std::string gives compiler warning in Visual Studio 2010

Question

I am migrating my Visual Studio 2005 C++ code to Visual Studio 2010. Unfortunately I am getting error on std::string on VS2010 whereas in VS2005 I never had this error before.

Here is the code sample

#include<string>

typedef std::string String

class __declspec(dllexport) SomeClass
{
public:
   String somevariable;  // compiler warning here.  Please see below for the compiler warning.

   void SomeFunction(String sName);  // No compiler errors or warning here
};

Compiler warning as:

error C2220: warning treated as error - no 'object' file generated
warning C4251: 'SomeClass::somevariable' : class 'std::basic_string<_Elem,_Traits,_Ax>' needs to have dll-interface to be used by clients of class 'SomeClass'

with
[
    _Elem=char,
    _Traits=std::char_traits<char>,
    _Ax=std::allocator<char>
]

Please help to give me solution for this issue.

http://stackoverflow.com/questions/5661738/common-practice-in-dealing-with-warning-c4251-class-needs-to-have-dll-inter — Arun, Mar 25 '13 at 03:35
A possible solution using PIMPL idiom is here -http://stackoverflow.com/questions/767579/exporting-classes-containing-std-objects-vector-map-etc-from-a-dll — Arun, Mar 25 '13 at 03:40

score 0 · Answer 1 · answered Mar 25 '13 at 18:42

I'd suggest reading and understanding the link that Arun gave first. Then, if you can be reasonably sure that you are not using different compilers (which is a recipe for disaster in C++ anyway), you can simply disable/ignore the warning.

BTW:

I get the same warning from VS2005 for some code.
You are perfectly right that the behaviour is inconsistent. The function and the membervariable should either both trigger the diagnostic or none of them.

std::string gives compiler warning in Visual Studio 2010

1 Answers1