anonymous structs in unions

anonymous structs in unions

[Mihnea Balta]

I've found out quite a while ago that gcc and g++ don't like constructs like:

union something{
   struct{
     int a, int b;
   };
   struct{
     float c, d;
   };
} a;

a.c = 12.f;

So far, the only place where I've gotten problems because of this was code 
that defined matrices as unions of a float array and a float struct, and that 
was quickly fixed by some #defines. Anyway, right now I have to port some 
visualc code to g++/linux and I stumbled across this problem in other areas 
which are harder to modify (mainly because the rest of the team members 
opposing to changing half their code :) and secondly because some hairy bit 
unions come into play).

My theoretical question is if this feature was not included in gcc/g++ because 
it does not comply with ANSI or for other reasons. My practical question is 
if anything can be done besides convincing my team mates to rewrite code or 
hacking gcc.

Thanks.

Re: anonymous structs in unions

[Dan Kegel]

Mihnea Balta wrote:
> I've found out quite a while ago that gcc and g++ don't like constructs like:
> 
> union something{
>    struct{
>      int a, int b;
>    };
>    struct{
>      float c, d;
>    };
> } a;
> 
> a.c = 12.f;

If you fix the typos (, -> ;), that compiles nicely with gcc3.2.
- Dan


-- 
Dan Kegel
http://www.kegel.com
http://counter.li.org/cgi-bin/runscript/display-person.cgi?user=78045

Re: anonymous structs in unions

[Mihnea Balta]

Hmm, I tried with 2.95.3 and it complained. I take it gcc 3.2 understands this 
kind of constructs, I might consider switching to it (and recompiling tons of 
software that uses the old ABI, but that's it, it had to happen someday :) )

Thank you for clearing this up for me.

On Thursday 27 February 2003 19:15, Dan Kegel wrote:
> Mihnea Balta wrote:
> > I've found out quite a while ago that gcc and g++ don't like constructs
> > like:
> >
> > union something{
> >    struct{
> >      int a, int b;
> >    };
> >    struct{
> >      float c, d;
> >    };
> > } a;
> >
> > a.c = 12.f;
>
> If you fix the typos (, -> ;), that compiles nicely with gcc3.2.
> - Dan