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Implement coherence checks for negative trait impls #90104

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merged 22 commits into from
Oct 23, 2021

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spastorino
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The main purpose of this PR is to be able to move Error trait to core.

This feature is necessary to handle the following from impl on box.

impl From<&str> for Box<dyn Error> { ... }

Without having negative traits affect coherence moving the error trait into core and moving that From impl to alloc will cause the from impl to no longer compiler because of a potential future incompatibility. The compiler indicates that &str could introduce an Error impl in the future, and thus prevents the From impl in alloc that would cause overlap with From<E: Error> for Box<dyn Error>. Adding impl !Error for &str {} with the negative trait coherence feature will disable this error by encoding a stability guarantee that &str will never implement Error, making the From impl compile.

We would have this in alloc:

impl From<&str> for Box<dyn Error> {} // A 
impl<E> From<E> for Box<dyn Error> where E: Error {} // B

and this in core:

trait Error {}
impl !Error for &str {}

r? @nikomatsakis

This PR was built on top of @yaahc PR #85764.

Language team proposal: to rust-lang/lang-team#96

@rust-highfive rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Oct 20, 2021
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@bors try @rust-timer queue

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Awaiting bors try build completion.

@rustbot label: +S-waiting-on-perf

@rustbot rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Oct 20, 2021
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bors commented Oct 20, 2021

⌛ Trying commit 68d444f with merge 2bf0405fabe34f62185aa4b41247aa4eed8b9785...

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rustdoc is failing, this is not unexpected :) and it's probably related to the handling of allow_negative_impls. Gonna check this quickly.

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@bors try @rust-timer queue

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Awaiting bors try build completion.

@rustbot label: +S-waiting-on-perf

@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 Oct 23, 2021
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@bors r- CI failed? :(

@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-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Oct 23, 2021
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@bors r=nikomatsakis

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bors commented Oct 23, 2021

📌 Commit 3287f72 has been approved by 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-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Oct 23, 2021
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bors commented Oct 23, 2021

⌛ Testing commit 3287f72 with merge aa5740c...

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bors commented Oct 23, 2021

☀️ Test successful - checks-actions
Approved by: nikomatsakis
Pushing aa5740c to master...

@bors bors added the merged-by-bors This PR was explicitly merged by bors. label Oct 23, 2021
@bors bors merged commit aa5740c into rust-lang:master Oct 23, 2021
@rustbot rustbot added this to the 1.58.0 milestone Oct 23, 2021
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Finished benchmarking commit (aa5740c): comparison url.

Summary: This benchmark run did not return any relevant changes.

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

@rustbot label: -perf-regression

@rustbot rustbot removed the perf-regression Performance regression. label Oct 23, 2021
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
bors added a commit to rust-lang-ci/rust that referenced this pull request Jul 27, 2023
Don't treat negative trait predicates as always knowable

We don't need this. It was added in rust-lang#90104 but I don't really know why. It's not sound afaict -- negative trait predicates need the same coherence-ambiguity/orphan check rules as positive ones.

r? `@lcnr`

cc `@spastorino,` do you remember why?
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9 participants