[Breaking change]: Specifying explicit struct Size is not disallowed with InlineArray

[VSadov]

Description

Applying explicit Size to a struct decorated with InlineArrayAttribute is ambiguous and now is not supported in the type Loader.

.NET 10 Preview 7

Version

Other (please put exact version in description textbox)

Previous behavior

Previously specifying explicit Size would result in implementation specific behavior that may or may not match user's expectations

New behavior

Creating instances of such struct and other uses will result in TypeLoadException thrown.

Type of breaking change

• Binary incompatible: Existing binaries might encounter a breaking change in behavior, such as failure to load or execute, and if so, require recompilation.
• Source incompatible: When recompiled using the new SDK or component or to target the new runtime, existing source code might require source changes to compile successfully.
• Behavioral change: Existing binaries might behave differently at run time.

Reason for change

Specifying Size for an inline array struct is ambiguous and any interpretation would contradict specification.

Recommended action

In unlikely case if user needs to specify explicit size either for the array element or for the whole inline array, a struct wrapping the element type or the whole array type can be introduced and in the layout of the wrapper the Size could be specified accordingly and unambiguously.

Feature area

Other (please put exact area in description textbox)

Affected APIs

Affects: TypeLoader. The loader may reject types that were not originally rejected.

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Associated WorkItem - 454941