cpp_extensions

Controls language extensions to ISO/IEC 14882-2003 C++.

  #pragma cpp_extensions on | off | reset  

If you enable this pragma, you can use the following extensions to the ISO/IEC 14882-2003 C++ standard that would otherwise be invalid:

• Anonymous struct & union objects. The following listing shows an example.
  Listing: Example of Anonymous struct & union Objects

  #pragma cpp_extensions on
  void func()
  
  {
  
    union {
  
      long  hilo;
  
      struct { short hi, lo; }; //  anonymous struct
  
    };
  
    hi=0x1234; 
  
    lo=0x5678;  //  hilo==0x12345678      
  
  }
  

• Unqualified pointer to a member function. The following listing shows an example.
  Listing: Example of an Unqualified Pointer to a Member Function

  #pragma cpp_extensions on
  struct RecA { void f(); }
  
  void RecA::f()
  
  {
  
    void (RecA::*ptmf1)() = &RecA::f; // ALWAYS OK
  
    void (RecA::*ptmf2)() = f; // OK if you enable cpp_extensions.
  
  }
  

• Inclusion of const data in precompiled headers.