Fix hashing of span end columns in incremental compilation by cuishuang · Pull Request #162250 · rust-lang/rust

cuishuang · 2026-09-03T15:51:50Z

stable_hash_span packs the span start/end line and column together with its length, but the col_hi mask was shifted before being applied, so the end column was effectively omitted from the hash.

Parenthesize the mask operation so col_hi is masked with 0xFF before being shifted into bits 32..39.

rustbot · 2026-09-03T15:51:56Z

r? @mu001999

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mu001999

Good catch! r=me after removing the unit test and ci green

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rustbot · 2026-09-04T01:09:52Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

cuishuang · 2026-09-04T02:37:01Z

@rustbot ready

mu001999

And please squash commits into one, thanks!

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Signed-off-by: cuishuang <imcusg@gmail.com>

mu001999

Thanks!

@bors r+ rollup

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rust-bors · 2026-09-04T23:44:01Z

📌 Commit 811384a has been approved by mu001999

It is now in the queue for this repository.

Fix hashing of span end columns in incremental compilation `stable_hash_span` packs the span start/end line and column together with its length, but the `col_hi` mask was shifted before being applied, so the end column was effectively omitted from the hash. Parenthesize the mask operation so `col_hi` is masked with `0xFF` before being shifted into bits 32..39.

Rollup of 14 pull requests Successful merges: - #162324 (miri subtree update) - #162170 (bootstrap: use target's LLVM libdir when cross-compiling) - #158312 (Adds support for AArch64 SVE to inline assembly) - #159792 (A more readable debug map for IndexMaps) - #160745 (make closures act like MaybeDangling) - #161263 (break rustc_expand-rustc_middle dependency) - #161895 (std::sys::pal::sgx: fix mismatched alloc/free alignment) - #161940 (Promote `wasm32-wasip3` to a tier 2 target) - #161397 (coverage: Tidy tests and add some new ones) - #161616 (Report precondition violation for `<usize as SliceIndex>::get_unchecked` in const-eval) - #162248 (Add regression test for unsized const parameter default ICE) - #162250 (Fix hashing of span end columns in incremental compilation) - #162265 (cargotest: add lockfiles) - #162318 (bootstrap: Fix broken path for `./x doc compiler/rustc --open`)

Rollup merge of #162250 - cuishuang:master, r=mu001999 Fix hashing of span end columns in incremental compilation `stable_hash_span` packs the span start/end line and column together with its length, but the `col_hi` mask was shifted before being applied, so the end column was effectively omitted from the hash. Parenthesize the mask operation so `col_hi` is masked with `0xFF` before being shifted into bits 32..39.

rust-timer · 2026-09-06T05:37:09Z

Note

This PR was benchmarked as part of triage of its containing rollup: triage URL.

Finished benchmarking commit (6f0ae4f): comparison URL.

Overall result: ❌ regressions - no action needed

@rustbot label: -perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.3%	[0.2%, 0.3%]	5
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (secondary 6.6%)

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)	6.6%	[6.6%, 6.6%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Cycles

Results (primary 2.5%, secondary 3.4%)

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

	mean	range	count
Regressions ❌ (primary)	2.5%	[2.5%, 2.5%]	1
Regressions ❌ (secondary)	3.4%	[3.4%, 3.4%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.5%	[2.5%, 2.5%]	1

Binary size

Results (primary 0.0%, secondary 0.1%)

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

	mean	range	count
Regressions ❌ (primary)	0.0%	[0.0%, 0.1%]	11
Regressions ❌ (secondary)	0.1%	[0.1%, 0.1%]	3
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.0%	[0.0%, 0.1%]	11

Bootstrap: missing data
Artifact size: 403.33 MiB -> 403.29 MiB (-0.01%)

Rollup of 14 pull requests Successful merges: - rust-lang/rust#162324 (miri subtree update) - rust-lang/rust#162170 (bootstrap: use target's LLVM libdir when cross-compiling) - rust-lang/rust#158312 (Adds support for AArch64 SVE to inline assembly) - rust-lang/rust#159792 (A more readable debug map for IndexMaps) - rust-lang/rust#160745 (make closures act like MaybeDangling) - rust-lang/rust#161263 (break rustc_expand-rustc_middle dependency) - rust-lang/rust#161895 (std::sys::pal::sgx: fix mismatched alloc/free alignment) - rust-lang/rust#161940 (Promote `wasm32-wasip3` to a tier 2 target) - rust-lang/rust#161397 (coverage: Tidy tests and add some new ones) - rust-lang/rust#161616 (Report precondition violation for `<usize as SliceIndex>::get_unchecked` in const-eval) - rust-lang/rust#162248 (Add regression test for unsized const parameter default ICE) - rust-lang/rust#162250 (Fix hashing of span end columns in incremental compilation) - rust-lang/rust#162265 (cargotest: add lockfiles) - rust-lang/rust#162318 (bootstrap: Fix broken path for `./x doc compiler/rustc --open`)

rustbot assigned mu001999 Sep 3, 2026

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. labels Sep 3, 2026

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Comment thread compiler/rustc_middle/src/ich.rs Outdated

rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Sep 4, 2026

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Sep 4, 2026

mu001999 requested changes Sep 4, 2026

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Comment thread compiler/rustc_middle/src/ich.rs Outdated

rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Sep 4, 2026

cuishuang force-pushed the master branch from ce58e59 to fcc2032 Compare September 4, 2026 11:06

mu001999 reviewed Sep 4, 2026

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Comment thread compiler/rustc_middle/src/ich.rs Outdated

Fix hashing of span end columns in incremental compilation

811384a

Signed-off-by: cuishuang <imcusg@gmail.com>

cuishuang force-pushed the master branch from fcc2032 to 811384a Compare September 4, 2026 14:59

mu001999 approved these changes Sep 4, 2026

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rust-bors Bot 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-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Sep 4, 2026

JonathanBrouwer mentioned this pull request Sep 5, 2026

Rollup of 14 pull requests #162327

Closed

Zalathar mentioned this pull request Sep 5, 2026

Rollup of 14 pull requests #162333

Merged

rust-bors Bot merged commit c5fd862 into rust-lang:main Sep 5, 2026
13 checks passed

rustbot added this to the 1.100.0 milestone Sep 5, 2026

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Fix hashing of span end columns in incremental compilation - #162250

Fix hashing of span end columns in incremental compilation#162250
rust-bors[bot] merged 1 commit into
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cuishuang:master

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Overall result: ❌ regressions - no action needed

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