Implement a lint for implicit autoref of raw pointer dereference - take 2 #123239

Urgau · 2024-03-30T16:28:03Z

This PR aims at implementing a lint for implicit autoref of raw pointer dereference, it is based on #103735 with suggestion and improvements from #103735 (comment).

The goal is to catch cases like this, where the user probably doesn't realise it just created a reference.

pub struct Test {
    data: [u8],
}

pub fn test_len(t: *const Test) -> usize {
    unsafe { (*t).data.len() }  // this calls <[T]>::len(&self)
}

Since #103735 already went 2 times through T-lang, where they T-lang ended-up asking for a more restricted version (which is what this PR does), I would prefer this PR to be reviewed first before re-nominating it for T-lang.

Compared to the PR it is as based on, this PR adds 3 restrictions on the outer most expression, which must either be:

A deref followed by any non-deref place projection (that intermediate deref will typically be auto-inserted)
A method call annotated with #[rustc_no_implicit_refs].
A deref followed by a addr_of! or addr_of_mut!. See bottom of post for details.

There are several points that are not 100% clear to me when implementing the modifications:

~~"4. Any number of automatically inserted deref/derefmut calls." I as never able to trigger this. Am I missing something?~~ Fixed
Are "index" and "field" enough?

cc @JakobDegen @WaffleLapkin
r? @RalfJung

try-job: dist-various-1
try-job: dist-various-2

rustbot · 2024-03-30T16:28:12Z

The Miri subtree was changed

cc @rust-lang/miri

RalfJung · 2024-03-30T16:32:58Z

Sorry, I can't take on more reviews currently.
r? compiler
(or feel free to pick someone specific who's suited)

compiler/rustc_lint/src/autorefs.rs

tests/ui/lint/implicit_autorefs.stderr

Dylan-DPC · 2024-08-12T11:58:19Z

@Urgau if you can rebase the latest conflicts we can push this forward and maybe get it reviewed by another reviewer

Urgau · 2024-08-12T17:49:41Z

@Dylan-DPC rebased.

@rustbot review

Urgau · 2025-04-28T05:37:53Z

@bors retry

bors · 2025-04-28T08:25:27Z

⌛ Testing commit 05f2b22 with merge a932eb3...

bors · 2025-04-28T11:34:42Z

☀️ Test successful - checks-actions
Approved by: jdonszelmann,traviscross
Pushing a932eb3 to master...

github-actions · 2025-04-28T11:37:04Z

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 0134651 (parent) -> a932eb3 (this PR)

Test differences

Show 1165 test diffs

Stage 1

[ui] tests/ui/lint/implicit_autorefs.rs: [missing] -> pass (J0)

Stage 2

[ui] tests/ui/lint/implicit_autorefs.rs: [missing] -> pass (J1)

Additionally, 1163 doctest diffs were found. These are ignored, as they are noisy.

Job group index

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard a932eb36f8adf6c8cdfc450f063943da3112d621 --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

x86_64-apple-1: 8218.0s -> 6083.4s (-26.0%)
dist-apple-various: 6754.9s -> 8167.9s (20.9%)
x86_64-msvc-ext2: 6995.0s -> 5859.1s (-16.2%)
dist-aarch64-apple: 5175.2s -> 4666.8s (-9.8%)
x86_64-msvc-2: 7361.5s -> 6645.3s (-9.7%)
dist-x86_64-apple: 10267.2s -> 9484.6s (-7.6%)
dist-i686-mingw: 7817.4s -> 8250.3s (5.5%)
dist-powerpc64le-linux: 9389.9s -> 9859.3s (5.0%)
x86_64-gnu-llvm-19-1: 5337.6s -> 5100.5s (-4.4%)
dist-i586-gnu-i586-i686-musl: 5084.7s -> 5301.8s (4.3%)

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 · 2025-04-28T14:19:48Z

Finished benchmarking commit (a932eb3): comparison URL.

Overall result: ❌ regressions - please read the text below

Our benchmarks found a performance regression caused by this PR.
This might be an actual regression, but it can also be just noise.

Next Steps:

If the regression was expected or you think it can be justified,
please write a comment with sufficient written justification, and add
@rustbot label: +perf-regression-triaged to it, to mark the regression as triaged.
If you think that you know of a way to resolve the regression, try to create
a new PR with a fix for the regression.
If you do not understand the regression or you think that it is just noise,
you can ask the @rust-lang/wg-compiler-performance working group for help (members of this group
were already notified of this PR).

@rustbot label: +perf-regression
cc @rust-lang/wg-compiler-performance

Instruction count

This is the most reliable metric that we have; it was used to determine the overall result at the top of this comment. However, even this metric can sometimes exhibit noise.

	mean	range	count
Regressions ❌ (primary)	1.8%	[0.3%, 3.6%]	6
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	1.8%	[0.3%, 3.6%]	6

Max RSS (memory usage)

Results (primary 0.4%, secondary -0.5%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	1.2%	[0.5%, 2.3%]	4
Regressions ❌ (secondary)	2.8%	[2.8%, 2.8%]	1
Improvements ✅ (primary)	-0.6%	[-0.7%, -0.5%]	3
Improvements ✅ (secondary)	-2.2%	[-3.2%, -1.2%]	2
All ❌✅ (primary)	0.4%	[-0.7%, 2.3%]	7

Cycles

Results (primary 1.0%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	2.1%	[0.5%, 2.7%]	4
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.5%	[-0.6%, -0.5%]	3
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	1.0%	[-0.6%, 2.7%]	7

Binary size

Results (primary 0.0%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.0%	[0.0%, 0.0%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.0%	[0.0%, 0.0%]	1

Bootstrap: 761.588s -> 761.378s (-0.03%)
Artifact size: 365.21 MiB -> 365.18 MiB (-0.01%)

perf: delay checking of `#[rustc_no_implicit_autorefs]` in autoref lint Try to address the regression seen in rust-lang#123239 (comment) by delaying the checking of `#[rustc_no_implicit_autorefs]` on method call.

…mann,traviscross Implement a lint for implicit autoref of raw pointer dereference - take 2 *[t-lang nomination comment](rust-lang/rust#123239 (comment) This PR aims at implementing a lint for implicit autoref of raw pointer dereference, it is based on #103735 with suggestion and improvements from rust-lang/rust#103735 (comment). The goal is to catch cases like this, where the user probably doesn't realise it just created a reference. ```rust pub struct Test { data: [u8], } pub fn test_len(t: *const Test) -> usize { unsafe { (*t).data.len() } // this calls <[T]>::len(&self) } ``` Since #103735 already went 2 times through T-lang, where they T-lang ended-up asking for a more restricted version (which is what this PR does), I would prefer this PR to be reviewed first before re-nominating it for T-lang. ---- Compared to the PR it is as based on, this PR adds 3 restrictions on the outer most expression, which must either be: 1. A deref followed by any non-deref place projection (that intermediate deref will typically be auto-inserted) 2. A method call annotated with `#[rustc_no_implicit_refs]`. 3. A deref followed by a `addr_of!` or `addr_of_mut!`. See bottom of post for details. There are several points that are not 100% clear to me when implementing the modifications: - ~~"4. Any number of automatically inserted deref/derefmut calls." I as never able to trigger this. Am I missing something?~~ Fixed - Are "index" and "field" enough? ---- cc `@JakobDegen` `@WaffleLapkin` r? `@RalfJung` try-job: dist-various-1 try-job: dist-various-2

rylev · 2025-04-29T11:48:30Z

The perf regression is reversed in #140406

@rustbot label: +perf-regression-triaged

# Objective - new nightly lint make CI fail ## Solution - Follow the lint: rust-lang/rust#123239

…mann,traviscross Implement a lint for implicit autoref of raw pointer dereference - take 2 *[t-lang nomination comment](rust-lang/rust#123239 (comment) This PR aims at implementing a lint for implicit autoref of raw pointer dereference, it is based on #103735 with suggestion and improvements from rust-lang/rust#103735 (comment). The goal is to catch cases like this, where the user probably doesn't realise it just created a reference. ```rust pub struct Test { data: [u8], } pub fn test_len(t: *const Test) -> usize { unsafe { (*t).data.len() } // this calls <[T]>::len(&self) } ``` Since #103735 already went 2 times through T-lang, where they T-lang ended-up asking for a more restricted version (which is what this PR does), I would prefer this PR to be reviewed first before re-nominating it for T-lang. ---- Compared to the PR it is as based on, this PR adds 3 restrictions on the outer most expression, which must either be: 1. A deref followed by any non-deref place projection (that intermediate deref will typically be auto-inserted) 2. A method call annotated with `#[rustc_no_implicit_refs]`. 3. A deref followed by a `addr_of!` or `addr_of_mut!`. See bottom of post for details. There are several points that are not 100% clear to me when implementing the modifications: - ~~"4. Any number of automatically inserted deref/derefmut calls." I as never able to trigger this. Am I missing something?~~ Fixed - Are "index" and "field" enough? ---- cc `@JakobDegen` `@WaffleLapkin` r? `@RalfJung` try-job: dist-various-1 try-job: dist-various-2

perf: delay checking of `#[rustc_no_implicit_autorefs]` in autoref lint Try to address the regression seen in rust-lang#123239 (comment) by delaying the checking of `#[rustc_no_implicit_autorefs]` on method call.

perf: delay checking of `#[rustc_no_implicit_autorefs]` in autoref lint Try to address the regression seen in rust-lang/rust#123239 (comment) by delaying the checking of `#[rustc_no_implicit_autorefs]` on method call.

…=jdonszelmann,traviscross Implement a lint for implicit autoref of raw pointer dereference - take 2 *[t-lang nomination comment](rust-lang#123239 (comment) This PR aims at implementing a lint for implicit autoref of raw pointer dereference, it is based on rust-lang#103735 with suggestion and improvements from rust-lang#103735 (comment). The goal is to catch cases like this, where the user probably doesn't realise it just created a reference. ```rust pub struct Test { data: [u8], } pub fn test_len(t: *const Test) -> usize { unsafe { (*t).data.len() } // this calls <[T]>::len(&self) } ``` Since rust-lang#103735 already went 2 times through T-lang, where they T-lang ended-up asking for a more restricted version (which is what this PR does), I would prefer this PR to be reviewed first before re-nominating it for T-lang. ---- Compared to the PR it is as based on, this PR adds 3 restrictions on the outer most expression, which must either be: 1. A deref followed by any non-deref place projection (that intermediate deref will typically be auto-inserted) 2. A method call annotated with `#[rustc_no_implicit_refs]`. 3. A deref followed by a `addr_of!` or `addr_of_mut!`. See bottom of post for details. There are several points that are not 100% clear to me when implementing the modifications: - ~~"4. Any number of automatically inserted deref/derefmut calls." I as never able to trigger this. Am I missing something?~~ Fixed - Are "index" and "field" enough? ---- cc `@JakobDegen` `@WaffleLapkin` r? `@RalfJung` try-job: dist-various-1 try-job: dist-various-2

# Objective - new nightly lint make CI fail ## Solution - Follow the lint: rust-lang/rust#123239

rustbot assigned RalfJung Mar 30, 2024

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Mar 30, 2024

rustbot assigned fmease and unassigned RalfJung Mar 30, 2024

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Urgau force-pushed the dangerous_implicit_autorefs branch from bb6ab41 to 2b3fe45 Compare March 30, 2024 17:17

WaffleLapkin mentioned this pull request Mar 31, 2024

Implement a lint for implicit autoref of raw pointer dereference #103735

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WaffleLapkin mentioned this pull request Apr 13, 2024

request: lint when raw pointer slicing implicitly creates a temporary reference #99437

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Urgau force-pushed the dangerous_implicit_autorefs branch from 2b3fe45 to 57f6416 Compare May 14, 2024 17:22

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Urgau force-pushed the dangerous_implicit_autorefs branch from 57f6416 to 824c1f5 Compare May 14, 2024 18:04

fmease reviewed May 15, 2024

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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 Apr 28, 2025

jieyouxu added the CI-spurious-fail-rust-lld-crash CI spurious failure: `rust-lld` crashing / SIGSEGV / 0xc0000374 heap corruption label Apr 28, 2025

ChrisDenton mentioned this pull request Apr 28, 2025

STATUS_HEAP_CORRUPTION in rust-lld with a custom target on x86_64-pc-windows-gnu #115985

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bors added the merged-by-bors This PR was explicitly merged by bors. label Apr 28, 2025

bors merged commit a932eb3 into rust-lang:master Apr 28, 2025
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bors mentioned this pull request Apr 28, 2025

Add lint against (some) interior mutable consts #132146

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rustbot added the perf-regression Performance regression. label Apr 28, 2025

Urgau mentioned this pull request Apr 28, 2025

perf: delay checking of #[rustc_no_implicit_autorefs] in autoref lint #140406

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rustbot added the perf-regression-triaged The performance regression has been triaged. label Apr 29, 2025

ejd mentioned this pull request Apr 29, 2025

fix format string in build.rs noritada/grib-rs#115

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mockersf mentioned this pull request Apr 29, 2025

fix new nightly lint on mikktspace bevyengine/bevy#18988

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github-merge-queue bot pushed a commit to bevyengine/bevy that referenced this pull request Apr 30, 2025

fix new nightly lint on mikktspace (#18988)

0fa115f

# Objective - new nightly lint make CI fail ## Solution - Follow the lint: rust-lang/rust#123239

andrewzhurov pushed a commit to andrewzhurov/bevy that referenced this pull request May 17, 2025

fix new nightly lint on mikktspace (bevyengine#18988)

e75402c

# Objective - new nightly lint make CI fail ## Solution - Follow the lint: rust-lang/rust#123239

Implement a lint for implicit autoref of raw pointer dereference - take 2 #123239

Implement a lint for implicit autoref of raw pointer dereference - take 2 #123239

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Test differences

Stage 1

Stage 2

Job duration changes

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rust-timer commented Apr 28, 2025

Overall result: ❌ regressions - please read the text below

Instruction count

Max RSS (memory usage)

Cycles

Binary size

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rylev commented Apr 29, 2025

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Urgau commented Mar 30, 2024 •

edited

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