netdev - Re: [PATCH 2/6] treewide: remove using list iterator after loop body as a ptr

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Date:   Mon, 28 Feb 2022 12:41:01 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Johannes Berg <johannes@...solutions.net>
Cc:     Matthew Wilcox <willy@...radead.org>,
        Christian König <christian.koenig@....com>,
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Subject: Re: [PATCH 2/6] treewide: remove using list iterator after loop body
 as a ptr

On Mon, Feb 28, 2022 at 12:29 PM Johannes Berg
<johannes@...solutions.net> wrote:
>
> If we're willing to change the API for the macro, we could do
>
>   list_for_each_entry(type, pos, head, member)
>
> and then actually take advantage of -Wshadow?

See my reply to Willy. There is no way -Wshadow will ever happen.

I considered that (type, pos, head, member) kind of thing, to the
point of trying it for one file, but it ends up as horrendous syntax.
It turns out that declaring the type separately really helps, and
avoids crazy long lines among other things.

It would be unacceptable for another reason too - the amount of churn
would just be immense. Every single use of that macro (and related
macros) would change, even the ones that really don't need it or want
it (ie the good kinds that already only use the variable inside the
loop).

So "typeof(pos) pos" may be ugly - but it's a very localized ugly.

                    Linus