Re: [PATCH v2 net-next 1/3] sfc: use padding to fix alignment in loopback test

[Edward Cree <ecree.xilinx@gmail.com>]

On 14/08/2023 14:45, Arnd Bergmann wrote:
> I think overall this is still a useful warning, in the sense that
> it can spot incorrect code elsewhere.

It's a valid concept for a warning, but it's badly implemented, because
 it fires on 'defining a type' rather than 'declaring an object'.
At no point is an object of the inner (anonymous) struct type declared
 (or a pointer to such constructed) without being (4n+2)-aligned, but
 the compiler isn't smart enough to figure that out.

And as Linus once said[1]:
    If you cannot distinguish it from incorrect uses, you shouldn't be
    warning the user, because the compiler obviously doesn't know
    enough to make a sufficiently educated guess.
(among other remarks on a theme of 'warnings with false positives are
 worse than useless'.  Especially when there's no way to shut them up
 without making the code objectively worse).

-e

[1]: https://yarchive.net/comp/linux/gcc.html#11