Marshal.GetHRForException(Exception) also sets up an IErrorInfo interface for the exception that can be obtained by calling the COM GetErrorInfoNEEDGUID function. You can use this function to return an HRESULT value on a managed class implementation of a COM interface where you apply the System.Runtime.InteropServices.PreserveSigAttribute. Have the attributed method catch all exceptions and use Marshal.GetHRForException(Exception) to return the appropriate HRESULT value. Allowing an exception to propagate outside the method produces incorrect behavior. (In fact, the common language runtime fails to pass an exception to a COM client that calls such a method through a v-table.)

Note that the Marshal.GetHRForException(Exception) method sets the IErrorInfo of the current thread. This can cause unexpected results for methods like the erload:System.Runtime.InteropServices.Marshal.ThrowExceptionForHR methods that default to using the IErrorInfo of the current thread if it is set.

Namespace: System.Runtime.InteropServices
Assembly: mscorlib (in mscorlib.dll)
Assembly Versions: 1.0.5000.0, 2.0.0.0, 4.0.0.0