Self-referring const array initialisation

Self-referring const array initialisation

[Hamilton, Ian]

Hi there

Here is a test program to illustrate a problem in some code
I have inherited:

#include <stdio.h>

const int array1[5]=
{
  1,
  2,
  3,
  4,
  5
};

const int array2[5]=
{
  1,
  array2[0] + 1,
  array2[1] + 1,
  array2[2] + 1,
  array2[3] + 1,
};

int main()
{
  printf ("Array values:\n\n");
  printf("array1  array2\n");

  printf("  %i       %i\n", array1[0], array2[0]);
  printf("  %i       %i\n", array1[1], array2[1]);
  printf("  %i       %i\n", array1[2], array2[2]);
  printf("  %i       %i\n", array1[3], array2[3]);
  printf("  %i       %i\n", array1[4], array2[4]);
}


If I build and run this on a Sun/Sparc/Solaris system using
gcc version 2.95.2, I get the following output:

Array values:

array1  array2
  1       1
  2       2
  3       3
  4       4
  5       5


However, if I use gcc version 3.3.2, I get this output:

Array values:

array1  array2
  1       1
  2       1
  3       1
  4       1
  5       1


A bit of investigation with the debugger revealed that the
initialisation code is producing the initialised array on the
stack, then copying it to its normal position in RAM. Unfortunately,
the initialisation code is reading values from the array's normal
position in RAM, so reads a zero for the array elements already
initialised instead of the initialised value.

My question is whether this sort of self-reference is allowed by
the C and/or C++ standards. In other words, is this a compiler bug,
or a bug in the above code?

Cheers,
Ian.

Re: Self-referring const array initialisation

[llewelly]

"Hamilton, Ian" <Ian.Hamilton@gbr.xerox.com> writes:

> Hi there
> 
> Here is a test program to illustrate a problem in some code
> I have inherited:
> 
> #include <stdio.h>
> 
> const int array1[5]=
> {
>   1,
>   2,
>   3,
>   4,
>   5
> };
> 
> const int array2[5]=
> {
>   1,
>   array2[0] + 1,
>   array2[1] + 1,
>   array2[2] + 1,
>   array2[3] + 1,
> };
> 
> int main()
> {
>   printf ("Array values:\n\n");
>   printf("array1  array2\n");
> 
>   printf("  %i       %i\n", array1[0], array2[0]);
>   printf("  %i       %i\n", array1[1], array2[1]);
>   printf("  %i       %i\n", array1[2], array2[2]);
>   printf("  %i       %i\n", array1[3], array2[3]);
>   printf("  %i       %i\n", array1[4], array2[4]);
> }
> 
> 
> If I build and run this on a Sun/Sparc/Solaris system using
> gcc version 2.95.2, I get the following output:
> 
> Array values:
> 
> array1  array2
>   1       1
>   2       2
>   3       3
>   4       4
>   5       5
> 
> 
> However, if I use gcc version 3.3.2, I get this output:
> 
> Array values:
> 
> array1  array2
>   1       1
>   2       1
>   3       1
>   4       1
>   5       1

FWIW, on i386-freebsd5.2, gcc 3.4 release cannidate gives the same
    output as gcc 2.95.2 . So I think this bug is fixed in 3.4 (but it is
    still present in 3.3.3). I can't find the bug report, however.

[snip]
> My question is whether this sort of self-reference is allowed by
> the C and/or C++ standards. In other words, is this a compiler bug,
> or a bug in the above code?

I am nearly certain C++ allows this. I can't find anything in 8.5.1
    that disallows it.

Undefined Referenced

[Aleksei Andevis]

Hello All!

Can you help me with explanation:

gcc 3.2 (mingw)

Folowing sources - which builded in DLL

in  header file
---------------------
calss CF1Variant
{
public
  CF1Variant& CF1Variant::operator=(CF1Variant const& var);
  CF1Variant& operator=(const CF1Reference& ref);
  CF1Variant& operator=(const CF1ConstReference& ref);
}

Library compiled and builded
but when I use in another source (another DLL ) 
    CF1Variant t1(tag);
    CF1Variant t2(tag);
    t1=t2;
compiled fine , but in Linking step
I have got follows error (???)
undefined reference to `CF1Variant::operator=(CF1Variant const&)'



Can you help me - how should string in def file for my CFVariant library
for I can check - is this operator properly esported ?


In present DEF file I CAN't seee any poits for this operator ....