编译器错误 C3741

“class”:当 event_receiver 的“layout_dependent”参数为 true 时,必须是组件类

layout_dependent=true 用于 event_receiver 类时,该类也必须具有 coclass 特性。

以下示例生成 C3741

// C3741.cpp
// compile with: /c
// C3741 expected
#define _ATL_ATTRIBUTES 1
#include <atlbase.h>
#include <atlcom.h>
[module(name="xx")];

[object, uuid("00000000-0000-0000-0000-000000000001")]
__interface I{ HRESULT f(); };

// Delete the following line to resolve.
[ event_receiver(com, layout_dependent=true)]

// class or struct must be declared with coclass
// Uncomment the following line to resolve.
// [ event_receiver(com, layout_dependent=true), coclass, uuid("00000000-0000-0000-0000-000000000002")]
struct R : I {
   HRESULT f(){ return 0; }
   R(){}
   R(I* a){ __hook(I, a); }
};