Accessing C struct as a C++ class

Question

Is there a workaround for this bug in gcc?

Specifically, I think I am running into the bug when compiling a wrapper for pthread_mutex_t. The header looks like:

class DerivedClass: public pthread_mutex_t{
  public:
     DerivedClass() {}
     ~DerivedClass(){}
     DerivedClass someFunction(){}
};

The code is from a legacy system and used to compile on GCC 3.2.x but won't do on GCC 4.1.2.

... In theory I guess I could recompile everything on a back-version GCC or refactor the referencing sources to disuse the wrapper, but I want to see if there is an easier way first.

Many Thanks.

Answer 1

The bug is fixed in GCC 4.6.0, but if you need it now, use composition instead:

class DerivedClass {
  public:
    pthread_mutex_t mutex;
// ...
}

If what you need is a class which can be casted to a pthread_mutex_t *, then make sure your class has no virtual functions, and put the mutex as the first element in the class; you can then convert between DerivedClass * and pthread_mutex_t * safely. Or add an operator pthread_mutex_t *().