CA1900: Value type fields should be portable

  • Article

TypeName

ValueTypeFieldsShouldBePortable

CheckId

CA1900

Category

Microsoft.Portability

Breaking Change

Breaking - If the field can be seen outside the assembly.

Non-breaking - If the field is not visible outside the assembly.

Cause

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

Rule Description

Structures that have explicit layout that contains misaligned fields cause crashes on 64-bit operating systems.

How to Fix Violations

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

When to Suppress Warnings

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