[QPID-3478] Windows Visual Studio 2010 warning C4251 'needs to have dll interface' qpid::amqp_0_10::MapCodec::contentType

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.12
• Fix Version/s: 0.17
• Component/s: C++ Broker, C++ Client

Environment

Windows builds using Visual Studio 2010

• Assignee: Charles E. Rolke
• Reporter: Charles E. Rolke
• Created: 08/Sep/11 18:03
• Updated: 29/Jul/13 18:53
• Resolved: 19/Jun/12 14:33

Description

File cpp/include/qpid/amqp_0_10/Codecs.h has code to the effect of:

class QPID_COMMON_EXTERN MapCodec
{
public:
static const std::string contentType;
private:
};

VS2010 warns that exporting a std::string from a DLL may have unexpected consequences.

One possible solution is from

http://www.eggheadcafe.com/software/aspnet/30952961/a-solution-to-warning-c4251--class-needs-to-have-dllinterface.aspx

2. You can define a wrapper class that has no inline functions and defines all the potentially compiler-generated functions (default ctor, copy ctor, dtor, and assignment operator) and dllexport that.

Other discussion of this issue:

http://stackoverflow.com/questions/2132747/warning-c4251-when-building-a-dll-that-exports-a-class-containing-an-atlcstring