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Compiler Warning (level 1) CS0684

  • Article

'interface' interface marked with 'CoClassAttribute' not marked with 'ComImportAttribute'

If you specify CoClassAttribute on an interface, you must also specify ComImportAttribute.

The following sample generates CS0684:

// CS0684.cs
// compile with: /W:1
using System;
using System.Runtime.InteropServices;

[CoClass(typeof(C))] // CS0684
// try the following line instead
// [CoClass(typeof(C)), ComImport]
interface I
{
}

class C
{
   static void Main() {}
}