Add `impl<T> FromIterator<T> for Arc/Rc<[T]>` #61953

Centril · 2019-06-19T10:17:03Z

Add implementations of FromIterator<T> for Arc/Rc<[T]> with symmetrical logic.

This also takes advantage of specialization in the case of iterators with known length (TrustedLen) to elide the final allocation/copying from a Vec<T> into Rc<[T]> because we can allocate the space for the Rc<[T]> directly when the size is known. This is the primary motivation and why this is to be preferred over iter.collect::<Vec<_>>().into(): Rc<[T]>.

Moreover, this PR does some refactoring in some places.

r? @RalfJung for the code
cc @alexcrichton from T-libs

RalfJung · 2019-06-20T18:01:51Z

Are there tests covering this new code? If not, could you add some? I'd like to run Miri on this.

Centril · 2019-06-20T18:03:37Z

@RalfJung There are some doc-tests, but they might be sparse? Does miri run doc-tests?

RalfJung · 2019-06-20T18:04:58Z

No it does not, unfortunately (rust-lang/miri#584). Could you add #[test] methods?

Centril · 2019-06-20T18:05:27Z

Sure; I'll do that and try to exercise some more pathological cases also.

src/liballoc/rc.rs

RalfJung · 2019-06-20T18:18:52Z

Well done overall! This all looks great, and I wish more code was commented like this.
Just found one comment nit.

I'd like to run Miri though before r+'ing.

Centril · 2019-06-21T01:53:11Z

Added some more tests... :)

src/liballoc/sync.rs

rfcbot · 2019-07-12T07:14:48Z

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.

The RFC will be merged soon.

alexcrichton · 2019-07-12T14:42:54Z

@bors: r=RalfJung

r? @RalfJung

Moving back to the technical reviewer

bors · 2019-07-12T14:42:56Z

📌 Commit 85def30 has been approved by RalfJung

bors · 2019-07-13T06:49:08Z

⌛ Testing commit 85def30 with merge 4a95e97...

@RalfJung

Add `impl<T> FromIterator<T> for Arc/Rc<[T]>` Add implementations of `FromIterator<T> for Arc/Rc<[T]>` with symmetrical logic. This also takes advantage of specialization in the case of iterators with known length (`TrustedLen`) to elide the final allocation/copying from a `Vec<T>` into `Rc<[T]>` because we can allocate the space for the `Rc<[T]>` directly when the size is known. This is the primary motivation and why this is to be preferred over `iter.collect::<Vec<_>>().into(): Rc<[T]>`. Moreover, this PR does some refactoring in some places. r? @RalfJung for the code cc @alexcrichton from T-libs

bors · 2019-07-13T10:15:34Z

☀️ Test successful - checks-azure, checks-travis, status-appveyor
Approved by: RalfJung
Pushing 4a95e97 to master...

Pkgsrc changes: * Adapt to the move of the implementation of random numbers. * Remove patch which is no longer relevant (Signals.inc) * Cross-build currently fails due to the still unresolved rust-lang/rust#62558, so bootstrap kits for 1.38.0 have to be built natively, and will follow shortly. * Bump bootstrap requirements to 1.37.0 except for armv7-unknown-netbsd-eabihf which I've neither managed to cross-build nor build natively. Upstream changes: Version 1.38.0 (2019-09-26) ========================== Language -------- - [The `#[global_allocator]` attribute can now be used in submodules.][62735] - [The `#[deprecated]` attribute can now be used on macros.][62042] Compiler -------- - [Added pipelined compilation support to `rustc`.][62766] This will improve compilation times in some cases. For further information please refer to the [_"Evaluating pipelined rustc compilation"_][pipeline-internals] thread. - [Added tier 3\* support for the `aarch64-uwp-windows-msvc`, `i686-uwp-windows-gnu`, `i686-uwp-windows-msvc`, `x86_64-uwp-windows-gnu`, and `x86_64-uwp-windows-msvc` targets.][60260] - [Added tier 3 support for the `armv7-unknown-linux-gnueabi` and `armv7-unknown-linux-musleabi` targets.][63107] - [Added tier 3 support for the `hexagon-unknown-linux-musl` target.][62814] - [Added tier 3 support for the `riscv32i-unknown-none-elf` target.][62784] \* Refer to Rust's [platform support page][forge-platform-support] for more information on Rust's tiered platform support. Libraries --------- - [`ascii::EscapeDefault` now implements `Clone` and `Display`.][63421] - [Derive macros for prelude traits (e.g. `Clone`, `Debug`, `Hash`) are now available at the same path as the trait.][63056] (e.g. The `Clone` derive macro is available at `std::clone::Clone`). This also makes all built-in macros available in `std`/`core` root. e.g. `std::include_bytes!`. - [`str::Chars` now implements `Debug`.][63000] - [`slice::{concat, connect, join}` now accepts `&[T]` in addition to `&T`.][62528] - [`*const T` and `*mut T` now implement `marker::Unpin`.][62583] - [`Arc<[T]>` and `Rc<[T]>` now implement `FromIterator<T>`.][61953] - [Added euclidean remainder and division operations (`div_euclid`, `rem_euclid`) to all numeric primitives.][61884] Additionally `checked`, `overflowing`, and `wrapping` versions are available for all integer primitives. - [`thread::AccessError` now implements `Clone`, `Copy`, `Eq`, `Error`, and `PartialEq`.][61491] - [`iter::{StepBy, Peekable, Take}` now implement `DoubleEndedIterator`.][61457] Stabilized APIs --------------- - [`<*const T>::cast`] - [`<*mut T>::cast`] - [`Duration::as_secs_f32`] - [`Duration::as_secs_f64`] - [`Duration::div_duration_f32`] - [`Duration::div_duration_f64`] - [`Duration::div_f32`] - [`Duration::div_f64`] - [`Duration::from_secs_f32`] - [`Duration::from_secs_f64`] - [`Duration::mul_f32`] - [`Duration::mul_f64`] - [`any::type_name`] Cargo ----- - [Added pipelined compilation support to `cargo`.][cargo/7143] - [You can now pass the `--features` option multiple times to enable multiple features.][cargo/7084] Misc ---- - [`rustc` will now warn about some incorrect uses of `mem::{uninitialized, zeroed}` that are known to cause undefined behaviour.][63346] Compatibility Notes ------------------- - Unfortunately the [`x86_64-unknown-uefi` platform can not be built][62785] with rustc 1.39.0. - The [`armv7-unknown-linux-gnueabihf` platform is also known to have issues][62896] for certain crates such as libc. [60260]: rust-lang/rust#60260 [61457]: rust-lang/rust#61457 [61491]: rust-lang/rust#61491 [61884]: rust-lang/rust#61884 [61953]: rust-lang/rust#61953 [62042]: rust-lang/rust#62042 [62528]: rust-lang/rust#62528 [62583]: rust-lang/rust#62583 [62735]: rust-lang/rust#62735 [62766]: rust-lang/rust#62766 [62784]: rust-lang/rust#62784 [62785]: rust-lang/rust#62785 [62814]: rust-lang/rust#62814 [62896]: rust-lang/rust#62896 [63000]: rust-lang/rust#63000 [63056]: rust-lang/rust#63056 [63107]: rust-lang/rust#63107 [63346]: rust-lang/rust#63346 [63421]: rust-lang/rust#63421 [cargo/7084]: rust-lang/cargo#7084 [cargo/7143]: rust-lang/cargo#7143 [`<*const T>::cast`]: https://doc.rust-lang.org/std/primitive.pointer.html#method.cast [`<*mut T>::cast`]: https://doc.rust-lang.org/std/primitive.pointer.html#method.cast [`Duration::as_secs_f32`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.as_secs_f32 [`Duration::as_secs_f64`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.as_secs_f64 [`Duration::div_duration_f32`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.div_duration_f32 [`Duration::div_duration_f64`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.div_duration_f64 [`Duration::div_f32`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.div_f32 [`Duration::div_f64`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.div_f64 [`Duration::from_secs_f32`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.from_secs_f32 [`Duration::from_secs_f64`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.from_secs_f64 [`Duration::mul_f32`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.mul_f32 [`Duration::mul_f64`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.mul_f64 [`any::type_name`]: https://doc.rust-lang.org/std/any/fn.type_name.html [forge-platform-support]: https://forge.rust-lang.org/platform-support.html [pipeline-internals]: https://internals.rust-lang.org/t/evaluating-pipelined-rustc-compilation/10199

Centril added T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. relnotes Marks issues that should be documented in the release notes of the next release. needs-fcp This change is insta-stable, so needs a completed FCP to proceed. labels Jun 19, 2019

Centril added this to the 1.37 milestone Jun 19, 2019

rust-highfive assigned RalfJung Jun 19, 2019

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jun 19, 2019

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Centril force-pushed the shared-from-iter branch from 096f5e2 to df5d3a4 Compare June 19, 2019 10:34

Centril added 9 commits June 20, 2019 09:28

Add basic 'shared_from_iter' impls.

689c64c

Rc: refactor away PhantomData noise.

19982f5

Rc: refactor data_offset{_sized}.

2efbc9e

Rc: reduce duplicate calls.

bf8f6c3

shared_from_iter/Rc: Use specialization to elide allocation.

353c8eb

Arc: refactor away PhantomData noise.

27f5d0f

Arc: refactor data_offset{_sized}.

59ecff9

shared_from_iter/Arc: Use specialization to elide allocation.

b1dbf15

deduplicate slice_from_raw_parts_mut.

4b44ad9

Centril force-pushed the shared-from-iter branch from df5d3a4 to 4b44ad9 Compare June 20, 2019 07:30

RalfJung reviewed Jun 20, 2019

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Centril added 3 commits June 20, 2019 23:13

data_offset_align: add inline attribute.

85978d0

shared_from_iter: Clarify slice::Iter specialization impl.

6b8417b

shared_from_iter: Add more tests.

8bbf1ab

RalfJung reviewed Jun 21, 2019

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rfcbot added finished-final-comment-period The final comment period is finished for this PR / Issue. and removed final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. labels Jul 12, 2019

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bors merged commit 85def30 into rust-lang:master Jul 13, 2019

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pickfire mentioned this pull request Sep 26, 2019

Lint against Rc<String> (and Rc<Vec<T>>) rust-lang/rust-clippy#2623

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the8472 mentioned this pull request Mar 23, 2022

Fix (A)Rc<[T]> slices larger than isize::MAX bytes when collecting from a TrustedLen iter #95252

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matthiaskrgr mentioned this pull request Apr 4, 2024

ICE: Failed to normalize Alias(Projection, AliasTy .. #113272

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Add `impl<T> FromIterator<T> for Arc/Rc<[T]>` #61953

Add `impl<T> FromIterator<T> for Arc/Rc<[T]>` #61953

Centril commented Jun 19, 2019 •

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Add impl<T> FromIterator<T> for Arc/Rc<[T]> #61953

Add impl<T> FromIterator<T> for Arc/Rc<[T]> #61953

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Add `impl<T> FromIterator<T> for Arc/Rc<[T]>` #61953

Add `impl<T> FromIterator<T> for Arc/Rc<[T]>` #61953

Centril commented Jun 19, 2019 •

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Centril commented Jun 20, 2019 •

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