Constify LinkedList new function #63684

GrayJack · 2019-08-18T10:34:06Z

Change the LinkedList::new() function to become a const fn, allowing the use in constant context.

rust-highfive · 2019-08-18T10:34:09Z

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @cramertj (or someone else) soon.

If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes.

Please see the contribution instructions for more information.

Centril · 2019-08-18T10:55:42Z

r? @alexcrichton

alexcrichton · 2019-08-19T13:10:36Z

@GrayJack FWIW could you perhaps elaborate on this PR a little bit? There's nothing in the PR description, nothing else in the commit except the title of the PR, and the change simply deletes one word. While self-explanatory enough it's generally good hygiene to have at least a few words motivating the change instead of just leaving it up to readers to figure out what's going on.

@rfcbot fcp merge

rfcbot · 2019-08-19T13:12:21Z

Team member @alexcrichton 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 · 2019-08-19T18:10:02Z

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

daboross · 2019-08-28T21:17:04Z

Just wondering: is the lack of unsafety here why this function can be insta-stable const while Vec::new remains marked const_unstable?

Vec::new was similarly marked const, but it was not marked stable:

rust/src/liballoc/vec.rs

Lines 316 to 317 in c422372

    
           #[rustc_const_unstable(feature = "const_vec_new")] 
        
           pub const fn new() -> Vec<T> {

GrayJack · 2019-08-28T21:49:34Z

@Centril said that Vec is under is blocked for other reason, but I have no more background to know what blocks it.

If in the end is decided that it should be behind a feature gate, I'll gladly do it

rfcbot · 2019-08-29T18:10:24Z

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.

Centril · 2019-08-29T18:13:16Z

r? @Centril @bors r+ rollup

bors · 2019-08-29T18:13:17Z

📌 Commit e0f7305 has been approved by Centril

Constify LinkedList new function Change the `LinkedList::new()` function to become a const fn, allowing the use in constant context.

@ghost

Rollup of 4 pull requests Successful merges: - #61626 (Get rid of special const intrinsic query in favour of `const_eval`) - #63600 (Merge oli-obk mail addresses) - #63684 (Constify LinkedList new function) - #63982 (When accessing private field of union, do not misidentify it as a struct) Failed merges: r? @ghost

Constify LinkedList new function Change the `LinkedList::new()` function to become a const fn, allowing the use in constant context.

@ghost

Rollup of 7 pull requests Successful merges: - #62957 (Match the loop examples) - #63600 (Merge oli-obk mail addresses) - #63684 (Constify LinkedList new function) - #63847 ([rustdoc] Fix system theme detection) - #63999 (Add missing links on AsRef trait) - #64014 ( miri: detect too large dynamically sized objects ) - #64015 (some const-eval test tweaks) Failed merges: r? @ghost

Pkgsrc changes: * Remove patch which no longer applies (but what about RPATH?) * Adapt a few patches to changed files upstream. Upstream changes: Version 1.39.0 (2019-11-07) =========================== Language -------- - [You can now create `async` functions and blocks with `async fn`, `async move {}`, and `async {}` respectively, and you can now call `.await` on async expressions.][63209] - [You can now use certain attributes on function, closure, and function pointer parameters.][64010] These attributes include `cfg`, `cfg_attr`, `allow`, `warn`, `deny`, `forbid` as well as inert helper attributes used by procedural macro attributes applied to items. e.g. ```rust fn len( #[cfg(windows)] slice: &[u16], #[cfg(not(windows))] slice: &[u8], ) -> usize { slice.len() } ``` - [You can now take shared references to bind-by-move patterns in the `if` guards of `match` arms.][63118] e.g. ```rust fn main() { let array: Box<[u8; 4]> = Box::new([1, 2, 3, 4]); match array { nums // ---- `nums` is bound by move. if nums.iter().sum::<u8>() == 10 // ^------ `.iter()` implicitly takes a reference to `nums`. => { drop(nums); // ----------- Legal as `nums` was bound by move and so we have ownership. } _ => unreachable!(), } } ``` Compiler -------- - [Added tier 3\* support for the `i686-unknown-uefi` target.][64334] - [Added tier 3 support for the `sparc64-unknown-openbsd` target.][63595] - [rustc will now trim code snippets in diagnostics to fit in your terminal.] [63402] **Note** Cargo currently doesn't use this feature. Refer to [cargo#7315][cargo/7315] to track this feature's progress. - [You can now pass `--show-output` argument to test binaries to print the output of successful tests.][62600] \* Refer to Rust's [platform support page][forge-platform-support] for more information on Rust's tiered platform support. Libraries --------- - [`Vec::new` and `String::new` are now `const` functions.][64028] - [`LinkedList::new` is now a `const` function.][63684] - [`str::len`, `[T]::len` and `str::as_bytes` are now `const` functions.][63770] - [The `abs`, `wrapping_abs`, and `overflowing_abs` numeric functions are now `const`.][63786] Stabilized APIs --------------- - [`Pin::into_inner`] - [`Instant::checked_duration_since`] - [`Instant::saturating_duration_since`] Cargo ----- - [You can now publish git dependencies if supplied with a `version`.] [cargo/7237] - [The `--all` flag has been renamed to `--workspace`.][cargo/7241] Using `--all` is now deprecated. Misc ---- - [You can now pass `-Clinker` to rustdoc to control the linker used for compiling doctests.][63834] Compatibility Notes ------------------- - [Code that was previously accepted by the old borrow checker, but rejected by the NLL borrow checker is now a hard error in Rust 2018.][63565] This was previously a warning, and will also become a hard error in the Rust 2015 edition in the 1.40.0 release. - [`rustdoc` now requires `rustc` to be installed and in the same directory to run tests.][63827] This should improve performance when running a large amount of doctests. - [The `try!` macro will now issue a deprecation warning.][62672] It is recommended to use the `?` operator instead. - [`asinh(-0.0)` now correctly returns `-0.0`.][63698] Previously this returned `0.0`. [62600]: rust-lang/rust#62600 [62672]: rust-lang/rust#62672 [63118]: rust-lang/rust#63118 [63209]: rust-lang/rust#63209 [63402]: rust-lang/rust#63402 [63565]: rust-lang/rust#63565 [63595]: rust-lang/rust#63595 [63684]: rust-lang/rust#63684 [63698]: rust-lang/rust#63698 [63770]: rust-lang/rust#63770 [63786]: rust-lang/rust#63786 [63827]: rust-lang/rust#63827 [63834]: rust-lang/rust#63834 [63927]: rust-lang/rust#63927 [63933]: rust-lang/rust#63933 [63934]: rust-lang/rust#63934 [63938]: rust-lang/rust#63938 [63940]: rust-lang/rust#63940 [63941]: rust-lang/rust#63941 [63945]: rust-lang/rust#63945 [64010]: rust-lang/rust#64010 [64028]: rust-lang/rust#64028 [64334]: rust-lang/rust#64334 [cargo/7237]: rust-lang/cargo#7237 [cargo/7241]: rust-lang/cargo#7241 [cargo/7315]: rust-lang/cargo#7315 [`Pin::into_inner`]: https://doc.rust-lang.org/std/pin/struct.Pin.html#method.into_inner [`Instant::checked_duration_since`]: https://doc.rust-lang.org/std/time/struct.Instant.html#method.checked_duration_since [`Instant::saturating_duration_since`]: https://doc.rust-lang.org/std/time/struct.Instant.html#method.saturating_duration_since

rust-lang#63684 was merged for 1.39 not 1.32

…t_new-since, r=dtolnay Fix since attribute for const_linked_list_new feature rust-lang#63684 was merged for 1.39 not 1.32

Constify LinkedList new function

e0f7305

rust-highfive assigned cramertj Aug 18, 2019

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Aug 18, 2019

Centril added needs-fcp This change is insta-stable, so needs a completed FCP to proceed. relnotes Marks issues that should be documented in the release notes of the next release. T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. labels Aug 18, 2019

Centril modified the milestones: 1.38, 1.39 Aug 18, 2019

Centril approved these changes Aug 18, 2019

View reviewed changes

rust-highfive assigned alexcrichton and unassigned cramertj Aug 18, 2019

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 Aug 19, 2019

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 Aug 29, 2019

Centril removed the needs-fcp This change is insta-stable, so needs a completed FCP to proceed. label Aug 29, 2019

rust-highfive unassigned alexcrichton Aug 29, 2019

rust-highfive assigned Centril Aug 29, 2019

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 29, 2019

Centril mentioned this pull request Aug 30, 2019

Rollup of 4 pull requests #64012

Closed

Centril mentioned this pull request Aug 30, 2019

Rollup of 7 pull requests #64026

Merged

bors merged commit e0f7305 into rust-lang:master Aug 31, 2019

jplatte mentioned this pull request Dec 10, 2021

Add and fix flags jplatte/caniuse.rs#42

Closed

not-my-profile added a commit to not-my-profile/rust that referenced this pull request Dec 10, 2021

Fix since attribute for const_linked_list_new feature

305dd69

rust-lang#63684 was merged for 1.39 not 1.32

not-my-profile mentioned this pull request Dec 10, 2021

Fix since attribute for const_linked_list_new feature #91755

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Constify LinkedList new function #63684

Constify LinkedList new function #63684

GrayJack commented Aug 18, 2019 •

edited

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rust-highfive commented Aug 18, 2019

Centril commented Aug 18, 2019

alexcrichton commented Aug 19, 2019

rfcbot commented Aug 19, 2019 •

edited by dtolnay

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rfcbot commented Aug 19, 2019

daboross commented Aug 28, 2019

GrayJack commented Aug 28, 2019

rfcbot commented Aug 29, 2019

Centril commented Aug 29, 2019

bors commented Aug 29, 2019

Constify LinkedList new function #63684

Constify LinkedList new function #63684

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GrayJack commented Aug 18, 2019 •

edited

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rfcbot commented Aug 19, 2019 •

edited by dtolnay

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