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

Linus Torvalds torvalds at linux-foundation.org
Tue Mar 1 07:37:15 AEDT 2022

On Mon, Feb 28, 2022 at 12:16 PM Matthew Wilcox <willy at infradead.org> wrote:
> Then we can never use -Wshadow ;-(  I'd love to be able to turn it on;
> it catches real bugs.

Oh, we already can never use -Wshadow regardless of things like this.
That bridge hasn't just been burned, it never existed in the first

The whole '-Wshadow' thing simply cannot work with local variables in
macros - something that we've used since day 1.

Try this (as a "p.c" file):

        #define min(a,b) ({                     \
                typeof(a) __a = (a);            \
                typeof(b) __b = (b);            \
                __a < __b ? __a : __b; })

        int min3(int a, int b, int c)
                return min(a,min(b,c));

and now do "gcc -O2 -S t.c".

Then try it with -Wshadow.

In other words, -Wshadow is simply not acceptable. Never has been,
never will be, and that has nothing to do with the

        typeof(pos) pos

kind of thing.

Your argument just isn't an argument.


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