C Semantics in K Framework

[Derek M Jones <derek AT knosof.co.uk>]

John,

> I can't find any language in the C99 standard which forces unnamed
> struct members to be bitfields.

The syntax of structure specifiers only supports optional
declarators for bit-fields.
Sentence 1390: http://c0x.coding-guidelines.com/6.7.2.1.html

  Rather, we see text like this which
> appears to refer to all member objects:
>
> "A structure type describes a sequentially allocated nonempty set of
> member objects (and, in certain circumstances, an incomplete array),
> each of which has an optionally specified name and possibly distinct type."
>
> Can you back up your interpretation?
>
> Thanks,
>
> John
>
>
>
>
> On 8/9/11 1:06 PM, Derek M Jones wrote:
> > John,
> >
> > > The C99 standard seems to make it clear that structs may contain unnamed
> > > members.  This argues that KCC and CompCert are correct.
> >
> > Unnamed BIT-FIELD members.
> >
> > > Both Clang and GCC (even when given the --std=c99 flag) complain that
> > > line 5 does not declare anything, and their output is consistent with
> > > this claim.
> >
> > This is correct.
> >
> > > Anyone know what's going on?
> >
> > The code is making use of an extension to C.
> >
> > > Thanks,
> > >
> > > John
> > >
> > >
> > >
> > > int printf (const char *, ...);
> > >
> > > struct S0
> > > {
> > >       int;
> > >       int f1;
> > > };
> > >
> > > struct S3
> > > {
> > >       int f2;
> > >       int f3;
> > > };
> > >
> > > union U4
> > > {
> > >       struct S3 f0;
> > >       struct S0 f3;
> > > };
> > >
> > > union U4 g_110;
> > >
> > > int main (void)
> > > {
> > >       g_110.f3.f1 = 1;
> > >       printf ("%d\n", g_110.f0.f2);
> > >       return 0;
> > > }
> > > _______________________________________________
> > > c-semantics mailing list
> > > c-semantics AT cs.illinois.edu
> > > http://lists.cs.uiuc.edu/mailman/listinfo/c-semantics
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--
Derek M. Jones                         tel: +44 (0) 1252 520 667
Knowledge Software Ltd                 
mailto:derek AT knosof.co.uk
Source code analysis                   http://www.knosof.co.uk