compiler-warning-level-1-c4584.md

description	title	ms.date	f1_keywords	helpviewer_keywords	ms.assetid
Learn more about: Compiler Warning (level 1) C4584	Compiler Warning (level 1) C4584	11/04/2016	C4584	C4584	ad86582f-cb8c-4d21-8c4c-a6c800059e25

Compiler Warning (level 1) C4584

'class1' : base-class 'class2' is already a base-class of 'class3'

The class you defined inherits from two classes, one of which inherits from the other. For example:

// C4584.cpp
// compile with: /W1 /LD
class A {
};

class B : public A {
};

class C : public A, public B { // C4584
};

In this case, a warning would be issued on class C because it inherits both from class A and class B, which also inherits from class A. This warning serves as a reminder that you must fully qualify the use of members from these base classes or a compiler error will be generated due to the ambiguity as to which class member you refer.