Re: Compiler ABI changes and XPCOM components

Christopher Blizzard wrote:
> Bradley Baetz wrote:
> 
>>>> A number of compilers have options to make virtual method tables follow
>>>> the Microsoft COM layout (which is documented in the COM Specification),
>>>> so I suppose that Mozilla should use these options as much as possible
>>>> (it is usually an attribute that you give to a parent-less class and
>>>> which is inherited).
>>>
>>>
>>> Is there a option for this in gcc?  bbaetz?
>>>
>>
>>
>> I don't think so, but I really haven't looked.
> 
> 
> No, there isn't.  We're essentially screwed.
> 

Hmm, here's what I see in the GCC 3.1 sources:

/* Handle a "com_interface" attribute; arguments as in
    struct attribute_spec.handler.  */
static tree
handle_com_interface_attribute (node, name, args, flags, no_add_attrs)
      tree *node;
      tree name;
      tree args ATTRIBUTE_UNUSED;
      int flags ATTRIBUTE_UNUSED;
      bool *no_add_attrs;
{
   static int warned;

   *no_add_attrs = true;

   if (DECL_P (*node)
       || !CLASS_TYPE_P (*node)
       || *node != TYPE_MAIN_VARIANT (*node))
     {
       warning ("`%s' attribute can only be applied to class definitions",
                IDENTIFIER_POINTER (name));
       return NULL_TREE;
     }

   if (!warned++)
     warning ("`%s' is obsolete; g++ vtables are now COM-compatible by 
default",
              IDENTIFIER_POINTER (name));

   return NULL_TREE;
}