Re: [RFC, PATCH] shrink struct vectorlike_header #2

[Dmitry Antipov <dmantipov@yandex.ru>]

On 11/06/2012 10:17 PM, Stefan Monnier wrote:

>> +/* When V is on the free list, first word after header is
>> +   used as a pointer to next vector on the free list.  */
>> +
>> +#define NEXT_IN_FREE_LIST(v)				\
>> +  (*(struct Lisp_Vector **)((char *) v + header_size))
>> +
>>   /* Common shortcut to setup vector on a free list.  */
>
> Why change the comment rather than the code.  IOW what don't you like in:
>
>     Please make the code match the comment, e.g:
>       (*(struct Lisp_Vector **)&(v->contents[0]))
>
> I personally find it much more elegant and robust than doing pointer
> arithmetic via conversion to char*.

I agree that your code looks better, but it causes 'dereferencing
type-punned pointer will break strict-aliasing rules' warning
(and so error if --enable-gcc-warnings, gcc 4.7.2).

> The rest looks fine, tho it still probably lacks the corresponding
> changes in .gdbinit, right?

Yes, it's still on the way...

Dmitry