Messages in this thread | | | Date | Sun, 24 Jun 2007 19:44:49 +0100 | From | Al Viro <> | Subject | Re: [PATCH 16/16] fix handling of integer constant expressions |
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On Sun, Jun 24, 2007 at 08:18:52PM +0200, Segher Boessenkool wrote: > >#define _IOC_TYPECHECK(t) \ > > ((sizeof(t) == sizeof(t[1]) && \ > > sizeof(t) < (1 << _IOC_SIZEBITS)) ? \ > > sizeof(t) : __invalid_size_argument_for_IOC) > >poisoning _IOW() et.al., so those who do something like > > > >static const char *v4l1_ioctls[] = { > > [_IOC_NR(VIDIOCGCAP)] = "VIDIOCGCAP", > > > >run into trouble. > > >The only reason that doesn't break gcc to hell and back is > >that gcc has unfixed bugs in that area. > > If I understand correctly what bugs you are talking about, > most (all?) of those were solved in the dark ages already > (i.e., the 3.x series).
Alas, no. gcc is amazingly (and inconsistently) sloppy about the things it accepts as integer constant expressions.
> >It certainly is not a valid C > > Why not? Nothing in the C standard says all your externs > have to be defined in some other translation unit you link > with AFAIK.
It's not about externs. It's about things like
unsigned n; int a[] = {[n - n + n - n] = 1};
And yes, gcc does eat that. With -pedantic -std=c99, at that. However,
unsigned n; int a[] = {[n + n - n - n] = 1};
gets you error: nonconstant array index in initializer
And that's 4.1, not 3.x... - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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