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Compiler Warning (level 1) C4350

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behavior change: 'member1' called instead of 'member2'

An rvalue cannot be bound to a non-const reference. In versions of Visual C++ before Visual Studio 2003, it was possible to bind an rvalue to a non-const reference in a direct initialization. This code now gives a warning.

For backward compatibility, it is still possible to bind rvalues to non-const references, but standard conversions are preferred wherever possible.

This warning represents a change of behavior from the Visual C++ .NET 2002 compiler. If enabled, this warning could possibly be given for correct code. For example, it could be given when using the std::auto_ptr class template.

If you get this warning, examine your code to see if it depends on binding rvalues to non-const references. Adding a const to the reference or providing a additional const-reference overload may solve the problem.

This warning is off by default. For more information, see Compiler Warnings That Are Off by Default.

The following sample generates C4350:

// C4350.cpp
// compile with: /W1
#pragma warning (default : 4350)
class A {};

class B
{
public:
   B(B&){}
   // try the following instead:
   // B(const B&){}

   B(A){}
   operator A(){ return A();}
};

B source() { return A(); }

int main()
{
   B ap(source());   // C4350
}