# System.Runtime.CompilerServices

``` diff
 namespace System.Runtime.CompilerServices {
+    public sealed class CppInlineNamespaceAttribute : Attribute {
+        public CppInlineNamespaceAttribute(string dottedName);
+    }
+    public static class IsExternalInit
+    public sealed class ModuleInitializerAttribute : Attribute {
+        public ModuleInitializerAttribute();
+    }
+    public sealed class PreserveBaseOverridesAttribute : Attribute {
+        public PreserveBaseOverridesAttribute();
+    }
     public static class RuntimeFeature {
+        public const string CovariantReturnsOfClasses = "CovariantReturnsOfClasses";
+        public const string UnmanagedSignatureCallingConvention = "UnmanagedSignatureCallingConvention";
     }
     public static class RuntimeHelpers {
+        public static IntPtr AllocateTypeAssociatedMemory(Type type, int size);
     }
+    public sealed class SkipLocalsInitAttribute : Attribute {
+        public SkipLocalsInitAttribute();
+    }
     public static class Unsafe {
+        public static bool IsNullRef<T>(ref T source);
+        public static ref T NullRef<T>();
+        public static void SkipInit<T>(out T value);
     }
 }
```

