Clarify sizeof rules for unsafe code blocks
#51543
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Some rules regarding nint, nuint, and ref struct types wasn't as clear as it should be. Fixes dotnet#51281
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Pull request overview
This pull request clarifies the documentation for the sizeof operator, specifically addressing issue #51281 regarding the rules for using sizeof with different types in safe and unsafe code contexts. The changes improve accuracy by explicitly stating that nint, nuint, and ref struct types like Span<T> require unsafe context, and provide concrete examples demonstrating their usage.
Changes:
- Updated documentation to clarify that safe code requires built-in unmanaged types whose size is not platform-dependent
- Rewrote the unsafe code section with more precise descriptions of how
sizeofworks with different type categories - Added code examples demonstrating
sizeofwithnint,nuint, andSpan<int>in unsafe blocks
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.
| File | Description |
|---|---|
| docs/csharp/language-reference/operators/sizeof.md | Updated documentation to clarify platform-dependent type restrictions and unsafe code rules, with improved descriptions of reference, value, and ref struct type behavior |
| docs/csharp/language-reference/operators/snippets/shared/SizeOfOperator.cs | Added three new examples within the unsafe block demonstrating sizeof usage with nint, nuint, and Span<int> |
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
gewarren
approved these changes
Feb 10, 2026
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Some rules regarding nint, nuint, and ref struct types wasn't as clear as it should be. Add examples for
nint,nuint, andSpan<T>.Fixes #51281
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