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Use long for hashCode in ReferentialComparer to avoid overflow#3204

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fix/qodana-referential-comparer-overflow
May 5, 2026
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Use long for hashCode in ReferentialComparer to avoid overflow#3204
dennisdoomen merged 1 commit into
mainfrom
fix/qodana-referential-comparer-overflow

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@dennisdoomen dennisdoomen commented May 5, 2026

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Problem

The Qodana workflow on main has been failing since bumping JetBrains/qodana-action from 2025.3 to 2026.1 (run #25039911647). The new Qodana version introduced an improved Possible overflow in 'unchecked' context (High severity) inspection.

Root Cause

ReferentialComparer.GetHashCode used an int hashCode accumulator with hashCode * 397 multiplications that can silently overflow. The equivalent pattern in Node.cs already wraps the computation in unchecked {}, but ReferentialComparer.cs did not.

Fix

Changed the hashCode local variable from int to long so the multiplications cannot overflow, then narrowed back to int on return via an explicit truncating cast (the correct and expected behavior for hash codes).

HashCode.Combine is not an option since the project targets net47 and netstandard2.0.

Copilot AI review requested due to automatic review settings May 5, 2026 13:58
@dennisdoomen
Use long for hashCode in ReferentialComparer to avoid overflow
bb72faf 
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@dennisdoomen dennisdoomen force-pushed the fix/qodana-referential-comparer-overflow branch from ce6a88c to bb72faf Compare May 5, 2026 14:00
@dennisdoomen dennisdoomen changed the title fix: use long for hashCode in ReferentialComparer to avoid overflow Use long for hashCode in ReferentialComparer to avoid overflow May 5, 2026
Copilot AI reviewed May 5, 2026
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Pull request overview

This PR addresses a new Qodana (2026.1) high-severity inspection by preventing potential overflow in ReferentialComparer.GetHashCode, which is used by the equivalency engine to key tuple-based caches by object identity and index.

Changes:

  • Switched the hash accumulator from int to long to avoid overflow during hashCode * 397 multiplications.
  • Narrowed back to int at return via an explicit cast to preserve the required int hash code API surface.

@coveralls

coveralls commented May 5, 2026 •
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Coverage Report for CI Build 25381023258

Coverage increased (+0.01%) to 97.183%

Details

  • Coverage increased (+0.01%) from the base build.
  • Patch coverage: 2 of 2 lines across 1 file are fully covered (100%).
  • No coverage regressions found.

Uncovered Changes

No uncovered changes found.

Coverage Regressions

No coverage regressions found.

Coverage Stats

Coverage Status
Relevant Lines: 13367
Covered Lines: 13142
Line Coverage: 98.32%
Relevant Branches: 4346
Covered Branches: 4072
Branch Coverage: 93.7%
Branches in Coverage %: Yes
Coverage Strength: 67289.28 hits per line
💛 - Coveralls

@github-actions

github-actions Bot commented May 5, 2026 •
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Test Results

    37 files  ±0      37 suites  ±0   2m 46s ⏱️ +4s
 6 363 tests ±0   6 362 ✅ ±0  1 💤 ±0  0 ❌ ±0 
39 524 runs  ±0  39 518 ✅ ±0  6 💤 ±0  0 ❌ ±0 

Results for commit bb72faf. ± Comparison against base commit 84b7cb6.

This pull request removes 10 and adds 8 tests. Note that renamed tests count towards both. 
FluentAssertions.Specs.Streams.StreamAssertionSpecs+HaveLength ‑ When_a_throwing_stream_should_have_a_length_it_should_fail(exception: System.ObjectDisposedException: Cannot access a disposed object.
FluentAssertions.Specs.Streams.StreamAssertionSpecs+HaveLength ‑ When_a_throwing_stream_should_have_a_length_it_should_fail(exception: System.ObjectDisposedException: Cannot access a disposed object.
FluentAssertions.Specs.Streams.StreamAssertionSpecs+HavePosition ‑ When_a_throwing_stream_should_have_a_position_it_should_fail(exception: System.ObjectDisposedException: Cannot access a disposed object.
FluentAssertions.Specs.Streams.StreamAssertionSpecs+HavePosition ‑ When_a_throwing_stream_should_have_a_position_it_should_fail(exception: System.ObjectDisposedException: Cannot access a disposed object.
FluentAssertions.Specs.Streams.StreamAssertionSpecs+NotHaveLength ‑ When_a_throwing_stream_should_not_have_a_length_it_should_fail(exception: System.ObjectDisposedException: Cannot access a disposed object.
FluentAssertions.Specs.Streams.StreamAssertionSpecs+NotHaveLength ‑ When_a_throwing_stream_should_not_have_a_length_it_should_fail(exception: System.ObjectDisposedException: Cannot access a disposed object.
FluentAssertions.Specs.Streams.StreamAssertionSpecs+NotHavePosition ‑ When_a_throwing_stream_should_not_have_a_position_it_should_fail(exception: System.ObjectDisposedException: Cannot access a disposed object.
FluentAssertions.Specs.Streams.StreamAssertionSpecs+NotHavePosition ‑ When_a_throwing_stream_should_not_have_a_position_it_should_fail(exception: System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'GetLengthExceptionMessage'.)
Object name: 'GetPositionExceptionMessage'.)

FluentAssertions.Specs.Streams.StreamAssertionSpecs+HaveLength ‑ When_a_throwing_stream_should_have_a_length_it_should_fail(exception: System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'GetLengthExceptionMessage'.)
FluentAssertions.Specs.Streams.StreamAssertionSpecs+HaveLength ‑ When_a_throwing_stream_should_have_a_length_it_should_fail(exception: System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'GetLengthExceptionMessage'.)
FluentAssertions.Specs.Streams.StreamAssertionSpecs+HavePosition ‑ When_a_throwing_stream_should_have_a_position_it_should_fail(exception: System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'GetPositionExceptionMessage'.)
FluentAssertions.Specs.Streams.StreamAssertionSpecs+HavePosition ‑ When_a_throwing_stream_should_have_a_position_it_should_fail(exception: System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'GetPositionExceptionMessage'.)
FluentAssertions.Specs.Streams.StreamAssertionSpecs+NotHaveLength ‑ When_a_throwing_stream_should_not_have_a_length_it_should_fail(exception: System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'GetLengthExceptionMessage'.)
FluentAssertions.Specs.Streams.StreamAssertionSpecs+NotHaveLength ‑ When_a_throwing_stream_should_not_have_a_length_it_should_fail(exception: System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'GetLengthExceptionMessage'.)
FluentAssertions.Specs.Streams.StreamAssertionSpecs+NotHavePosition ‑ When_a_throwing_stream_should_not_have_a_position_it_should_fail(exception: System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'GetPositionExceptionMessage'.)
FluentAssertions.Specs.Streams.StreamAssertionSpecs+NotHavePosition ‑ When_a_throwing_stream_should_not_have_a_position_it_should_fail(exception: System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'GetPositionExceptionMessage'.)

♻️ This comment has been updated with latest results.

@github-actions

github-actions Bot commented May 5, 2026 •
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Qodana for .NET

It seems all right 👌

No new problems were found according to the checks applied

💡 Qodana analysis was run in the pull request mode: only the changed files were checked
☁️ View the detailed Qodana report

Contact Qodana team

Contact us at qodana-support@jetbrains.com

@dennisdoomen dennisdoomen merged commit f81cb7c into main May 5, 2026
17 of 18 checks passed
@dennisdoomen dennisdoomen deleted the fix/qodana-referential-comparer-overflow branch May 5, 2026 14:30
This was referenced May 12, 2026
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searledan added a commit to fiscaltec/vitally-mcp that referenced this pull request May 12, 2026
@dependabot @searledan
build: bump FluentAssertions from 8.9.0 to 8.10.0 (#10)
096143a 
Updated
[FluentAssertions](https://github.com/fluentassertions/fluentassertions)
from 8.9.0 to 8.10.0.

<details>
<summary>Release notes</summary>

_Sourced from [FluentAssertions's
releases](https://github.com/fluentassertions/fluentassertions/releases)._

## 8.10.0

<!-- Release notes generated using configuration in .github/release.yml
at main -->

## What's Changed
### Improvements
* Fail with a descriptive error when path-based rules are used on
value-semantic types by @​dennisdoomen in
fluentassertions/fluentassertions#3187
* Significantly speed up BeEquivalentTo for large unordered collections
by @​dennisdoomen in
fluentassertions/fluentassertions#3188
* Add ComparingNullCollectionsAsEmpty and ComparingNullStringsAsEmpty
options to BeEquivalentTo by @​dennisdoomen in
fluentassertions/fluentassertions#3202
* Include original index in extraneous item failure messages by
@​dennisdoomen in
fluentassertions/fluentassertions#3203
### Documentation
* Reroute the docs link to Xceed by @​dennisdoomen in
fluentassertions/fluentassertions#3183
* Fix typo in release notes by @​jnyrup in
fluentassertions/fluentassertions#3194
* Fix typos in docs by @​jnyrup in
fluentassertions/fluentassertions#3197
### Others
* Bump flatted from 3.4.1 to 3.4.2 in the npm_and_yarn group across 1
directory by @​dependabot[bot] in
fluentassertions/fluentassertions#3184
* Add AI assistant instruction file (agents.md) for Copilot, Claude, and
JetBrains Junie by @​Copilot in
fluentassertions/fluentassertions#3176
* Bump smol-toml from 1.6.0 to 1.6.1 in the npm_and_yarn group across 1
directory by @​dependabot[bot] in
fluentassertions/fluentassertions#3185
* Bump the npm_and_yarn group across 1 directory with 2 updates by
@​dependabot[bot] in
fluentassertions/fluentassertions#3186
* Bump cspell from 9.7.0 to 10.0.0 by @​dependabot[bot] in
fluentassertions/fluentassertions#3189
* Update nugets by @​jnyrup in
fluentassertions/fluentassertions#3192
* Fixup Qodana issues by @​jnyrup in
fluentassertions/fluentassertions#3193
* Fix Qodana argument separator by @​jnyrup in
fluentassertions/fluentassertions#3195
* Use new Qodana linter option by @​jnyrup in
fluentassertions/fluentassertions#3196
* Fix flaky BeLessThanOrEqualTo execution time test by @​Copilot in
fluentassertions/fluentassertions#3200
* Bump JetBrains/qodana-action from 2025.3 to 2026.1 by
@​dependabot[bot] in
fluentassertions/fluentassertions#3201
* Use long for hashCode in ReferentialComparer to avoid overflow by
@​dennisdoomen in
fluentassertions/fluentassertions#3204


**Full Changelog**:
fluentassertions/fluentassertions@8.9.0...8.10.0

Commits viewable in [compare
view](fluentassertions/fluentassertions@8.9.0...8.10.0).
</details>

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Dan Searle <dan_searle@outlook.com>
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