(Please don't top-post - you make a mess of the flow of the
conversation, especially for people who haven't been following it. I've
moved your comments below.)
On 10/12/11 05:15, Divyesh wrote:
David Brown-4 wrote:
On 09/12/2011 08:26, Divyesh wrote:
Hi,
Please refer to the following code snippet.
struct strArr;
typedef struct strArr myStAr[17];
typedef struct
{
unsigned short DISPLAY_:1;
} structDisp;
typedef structDisp disp;
struct strArr
{
disp dispBit;
} ;
int f()
{
return 0;
}
In the code we have a typedef to an array of struct.
Now since the definition of that struct is given after the use, gcc
cribs.
The error reported by gcc is : array type has incomplete element type.
Interesting thing is gcc 3.4.4 compiles the code where as gcc 4.3.4 and
4.6
doesn't.
I think this is a gcc bug.
Request assistance for the same.
Thanks and Regards,
Divyesh
It is not a bug. It is interesting that gcc 3.4.4 accepted the code, as
it is (AFAIK) invalid C.
It is easy to see what is going on when you think about how the compiler
will interpret this - starting from the top and moving down. The usual
use of forward struct declarations is so that you can make pointers to
them in a circular type definition - that works fine, because the
compiler can conceive of a "pointer to struct" without knowing the
details of the struct. But the compiler cannot work with an instance of
the forward-declared struct, or an array of them, or use it as an
element in another struct (only pointers are allowed) - all these things
require a knowledge of the size of the struct.
>
> But it is interesting to see that g++ does compile this sample of code
>
> So I am confused now as there are inconsistencies between gcc and g++
>
>
It's easy to see that a C compiler /could/ accept the code - as long as
the typedef you made there was never used. I think it's just a case of
newer gcc being stricter about not accepting bad code.
mvh.,
David
