BUG: C2483 Instantiating Objects with the Thread Attribute

ID: Q117383

The information in this article applies to:

The C/C++ Compiler (CL.EXE), used with:
- Microsoft Visual C++, 32-bit Editions, versions 1.0, 2.0, 4.0, 4.1, 4.2, 5.0, 6.0

SYMPTOMS

Instantiating a C++ object with the thread attribute generates the following error message if the class contains private or protected members:

error C2483: object with constructor cannot be declared 'thread'

To paraphrase page 397 of the "C++ Language Reference," class objects may be instantiated with the thread attribute if the objects do not need to be constructed or destructed. However, this error occurs even though the class does not have a constructor or a destructor.

CAUSE

Currently, thread local storage has only been implemented for aggregate types. An aggregate type is defined as an array or object of a class with no constructors, no private or protected members, no base classes, and no virtual functions. In this case, private or protected members make the class an aggregate; therefore, the error message is generated.

RESOLUTION

To avoid this error, make all private or protected members of the class public members.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article.

MORE INFORMATION

The sample code below demonstrates how to produce and avoid the error message. Uncomment the "public" keyword before the data member to avoid the error.

Sample Code


/* Compile options needed: /c /MT
*/ 

class B
{
// Uncomment the following line to eliminate compiler error
// public:
      int i;
};

__declspec(thread) B b; // error C2483

Additional query words: kbVC400bug 8.00 9.00

Keywords : kbCompiler kbCPPonly kbVC kbVC100bug kbVC200bug kbVC400bug kbVC410bug kbVC420bug kbVC500bug kbVC600bug
Version : winnt:1.0,2.0,4.0,4.1,4.2,5.0,6.0
Platform : winnt
Issue type : kbbug