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Avoid zero-length array allocations and storing them in static fields (CA1825) #10267

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Merged
merged 3 commits into from
Apr 7, 2025
Merged

Avoid zero-length array allocations and storing them in static fields (CA1825) #10267

merged 3 commits into from
Apr 7, 2025

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h3xds1nz
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@h3xds1nz h3xds1nz commented Jan 11, 2025 •
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Fixes #10286

Description

This PR mainly resolves CA1825 but in some cases goes a step further over standard analyzer fix.

  • In addition to using singleton over allocating zero-length array everytime, we want to avoid storing those in readonly fields (whether they're marked or not), as the pointer to such array is already accessible via Array.Empty<Type>().
  • XamlTypeMapper was going step further and cloning this zero-length array even. Happy days.
  • RowSpanVector was performing unnecessary assigment if the branch was not taken.

Customer Impact

Increased performance, decreased allocations.

Regression

No.

Testing

Local build.

Risk

Should be low.

Microsoft Reviewers: Open in CodeFlow

@h3xds1nz h3xds1nz requested review from a team as code owners January 11, 2025 21:36
@dotnet-policy-service dotnet-policy-service bot added PR metadata: Label to tag PRs, to facilitate with triage Community Contribution A label for all community Contributions labels Jan 11, 2025
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omariom commented Jan 13, 2025

Could [] be used insted of Array.Empty?

@h3xds1nz
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Could [] be used insted of Array.Empty?

I'm not a fan. In cases like assigning to already defined field or parameter you lose the visible type information.

harshit7962
harshit7962 approved these changes Apr 7, 2025
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Changes LGTM

@harshit7962 harshit7962 merged commit 7f6d4aa into dotnet:main Apr 7, 2025
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Thank you @h3xds1nz for these contributions. We will be taking the next batch of changes for the test pass soon.

@harshit7962 harshit7962 self-assigned this Apr 7, 2025
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h3xds1nz commented Apr 7, 2025 •
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@harshit7962 Thank you, happy to hear :)

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@harshit7962 harshit7962 harshit7962 approved these changes

@dipeshmsft dipeshmsft Awaiting requested review from dipeshmsft

@singhashish-wpf singhashish-wpf Awaiting requested review from singhashish-wpf

@Kuldeep-MS Kuldeep-MS Awaiting requested review from Kuldeep-MS

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CA1825: Avoid zero-length array allocations
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