Error Message
missing type specifier - int assumed. Note: C++ does not support default-int

Example
The following sample generates C4430.
// C4430.cpp
// compile with: /c
struct CMyClass {
CUndeclared m_myClass; // C4430
int m_myClass; // OK
};
typedef struct {
POINT(); // C4430
// try the following line instead
// int POINT();
unsigned x;
unsigned y;
} POINT;