[Bug tree-optimization/22043] New: [4.0/4.1 Regression] Fields not initialized for automatic structs with flexible array members

["jakub at redhat dot com" <gcc-bugzilla at gcc dot gnu dot org>]

In:
extern void abort (void);

struct A { int i; int j; int k; int l; };
struct B { struct A a; int r[1]; };
struct C { struct A a; int r[0]; };
struct D { struct A a; int r[]; };

void
foo (struct A *x)
{
  if (x->i != 0 || x->j != 5 || x->k != 0 || x->l != 0)
    abort ();
}

int
main ()
{
  struct B b = { .a.j = 5 };
  struct C c = { .a.j = 5 };
  struct D d = { .a.j = 5 };
  foo (&b.a);
  foo (&c.a);
  foo (&d.a);
  return 0;
}

GCC 4.0/HEAD only zero initialize a.i, a.k and a.l for the b variable, not for
c nor d, while 3.4.x and older initialized them for all 3 variables.
This causes miscompilation of glibc by GCC 4.0+.

-- 
           Summary: [4.0/4.1 Regression] Fields not initialized for
                    automatic structs with flexible array members
           Product: gcc
           Version: 4.0.1
            Status: UNCONFIRMED
          Severity: critical
          Priority: P2
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jakub at redhat dot com
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22043