josh@xxxxxxxxxxxxxxxx writes: > [Side note: for some reason, your mail had your message ordered *after* > your attached diff, so replies quote the diff before the message.] Yes, I messed it up for some reason. Sorry for that. >> Since the additional information on expressions obtained through the >> first two parts is rather pointless without making any use of it, I >> implemented part three, the checking of static storage duration >> objects' initializers for constness. >> This part is the reason why there is a 'RFC' tag in the subject. >> It is up to you to decide whether letting sparse check for C99 >> conformity is a valuable thing to have or whether being stricter than >> GCC is counter-productive/completely idiotic. > > I think it's absolutely a valuable thing to have. It may or may not be > the right *default* behavior, but having an appropriate -W option to > enable it would be a good start. My next resend will contain such a -Wcheck-static-initializers then. However, I will delay that resend in order to be able to incorporate other reviews arriving in the meantime. > On Thu, Jul 23, 2015 at 12:54:25AM +0200, Nicolai Stange wrote: >> sparse now finds 519 occurences of non-const initializers of static >> storage duration objects, 474 of which are located in drivers/acpi >> and stem from this subsystem's custom offsetof macro implemented by >> means of taking pointer differences. > > Ideally, I'd suggest that ACPICA should add a translation from > ACPI_OFFSET to offsetof as part of its Linux-izing scripts. > > That said, I also can't think of an obvious reason why ACPI_OFFSET > *should* be considered non-constant. Perhaps there's a detail in the > C99 spec that explains why what it does isn't OK, but it *seems* like it > should be a compile-time constant expression. I've CCed Al Viro, who > knows the C99 constant expression rules very well; Al, could you provide > some clarity here? The ACPI_OFFSET macro in question expands to this: > > (acpi_size) (((u8 *) (void *) ((&(((struct some_struct *) 0)->fieldname)))) - ((u8 *) (void *) (((void *) (void *) 0)))) > > Does the -> make this non-constant? No, it is the pointer difference. At least to my interpretion of C99 [6.6(9)] which might be arguable. Upon your request, I could relax these constraints as I have did already for some special cases of conditionals in [11/13]. -- To unsubscribe from this list: send the line "unsubscribe linux-sparse" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
