.NET Information center: Lesser Known CLR Custom Attributes -- UnsafeValueType

Tuesday, March 20, 2012

Lesser Known CLR Custom Attributes -- UnsafeValueType

In a comment to the previous post about CLR Custom Attributes I listed some other custom attributes that the CLR recognizes (by name). Some of them I previously thought were compiler only custom attributes, so I decided to investigate them.

System.Runtime.CompilerServices.UnsafeValueTypeAttribute

The documentation for this attribute, somewhat uncharacteristically, actually explains what it does, but I decided to try it out.

Here's an example that demonstrates what it does:

using System;

using System.Runtime.CompilerServices;

//[UnsafeValueType]

struct Foo {

public int field;

}

class Program {

[MethodImpl(MethodImplOptions.NoOptimization)]

static void Main() {

int i = 1234;

Foo foo = new Foo();