Rule Definition
An overridden virtual method should have the same default values as the base class method. Default parameter values are determined by the static type of the object on which the method call is done. This means that the default values used may not match those of the virtual method being called. For non virtual methods, this makes the code more complex to understand.

Remediation
Check the parameter default value and try to align them with those that are defined in the overridden method.

Violation Code Sample

class Base 
{ 
 public: 
  virtual void myfct( int a = 0 ); 
}; 

class Derived : public Base 
{ 
 public: 
  virtual void myfct( int a = 10 );  // VIOLATION
};

Fixed Code Sample

class Base 
{ 
 public: 
  virtual void myfct( int a = 0 ); 
}; 

class Derived : public Base 
{ 
 public: 
  virtual void myfct( int a = 0 );  // FIXED
};

Effective C++, Item 38;