core: Add `BorrowedCursor::with_unfilled_buf` #142885

a1phyr · 2025-06-22T18:51:29Z

Implementation of rust-lang/libs-team#367.

This mainly adds BorrowedCursor::with_unfilled_buf, with enables using the unfilled part of a cursor as a BorrowedBuf.

Note that unlike the ACP, BorrowedCursor::unfilled_buf was moved to a From conversion. This is more consistent with other ways of creating a BorrowedBuf and hides a bit this conversion that requires unsafe code to be used correctly.

Cc #78485 #117693

rustbot · 2025-06-22T18:51:33Z

r? @Mark-Simulacrum

rustbot has assigned @Mark-Simulacrum.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

library/core/src/io/borrowed_buf.rs

Implementation of rust-lang/libs-team#367. This mainly adds `BorrowedCursor::with_unfilled_buf`, with enables using the unfilled part of a cursor as a `BorrowedBuf`. Note that unlike the ACP, `BorrowedCursor::unfilled_buf` was moved to a `From` conversion. This is more consistent with other ways of creating a `BorrowedBuf` and hides a bit this conversion that requires unsafe code to be used correctly.

Mark-Simulacrum · 2025-07-13T12:06:22Z

@bors r+

bors · 2025-07-13T12:06:25Z

📌 Commit 136d24f has been approved by Mark-Simulacrum

It is now in the queue for this repository.

…ark-Simulacrum core: Add `BorrowedCursor::with_unfilled_buf` Implementation of rust-lang/libs-team#367. This mainly adds `BorrowedCursor::with_unfilled_buf`, with enables using the unfilled part of a cursor as a `BorrowedBuf`. Note that unlike the ACP, `BorrowedCursor::unfilled_buf` was moved to a `From` conversion. This is more consistent with other ways of creating a `BorrowedBuf` and hides a bit this conversion that requires unsafe code to be used correctly. Cc rust-lang#78485 rust-lang#117693

Rollup of 8 pull requests Successful merges: - #142885 (core: Add `BorrowedCursor::with_unfilled_buf`) - #143217 (Port #[link_ordinal] to the new attribute parsing infrastructure) - #143355 (wrapping shift: remove first bitmask and table) - #143448 (remote-test-client: Exit code `128 + <signal-number>` instead of `3`) - #143724 (Tidy cleanup) - #143820 (Fixed a core crate compilation failure when enabling the `optimize_for_size` feature on some targets) - #143850 (Compiletest: Simplify {Html,Json}DocCk directive handling) - #143880 (tests: Test line debuginfo for linebreaked function parameters) Failed merges: - #143630 (Drop `./x suggest`) - #143733 (Change bootstrap's `tool.TOOL_NAME.features` to work on any subcommand) r? `@ghost` `@rustbot` modify labels: rollup

…ark-Simulacrum core: Add `BorrowedCursor::with_unfilled_buf` Implementation of rust-lang/libs-team#367. This mainly adds `BorrowedCursor::with_unfilled_buf`, with enables using the unfilled part of a cursor as a `BorrowedBuf`. Note that unlike the ACP, `BorrowedCursor::unfilled_buf` was moved to a `From` conversion. This is more consistent with other ways of creating a `BorrowedBuf` and hides a bit this conversion that requires unsafe code to be used correctly. Cc rust-lang#78485 rust-lang#117693

Rollup of 16 pull requests Successful merges: - #142885 (core: Add `BorrowedCursor::with_unfilled_buf`) - #143217 (Port #[link_ordinal] to the new attribute parsing infrastructure) - #143355 (wrapping shift: remove first bitmask and table) - #143448 (remote-test-client: Exit code `128 + <signal-number>` instead of `3`) - #143592 (UWP: link ntdll functions using raw-dylib) - #143681 (bootstrap/miri: avoid rebuilds for test builds) - #143710 (Updates to random number generation APIs) - #143724 (Tidy cleanup) - #143820 (Fixed a core crate compilation failure when enabling the `optimize_for_size` feature on some targets) - #143850 (Compiletest: Simplify {Html,Json}DocCk directive handling) - #143855 (Port `#[omit_gdb_pretty_printer_section]` to the new attribute parsing) - #143868 (warn on align on fields to avoid breaking changes) - #143875 (update issue number for `const_trait_impl`) - #143881 (Use zero for initialized Once state) - #143887 (Run bootstrap tests sooner in the `x test` pipeline) - #143893 (Don't require `eh_personality` lang item on targets that have a personality) Failed merges: - #143878 (Port `#[pointee]` to the new attribute parsing infrastructure) - #143891 (Port `#[coverage]` to the new attribute system) r? `@ghost` `@rustbot` modify labels: rollup

…ark-Simulacrum core: Add `BorrowedCursor::with_unfilled_buf` Implementation of rust-lang/libs-team#367. This mainly adds `BorrowedCursor::with_unfilled_buf`, with enables using the unfilled part of a cursor as a `BorrowedBuf`. Note that unlike the ACP, `BorrowedCursor::unfilled_buf` was moved to a `From` conversion. This is more consistent with other ways of creating a `BorrowedBuf` and hides a bit this conversion that requires unsafe code to be used correctly. Cc rust-lang#78485 rust-lang#117693

Rollup of 17 pull requests Successful merges: - #142885 (core: Add `BorrowedCursor::with_unfilled_buf`) - #143217 (Port #[link_ordinal] to the new attribute parsing infrastructure) - #143355 (wrapping shift: remove first bitmask and table) - #143448 (remote-test-client: Exit code `128 + <signal-number>` instead of `3`) - #143681 (bootstrap/miri: avoid rebuilds for test builds) - #143710 (Updates to random number generation APIs) - #143724 (Tidy cleanup) - #143738 (Move several float tests to floats/mod.rs) - #143820 (Fixed a core crate compilation failure when enabling the `optimize_for_size` feature on some targets) - #143850 (Compiletest: Simplify {Html,Json}DocCk directive handling) - #143855 (Port `#[omit_gdb_pretty_printer_section]` to the new attribute parsing) - #143868 (warn on align on fields to avoid breaking changes) - #143875 (update issue number for `const_trait_impl`) - #143881 (Use zero for initialized Once state) - #143887 (Run bootstrap tests sooner in the `x test` pipeline) - #143893 (Don't require `eh_personality` lang item on targets that have a personality) - #143901 (Region constraint nits) Failed merges: - #143878 (Port `#[pointee]` to the new attribute parsing infrastructure) - #143891 (Port `#[coverage]` to the new attribute system) r? `@ghost` `@rustbot` modify labels: rollup

bors · 2025-07-14T23:45:21Z

⌛ Testing commit 136d24f with merge 7f2065a...

bors · 2025-07-15T02:46:26Z

☀️ Test successful - checks-actions
Approved by: Mark-Simulacrum
Pushing 7f2065a to master...

github-actions · 2025-07-15T02:49:40Z

What is this?

This is an experimental post-merge analysis report that shows differences in test outcomes between the merged PR and its parent PR.

Comparing a001497 (parent) -> 7f2065a (this PR)

Test differences

Show 5 test diffs

Stage 1

io::borrowed_buf::cursor_with_unfilled_buf: [missing] -> pass (J0)

Additionally, 4 doctest diffs were found. These are ignored, as they are noisy.

Job group index

J0: aarch64-apple, aarch64-gnu, aarch64-msvc-1, arm-android, armhf-gnu, dist-i586-gnu-i586-i686-musl, i686-gnu-1, i686-gnu-nopt-1, i686-msvc-1, pr-check-2, test-various, x86_64-apple-1, x86_64-gnu, x86_64-gnu-aux, x86_64-gnu-llvm-19-2, x86_64-gnu-llvm-19-3, x86_64-gnu-llvm-20-2, x86_64-gnu-llvm-20-3, x86_64-gnu-nopt, x86_64-gnu-stable, x86_64-mingw-1, x86_64-msvc-1

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard 7f2065a4bae1faed5bab928c670964eafbf43b55 --output-dir test-dashboard

And then open test-dashboard/index.html in your browser to see an overview of all executed tests.

Job duration changes

dist-aarch64-linux: 6071.9s -> 8199.1s (35.0%)
x86_64-apple-1: 7490.2s -> 10077.7s (34.5%)
aarch64-apple: 4936.8s -> 3820.7s (-22.6%)
dist-apple-various: 9048.0s -> 7510.5s (-17.0%)
dist-x86_64-apple: 10317.8s -> 9030.2s (-12.5%)
x86_64-gnu-llvm-20-1: 3702.2s -> 3286.7s (-11.2%)
x86_64-msvc-ext1: 7581.1s -> 6901.4s (-9.0%)
x86_64-apple-2: 5015.3s -> 4612.8s (-8.0%)
x86_64-msvc-1: 8616.6s -> 9232.2s (7.1%)
x86_64-mingw-2: 7527.7s -> 7000.3s (-7.0%)

How to interpret the job duration changes?

Job durations can vary a lot, based on the actual runner instance
that executed the job, system noise, invalidated caches, etc. The table above is provided
mostly for t-infra members, for simpler debugging of potential CI slow-downs.

rust-timer · 2025-07-15T03:58:00Z

Finished benchmarking commit (7f2065a): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

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

Max RSS (memory usage)

Results (primary -2.3%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-2.3%	[-3.6%, -1.2%]	3
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-2.3%	[-3.6%, -1.2%]	3

Cycles

Results (secondary -2.2%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.2%	[-2.2%, -2.2%]	1
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 464.247s -> 463.94s (-0.07%)
Artifact size: 374.71 MiB -> 374.74 MiB (0.01%)

…k-Simulacrum core: Add `BorrowedCursor::with_unfilled_buf` Implementation of rust-lang/libs-team#367. This mainly adds `BorrowedCursor::with_unfilled_buf`, with enables using the unfilled part of a cursor as a `BorrowedBuf`. Note that unlike the ACP, `BorrowedCursor::unfilled_buf` was moved to a `From` conversion. This is more consistent with other ways of creating a `BorrowedBuf` and hides a bit this conversion that requires unsafe code to be used correctly. Cc rust-lang#78485 rust-lang#117693

rustbot assigned Mark-Simulacrum Jun 22, 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 Jun 22, 2025

Mark-Simulacrum reviewed Jun 28, 2025

View reviewed changes

library/core/src/io/borrowed_buf.rs Show resolved Hide resolved

a1phyr force-pushed the borrowed_cursor_to_buf branch from 1b4a047 to 136d24f Compare July 1, 2025 12:06

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 Jul 13, 2025

a1phyr mentioned this pull request Jul 13, 2025

Trim BorrowedCursor API #143829

Merged

matthiaskrgr mentioned this pull request Jul 13, 2025

Rollup of 8 pull requests #143899

Closed

fmease mentioned this pull request Jul 14, 2025

Rollup of 16 pull requests #143912

Closed

jhpratt mentioned this pull request Jul 14, 2025

Rollup of 17 pull requests #143916

Closed

bors added the merged-by-bors This PR was explicitly merged by bors. label Jul 15, 2025

bors merged commit 7f2065a into rust-lang:master Jul 15, 2025
11 checks passed

rustbot added this to the 1.90.0 milestone Jul 15, 2025

SUPERCILEX mentioned this pull request Jul 18, 2025

Build error: no method named uninit_mut found for struct BorrowedCursor SUPERCILEX/clipboard-history#67

Closed

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

core: Add `BorrowedCursor::with_unfilled_buf` #142885

core: Add `BorrowedCursor::with_unfilled_buf` #142885

a1phyr commented Jun 22, 2025 •

edited by rustbot

Loading

Uh oh!

rustbot commented Jun 22, 2025

Uh oh!

Uh oh!

Mark-Simulacrum commented Jul 13, 2025

Uh oh!

bors commented Jul 13, 2025

Uh oh!

bors commented Jul 14, 2025

Uh oh!

bors commented Jul 15, 2025

Uh oh!

Uh oh!

github-actions bot commented Jul 15, 2025

Stage 1

Uh oh!

rust-timer commented Jul 15, 2025

Uh oh!

Uh oh!

core: Add BorrowedCursor::with_unfilled_buf #142885

core: Add BorrowedCursor::with_unfilled_buf #142885

Conversation

a1phyr commented Jun 22, 2025 • edited by rustbot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

rustbot commented Jun 22, 2025

Uh oh!

Uh oh!

Mark-Simulacrum commented Jul 13, 2025

Uh oh!

bors commented Jul 13, 2025

Uh oh!

bors commented Jul 14, 2025

Uh oh!

bors commented Jul 15, 2025

Uh oh!

Uh oh!

github-actions bot commented Jul 15, 2025

Test differences

Stage 1

Job duration changes

Uh oh!

rust-timer commented Jul 15, 2025

Overall result: no relevant changes - no action needed

Instruction count

Max RSS (memory usage)

Cycles

Binary size

Uh oh!

Uh oh!

core: Add `BorrowedCursor::with_unfilled_buf` #142885

core: Add `BorrowedCursor::with_unfilled_buf` #142885

a1phyr commented Jun 22, 2025 •

edited by rustbot

Loading