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relate closure_substs.parent_substs() to parent fn in NLL #98835

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merged 3 commits into from
Aug 4, 2022

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aliemjay
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@aliemjay aliemjay commented Jul 3, 2022

Fixes #98589

The discrepancy between early- and late-bound lifetimes is because we map early-bound lifetimes into those found in the closure_substs while late-bound lifetimes are mapped into liberated free regions:

tcx.for_each_free_region(&closure_substs, |fr| {
region_mapping.push(fr);
});
for_each_late_bound_region_defined_on(tcx, typeck_root_def_id, |r| {
region_mapping.push(r);
});

r? @rust-lang/types

@rustbot rustbot added the T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. label Jul 3, 2022
@rust-highfive rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jul 3, 2022
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src/librustdoc/clean/auto_trait.rs:294:23

huh, was this code that's failing committed after nll was enabled on this crate or something? if so, then maybe it's ok? regardless, maybe we can do a crater run for this.

@bors try

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bors commented Jul 3, 2022

⌛ Trying commit 48ba16b3bc55d3d41cc3a226a321292467966e6f with merge 430fd2d8141f9ec36db37c8821e1f5bb3a620a79...

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someone should run @ craterbot check in approximately 2.5 hours when this try build is done, i will be asleep 😴

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bors commented Jul 3, 2022

💔 Test failed - checks-actions

@bors bors added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jul 3, 2022
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of course it doesn't try-build... i totally didn't think that through.

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@aliemjay aliemjay marked this pull request as draft July 3, 2022 08:53
@aliemjay aliemjay marked this pull request as ready for review July 3, 2022 16:58
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aliemjay commented Jul 3, 2022

rustdoc regressed because the following passed on nightly:

struct Ty<'a, 'b>(&'a &'b ());

impl<'a, 'b> Ty<'a, 'b> {
    fn f() {
        || { Self::f(); };
    }
}

but it doesn't compile on stable because of #98852.

Now I think this fix should be backported to avoid users relying on this behavior.

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@bors try

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bors commented Jul 3, 2022

⌛ Trying commit 499a0823b7bdcf222ed2d200dc0b6622d7684a50 with merge cb1f7c96119295882e08b09b4bd01051669c071b...

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bors commented Jul 3, 2022

☀️ Try build successful - checks-actions
Build commit: cb1f7c96119295882e08b09b4bd01051669c071b (cb1f7c96119295882e08b09b4bd01051669c071b)

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@craterbot check

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👌 Experiment pr-98835 created and queued.
🤖 Automatically detected try build cb1f7c96119295882e08b09b4bd01051669c071b
🔍 You can check out the queue and this experiment's details.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

@craterbot craterbot added S-waiting-on-crater Status: Waiting on a crater run to be completed. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jul 3, 2022
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🚧 Experiment pr-98835 is now running

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

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🎉 Experiment pr-98835 is completed!
📊 28 regressed and 5 fixed (238905 total)
📰 Open the full report.

⚠️ If you notice any spurious failure please add them to the blacklist!
ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

@craterbot craterbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-crater Status: Waiting on a crater run to be completed. labels Jul 6, 2022
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aliemjay commented Jul 7, 2022

crater showed 5 root regressions:

charcoal-1.1.0 doesn't compile on the current stable versions and was one of the "fixed" crates by #95565.

Other 4 regressions (detailed below) are indeed stable regressions. They are variants of #98589 that somehow previously passed lexical region resolution (as well as NLL). An example regression is the one from parse-hyperlink-0.23.3, it passes on stable but is rejected by this PR

fn test<'a>()
where
    'a, 'a, // <- makes sure `'a` is early-bound; late-bound lifetimes are already rejected
{
    let f = |_: &'a str| {};
    f(&String::new());
}

A few notes on these regressions:

  • This is not a soundness fix. It just fixes language semantics IMO. The difference in behavior between early- and late-bound lifetimes is another source of confusion.
  • It only affects users of explicit lifetime annotations on closure signature and body only if one of the lifetimes happens to be early-bound.
  • They were rejected by AST borrowck.
  • The migration is trivial in most cases: removing lifetime annotations is sufficient, however innernet requires replacing Self constructor with the struct name.
  • On the impact: parse-hyperlinks has 6 dependent crates, others don't have any.
  • When NLL reaches stable without this fix, the impact MAY be greater since NLL allows more code to compile with this behavior.

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r? @nikomatsakis

@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 Aug 3, 2022
bors added a commit to rust-lang-ci/rust that referenced this pull request Aug 4, 2022
…iaskrgr

Rollup of 6 pull requests

Successful merges:

 - rust-lang#98771 (Add support for link-flavor rust-lld for iOS, tvOS and watchOS)
 - rust-lang#98835 (relate `closure_substs.parent_substs()` to parent fn in NLL)
 - rust-lang#99746 (Use `TraitEngine` in more places that don't specifically need `FulfillmentContext::new_in_snapshot`)
 - rust-lang#99786 (Recover from C++ style `enum struct`)
 - rust-lang#99795 (Delay a bug when failed to normalize trait ref during specialization)
 - rust-lang#100029 (Prevent ICE for `doc_alias` on match arm, statement, expression)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit 88e9417 into rust-lang:master Aug 4, 2022
@rustbot rustbot added this to the 1.64.0 milestone Aug 4, 2022
@aliemjay aliemjay deleted the relate_closure_substs branch August 4, 2022 07:19
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aliemjay commented Aug 4, 2022

Here is my attempt for relnotes. It may need polishing and the code example may be removed to reduce verbosity.


This change fixes a correctness bug that affects lifetime annotations in closure signature and body. For example, the following was incorrectly accepted:

async fn test<'a>() { // `'a`, being a lifetime parameter, must be longer than the entire function body
    let f = |_: &'a str| {}; // the argument is required to outlive `'a`
    f(&String::new()); // an argument of shorter lifetime is passed!
}

The code that relies on this bug must remove the lifetime annotation from the closure to allow the compiler to infer an appropriate lifetime. However, migration may require additional subtle changes:

@rfcbot rfcbot added finished-final-comment-period The final comment period is finished for this PR / Issue. 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 Aug 8, 2022
github-actions bot pushed a commit to gnoliyil/fuchsia that referenced this pull request Aug 8, 2022
Github issue: rust-lang/rust#98835
Breakage: https://ci.chromium.org/ui/p/fuchsia/builders/toolchain.ci/rust_toolchain.core.x64-release-subbuild/b8806754452009409777/overview

Change-Id: I9b2a76324a3a1e7310066fe87169babaeefb19bc
Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/707812
Reviewed-by: Kevin Twidle <kpt@google.com>
Fuchsia-Auto-Submit: Andrew Pollack <andrewpollack@google.com>
Commit-Queue: Auto-Submit <auto-submit@fuchsia-infra.iam.gserviceaccount.com>
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steffahn commented Aug 18, 2022

  • It only affects users of explicit lifetime annotations on closure signature and body only if one of the lifetimes happens to be early-bound.
  • They were rejected by AST borrowck.

Here’s an interesting code example that checks neither of these boxes. (Slightly modified from #100725)

pub struct Bigger<'a> {
    _marker: &'a (),
}
impl<'a> Bigger<'a> {
    pub fn get_addr(byte_list: &'a mut Vec<u8>) -> &mut u8 {
        let _ = byte_list.iter_mut().map(|item| {
            Self::other(item);
        }).collect::<Vec<_>>();

        byte_list.push(0);
        byte_list.last_mut().unwrap()
    }

    pub fn other<'b: 'a>(_value: &'b mut u8) {
        panic!()
    }
}

Doesn’t involve explicit lifetime annotations in the closure and compiles successfully since Rust 1.2.0, broken in 1.64 beta (bisects to this PR).

Edit: Oh, wait, my bad, the Self of course stands for Bigger::<'a> so there is a lifetime in the closure. Still, the point that this was not rejected by AST borrow checking still stands.

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Yeah, it is indeed because of Self there. I'm curious if #100375 fixes it. If not, I think we should consider reverting this.

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For the record, #100375 doesn't change this behavior.

@apiraino apiraino removed the to-announce Announce this issue on triage meeting label Sep 8, 2022
@jackh726 jackh726 removed the I-types-nominated Nominated for discussion during a types team meeting. label Sep 20, 2022
wip-sync pushed a commit to NetBSD/pkgsrc-wip that referenced this pull request Oct 11, 2022
Pkgsrc changes:
 * Add patch to fix vendor/kqueue issue (on 32-bit hosts)
 * Adjust other patches & line numbers
 * Version bumps & checksum changes.

Upstream changes:

Version 1.64.0 (2022-09-22)
===========================

Language
--------
- [Unions with mutable references or tuples of allowed types are
  now allowed](rust-lang/rust#97995)

- It is now considered valid to deallocate memory pointed to by a
  shared reference `&T` [if every byte in `T` is inside an
  `UnsafeCell`](rust-lang/rust#98017)

- Unused tuple struct fields are now warned against in an
  allow-by-default lint, [`unused_tuple_struct_fields`]
  (rust-lang/rust#95977), similar to the
  existing warning for unused struct fields. This lint will become
  warn-by-default in the future.

Compiler
--------
- [Add Nintendo Switch as tier 3 target]
  (rust-lang/rust#88991)
  - Refer to Rust's [platform support page][platform-support-doc] for more
    information on Rust's tiered platform support.
- [Only compile `#[used]` as llvm.compiler.used for ELF targets]
  (rust-lang/rust#93718)
- [Add the `--diagnostic-width` compiler flag to define the terminal width.]
  (rust-lang/rust#95635)
- [Add support for link-flavor `rust-lld` for iOS, tvOS and watchOS]
  (rust-lang/rust#98771)

Libraries
---------
- [Remove restrictions on compare-exchange memory ordering.]
  (rust-lang/rust#98383)
- You can now `write!` or `writeln!` into an `OsString`: [Implement
  `fmt::Write` for `OsString`](rust-lang/rust#97915)
- [Make RwLockReadGuard covariant]
  (rust-lang/rust#96820)
- [Implement `FusedIterator` for `std::net::[Into]Incoming`]
  (rust-lang/rust#97300)
- [`impl<T: AsRawFd> AsRawFd for {Arc,Box}<T>`]
  (rust-lang/rust#97437)
- [`ptr::copy` and `ptr::swap` are doing untyped copies]
  (rust-lang/rust#97712)
- [Add cgroupv1 support to `available_parallelism`]
  (rust-lang/rust#97925)
- [Mitigate many incorrect uses of `mem::uninitialized`]
  (rust-lang/rust#99182)

Stabilized APIs
---------------
- [`future::IntoFuture`]
  (https://doc.rust-lang.org/stable/std/future/trait.IntoFuture.html)
- [`future::poll_fn`]
  (https://doc.rust-lang.org/stable/std/future/fn.poll_fn.html)
- [`task::ready!`]
  (https://doc.rust-lang.org/stable/std/task/macro.ready.html)
- [`num::NonZero*::checked_mul`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroUsize.html#method.checked_mul)
- [`num::NonZero*::checked_pow`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroUsize.html#method.checked_pow)
- [`num::NonZero*::saturating_mul`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroUsize.html#method.saturating_mul)
- [`num::NonZero*::saturating_pow`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroUsize.html#method.saturating_pow)
- [`num::NonZeroI*::abs`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroIsize.html#method.abs)
- [`num::NonZeroI*::checked_abs`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroIsize.html#method.checked_abs)
- [`num::NonZeroI*::overflowing_abs`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroIsize.html#method.overflowing_abs)
- [`num::NonZeroI*::saturating_abs`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroIsize.html#method.saturating_abs)
- [`num::NonZeroI*::unsigned_abs`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroIsize.html#method.unsigned_abs)
- [`num::NonZeroI*::wrapping_abs`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroIsize.html#method.wrapping_abs)
- [`num::NonZeroU*::checked_add`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroUsize.html#method.checked_add)
- [`num::NonZeroU*::checked_next_power_of_two`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroUsize.html#method.checked_next_power_of_two)
- [`num::NonZeroU*::saturating_add`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroUsize.html#method.saturating_add)
- [`os::unix::process::CommandExt::process_group`]
  (https://doc.rust-lang.org/stable/std/os/unix/process/trait.CommandExt.html#tymethod.process_group)
- [`os::windows::fs::FileTypeExt::is_symlink_dir`]
  (https://doc.rust-lang.org/stable/std/os/windows/fs/trait.FileTypeExt.html#tymethod.is_symlink_dir)
- [`os::windows::fs::FileTypeExt::is_symlink_file`]
  (https://doc.rust-lang.org/stable/std/os/windows/fs/trait.FileTypeExt.html#tymethod.is_symlink_file)

These types were previously stable in `std::ffi`, but are now also
available in `core` and `alloc`:

- [`core::ffi::CStr`]
  (https://doc.rust-lang.org/stable/core/ffi/struct.CStr.html)
- [`core::ffi::FromBytesWithNulError`]
  (https://doc.rust-lang.org/stable/core/ffi/struct.FromBytesWithNulError.html)
- [`alloc::ffi::CString`]
  (https://doc.rust-lang.org/stable/alloc/ffi/struct.CString.html)
- [`alloc::ffi::FromVecWithNulError`]
  (https://doc.rust-lang.org/stable/alloc/ffi/struct.FromVecWithNulError.html)
- [`alloc::ffi::IntoStringError`]
  (https://doc.rust-lang.org/stable/alloc/ffi/struct.IntoStringError.html)
- [`alloc::ffi::NulError`]
  (https://doc.rust-lang.org/stable/alloc/ffi/struct.NulError.html)

These types were previously stable in `std::os::raw`, but are now also available in `core::ffi` and `std::ffi`:

- [`ffi::c_char`]
  (https://doc.rust-lang.org/stable/std/ffi/type.c_char.html)
- [`ffi::c_double`]
  (https://doc.rust-lang.org/stable/std/ffi/type.c_double.html)
- [`ffi::c_float`]
  (https://doc.rust-lang.org/stable/std/ffi/type.c_float.html)
- [`ffi::c_int`]
  (https://doc.rust-lang.org/stable/std/ffi/type.c_int.html)
- [`ffi::c_long`]
  (https://doc.rust-lang.org/stable/std/ffi/type.c_long.html)
- [`ffi::c_longlong`]
  (https://doc.rust-lang.org/stable/std/ffi/type.c_longlong.html)
- [`ffi::c_schar`]
  (https://doc.rust-lang.org/stable/std/ffi/type.c_schar.html)
- [`ffi::c_short`]
  (https://doc.rust-lang.org/stable/std/ffi/type.c_short.html)
- [`ffi::c_uchar`]
  (https://doc.rust-lang.org/stable/std/ffi/type.c_uchar.html)
- [`ffi::c_uint`]
  (https://doc.rust-lang.org/stable/std/ffi/type.c_uint.html)
- [`ffi::c_ulong`]
  (https://doc.rust-lang.org/stable/std/ffi/type.c_ulong.html)
- [`ffi::c_ulonglong`]
  (https://doc.rust-lang.org/stable/std/ffi/type.c_ulonglong.html)
- [`ffi::c_ushort`]
  (https://doc.rust-lang.org/stable/std/ffi/type.c_ushort.html)

These APIs are now usable in const contexts:

- [`slice::from_raw_parts`]
  (https://doc.rust-lang.org/stable/core/slice/fn.from_raw_parts.html)

Cargo
-----
- [Packages can now inherit settings from the workspace so that
  the settings can be centralized in one place.]
  (rust-lang/cargo#10859) See
  [`workspace.package`](https://doc.rust-lang.org/nightly/cargo/reference/workspaces.html#the-workspacepackage-table)
  and
  [`workspace.dependencies`](https://doc.rust-lang.org/nightly/cargo/reference/workspaces.html#the-workspacedependencies-table)
  for more details on how to define these common settings.
- [Cargo commands can now accept multiple `--target` flags to build
  for multiple targets at once]
  (rust-lang/cargo#10766), and the
  [`build.target`](https://doc.rust-lang.org/nightly/cargo/reference/config.html#buildtarget)
  config option may now take an array of multiple targets.
- [The `--jobs` argument can now take a negative number to count
  backwards from the max CPUs.]
  (rust-lang/cargo#10844)
- [`cargo add` will now update `Cargo.lock`.]
  (rust-lang/cargo#10902)
- [Added](rust-lang/cargo#10838) the
  [`--crate-type`](https://doc.rust-lang.org/nightly/cargo/commands/cargo-rustc.html#option-cargo-rustc---crate-type)
  flag to `cargo rustc` to override the crate type.
- [Significantly improved the performance fetching git dependencies from GitHub
  when using a hash in the `rev` field.]
  (rust-lang/cargo#10079)

Misc
----
- [The `rust-analyzer` rustup component is now available on the stable channel.]
  (rust-lang/rust#98640)

Compatibility Notes
-------------------
- The minimum required versions for all `-linux-gnu` targets are
  now at least kernel 3.2 and glibc 2.17, for targets that previously
  supported older versions: [Increase the minimum linux-gnu
  versions](rust-lang/rust#95026)
- [Network primitives are now implemented with the ideal Rust
  layout, not the C system layout]
  (rust-lang/rust#78802). This can
  cause problems when transmuting the types.
- [Add assertion that `transmute_copy`'s `U` is not larger than `T`]
  (rust-lang/rust#98839)
- [A soundness bug in `BTreeMap` was fixed]
  (rust-lang/rust#99413) that allowed data
  it was borrowing to be dropped before the container.
- [The Drop behavior of C-like enums cast to ints has changed]
  (rust-lang/rust#96862). These are already
  discouraged by a compiler warning.
- [Relate late-bound closure lifetimes to parent fn in NLL]
  (rust-lang/rust#98835)
- [Errors at const-eval time are now in future incompatibility reports]
  (rust-lang/rust#97743)
- On the `thumbv6m-none-eabi` target, some incorrect `asm!` statements
  were erroneously accepted if they used the high registers (r8 to
  r14) as an input/output operand. [This is no longer accepted]
  (rust-lang/rust#99155).
- [`impl Trait` was accidentally accepted as the associated type
  value of return-position `impl Trait`]
  (rust-lang/rust#97346), without
  fulfilling all the trait bounds of that associated type, as long
  as the hidden type satisfies said bounds. This has been fixed.

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.

- Windows builds now use profile-guided optimization, providing
  10-20% improvements to compiler performance: [Utilize PGO for
  windows x64 rustc dist builds]
  (rust-lang/rust#96978)
- [Stop keeping metadata in memory before writing it to disk]
  (rust-lang/rust#96544)
- [compiletest: strip debuginfo by default for mode=ui]
  (rust-lang/rust#98140)
- Many improvements to generated code for derives, including
  performance improvements:
  - [Don't use match-destructuring for derived ops on structs.]
    (rust-lang/rust#98446)
  - [Many small deriving cleanups]
    (rust-lang/rust#98741)
  - [More derive output improvements]
    (rust-lang/rust#98758)
  - [Clarify deriving code](rust-lang/rust#98915)
  - [Final derive output improvements]
    (rust-lang/rust#99046)
  - [Stop injecting `#[allow(unused_qualifications)]` in generated
    `derive` implementations](rust-lang/rust#99485)
  - [Improve `derive(Debug)`](rust-lang/rust#98190)
- [Bump to clap 3](rust-lang/rust#98213)
- [fully move dropck to mir](rust-lang/rust#98641)
- [Optimize `Vec::insert` for the case where `index == len`.]
  (rust-lang/rust#98755)
- [Convert rust-analyzer to an in-tree tool]
  (rust-lang/rust#99603)
netbsd-srcmastr pushed a commit to NetBSD/pkgsrc that referenced this pull request Nov 16, 2022
Pkgsrc changes:
 * This package now contains rust-analyzer, so implicitly
   conflicts with that pkgsrc package.  The same goes for
   the rust-src package.
 * Add NetBSD/arm6 port
 * Add unfinished NetBSD/mipsel port
 * Revert the use of the internal LLVM,
   should now build with the new pkgsrc LLVM (15).
 * Add depndence on compat80 for sparc64 to fix the build
 * Adapt patches
 * Add CHECK_INTERPRETER_SKIP for a few (mostly unused) files.
   (A proper fix may come later.)

Upstream changes:

Version 1.64.0 (2022-09-22)
===========================

Language
--------
- [Unions with mutable references or tuples of allowed types are
  now allowed](rust-lang/rust#97995)

- It is now considered valid to deallocate memory pointed to by a
  shared reference `&T` [if every byte in `T` is inside an
  `UnsafeCell`](rust-lang/rust#98017)

- Unused tuple struct fields are now warned against in an
  allow-by-default lint, [`unused_tuple_struct_fields`]
  (rust-lang/rust#95977), similar to the
  existing warning for unused struct fields. This lint will become
  warn-by-default in the future.

Compiler
--------
- [Add Nintendo Switch as tier 3 target]
  (rust-lang/rust#88991)
  - Refer to Rust's [platform support page][platform-support-doc] for more
    information on Rust's tiered platform support.
- [Only compile `#[used]` as llvm.compiler.used for ELF targets]
  (rust-lang/rust#93718)
- [Add the `--diagnostic-width` compiler flag to define the terminal width.]
  (rust-lang/rust#95635)
- [Add support for link-flavor `rust-lld` for iOS, tvOS and watchOS]
  (rust-lang/rust#98771)

Libraries
---------
- [Remove restrictions on compare-exchange memory ordering.]
  (rust-lang/rust#98383)
- You can now `write!` or `writeln!` into an `OsString`: [Implement
  `fmt::Write` for `OsString`](rust-lang/rust#97915)
- [Make RwLockReadGuard covariant]
  (rust-lang/rust#96820)
- [Implement `FusedIterator` for `std::net::[Into]Incoming`]
  (rust-lang/rust#97300)
- [`impl<T: AsRawFd> AsRawFd for {Arc,Box}<T>`]
  (rust-lang/rust#97437)
- [`ptr::copy` and `ptr::swap` are doing untyped copies]
  (rust-lang/rust#97712)
- [Add cgroupv1 support to `available_parallelism`]
  (rust-lang/rust#97925)
- [Mitigate many incorrect uses of `mem::uninitialized`]
  (rust-lang/rust#99182)

Stabilized APIs
---------------
- [`future::IntoFuture`]
  (https://doc.rust-lang.org/stable/std/future/trait.IntoFuture.html)
- [`future::poll_fn`]
  (https://doc.rust-lang.org/stable/std/future/fn.poll_fn.html)
- [`task::ready!`]
  (https://doc.rust-lang.org/stable/std/task/macro.ready.html)
- [`num::NonZero*::checked_mul`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroUsize.html#method.checked_mul)
- [`num::NonZero*::checked_pow`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroUsize.html#method.checked_pow)
- [`num::NonZero*::saturating_mul`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroUsize.html#method.saturating_mul)
- [`num::NonZero*::saturating_pow`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroUsize.html#method.saturating_pow)
- [`num::NonZeroI*::abs`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroIsize.html#method.abs)
- [`num::NonZeroI*::checked_abs`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroIsize.html#method.checked_abs)
- [`num::NonZeroI*::overflowing_abs`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroIsize.html#method.overflowing_abs)
- [`num::NonZeroI*::saturating_abs`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroIsize.html#method.saturating_abs)
- [`num::NonZeroI*::unsigned_abs`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroIsize.html#method.unsigned_abs)
- [`num::NonZeroI*::wrapping_abs`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroIsize.html#method.wrapping_abs)
- [`num::NonZeroU*::checked_add`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroUsize.html#method.checked_add)
- [`num::NonZeroU*::checked_next_power_of_two`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroUsize.html#method.checked_next_power_of_two)
- [`num::NonZeroU*::saturating_add`]
  (https://doc.rust-lang.org/stable/std/num/struct.NonZeroUsize.html#method.saturating_add)
- [`os::unix::process::CommandExt::process_group`]
  (https://doc.rust-lang.org/stable/std/os/unix/process/trait.CommandExt.html#tymethod.process_group)
- [`os::windows::fs::FileTypeExt::is_symlink_dir`]
  (https://doc.rust-lang.org/stable/std/os/windows/fs/trait.FileTypeExt.html#tymethod.is_symlink_dir)
- [`os::windows::fs::FileTypeExt::is_symlink_file`]
  (https://doc.rust-lang.org/stable/std/os/windows/fs/trait.FileTypeExt.html#tymethod.is_symlink_file)

These types were previously stable in `std::ffi`, but are now also
available in `core` and `alloc`:

- [`core::ffi::CStr`]
  (https://doc.rust-lang.org/stable/core/ffi/struct.CStr.html)
- [`core::ffi::FromBytesWithNulError`]
  (https://doc.rust-lang.org/stable/core/ffi/struct.FromBytesWithNulError.html)
- [`alloc::ffi::CString`]
  (https://doc.rust-lang.org/stable/alloc/ffi/struct.CString.html)
- [`alloc::ffi::FromVecWithNulError`]
  (https://doc.rust-lang.org/stable/alloc/ffi/struct.FromVecWithNulError.html)
- [`alloc::ffi::IntoStringError`]
  (https://doc.rust-lang.org/stable/alloc/ffi/struct.IntoStringError.html)
- [`alloc::ffi::NulError`]
  (https://doc.rust-lang.org/stable/alloc/ffi/struct.NulError.html)

These types were previously stable in `std::os::raw`, but are now
also available in `core::ffi` and `std::ffi`:

- [`ffi::c_char`]
  (https://doc.rust-lang.org/stable/std/ffi/type.c_char.html)
- [`ffi::c_double`]
  (https://doc.rust-lang.org/stable/std/ffi/type.c_double.html)
- [`ffi::c_float`]
  (https://doc.rust-lang.org/stable/std/ffi/type.c_float.html)
- [`ffi::c_int`]
  (https://doc.rust-lang.org/stable/std/ffi/type.c_int.html)
- [`ffi::c_long`]
  (https://doc.rust-lang.org/stable/std/ffi/type.c_long.html)
- [`ffi::c_longlong`]
  (https://doc.rust-lang.org/stable/std/ffi/type.c_longlong.html)
- [`ffi::c_schar`]
  (https://doc.rust-lang.org/stable/std/ffi/type.c_schar.html)
- [`ffi::c_short`]
  (https://doc.rust-lang.org/stable/std/ffi/type.c_short.html)
- [`ffi::c_uchar`]
  (https://doc.rust-lang.org/stable/std/ffi/type.c_uchar.html)
- [`ffi::c_uint`]
  (https://doc.rust-lang.org/stable/std/ffi/type.c_uint.html)
- [`ffi::c_ulong`]
  (https://doc.rust-lang.org/stable/std/ffi/type.c_ulong.html)
- [`ffi::c_ulonglong`]
  (https://doc.rust-lang.org/stable/std/ffi/type.c_ulonglong.html)
- [`ffi::c_ushort`]
  (https://doc.rust-lang.org/stable/std/ffi/type.c_ushort.html)

These APIs are now usable in const contexts:

- [`slice::from_raw_parts`]
  (https://doc.rust-lang.org/stable/core/slice/fn.from_raw_parts.html)

Cargo
-----
- [Packages can now inherit settings from the workspace so that
  the settings can be centralized in one place.]
  (rust-lang/cargo#10859) See
  [`workspace.package`](https://doc.rust-lang.org/nightly/cargo/reference/workspaces.html#the-workspacepackage-table)
  and
  [`workspace.dependencies`](https://doc.rust-lang.org/nightly/cargo/reference/workspaces.html#the-workspacedependencies-table)
  for more details on how to define these common settings.
- [Cargo commands can now accept multiple `--target` flags to build
  for multiple targets at once]
  (rust-lang/cargo#10766), and the
  [`build.target`](https://doc.rust-lang.org/nightly/cargo/reference/config.html#buildtarget)
  config option may now take an array of multiple targets.
- [The `--jobs` argument can now take a negative number to count
  backwards from the max CPUs.]
  (rust-lang/cargo#10844)
- [`cargo add` will now update `Cargo.lock`.]
  (rust-lang/cargo#10902)
- [Added](rust-lang/cargo#10838) the
  [`--crate-type`](https://doc.rust-lang.org/nightly/cargo/commands/cargo-rustc.html#option-cargo-rustc---crate-type)
  flag to `cargo rustc` to override the crate type.
- [Significantly improved the performance fetching git dependencies from GitHub
  when using a hash in the `rev` field.]
  (rust-lang/cargo#10079)

Misc
----
- [The `rust-analyzer` rustup component is now available on the stable channel.]
  (rust-lang/rust#98640)

Compatibility Notes
-------------------
- The minimum required versions for all `-linux-gnu` targets are
  now at least kernel 3.2 and glibc 2.17, for targets that previously
  supported older versions: [Increase the minimum linux-gnu
  versions](rust-lang/rust#95026)
- [Network primitives are now implemented with the ideal Rust
  layout, not the C system layout]
  (rust-lang/rust#78802). This can
  cause problems when transmuting the types.
- [Add assertion that `transmute_copy`'s `U` is not larger than `T`]
  (rust-lang/rust#98839)
- [A soundness bug in `BTreeMap` was fixed]
  (rust-lang/rust#99413) that allowed data
  it was borrowing to be dropped before the container.
- [The Drop behavior of C-like enums cast to ints has changed]
  (rust-lang/rust#96862). These are already
  discouraged by a compiler warning.
- [Relate late-bound closure lifetimes to parent fn in NLL]
  (rust-lang/rust#98835)
- [Errors at const-eval time are now in future incompatibility reports]
  (rust-lang/rust#97743)
- On the `thumbv6m-none-eabi` target, some incorrect `asm!` statements
  were erroneously accepted if they used the high registers (r8 to
  r14) as an input/output operand. [This is no longer accepted]
  (rust-lang/rust#99155).
- [`impl Trait` was accidentally accepted as the associated type
  value of return-position `impl Trait`]
  (rust-lang/rust#97346), without
  fulfilling all the trait bounds of that associated type, as long
  as the hidden type satisfies said bounds. This has been fixed.

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.

- Windows builds now use profile-guided optimization, providing
  10-20% improvements to compiler performance: [Utilize PGO for
  windows x64 rustc dist builds]
  (rust-lang/rust#96978)
- [Stop keeping metadata in memory before writing it to disk]
  (rust-lang/rust#96544)
- [compiletest: strip debuginfo by default for mode=ui]
  (rust-lang/rust#98140)
- Many improvements to generated code for derives, including
  performance improvements:
  - [Don't use match-destructuring for derived ops on structs.]
    (rust-lang/rust#98446)
  - [Many small deriving cleanups]
    (rust-lang/rust#98741)
  - [More derive output improvements]
    (rust-lang/rust#98758)
  - [Clarify deriving code](rust-lang/rust#98915)
  - [Final derive output improvements]
    (rust-lang/rust#99046)
  - [Stop injecting `#[allow(unused_qualifications)]` in generated
    `derive` implementations](rust-lang/rust#99485)
  - [Improve `derive(Debug)`](rust-lang/rust#98190)
- [Bump to clap 3](rust-lang/rust#98213)
- [fully move dropck to mir](rust-lang/rust#98641)
- [Optimize `Vec::insert` for the case where `index == len`.]
  (rust-lang/rust#98755)
- [Convert rust-analyzer to an in-tree tool]
  (rust-lang/rust#99603)
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NLL: named lifetimes in closures can be unrelated to those in parent function