[Bug middle-end/10138] warn for uninitialized arrays passed as const* arguments

["bangerth at dealii dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #16 from bangerth at dealii dot org  2007-08-20 16:21 -------
(In reply to comment #15)

> Of course, the output is '5' and not '0'. So yes, atoi() seems perfectly able
> to  initialize buf. (or perhaps, I am still confused).

I think you are. This program here segfaults:
---------------------
#include <cstdio>

const int i=0;

void use(const int *a)
{
  int * b = (int *)a;
  b[0] = 5;
}

int main(void)
{
  use(&i);
  printf("%d\n", i);
  return 0;
}
----------------------------
Since use() (like atoi) can't know whether its argument is a local automatic
or a global variable, there is no way for it to reliably initialize its
argument. Casting away constness invokes undefined behavior if the static
type of the object is const.

W.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=10138