Re: Clarifying confusion of our variable placement rules caused by cleanup.h
From: Bart Van Assche
Date: Tue Nov 18 2025 - 12:19:04 EST
On 11/18/25 8:39 AM, James Bottomley wrote:
The problem specifically is this added comment in cleanup.h:A related question is whether or not to allow declarations in the
* That bug is fixed by changing init() to call guard() and define +
* initialize @obj in this order::
*
* guard(mutex)(&lock);
* struct object *obj __free(remove_free) = alloc_add();
Which is recommending mixing declarations and code contrary to our
prior rule. I note the rule against mixing variables and code was
relaxed in the C99 standard (and in a lot of other languages), but
we've never formally changed our coding rules.
I'm not saying we have to stick with C89, just that if we change
adherence to it, we should do so globally and document it because
having incosistency for __free vs other variables really isn't a good
idea.
initialization expression of for-statements. Although some maintainers reject patches that use this C99 feature, apparently this feature is
already used extensively:
$ git grep -nH 'for (int ' | grep -vE '^Documentation/|^tools/' | wc -l
1239
Thanks,
Bart.