Implement Copy, Clone, PartialEq and Eq for core::fmt::Alignment #94530

tmiasko · 2022-03-02T17:35:18Z

Alignment is a fieldless exhaustive enum, so it is already possible to
clone and compare it by matching, but it is inconvenient to do so. For
example, if one would like to create a struct describing a formatter
configuration and provide a clone implementation:

pub struct Format {
    fill: char,
    width: Option<usize>,
    align: fmt::Alignment,
}

impl Clone for Format {
    fn clone(&self) -> Self {
        Format {
            align: match self.align {
                fmt::Alignment::Left => fmt::Alignment::Left,
                fmt::Alignment::Right => fmt::Alignment::Right,
                fmt::Alignment::Center => fmt::Alignment::Center,
            },
            .. *self
        }
    }
}

Derive Copy, Clone, PartialEq, and Eq for Alignment for convenience.

rust-highfive · 2022-03-02T17:35:24Z

r? @joshtriplett

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

joshtriplett · 2022-03-02T21:01:03Z

Trait impls are insta-stable, so this would need an FCP.

What do folks on @rust-lang/libs-api think about this?

yaahc · 2022-03-02T21:37:15Z

Trait impls are insta-stable, so this would need an FCP.

What do folks on @rust-lang/libs-api think about this?

These seem reasonable, but I would the PR description to be updated with more detail including an example situation of when these impls would be useful.

Alignment is a fieldless exhaustive enum, so it is already possible to clone and compare it by matching, but it is inconvenient to do so. For example, if one would like to create a struct describing a formatter configuration and provide a clone implementation: ```rust pub struct Format { fill: char, width: Option<usize>, align: fmt::Alignment, } impl Clone for Format { fn clone(&self) -> Self { Format { align: match self.align { fmt::Alignment::Left => fmt::Alignment::Left, fmt::Alignment::Right => fmt::Alignment::Right, fmt::Alignment::Center => fmt::Alignment::Center, }, .. *self } } } ``` Derive Copy, Clone, PartialEq, and Eq for Alignment for convenience.

yaahc · 2022-03-04T22:17:56Z

@rfcbot merge

rfcbot · 2022-03-04T22:17:57Z

Team member @yaahc 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 · 2022-05-11T14:41:17Z

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

rfcbot · 2022-05-21T14:51:36Z

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.

dtolnay · 2022-05-21T15:52:26Z

@bors r

bors · 2022-05-21T15:52:28Z

📌 Commit a8acfa8 has been approved by dtolnay

bors · 2022-05-21T19:49:55Z

⌛ Testing commit a8acfa8 with merge 9257f5a...

bors · 2022-05-21T22:30:28Z

☀️ Test successful - checks-actions
Approved by: dtolnay
Pushing 9257f5a to master...

rust-timer · 2022-05-21T23:49:19Z

Finished benchmarking commit (9257f5a): comparison url.

Instruction count

This benchmark run did not return any relevant results for this metric.

Max RSS (memory usage)

Results

Primary benchmarks: mixed results
Secondary benchmarks: mixed results

	Regressions 😿 (primary)	Regressions 😿 (secondary)	Improvements 🎉 (primary)	Improvements 🎉 (secondary)	All 😿 🎉 (primary)
count¹	1	2	1	2	2
mean²	1.2%	3.7%	-3.1%	-2.0%	-1.0%
max	1.2%	5.1%	-3.1%	-2.3%	-3.1%

Cycles

Results

Primary benchmarks: 🎉 relevant improvements found
Secondary benchmarks: mixed results

	Regressions 😿 (primary)	Regressions 😿 (secondary)	Improvements 🎉 (primary)	Improvements 🎉 (secondary)	All 😿 🎉 (primary)
count¹	0	1	2	2	2
mean²	N/A	3.8%	-2.2%	-3.9%	-2.2%
max	N/A	3.8%	-2.9%	-4.0%	-2.9%

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

@rustbot label: -perf-regression

number of relevant changes ↩ ↩²
the arithmetic mean of the percent change ↩ ↩²

Pkgsrc changes: * Adjust patches as needed & checksum updates. Upstream changes: Version 1.63.0 (2022-08-11) ========================== Language -------- - [Remove migrate borrowck mode for pre-NLL errors.][95565] - [Modify MIR building to drop repeat expressions with length zero.][95953] - [Remove label/lifetime shadowing warnings.][96296] - [Allow explicit generic arguments in the presence of `impl Trait` args.] [96868] - [Make `cenum_impl_drop_cast` warnings deny-by-default.][97652] - [Prevent unwinding when `-C panic=abort` is used regardless of declared ABI.][96959] - [lub: don't bail out due to empty binders.][97867] Compiler -------- - [Stabilize the `bundle` native library modifier,][95818] also removing the deprecated `static-nobundle` linking kind. - [Add Apple WatchOS compile targets\*.][95243] - [Add a Windows application manifest to rustc-main.][96737] \* Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support. Libraries --------- - [Implement `Copy`, `Clone`, `PartialEq` and `Eq` for `core::fmt::Alignment`.][94530] - [Extend `ptr::null` and `null_mut` to all thin (including extern) types.][94954] - [`impl Read and Write for VecDeque<u8>`.][95632] - [STD support for the Nintendo 3DS.][95897] - [Make write/print macros eagerly drop temporaries.][96455] - [Implement internal traits that enable `[OsStr]::join`.][96881] - [Implement `Hash` for `core::alloc::Layout`.][97034] - [Add capacity documentation for `OsString`.][97202] - [Put a bound on collection misbehavior.][97316] - [Make `std::mem::needs_drop` accept `?Sized`.][97675] - [`impl Termination for Infallible` and then make the `Result` impls of `Termination` more generic.][97803] - [Document Rust's stance on `/proc/self/mem`.][97837] Stabilized APIs --------------- - [`array::from_fn`] - [`Box::into_pin`] - [`BinaryHeap::try_reserve`] - [`BinaryHeap::try_reserve_exact`] - [`OsString::try_reserve`] - [`OsString::try_reserve_exact`] - [`PathBuf::try_reserve`] - [`PathBuf::try_reserve_exact`] - [`Path::try_exists`] - [`Ref::filter_map`] - [`RefMut::filter_map`] - [`NonNull::<[T]>::len`][`NonNull::<slice>::len`] - [`ToOwned::clone_into`] - [`Ipv6Addr::to_ipv4_mapped`] - [`unix::io::AsFd`] - [`unix::io::BorrowedFd<'fd>`] - [`unix::io::OwnedFd`] - [`windows::io::AsHandle`] - [`windows::io::BorrowedHandle<'handle>`] - [`windows::io::OwnedHandle`] - [`windows::io::HandleOrInvalid`] - [`windows::io::HandleOrNull`] - [`windows::io::InvalidHandleError`] - [`windows::io::NullHandleError`] - [`windows::io::AsSocket`] - [`windows::io::BorrowedSocket<'handle>`] - [`windows::io::OwnedSocket`] - [`thread::scope`] - [`thread::Scope`] - [`thread::ScopedJoinHandle`] These APIs are now usable in const contexts: - [`array::from_ref`] - [`slice::from_ref`] - [`intrinsics::copy`] - [`intrinsics::copy_nonoverlapping`] - [`<*const T>::copy_to`] - [`<*const T>::copy_to_nonoverlapping`] - [`<*mut T>::copy_to`] - [`<*mut T>::copy_to_nonoverlapping`] - [`<*mut T>::copy_from`] - [`<*mut T>::copy_from_nonoverlapping`] - [`str::from_utf8`] - [`Utf8Error::error_len`] - [`Utf8Error::valid_up_to`] - [`Condvar::new`] - [`Mutex::new`] - [`RwLock::new`] Cargo ----- - [Stabilize the `--config path` command-line argument.][cargo/10755] - [Expose rust-version in the environment as `CARGO_PKG_RUST_VERSION`.][cargo/10713] Compatibility Notes ------------------- - [`#[link]` attributes are now checked more strictly,][96885] which may introduce errors for invalid attribute arguments that were previously ignored. 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. - [Prepare Rust for LLVM opaque pointers.][94214] [94214]: rust-lang/rust#94214 [94530]: rust-lang/rust#94530 [94954]: rust-lang/rust#94954 [95243]: rust-lang/rust#95243 [95565]: rust-lang/rust#95565 [95632]: rust-lang/rust#95632 [95818]: rust-lang/rust#95818 [95897]: rust-lang/rust#95897 [95953]: rust-lang/rust#95953 [96296]: rust-lang/rust#96296 [96455]: rust-lang/rust#96455 [96737]: rust-lang/rust#96737 [96868]: rust-lang/rust#96868 [96881]: rust-lang/rust#96881 [96885]: rust-lang/rust#96885 [96959]: rust-lang/rust#96959 [97034]: rust-lang/rust#97034 [97202]: rust-lang/rust#97202 [97316]: rust-lang/rust#97316 [97652]: rust-lang/rust#97652 [97675]: rust-lang/rust#97675 [97803]: rust-lang/rust#97803 [97837]: rust-lang/rust#97837 [97867]: rust-lang/rust#97867 [cargo/10713]: rust-lang/cargo#10713 [cargo/10755]: rust-lang/cargo#10755 [`array::from_fn`]: https://doc.rust-lang.org/stable/std/array/fn.from_fn.html [`Box::into_pin`]: https://doc.rust-lang.org/stable/std/boxed/struct.Box.html#method.into_pin [`BinaryHeap::try_reserve_exact`]: https://doc.rust-lang.org/stable/alloc/collections/binary_heap/struct.BinaryHeap.html#method.try_reserve_exact [`BinaryHeap::try_reserve`]: https://doc.rust-lang.org/stable/std/collections/struct.BinaryHeap.html#method.try_reserve [`OsString::try_reserve`]: https://doc.rust-lang.org/stable/std/ffi/struct.OsString.html#method.try_reserve [`OsString::try_reserve_exact`]: https://doc.rust-lang.org/stable/std/ffi/struct.OsString.html#method.try_reserve_exact [`PathBuf::try_reserve`]: https://doc.rust-lang.org/stable/std/path/struct.PathBuf.html#method.try_reserve [`PathBuf::try_reserve_exact`]: https://doc.rust-lang.org/stable/std/path/struct.PathBuf.html#method.try_reserve_exact [`Path::try_exists`]: https://doc.rust-lang.org/stable/std/path/struct.Path.html#method.try_exists [`Ref::filter_map`]: https://doc.rust-lang.org/stable/std/cell/struct.Ref.html#method.filter_map [`RefMut::filter_map`]: https://doc.rust-lang.org/stable/std/cell/struct.RefMut.html#method.filter_map [`NonNull::<slice>::len`]: https://doc.rust-lang.org/stable/std/ptr/struct.NonNull.html#method.len [`ToOwned::clone_into`]: https://doc.rust-lang.org/stable/std/borrow/trait.ToOwned.html#method.clone_into [`Ipv6Addr::to_ipv4_mapped`]: https://doc.rust-lang.org/stable/std/net/struct.Ipv6Addr.html#method.to_ipv4_mapped [`unix::io::AsFd`]: https://doc.rust-lang.org/stable/std/os/unix/io/trait.AsFd.html [`unix::io::BorrowedFd<'fd>`]: https://doc.rust-lang.org/stable/std/os/unix/io/struct.BorrowedFd.html [`unix::io::OwnedFd`]: https://doc.rust-lang.org/stable/std/os/unix/io/struct.OwnedFd.html [`windows::io::AsHandle`]: https://doc.rust-lang.org/stable/std/os/windows/io/trait.AsHandle.html [`windows::io::BorrowedHandle<'handle>`]: https://doc.rust-lang.org/stable/std/os/windows/io/struct.BorrowedHandle.html [`windows::io::OwnedHandle`]: https://doc.rust-lang.org/stable/std/os/windows/io/struct.OwnedHandle.html [`windows::io::HandleOrInvalid`]: https://doc.rust-lang.org/stable/std/os/windows/io/struct.HandleOrInvalid.html [`windows::io::HandleOrNull`]: https://doc.rust-lang.org/stable/std/os/windows/io/struct.HandleOrNull.html [`windows::io::InvalidHandleError`]: https://doc.rust-lang.org/stable/std/os/windows/io/struct.InvalidHandleError.html [`windows::io::NullHandleError`]: https://doc.rust-lang.org/stable/std/os/windows/io/struct.NullHandleError.html [`windows::io::AsSocket`]: https://doc.rust-lang.org/stable/std/os/windows/io/trait.AsSocket.html [`windows::io::BorrowedSocket<'handle>`]: https://doc.rust-lang.org/stable/std/os/windows/io/struct.BorrowedSocket.html [`windows::io::OwnedSocket`]: https://doc.rust-lang.org/stable/std/os/windows/io/struct.OwnedSocket.html [`thread::scope`]: https://doc.rust-lang.org/stable/std/thread/fn.scope.html [`thread::Scope`]: https://doc.rust-lang.org/stable/std/thread/struct.Scope.html [`thread::ScopedJoinHandle`]: https://doc.rust-lang.org/stable/std/thread/struct.ScopedJoinHandle.html [`array::from_ref`]: https://doc.rust-lang.org/stable/std/array/fn.from_ref.html [`slice::from_ref`]: https://doc.rust-lang.org/stable/std/slice/fn.from_ref.html [`intrinsics::copy`]: https://doc.rust-lang.org/stable/std/intrinsics/fn.copy.html [`intrinsics::copy_nonoverlapping`]: https://doc.rust-lang.org/stable/std/intrinsics/fn.copy_nonoverlapping.html [`<*const T>::copy_to`]: https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.copy_to [`<*const T>::copy_to_nonoverlapping`]: https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.copy_to_nonoverlapping [`<*mut T>::copy_to`]: https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.copy_to-1 [`<*mut T>::copy_to_nonoverlapping`]: https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.copy_to_nonoverlapping-1 [`<*mut T>::copy_from`]: https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.copy_from [`<*mut T>::copy_from_nonoverlapping`]: https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.copy_from_nonoverlapping [`str::from_utf8`]: https://doc.rust-lang.org/stable/std/str/fn.from_utf8.html [`Utf8Error::error_len`]: https://doc.rust-lang.org/stable/std/str/struct.Utf8Error.html#method.error_len [`Utf8Error::valid_up_to`]: https://doc.rust-lang.org/stable/std/str/struct.Utf8Error.html#method.valid_up_to [`Condvar::new`]: https://doc.rust-lang.org/stable/std/sync/struct.Condvar.html#method.new [`Mutex::new`]: https://doc.rust-lang.org/stable/std/sync/struct.Mutex.html#method.new [`RwLock::new`]: https://doc.rust-lang.org/stable/std/sync/struct.RwLock.html#method.new

rust-highfive assigned joshtriplett Mar 2, 2022

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Mar 2, 2022

joshtriplett 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 Mar 2, 2022

tmiasko force-pushed the alignment-impls branch from 12f2c6c to a8acfa8 Compare March 4, 2022 22:07

rfcbot added proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. disposition-merge This issue / PR is in PFCP or FCP with a disposition to merge it. labels Mar 4, 2022

rfcbot added the final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. label May 11, 2022

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 May 11, 2022

dtolnay approved these changes May 21, 2022

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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 May 21, 2022

dtolnay assigned dtolnay and unassigned joshtriplett May 21, 2022

bors added the merged-by-bors This PR was explicitly merged by bors. label May 21, 2022

bors merged commit 9257f5a into rust-lang:master May 21, 2022

rustbot added this to the 1.63.0 milestone May 21, 2022

tmiasko deleted the alignment-impls branch May 22, 2022 10:21

apiraino removed the to-announce Announce this issue on triage meeting label May 27, 2022

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Implement Copy, Clone, PartialEq and Eq for core::fmt::Alignment #94530

Implement Copy, Clone, PartialEq and Eq for core::fmt::Alignment #94530

tmiasko commented Mar 2, 2022 •

edited

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rust-highfive commented Mar 2, 2022

joshtriplett commented Mar 2, 2022 •

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yaahc commented Mar 2, 2022 •

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yaahc commented Mar 4, 2022

rfcbot commented Mar 4, 2022 •

edited by BurntSushi

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rfcbot commented May 11, 2022

rfcbot commented May 21, 2022

dtolnay commented May 21, 2022

bors commented May 21, 2022

bors commented May 21, 2022

bors commented May 21, 2022

rust-timer commented May 21, 2022

Implement Copy, Clone, PartialEq and Eq for core::fmt::Alignment #94530

Implement Copy, Clone, PartialEq and Eq for core::fmt::Alignment #94530

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tmiasko commented Mar 2, 2022 • edited Loading

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rust-timer commented May 21, 2022

Instruction count

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tmiasko commented Mar 2, 2022 •

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joshtriplett commented Mar 2, 2022 •

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yaahc commented Mar 2, 2022 •

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rfcbot commented Mar 4, 2022 •

edited by BurntSushi

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