LANG.STRUCT.INIT.OOMI : Out of Order Member Initializers

Summary

The ordering in the member initializer list for a class constructor does not match the order in which the initializers will be invoked.

The order of invocation for member initializers is specified in the C++ standard and is independent of their order in the initializer list. A warning of this class is issued if a constructor for class C is invoked at least once in the analyzed code but the member initializer list for the constructor does not meet all of the following requirements.

• Virtual base classes.
  • Initializers for virtual base classes must occur before initializers for direct base classes and member data initializers.
  • The ordering of virtual base class initializers must correspond to the order in which the virtual base classes occur in the specifier list for C.
• Direct base classes.
  • Initializers for direct base classes must occur before member data initializers.
  • The ordering of direct base class initializers must correspond to the order in which the direct base classes occur in the specifier list for C.
• Data members.
  • The ordering of data member initializers must correspond to the order in which the daata members are declared in the class definition for C.

A member initializer list that does not reflect this ordering may cause confusion for human readers.

Properties

WARNING_FILTER += allow class="Out of Order Member Initializers"

WARNING_FILTER += discard class="Out of Order Member Initializers"

Example

namespace lang_struct_init_oomi{

  class VirtualBase {
  public:
    VirtualBase(void): second_int(1),
                       first_int(2) {}; // 'Out of Order Member Initializers' warning issued here
    VirtualBase(int i){}
  private:
    int first_int;
    int second_int;
  };

  class FirstClass {
  public:
    FirstClass(void){}
    FirstClass(int i){}
  };

  class SecondClass {
  public:
    SecondClass(void){}
    SecondClass(int i){}
  };

  class Derived:  virtual VirtualBase,  FirstClass,  SecondClass {
  public:
    Derived(void) : mychar('x'),
                    FirstClass(1),    // 'Out of Order Member Initializers' warning issued here
                    VirtualBase(2) {}

    Derived(int i) : SecondClass(i),
                     FirstClass(i) {}  // 'Out of Order Member Initializers' warning issued here

    Derived(char c) : VirtualBase(1),               // ok: 
                      FirstClass(1),                //   all initializer list ordering requirements
                      SecondClass(1),               //   met for this constructor
                      mychar(c) {}
  private:
    char mychar;
  };

  Derived d1;                                       // invokes Derived::Derived(void) 
  Derived d2(2);                                    // invokes Derived::Derived(int i), which in turn invokes VirtualBase::VirtualBase(void) 
  Derived d3('c');                                  // invokes Derived::Derived(char c) 
}

Relevant Configuration File Parameters

The following configuration file parameters affect checks for this warning class.

• REPORT_SIMILAR_WARNINGS
• WARNING_FILTER