> From: linux-hyperv-owner@xxxxxxxxxxxxxxx
> <linux-hyperv-owner@xxxxxxxxxxxxxxx> On Behalf Of Gustavo A. R. Silva
> Sent: Wednesday, February 12, 2020 4:51 PM
> ...
> The current codebase makes use of the zero-length array language
> extension to the C90 standard, but the preferred mechanism to declare
> variable-length types such as these ones is a flexible array member[1][2],
> introduced in C99:
>
> struct foo {
> int stuff;
> struct boo array[];
> };
>
> By making use of the mechanism above, we will get a compiler warning
> in case the flexible array does not occur last in the structure, which
> will help us prevent some kind of undefined behavior bugs from being
> inadvertently introduced[3] to the codebase from now on.
>
> Also, notice that, dynamic memory allocations won't be affected by
> this change:
>
> "Flexible array members have incomplete type, and so the sizeof operator
> may not be applied. As a quirk of the original implementation of
> zero-length arrays, sizeof evaluates to zero."[1]
>
> This issue was found with the help of Coccinelle.
Looks good to me. Thanks, Gustavo!
Reviewed-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
FWIW, it looks there are a lot of more to fix in the kernel tree: the below
commands return 1373 for me:
grep -nr '\[0\];$' * | grep '\.h:' | grep -v = | wc -l
Running the commands against the kernel/ directory returns 3.
Thanks,
-- Dexuan
