Microsoft KB Archive/149327

= FIX: C2440 Expanding Template with a Pointer to a Nested Class =

Article ID: 149327

Article Last Modified on 7/5/2005

-

APPLIES TO


 * Microsoft Visual C++ 4.0 Standard Edition
 * Microsoft Visual C++ 4.1 Subscription
 * Microsoft Visual C++ 4.2 Enterprise Edition
 * Microsoft Visual C++ 4.2 Professional Edition
 * Microsoft Visual C++ 5.0 Enterprise Edition
 * Microsoft Visual C++ 5.0 Professional Edition

-



This article was previously published under Q149327



SYMPTOMS
At the point where a class template is expanded using a pointer to a nested class, the compiler reports the following errors (generated by the sample code listed in this article):

[FileName](14) : error C2440: 'initializing' : cannot convert from 'class A::B' to 'class A::B *' (new behavior; please see help)

[FileName](14) : error C2439: 't' : member could not be initialized

Lines 13 and 14 in the sample code are: template  C::C : t(T) // error {



RESOLUTION
There are three possible workarounds to this problem. Each is stated here in terms of the sample code included in this article:


 * Remove t(T) from the initializer list and add t = T; to the body of the constructor. This workaround assumes there is an operator= defined for class T.
 * Change C c; to C c; or C c:
 * Change the definitions of class A and class B to that B is no longer nested in the definition of A.



STATUS
Microsoft has confirmed that this is a bug in the Microsoft products that are listed at the beginning of this article.



MORE INFORMATION
In this case, the problem is caused by the attempt to initialize the data member t.

Sample Code
/* Compile options needed: None */ template  class C { public: C; private: T t; };

template  C::C : t(T) // error { }

class A { public:

class B  { };

};

main {

C c;  return 0;

}

Keywords: kbbug kbfix kbvc600fix KB149327

-

[mailto:TECHNET@MICROSOFT.COM Send feedback to Microsoft]

© Microsoft Corporation. All rights reserved.