On Tue, Sep 14, 2021 at 03:03:51PM +0000, David Laight wrote: > From: Arnd Bergmann > > Sent: 14 September 2021 15:54 > > > > On Tue, Sep 14, 2021 at 4:24 PM Guenter Roeck <linux@xxxxxxxxxxxx> wrote: > > > On 9/14/21 7:17 AM, David Laight wrote: > > > >> Sorry, I didn't realize that a field of size 0 increases the structure size > > > >> on sparc. I had checked the size of the old and the new structure with gcc > > > >> on x86_64 and didn't see a field size increase. > > > > > > > > clang output doesn't change: > > > > > > > > https://godbolt.org/z/bTeeq19j1 > > > > > > > > gcc ought to generate the same size. > > > > > > > > It ought to be 'char data[];' though. > > > > > > > > > > I am never sure if [] or [0] is "correct". Anyway, is there agreement that this > > > is an acceptable solution ? I'll be happy to resend if that is the case. > > > > Yes, looks good to me, in the [] version. I think the [0] version can be > > interpreted as a zero-length array that may not be accessed, while the > > [] flexible array syntax clearly means that extra data follows, and it's > > part of the C standard now, while [0] is a gcc extension. > > More problematic is where is the correct place for the 'char data[]'. > It follows the header rather than being part of it. I personally always prefer the simple solution, and I don't really care about such nuances. I take it as granted that a header is followed by data, and I think that a zero-length field at the end of a header is a perfectly valid means to express that, but that is just my personal opinion. Anyway, I take that as non-agreement and won't resend at this time. Thanks, Guenter
