Does you cfe consider this code in error?

Clang Frontend
1

clang and EDG reject the following code (GCC accepts it),

struct {
   char control[((int)(char *)2)];
} xx;

What about your cfe?

Thanks,

snaroff

2

I just noticed that GCC does complain if the "char *" is the topmost cast.

[steve-naroffs-imac:llvm/tools/clang] snaroff% ../../Debug/bin/clang ary.c
ary.c:3:16: error: size of array has non-integer type 'char *'
   char control[(char *)2];
                ^~~~~~~~~

Looks like it could be a GCC bug related to how it does constant folding...

snaroff

3

I just noticed that GCC does complain if the "char *" is the topmost
cast.

[steve-naroffs-imac:llvm/tools/clang] snaroff% ../../Debug/bin/clang
ary.c
ary.c:3:16: error: size of array has non-integer type 'char *'
  char control[(char *)2];
               ^~~~~~~~~

This isn't legal simply because the size of an array must have an
integer type. This doesn't say anything useful.

struct {
  char control[((int)(char *)2)];
} xx;

"Cast operators in an integer constant expression shall only convert
arithmetic types to integer types", so (int)(char*)2 is not an ICE.
Therefore, the declarator declares a variable length array, and since
struct members aren't allowed to have a variably modified type, this
is illegal.

This was already discussed recently; see
http://lists.cs.uiuc.edu/pipermail/cfe-dev/2008-May/001771.html.

-Eli