A better way to deal with gcc's 'strict aliasing' warning

[Alejandro Mery]

sorry for the noise... thunderbird decided to reorder the mails and I 
didn't look at the date before replying :<

On 15.12.2014 23:45, Alejandro Mery wrote:
>
>
> On 30.07.2012 12:04, Jianbin Kang wrote:
>> Hello,
>>
>>         In `ev.h', the macro using (type of ev_watch *)(void *)(ev) to
>> convert `ev' to a required type.
>>         The (void *) conversion may be used to supress gcc's 'strict
>> aliasing' warning (not sure).
>>         This may work in previous version of gcc, but failed with gcc
>> 4.7:
>>                   warning: dereferencing type-punned pointer will break
>> strict-aliasing rules [-Wstrict-aliasing]
>>
>>        The better way is to put all ev_watch type to an union (such as
>> union ev_any_watcher in "ev.h"),
>>        and convert the pointer to (union ev_any_watch *).
>>        For example, the following code can supress strict-aliasing
>> warning for macro 'ev_init':
>>               typedef ev_any_watcher ev_any;
>>               #define ev_init(ev,cb_) do {                    \
>>                 ((ev_any *)(ev))->w.active  =                \
>>                 ((ev_any *)(ev))->w.pending = 0;         \
>>                 ev_set_priority ((ev), 0);                      \
>>                 ev_set_cb ((ev), cb_);                         \
>>              } while (0)
>>             # define ev_set_priority(ev,pri)             (   (ev_any
>> *)(ev))->w.priority = (pri)
>>
>>
>>        Is there any suggestion?
>
> I usually reimplement ev_foo_init() macros the as static inline
> functions with explicit types, and then everything goes smoothly.