grouping m\*2^n-sized fields with
  equivalently aligned ones.] (rust-lang/rust#102750)
- [Stabilize native library modifier `verbatim`.]
  (rust-lang/rust#104360)

Added and removed targets:

- [Add a tier 3 target for PowerPC on AIX]
  (rust-lang/rust#102293), `powerpc64-ibm-aix`.
- [Add a tier 3 target for the Sony PlayStation 1]
  (rust-lang/rust#102689), `mipsel-sony-psx`.
- [Add tier 3 `no_std` targets for the QNX Neutrino RTOS]
  (rust-lang/rust#102701),
  `aarch64-unknown-nto-qnx710` and `x86_64-pc-nto-qnx710`.
- [Remove tier 3 `linuxkernel` targets]
  (rust-lang/rust#104015) (not used by the
  actual kernel).

Refer to Rust's [platform support page][platform-support-doc]
for more information on Rust's tiered platform support.

Libraries
---------

- [Merge `crossbeam-channel` into `std::sync::mpsc`.]
  (rust-lang/rust#93563)
- [Fix inconsistent rounding of 0.5 when formatted to 0 decimal places.]
  (rust-lang/rust#102935)
- [Derive `Eq` and `Hash` for `ControlFlow`.]
  (rust-lang/rust#103084)
- [Don't build `compiler_builtins` with `-C panic=abort`.]
  (rust-lang/rust#103786)

Stabilized APIs
---------------

- [`{integer}::checked_ilog`]
  (https://doc.rust-lang.org/stable/std/primitive.i32.html#method.checked_ilog)
- [`{integer}::checked_ilog2`]
  (https://doc.rust-lang.org/stable/std/primitive.i32.html#method.checked_ilog2)
- [`{integer}::checked_ilog10`]
  (https://doc.rust-lang.org/stable/std/primitive.i32.html#method.checked_ilog10)
- [`{integer}::ilog`]
  (https://doc.rust-lang.org/stable/std/primitive.i32.html#method.ilog)
- [`{integer}::ilog2`]
  (https://doc.rust-lang.org/stable/std/primitive.i32.html#method.ilog2)
- [`{integer}::ilog10`]
  (https://doc.rust-lang.org/stable/std/primitive.i32.html#method.ilog10)
- [`NonZeroU*::ilog2`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroU32.html#method.ilog2)
- [`NonZeroU*::ilog10`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroU32.html#method.ilog10)
- [`NonZero*::BITS`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroU32.html#associatedconstant.BITS)

These APIs are now stable in const contexts:

- [`char::from_u32`]
  (https://doc.rust-lang.org/stable/std/primitive.char.html#method.from_u32)
- [`char::from_digit`]
  (https://doc.rust-lang.org/stable/std/primitive.char.html#method.from_digit)
- [`char::to_digit`]
  (https://doc.rust-lang.org/stable/std/primitive.char.html#method.to_digit)
- [`core::char::from_u32`]
  (https://doc.rust-lang.org/stable/core/char/fn.from_u32.html)
- [`core::char::from_digit`]
  (https://doc.rust-lang.org/stable/core/char/fn.from_digit.html)

Compatibility Notes
-------------------

- [The layout of `repr(Rust)` types now groups m\*2^n-sized fields
  with equivalently aligned ones.]
  (rust-lang/rust#102750) This is intended
  to be an optimization, but it is also known to increase type
  sizes in a few cases for the placement of enum tags. As a reminder,
  the layout of `repr(Rust)` types is an implementation detail,
  subject to change.
- [0.5 now rounds to 0 when formatted to 0 decimal places.]
  (rust-lang/rust#102935)
  This makes it consistent with the rest of floating point formatting that
  rounds ties toward even digits.
- [Chains of `&&` and `||` will now drop temporaries from their
  sub-expressions in evaluation order, left-to-right.]
  (rust-lang/rust#103293) Previously, it
  was "twisted" such that the _first_ expression dropped its
  temporaries _last_, after all of the other expressions dropped
  in order.
- [Underscore suffixes on string literals are now a hard error.]
  (rust-lang/rust#103914)
  This has been a future-compatibility warning since 1.20.0.
- [Stop passing `-export-dynamic` to `wasm-ld`.]
  (rust-lang/rust#105405)
- [`main` is now mangled as `__main_void` on `wasm32-wasi`.]
  (rust-lang/rust#105468)
- [Cargo now emits an error if there are multiple registries in
  the configuration with the same index URL.]
  (rust-lang/cargo#10592)

Internal Changes
----------------

These changes do not affect any public interfaces of Rust, but they
represent significant improvements to the performance or internals
of rustc and related tools.

- [Rewrite LLVM's archive writer in Rust.]
  (rust-lang/rust#97485)
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disposition-merge This issue / PR is in PFCP or FCP with a disposition to merge it. finished-final-comment-period The final comment period is finished for this PR / Issue. relnotes Marks issues that should be documented in the release notes of the next release. S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. T-libs-api Relevant to the library API team, which will review and decide on the PR/issue.
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