Implement Copy, Clone, PartialEq and Eq for core::fmt::Alignment by tmiasko · Pull Request #94530 · rust-lang/rust

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:

pubstructFormat{fill:char,width:Option<usize>,align: fmt::Alignment,}implCloneforFormat{fnclone(&self) -> Self{Format{align:matchself.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, or significant enough to need a team FCP to proceed. T-libs-api [DEPRECATED; DO NOT USE] labels Mar 2, 2022

tmiasko force-pushed the alignment-impls branch from 12f2c6c to a8acfa8Compare 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
View reviewed changes

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:masterMay 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
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