On Fri, May 18, 2018 at 03:23:32PM -0700, Linus Torvalds wrote: > On Fri, May 18, 2018 at 2:56 PM Ramsay Jones <ramsay@xxxxxxxxxxxxxxxxxxxx> > wrote: > > > /usr/include/x86_64-linux-gnu/sys/sysmacros.h:79:1: warning: constant > 0xfffff00000000000u is so big it is unsigned long > > /usr/include/x86_64-linux-gnu/sys/sysmacros.h:80:1: warning: constant > 0x00000ffffff00000u is so big it is unsigned long > > I do wonder if we should just remove this warning, at least for files that > have been looked up using the system include directories. > > This warning keeps on happening, and nobody ever seems to much care. And > that's because it often warns for code that is "obviously correct" (like > your example), which is a mark of a bad warning. Yes, I agree. > It's not like the implicit type changes ever drops bits, or even does > anything truly surprising. > > The "do_warn & 2" case where C99 and C90 compilers actually have different > types, now _that_ is worth warning for. > > And we do warn for actual lost bits in implicit casts, so if people use a > constant that is too large in a context where it then loses bits, we give > that other warning > > warning: cast truncates bits from constant value (abc becomes xyz) > > so the value of the odd constant sizing warning is debatable. Maybe we > could move it to pedantic warnings? I'm all for it. Sparse doesn't yet handle -Wpedantic but it should be very easy to add. -- Luc -- 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
