[Bug c/53091] Const assignment fails in GCC 4.2, 4.4, 4.6, 4.7 - works fine in clang

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53091

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-04-23 
18:38:29 UTC ---
The bug reporting guidelines ask for source code, not a URL.

Here's the code from the URL

#include <stdio.h>

const int SDL_HAT_UP = 0x01;
const int SDL_HAT_RIGHT = 0x02;
const int SDL_HAT_RIGHTUP = (SDL_HAT_RIGHT | SDL_HAT_UP);

int main(int argc, char **argv)
{
  printf("%x\n",SDL_HAT_RIGHTUP);
  return 0;
}

I think GCC is correct, the code is valid C++ but not valid C.

In C the initializer for a global variable must be a constant expression ("All
the expressions in an initializer for an object that has static storage
duration shall be constant expressions or string literals.") and (SDL_HAT_RIGHT
| SDL_HAT_UP) is not a constant expression.

http://c-faq.com/ansi/constasconst.html

I believe Clang is allowed to accept the code because the C standard also says
implementations may accept other forms of constant expression.