Allow comparisons between `CStr`, `CString`, and `Cow<CStr>`. #137268

bjoernager · 2025-02-19T09:41:32Z

This PR adds the trait implementations proposed in the ACP under the c_string_eq_c_str feature gate:

// core::ffi

impl PartialEq<&Self> for CStr;

impl PartialEq<CString> for CStr;

impl PartialEq<Cow<'_, Self>> for CStr;

// alloc::ffi

impl PartialEq<CStr> for CString;

impl PartialEq<&CStr> for CString;

impl PartialEq<Cow<'_, CStr>> for CString;

// alloc::borrow

impl PartialEq<CStr> for Cow<'_, CStr>;

impl PartialEq<&CStr> for Cow<'_, CStr>;

impl PartialEq<CString> for Cow<'_, CStr>;

As I understand it, stable traits cannot be unstably implemented for stable types, and we would thereby be forced to skip the FCP and directly stabilise these implementations (as is done in this PR).

(@joshtriplett mentioned that Crater may have to be run).

rustbot · 2025-02-19T09:41:42Z

r? @Amanieu

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bjoernager · 2025-02-19T09:42:09Z

@rustbot label +T-libs-api -T-libs

r? libs-api

…ent 'PartialEq<{CStr, &CStr, Cow<CStr>}>' for 'CString'; Implement 'PartialEq<{CStr, &CStr, CString}>' for 'Cow<CStr>';

bjoernager · 2025-03-22T09:51:19Z

Friendly ping @BurntSushi :)

jieyouxu · 2025-04-28T09:26:00Z

r? libs-api

Amanieu · 2025-04-30T12:45:58Z

@bors try

Allow comparisons between `CStr`, `CString`, and `Cow<CStr>`. Closes: rust-lang#137265 This PR adds the trait implementations proposed in the [ACP](rust-lang/libs-team#517) under the `c_string_eq_c_str` feature gate: ```rust // core::ffi impl PartialEq<&Self> for CStr; impl PartialEq<CString> for CStr; impl PartialEq<Cow<'_, Self>> for CStr; // alloc::ffi impl PartialEq<CStr> for CString; impl PartialEq<&CStr> for CString; impl PartialEq<Cow<'_, CStr>> for CString; // alloc::borrow impl PartialEq<CStr> for Cow<'_, CStr>; impl PartialEq<&CStr> for Cow<'_, CStr>; impl PartialEq<CString> for Cow<'_, CStr>; ``` As I understand it, stable traits cannot be unstably implemented for stable types, and we would thereby be forced to skip the FCP and directly stabilise these implementations (as is done in this PR). (`@joshtriplett` mentioned that Crater may have to be run).

bors · 2025-04-30T12:47:15Z

⌛ Trying commit 817b093 with merge 1f308f1...

bors · 2025-04-30T14:54:33Z

☀️ Try build successful - checks-actions
Build commit: 1f308f1 (1f308f12738d8cc40bb23bf0c8114b37c164bb49)

Amanieu · 2025-04-30T22:56:37Z

@craterbot check

craterbot · 2025-04-30T22:56:53Z

👌 Experiment pr-137268 created and queued.
🤖 Automatically detected try build 1f308f1
🔍 You can check out the queue and this experiment's details.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

craterbot · 2025-05-02T09:24:38Z

🎉 Experiment pr-137268 is completed!
📊 3 regressed and 3 fixed (623643 total)
📰 Open the full report.

⚠️ If you notice any spurious failure please add them to the denylist!
ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

Amanieu · 2025-05-03T10:32:15Z

@rfcbot merge

rfcbot · 2025-05-03T10:32:18Z

Team member @Amanieu 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 · 2025-05-25T22:45:50Z

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

rfcbot · 2025-06-04T22:46:29Z

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.

Amanieu · 2025-06-24T09:36:55Z

@bors r+

bors · 2025-06-24T09:36:57Z

📌 Commit 817b093 has been approved by Amanieu

It is now in the queue for this repository.

Rollup of 7 pull requests Successful merges: - #137268 (Allow comparisons between `CStr`, `CString`, and `Cow<CStr>`.) - #142704 (Remove the deprecated unstable `concat_idents!` macro) - #142742 ([win][aarch64] Fix linking statics on Arm64EC, take 2) - #142843 (Enable reproducible-build-2 for Windows MSVC) - #142916 (rustdoc-json: Add test for `#[optimize(..)]`) - #142919 (rustdoc-json: Add test for `#[cold]`) - #142944 (Stats output tweaks) Failed merges: - #142825 (Port `#[track_caller]` to the new attribute system) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #137268 - bjoernager:c-string-eq-c-str, r=Amanieu Allow comparisons between `CStr`, `CString`, and `Cow<CStr>`. Closes: #137265 This PR adds the trait implementations proposed in the [ACP](rust-lang/libs-team#517) under the `c_string_eq_c_str` feature gate: ```rust // core::ffi impl PartialEq<&Self> for CStr; impl PartialEq<CString> for CStr; impl PartialEq<Cow<'_, Self>> for CStr; // alloc::ffi impl PartialEq<CStr> for CString; impl PartialEq<&CStr> for CString; impl PartialEq<Cow<'_, CStr>> for CString; // alloc::borrow impl PartialEq<CStr> for Cow<'_, CStr>; impl PartialEq<&CStr> for Cow<'_, CStr>; impl PartialEq<CString> for Cow<'_, CStr>; ``` As I understand it, stable traits cannot be unstably implemented for stable types, and we would thereby be forced to skip the FCP and directly stabilise these implementations (as is done in this PR). (`@joshtriplett` mentioned that Crater may have to be run).

…tr, r=Amanieu" This reverts commit 30550c0, reversing changes made to 36b2163.

Revert "Rollup merge of #137268 - bjoernager:c-string-eq-c-str, r=Amanieu" This reverts commit 30550c0, reversing changes made to 36b2163. This is an experiment for purposes of retrying the relevant crater run. r? `@ghost`

…anieu Allow comparisons between `CStr`, `CString`, and `Cow<CStr>`. Closes: rust-lang#137265 This PR adds the trait implementations proposed in the [ACP](rust-lang/libs-team#517) under the `c_string_eq_c_str` feature gate: ```rust // core::ffi impl PartialEq<&Self> for CStr; impl PartialEq<CString> for CStr; impl PartialEq<Cow<'_, Self>> for CStr; // alloc::ffi impl PartialEq<CStr> for CString; impl PartialEq<&CStr> for CString; impl PartialEq<Cow<'_, CStr>> for CString; // alloc::borrow impl PartialEq<CStr> for Cow<'_, CStr>; impl PartialEq<&CStr> for Cow<'_, CStr>; impl PartialEq<CString> for Cow<'_, CStr>; ``` As I understand it, stable traits cannot be unstably implemented for stable types, and we would thereby be forced to skip the FCP and directly stabilise these implementations (as is done in this PR). (`@joshtriplett` mentioned that Crater may have to be run).

rustbot assigned Amanieu Feb 19, 2025

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Feb 19, 2025

bjoernager mentioned this pull request Feb 19, 2025

Tracking Issue for allowing comparisons between CStr, CString, and Cow<CStr>. #137265

Closed

2 tasks

rustbot added T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. and removed T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Feb 19, 2025

rustbot assigned BurntSushi and unassigned Amanieu Feb 19, 2025

bjoernager force-pushed the c-string-eq-c-str branch from b91862d to 4acd142 Compare February 19, 2025 10:11

rustbot added has-merge-commits PR has merge commits, merge with caution. S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Feb 19, 2025

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bjoernager force-pushed the c-string-eq-c-str branch from f82bfac to 3472f5f Compare February 19, 2025 21:07

rustbot removed has-merge-commits PR has merge commits, merge with caution. S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Feb 19, 2025

bjoernager changed the title ~~Implement PartialEq<{&Self, CString}> for CStr and PartialEq<{CStr, &CStr}> for CString.~~ Allow comparisons between CStr, CString, and Cow<CStr>. Feb 19, 2025

Implement 'PartialEq<{&Self, CString, Cow<Self>}>' for 'CStr'; Implem…

817b093

…ent 'PartialEq<{CStr, &CStr, Cow<CStr>}>' for 'CString'; Implement 'PartialEq<{CStr, &CStr, CString}>' for 'Cow<CStr>';

bjoernager force-pushed the c-string-eq-c-str branch from 3472f5f to 817b093 Compare February 20, 2025 16:51

rustbot assigned Amanieu and unassigned BurntSushi Apr 28, 2025

craterbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-crater Status: Waiting on a crater run to be completed. labels May 2, 2025

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 May 3, 2025

rfcbot added final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. and removed proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. labels May 25, 2025

rfcbot added finished-final-comment-period The final comment period is finished for this PR / Issue. to-announce Announce this issue on triage meeting and removed final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. labels Jun 4, 2025

rustbot mentioned this pull request Jun 4, 2025

Tracking issue for release notes of #137268: Allow comparisons between CStr, CString, and Cow<CStr>. #142049

Open

apiraino removed the to-announce Announce this issue on triage meeting label Jun 5, 2025

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 Jun 24, 2025

GuillaumeGomez mentioned this pull request Jun 24, 2025

Rollup of 7 pull requests #142962

Merged

bors merged commit 30550c0 into rust-lang:master Jun 24, 2025
1 check passed

rustbot added this to the 1.90.0 milestone Jun 24, 2025

workingjubilee mentioned this pull request Jun 28, 2025

New "type annotations needed" error in Rust nightly-2025-06-24 #143164

Closed

workingjubilee added a commit to workingjubilee/rustc that referenced this pull request Jun 28, 2025

Revert "Rollup merge of rust-lang#137268 - bjoernager:c-string-eq-c-s…

22407dc

…tr, r=Amanieu" This reverts commit 30550c0, reversing changes made to 36b2163.

BoxyUwU mentioned this pull request Aug 21, 2025

Draft release notes for 1.90 #145730

Open

Allow comparisons between CStr, CString, and Cow<CStr>. #137268

Allow comparisons between CStr, CString, and Cow<CStr>. #137268

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Allow comparisons between `CStr`, `CString`, and `Cow<CStr>`. #137268

Allow comparisons between `CStr`, `CString`, and `Cow<CStr>`. #137268

bjoernager commented Feb 19, 2025 •

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