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Implement RefUnwindSafe for Rc<T> #87467

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merged 1 commit into from
Nov 4, 2021

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inquisitivecrystal
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This PR implements RefUnwindSafe for Rc<T>, where T: RefUnwindSafe.

This impl was omitted by an apparent oversight. Rc<T> already implements UnwindSafe. Arc<T> implements both UnwindSafe and RefUnwindSafe. There is no reason why an &Rc<T> is any less unwind safe than a Rc<T> or an &Arc<T>, so this should be safe to add.

Resolves #45924.

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r? @joshtriplett

(rust-highfive has picked a reviewer for you, use r? to override)

@rust-highfive rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jul 26, 2021
@inquisitivecrystal inquisitivecrystal added needs-fcp This change is insta-stable, so needs a completed FCP to proceed. T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. labels Jul 26, 2021
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bors commented Aug 1, 2021

☔ The latest upstream changes (presumably #84662) made this pull request unmergeable. Please resolve the merge conflicts.

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Rebased!

@inquisitivecrystal inquisitivecrystal added the relnotes Marks issues that should be documented in the release notes of the next release. label Aug 14, 2021
@camelid camelid added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Sep 2, 2021
@@ -317,6 +317,8 @@ impl<T: ?Sized> !marker::Sync for Rc<T> {}

#[stable(feature = "catch_unwind", since = "1.9.0")]
impl<T: RefUnwindSafe + ?Sized> UnwindSafe for Rc<T> {}
#[stable(feature = "rc_ref_unwind_safe", since = "1.56.0")]
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(Just noting that this will likely require a version bump because there's a release next week.)

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dtolnay commented Oct 3, 2021

This LGTM. Rc contains a Cell for the strong and weak reference counts which does not implement RefUnwindSafe, but all the public APIs on Rc are atomic w.r.t. panicking. There is no possibility that a panic during some operation on the Rc would leave the reference counts in an unintended state.

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

@dtolnay dtolnay assigned dtolnay and unassigned joshtriplett Oct 3, 2021
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dtolnay commented Oct 3, 2021

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rfcbot commented Oct 3, 2021

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. final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. labels Oct 3, 2021
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rfcbot commented Oct 7, 2021

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

@rfcbot rfcbot removed the proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. label Oct 7, 2021
@rfcbot rfcbot added the finished-final-comment-period The final comment period is finished for this PR / Issue. label Oct 17, 2021
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rfcbot commented Oct 17, 2021

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 to-announce Announce this issue on triage meeting and removed final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. labels Oct 17, 2021
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I'll adjust the version number after the release is out of the way, since I don't see any reason for rushing to merge this before then.

@apiraino apiraino removed the to-announce Announce this issue on triage meeting label Oct 21, 2021
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inquisitivecrystal commented Nov 3, 2021

@dtolnay: this should be ready to merge. I apologize for the delay.

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Thanks!

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dtolnay commented Nov 3, 2021

@bors r+

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bors commented Nov 3, 2021

📌 Commit bd194da has been approved by dtolnay

@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 Nov 3, 2021
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bors commented Nov 4, 2021

⌛ Testing commit bd194da with merge 4061c04...

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bors commented Nov 4, 2021

☀️ Test successful - checks-actions
Approved by: dtolnay
Pushing 4061c04 to master...

@bors bors added the merged-by-bors This PR was explicitly merged by bors. label Nov 4, 2021
@bors bors merged commit 4061c04 into rust-lang:master Nov 4, 2021
@rustbot rustbot added this to the 1.58.0 milestone Nov 4, 2021
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Finished benchmarking commit (4061c04): comparison url.

Summary: This change led to large relevant regressions 😿 in compiler performance.

  • Large regression in instruction counts (up to 1.1% on full builds of cargo)

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

Next Steps: If you can justify the regressions found in this perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please open an issue or create a new PR that fixes the regressions, add a comment linking to the newly created issue or PR, and then add the perf-regression-triaged label to this PR.

@rustbot label: +perf-regression

@rustbot rustbot added the perf-regression Performance regression. label Nov 4, 2021
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rylev commented Nov 9, 2021

The regression is extremely surprising but only impacts one test case "cargo + doc + full". This is likely a fluke of some sort, but it is is concerning as the regressed test case shows a rather large regression (19x the significance threshold) which we would not expect from a non-noisy benchmark. The get_auto_trait_impls query seems to have been impacted though I'm not sure if this change would exercise that query.

I'm going to leave this as a perf regression for now, but no action is needed from the author or reviewers. The perf team will try to investigate why this regression happened.

cc @jyn514 @Mark-Simulacrum

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jyn514 commented Nov 9, 2021

The get_auto_trait_impls query seems to have been impacted though I'm not sure if this change would exercise that query.

I'm only slightly surprised by this; get_auto_trait_impls has horrific algorithmic complexity and this presumably adds a bunch more types that implement RefUnwindSafe if they use Rc internally. There's a bunch of issues floating around, I'll try to find one.

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jyn514 commented Nov 9, 2021

This is somewhat related to #90512 in that rustdoc does a bunch of global analyses the compiler never does.

wip-sync pushed a commit to NetBSD/pkgsrc-wip that referenced this pull request Jan 22, 2022
Pkgsrc changes:
 * Bump available bootstraps to 1.57.0.
 * For some reason, the vendor/libc checksums don't need fixing.
 * Bump required external LLVM to 12.0, according to upstream change log.
 * Adapt the Darwin linker patch.

(For some reason I've not figured out yet, cargo is a lot more
verbose while building, echoes the rustc invocation.)

Upstream changes:

Version 1.58.1 (2022-01-19)
===========================

* Fix race condition in `std::fs::remove_dir_all` ([CVE-2022-21658])
* [Handle captured arguments in the `useless_format` Clippy lint][clippy/8295]
* [Move `non_send_fields_in_send_ty` Clippy lint to nursery][clippy/8075]
* [Fix wrong error message displayed when some imports are missing][91254]
* [Fix rustfmt not formatting generated files from stdin][92912]

[CVE-2022-21658]: https://www.cve.org/CVERecord?id=CVE-2022-21658]
[91254]: rust-lang/rust#91254
[92912]: rust-lang/rust#92912
[clippy/8075]: rust-lang/rust-clippy#8075
[clippy/8295]: rust-lang/rust-clippy#8295

Version 1.58.0 (2022-01-13)
==========================

Language
--------

- [Format strings can now capture arguments simply by writing
  `{ident}` in the string.][90473] This works in all macros accepting
  format strings. Support for this in `panic!` (`panic!("{ident}")`)
  requires the 2021 edition; panic invocations in previous editions
  that appear to be trying to use this will result in a warning lint
  about not having the intended effect.
- [`*const T` pointers can now be dereferenced in const contexts.][89551]
- [The rules for when a generic struct implements `Unsize` have
  been relaxed.][90417]

Compiler
--------

- [Add LLVM CFI support to the Rust compiler][89652]
- [Stabilize -Z strip as -C strip][90058]. Note that while release
  builds already don't add debug symbols for the code you compile,
  the compiled standard library that ships with Rust includes debug
  symbols, so you may want to use the `strip` option to remove these
  symbols to produce smaller release binaries. Note that this release
  only includes support in rustc, not directly in cargo.
- [Add support for LLVM coverage mapping format versions 5 and 6][91207]
- [Emit LLVM optimization remarks when enabled with `-Cremark`][90833]
- [Update the minimum external LLVM to 12][90175]
- [Add `x86_64-unknown-none` at Tier 3*][89062]
- [Build musl dist artifacts with debuginfo enabled][90733]. When
  building release binaries using musl, you may want to use the newly
  stabilized strip option to remove these debug symbols, reducing
  the size of your binaries.
- [Don't abort compilation after giving a lint error][87337]
- [Error messages point at the source of trait bound obligations
  in more places][89580]

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

Libraries
---------

- [All remaining functions in the standard library have `#[must_use]`
  annotations where appropriate][89692], producing a warning when
  ignoring their return value. This helps catch mistakes such as
  expecting a function to mutate a value in place rather than return
  a new value.
- [Paths are automatically canonicalized on Windows for operations
  that support it][89174]
- [Re-enable debug checks for `copy` and `copy_nonoverlapping`][90041]
- [Implement `RefUnwindSafe` for `Rc<T>`][87467]
- [Make RSplit<T, P>: Clone not require T: Clone][90117]
- [Implement `Termination` for `Result<Infallible, E>`][88601].
  This allows writing `fn main() -> Result<Infallible, ErrorType>`,
  for a program whose successful exits never involve returning from
  `main` (for instance, a program that calls `exit`, or that uses
  `exec` to run another program).

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

- [`Metadata::is_symlink`]
- [`Path::is_symlink`]
- [`{integer}::saturating_div`]
- [`Option::unwrap_unchecked`]
- [`Result::unwrap_unchecked`]
- [`Result::unwrap_err_unchecked`]
- [`NonZero{unsigned}::is_power_of_two`]
- [`File::options`]

These APIs are now usable in const contexts:

- [`Duration::new`]
- [`Duration::checked_add`]
- [`Duration::saturating_add`]
- [`Duration::checked_sub`]
- [`Duration::saturating_sub`]
- [`Duration::checked_mul`]
- [`Duration::saturating_mul`]
- [`Duration::checked_div`]
- [`MaybeUninit::as_ptr`]
- [`MaybeUninit::as_mut_ptr`]
- [`MaybeUninit::assume_init`]
- [`MaybeUninit::assume_init_ref`]

Cargo
-----

- [Add --message-format for install command][cargo/10107]
- [Warn when alias shadows external subcommand][cargo/10082]

Rustdoc
-------

- [Show all Deref implementations recursively in rustdoc][90183]
- [Use computed visibility in rustdoc][88447]

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

- [Try all stable method candidates first before trying unstable
  ones][90329]. This change ensures that adding new nightly-only
  methods to the Rust standard library will not break code invoking
  methods of the same name from traits outside the standard library.
- Windows: [`std::process::Command` will no longer search the
  current directory for executables.][87704]
- [All proc-macro backward-compatibility lints are now deny-by-default.][88041]
- [proc_macro: Append .0 to unsuffixed float if it would otherwise
  become int token][90297]
- [Refactor weak symbols in std::sys::unix][90846]. This optimizes
  accesses to glibc functions, by avoiding the use of dlopen. This
  does not increase the [minimum expected version of
  glibc](https://doc.rust-lang.org/nightly/rustc/platform-support.html).
  However, software distributions that use symbol versions to detect
  library dependencies, and which take weak symbols into account in
  that analysis, may detect rust binaries as requiring newer versions
  of glibc.
- [rustdoc now rejects some unexpected semicolons in doctests][91026]

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

These changes provide no direct user facing benefits, but represent
significant improvements to the internals and overall performance
of rustc and related tools.

- [Implement coherence checks for negative trait impls][90104]
- [Add rustc lint, warning when iterating over hashmaps][89558]
- [Optimize live point computation][90491]
- [Enable verification for 1/32nd of queries loaded from disk][90361]
- [Implement version of normalize_erasing_regions that allows for
  normalization failure][91255]

[87337]: rust-lang/rust#87337
[87467]: rust-lang/rust#87467
[87704]: rust-lang/rust#87704
[88041]: rust-lang/rust#88041
[88300]: rust-lang/rust#88300
[88447]: rust-lang/rust#88447
[88601]: rust-lang/rust#88601
[88624]: rust-lang/rust#88624
[89062]: rust-lang/rust#89062
[89174]: rust-lang/rust#89174
[89542]: rust-lang/rust#89542
[89551]: rust-lang/rust#89551
[89558]: rust-lang/rust#89558
[89580]: rust-lang/rust#89580
[89652]: rust-lang/rust#89652
[89677]: rust-lang/rust#89677
[89951]: rust-lang/rust#89951
[90041]: rust-lang/rust#90041
[90058]: rust-lang/rust#90058
[90104]: rust-lang/rust#90104
[90117]: rust-lang/rust#90117
[90175]: rust-lang/rust#90175
[90183]: rust-lang/rust#90183
[90297]: rust-lang/rust#90297
[90329]: rust-lang/rust#90329
[90361]: rust-lang/rust#90361
[90417]: rust-lang/rust#90417
[90473]: rust-lang/rust#90473
[90491]: rust-lang/rust#90491
[90733]: rust-lang/rust#90733
[90833]: rust-lang/rust#90833
[90846]: rust-lang/rust#90846
[90896]: rust-lang/rust#90896
[91026]: rust-lang/rust#91026
[91207]: rust-lang/rust#91207
[91255]: rust-lang/rust#91255
[91301]: rust-lang/rust#91301
[cargo/10082]: rust-lang/cargo#10082
[cargo/10107]: rust-lang/cargo#10107
[`Metadata::is_symlink`]: https://doc.rust-lang.org/stable/std/fs/struct.Metadata.html#method.is_symlink
[`Path::is_symlink`]: https://doc.rust-lang.org/stable/std/path/struct.Path.html#method.is_symlink
[`{integer}::saturating_div`]: https://doc.rust-lang.org/stable/std/primitive.i8.html#method.saturating_div
[`Option::unwrap_unchecked`]: https://doc.rust-lang.org/stable/std/option/enum.Option.html#method.unwrap_unchecked
[`Result::unwrap_unchecked`]: https://doc.rust-lang.org/stable/std/result/enum.Result.html#method.unwrap_unchecked
[`Result::unwrap_err_unchecked`]: https://doc.rust-lang.org/stable/std/result/enum.Result.html#method.unwrap_err_unchecked
[`NonZero{unsigned}::is_power_of_two`]: https://doc.rust-lang.org/stable/std/num/struct.NonZeroU8.html#method.is_power_of_two
[`File::options`]: https://doc.rust-lang.org/stable/std/fs/struct.File.html#method.options
[`unix::process::ExitStatusExt::core_dumped`]: https://doc.rust-lang.org/stable/std/os/unix/process/trait.ExitStatusExt.html#tymethod.core_dumped
[`unix::process::ExitStatusExt::stopped_signal`]: https://doc.rust-lang.org/stable/std/os/unix/process/trait.ExitStatusExt.html#tymethod.stopped_signal
[`unix::process::ExitStatusExt::continued`]: https://doc.rust-lang.org/stable/std/os/unix/process/trait.ExitStatusExt.html#tymethod.continued
[`unix::process::ExitStatusExt::into_raw`]: https://doc.rust-lang.org/stable/std/os/unix/process/trait.ExitStatusExt.html#tymethod.into_raw
[`Duration::new`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.new
[`Duration::checked_add`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.checked_add
[`Duration::saturating_add`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.saturating_add
[`Duration::checked_sub`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.checked_sub
[`Duration::saturating_sub`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.saturating_sub
[`Duration::checked_mul`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.checked_mul
[`Duration::saturating_mul`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.saturating_mul
[`Duration::checked_div`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.checked_div
[`Duration::as_secs_f64`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.as_secs_f64
[`Duration::as_secs_f32`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.as_secs_f32
[`Duration::from_secs_f64`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.from_secs_f64
[`Duration::from_secs_f32`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.from_secs_f32
[`Duration::mul_f64`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.mul_f64
[`Duration::mul_f32`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.mul_f32
[`Duration::div_f64`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.div_f64
[`Duration::div_f32`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.div_f32
[`Duration::div_duration_f64`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.div_duration_f64
[`Duration::div_duration_f32`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.div_duration_f32
[`MaybeUninit::as_ptr`]: https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.as_ptr
[`MaybeUninit::as_mut_ptr`]: https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.as_mut_ptr
[`MaybeUninit::assume_init`]: https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.assume_init
[`MaybeUninit::assume_init_ref`]: https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.assume_init_ref
netbsd-srcmastr pushed a commit to NetBSD/pkgsrc that referenced this pull request Mar 1, 2022
Pkgsrc changes:
 * Bump bootstrap kit version to 1.57.0.
 * Bump require external LLVM to 12.0, according to upstream change log.
 * Adjust patches as needed, adjust line numbers.
 * Update checksum adjustments.  For some reason the vendor/libc checksum
   doesn't need fixing, apparently, it remains as commented out.
 * Add makefile to do all the NetBSD boostrap/cross builds (do-cross.mk).
   Allow passing in additions to CONFIGURE_ARGS via ADD_CONFIGURE_ARGS.

Upstream changes:

Version 1.58.1 (2022-01-19)
===========================

* Fix race condition in `std::fs::remove_dir_all` ([CVE-2022-21658])
* [Handle captured arguments in the `useless_format` Clippy lint][clippy/8295]
* [Move `non_send_fields_in_send_ty` Clippy lint to nursery][clippy/8075]
* [Fix wrong error message displayed when some imports are missing][91254]
* [Fix rustfmt not formatting generated files from stdin][92912]

[CVE-2022-21658]: https://www.cve.org/CVERecord?id=CVE-2022-21658]
[91254]: rust-lang/rust#91254
[92912]: rust-lang/rust#92912
[clippy/8075]: rust-lang/rust-clippy#8075
[clippy/8295]: rust-lang/rust-clippy#8295

Version 1.58.0 (2022-01-13)
==========================

Language
--------

- [Format strings can now capture arguments simply by writing
  `{ident}` in the string.][90473] This works in all macros accepting
  format strings. Support for this in `panic!` (`panic!("{ident}")`)
  requires the 2021 edition; panic invocations in previous editions
  that appear to be trying to use this will result in a warning lint
  about not having the intended effect.
- [`*const T` pointers can now be dereferenced in const contexts.][89551]
- [The rules for when a generic struct implements `Unsize` have
  been relaxed.][90417]

Compiler
--------

- [Add LLVM CFI support to the Rust compiler][89652]
- [Stabilize -Z strip as -C strip][90058]. Note that while release
  builds already don't add debug symbols for the code you compile,
  the compiled standard library that ships with Rust includes debug
  symbols, so you may want to use the `strip` option to remove these
  symbols to produce smaller release binaries. Note that this release
  only includes support in rustc, not directly in cargo.
- [Add support for LLVM coverage mapping format versions 5 and 6][91207]
- [Emit LLVM optimization remarks when enabled with `-Cremark`][90833]
- [Update the minimum external LLVM to 12][90175]
- [Add `x86_64-unknown-none` at Tier 3*][89062]
- [Build musl dist artifacts with debuginfo enabled][90733]. When
  building release binaries using musl, you may want to use the newly
  stabilized strip option to remove these debug symbols, reducing
  the size of your binaries.
- [Don't abort compilation after giving a lint error][87337]
- [Error messages point at the source of trait bound obligations
  in more places][89580]

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

Libraries
---------

- [All remaining functions in the standard library have `#[must_use]`
  annotations where appropriate][89692], producing a warning when
  ignoring their return value. This helps catch mistakes such as
  expecting a function to mutate a value in place rather than return
  a new value.
- [Paths are automatically canonicalized on Windows for operations
  that support it][89174]
- [Re-enable debug checks for `copy` and `copy_nonoverlapping`][90041]
- [Implement `RefUnwindSafe` for `Rc<T>`][87467]
- [Make RSplit<T, P>: Clone not require T: Clone][90117]
- [Implement `Termination` for `Result<Infallible, E>`][88601].
  This allows writing `fn main() -> Result<Infallible, ErrorType>`,
  for a program whose successful exits never involve returning from
  `main` (for instance, a program that calls `exit`, or that uses
  `exec` to run another program).

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

- [`Metadata::is_symlink`]
- [`Path::is_symlink`]
- [`{integer}::saturating_div`]
- [`Option::unwrap_unchecked`]
- [`Result::unwrap_unchecked`]
- [`Result::unwrap_err_unchecked`]
- [`NonZero{unsigned}::is_power_of_two`]
- [`File::options`]

These APIs are now usable in const contexts:

- [`Duration::new`]
- [`Duration::checked_add`]
- [`Duration::saturating_add`]
- [`Duration::checked_sub`]
- [`Duration::saturating_sub`]
- [`Duration::checked_mul`]
- [`Duration::saturating_mul`]
- [`Duration::checked_div`]
- [`MaybeUninit::as_ptr`]
- [`MaybeUninit::as_mut_ptr`]
- [`MaybeUninit::assume_init`]
- [`MaybeUninit::assume_init_ref`]

Cargo
-----

- [Add --message-format for install command][cargo/10107]
- [Warn when alias shadows external subcommand][cargo/10082]

Rustdoc
-------

- [Show all Deref implementations recursively in rustdoc][90183]
- [Use computed visibility in rustdoc][88447]

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

- [Try all stable method candidates first before trying unstable
  ones][90329]. This change ensures that adding new nightly-only
  methods to the Rust standard library will not break code invoking
  methods of the same name from traits outside the standard library.
- Windows: [`std::process::Command` will no longer search the
  current directory for executables.][87704]
- [All proc-macro backward-compatibility lints are now deny-by-default.][88041]
- [proc_macro: Append .0 to unsuffixed float if it would otherwise
  become int token][90297]
- [Refactor weak symbols in std::sys::unix][90846]. This optimizes
  accesses to glibc functions, by avoiding the use of dlopen. This
  does not increase the [minimum expected version of
  glibc](https://doc.rust-lang.org/nightly/rustc/platform-support.html).
  However, software distributions that use symbol versions to detect
  library dependencies, and which take weak symbols into account in
  that analysis, may detect rust binaries as requiring newer versions
  of glibc.
- [rustdoc now rejects some unexpected semicolons in doctests][91026]

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

These changes provide no direct user facing benefits, but represent
significant improvements to the internals and overall performance
of rustc and related tools.

- [Implement coherence checks for negative trait impls][90104]
- [Add rustc lint, warning when iterating over hashmaps][89558]
- [Optimize live point computation][90491]
- [Enable verification for 1/32nd of queries loaded from disk][90361]
- [Implement version of normalize_erasing_regions that allows for
  normalization failure][91255]

[87337]: rust-lang/rust#87337
[87467]: rust-lang/rust#87467
[87704]: rust-lang/rust#87704
[88041]: rust-lang/rust#88041
[88300]: rust-lang/rust#88300
[88447]: rust-lang/rust#88447
[88601]: rust-lang/rust#88601
[88624]: rust-lang/rust#88624
[89062]: rust-lang/rust#89062
[89174]: rust-lang/rust#89174
[89542]: rust-lang/rust#89542
[89551]: rust-lang/rust#89551
[89558]: rust-lang/rust#89558
[89580]: rust-lang/rust#89580
[89652]: rust-lang/rust#89652
[89677]: rust-lang/rust#89677
[89951]: rust-lang/rust#89951
[90041]: rust-lang/rust#90041
[90058]: rust-lang/rust#90058
[90104]: rust-lang/rust#90104
[90117]: rust-lang/rust#90117
[90175]: rust-lang/rust#90175
[90183]: rust-lang/rust#90183
[90297]: rust-lang/rust#90297
[90329]: rust-lang/rust#90329
[90361]: rust-lang/rust#90361
[90417]: rust-lang/rust#90417
[90473]: rust-lang/rust#90473
[90491]: rust-lang/rust#90491
[90733]: rust-lang/rust#90733
[90833]: rust-lang/rust#90833
[90846]: rust-lang/rust#90846
[90896]: rust-lang/rust#90896
[91026]: rust-lang/rust#91026
[91207]: rust-lang/rust#91207
[91255]: rust-lang/rust#91255
[91301]: rust-lang/rust#91301
[cargo/10082]: rust-lang/cargo#10082
[cargo/10107]: rust-lang/cargo#10107
[`Metadata::is_symlink`]: https://doc.rust-lang.org/stable/std/fs/struct.Metadata.html#method.is_symlink
[`Path::is_symlink`]: https://doc.rust-lang.org/stable/std/path/struct.Path.html#method.is_symlink
[`{integer}::saturating_div`]: https://doc.rust-lang.org/stable/std/primitive.i8.html#method.saturating_div
[`Option::unwrap_unchecked`]: https://doc.rust-lang.org/stable/std/option/enum.Option.html#method.unwrap_unchecked
[`Result::unwrap_unchecked`]: https://doc.rust-lang.org/stable/std/result/enum.Result.html#method.unwrap_unchecked
[`Result::unwrap_err_unchecked`]: https://doc.rust-lang.org/stable/std/result/enum.Result.html#method.unwrap_err_unchecked
[`NonZero{unsigned}::is_power_of_two`]: https://doc.rust-lang.org/stable/std/num/struct.NonZeroU8.html#method.is_power_of_two
[`File::options`]: https://doc.rust-lang.org/stable/std/fs/struct.File.html#method.options
[`unix::process::ExitStatusExt::core_dumped`]: https://doc.rust-lang.org/stable/std/os/unix/process/trait.ExitStatusExt.html#tymethod.core_dumped
[`unix::process::ExitStatusExt::stopped_signal`]: https://doc.rust-lang.org/stable/std/os/unix/process/trait.ExitStatusExt.html#tymethod.stopped_signal
[`unix::process::ExitStatusExt::continued`]: https://doc.rust-lang.org/stable/std/os/unix/process/trait.ExitStatusExt.html#tymethod.continued
[`unix::process::ExitStatusExt::into_raw`]: https://doc.rust-lang.org/stable/std/os/unix/process/trait.ExitStatusExt.html#tymethod.into_raw
[`Duration::new`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.new
[`Duration::checked_add`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.checked_add
[`Duration::saturating_add`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.saturating_add
[`Duration::checked_sub`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.checked_sub
[`Duration::saturating_sub`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.saturating_sub
[`Duration::checked_mul`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.checked_mul
[`Duration::saturating_mul`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.saturating_mul
[`Duration::checked_div`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.checked_div
[`Duration::as_secs_f64`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.as_secs_f64
[`Duration::as_secs_f32`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.as_secs_f32
[`Duration::from_secs_f64`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.from_secs_f64
[`Duration::from_secs_f32`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.from_secs_f32
[`Duration::mul_f64`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.mul_f64
[`Duration::mul_f32`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.mul_f32
[`Duration::div_f64`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.div_f64
[`Duration::div_f32`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.div_f32
[`Duration::div_duration_f64`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.div_duration_f64
[`Duration::div_duration_f32`]: https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.div_duration_f32
[`MaybeUninit::as_ptr`]: https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.as_ptr
[`MaybeUninit::as_mut_ptr`]: https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.as_mut_ptr
[`MaybeUninit::assume_init`]: https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.assume_init
[`MaybeUninit::assume_init_ref`]: https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.assume_init_ref
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Rc<T> does not implement RefUnwindSafe