Value type fields should be portable

This rule checks that structures declared with explicit layout will align correctly when marshaled to unmanaged code on 64-bit platforms. IA-64 does not allow unaligned memory accesses and the process will crash if this violation is not fixed.

Structures with explicit layout that contain misaligned fields cause crashes on 64-bit platforms.

All fields that are smaller than 8 bytes must have offsets that are multiple of their size, and fields that are 8 bytes or greater must have offsets that are a multiple of 8. Another solution is to use LayoutKind.Sequential instead of LayoutKind.Explicit if reasonable.

This warning should be suppressed only if it occurs in error.