Document InlineArray explicit Size breaking change for .NET 10 #47906
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Co-authored-by: gewarren <[email protected]>
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[WIP] [Breaking change]: Specifying explicit struct Size is not disallowed with InlineArray
Document InlineArray explicit Size breaking change for .NET 10
Aug 8, 2025
BillWagner
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Aug 13, 2025
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This LGTM, once @VSadov approves.
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This PR documents a breaking change introduced in .NET 10 Preview 7 where specifying explicit
Sizeto a struct decorated withInlineArrayAttributeis now disallowed and throws aTypeLoadException.Changes Made
docs/core/compatibility/core-libraries/10.0/inlinearray-explicit-size-disallowed.mddocs/core/compatibility/10.0.mdto include the new breaking change in the Core .NET libraries tabledocs/core/compatibility/toc.ymlto add navigation entry for the new documentBreaking Change Details
Previous behavior: Specifying explicit
Sizeon structs withInlineArrayAttributeresulted in implementation-specific behavior that might not match user expectations.New behavior: Starting in .NET 10 Preview 7, such usage now throws a
TypeLoadExceptionwhen creating instances or performing other operations on these types.Type: Binary incompatible change - existing binaries may fail to load or execute and require recompilation.
Reason: The explicit
Sizespecification for inline array structs is ambiguous and contradicts the specification.Recommended action: Use wrapper structs when explicit size specification is needed for either array elements or the whole inline array.
The documentation follows established patterns and Microsoft Writing Style Guide principles, providing clear explanations and actionable guidance for developers affected by this change.
Fixes #47435.
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