Compiler Warning (level 1) C4269

'identifier' : 'const' automatic data initialized with compiler generated default constructor produces unreliable results

A const automatic instance of a non-trivial class is initialized with a compiler generated default constructor. For example:

class X {
public:
   int m_data;
};

void g() {
   const X x1;   //Generates the warning
};

Since this instance of the class is generated on the stack, the initial value of m_data can be anything. Also, since it is a const instance, the value of m_data can never be changed.