Inline array struct size limit is enforced
The InlineArrayAttribute attribute was introduced in .NET 8 to annotate struct types that have a single field. Inline array structs were intended to have a size limit of 1 mebibyte (MiB). However, due to a bug, the limit wasn't enforced for inline array structs that have a sequential layout, which is also the default layout as emitted by C#. This change enforces the size limit.
Previous behavior
In .NET 8, you could declare an inline array struct with any positive, non-zero size. In extreme cases, the effective size was unpredictable. For example, a struct whose size was declared as Int32.MaxValue + 1 ended up having a size of 1 due to wrap-around.
New behavior
Starting in .NET 9, the size limit of 1 MiB is enforced.
Version introduced
.NET 9 Preview 1
Type of breaking change
This change is a behavioral change.
Reason for change
This change fixes a bug in the implementation where the size limit wasn't enforced.
Recommended action
If you have code that uses inline array structs with very large instances that exceed the limit, reduce the size of these structs.
