Re: [commit] new observer.[hc] files

[Andrew Cagney <ac131313@redhat.com>]

> static void
>> observer_normal_stop_notification_stub (const void *data,
>> 					const void *unused_args)
>> {
>>   observer_normal_stop_ftype *notify = (observer_normal_stop_ftype *) data;
>>   (*notify) ();
>> }
> 
> 
> Is this extra indirection really necessary?  Because I'm 99% sure it
> won't work on several 64-bit platforms.  Function pointers and data
> pointers are not required to have the same size; on IA-64 I believe
> that a function pointer is 128 bits and a data pointer is 64 bits.

Like the PowerABI?  That has a 32 bit pointer but a 64 bit function 
descriptor.  void* ends up containing the address of the function 
descriptor.  Anyway, "defs.h" has the comment:

/* NOTE: cagney/2000-03-04: This typedef is strictly for the
    make_cleanup function declarations below. Do not use this typedef
    as a cast when passing functions into the make_cleanup() code.
    Instead either use a bounce function or add a wrapper function.
    Calling a f(char*) function with f(void*) is non-portable. */
typedef void (make_cleanup_ftype) (void *);

Once the code gets converted into a SED script, it can always be changed 
to something more strict.

> Why not require all observer functions to take the same arguments
> instead?

Per the original thread, it is to ensure strongly typed interfaces.

Andrew