[Bug tree-optimization/110743] Unexpected -ftrivial-auto-var-init=pattern behavior with partial bitfields

[arnd at linaro dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110743

--- Comment #5 from Arnd Bergmann <arnd at linaro dot org> ---
I came across another warning of this type in the Linux kernel with gcc-16.1,
reduced a test case to

https://godbolt.org/z/K8974sEq9

void security_add_hooks(void *);
struct layer_mask {
  int access : 7;
};
struct layer_masks {
  struct layer_mask layers[5];
};
void hook_unix_find(void)
{
  struct layer_masks layer_masks;
  security_add_hooks(&layer_masks);
}

In kernel builds, this only happens with gcc-16 and not with earlier versions,
but the reduced test case still happens with gcc-12, which introduced
-ftrivial-auto-var-init=pattern