_ATL_MIXED specifies that your ATL application is comprised of native and /clr compilands.


When building an application that uses ATL, and where the compilands are not all native or all /clr, then you must add this macro to each compiland.

#define _ATL_MIXED

This will cause all startup code to run as native. You may need to ensure that all startup code is native. See Initialization of Mixed Assemblies for more information.