Atomic operations and unaligned memory

[Jason Merrill <jason at redhat dot com>]

The wiki page https://gcc.gnu.org/wiki/Atomic/GCCMM/UnalignedPolicy says,

---
  typedef char B3[3];
  _Atomic B3 obj2;

An object will be promoted up to the next lock-free size in order to 
enable lock free operations, as long as it isn't already a documented 
lock free size. So obj2 will be promoted to a 4 byte object with 
whatever alignment is required in order to enable lock-free operations.
---

But the implementation doesn't follow this.  First, the above is 
rejected due to applying _Atomic to an array type.  If we wrap the array 
in a struct, the resulting atomic object still has size 3 and alignment 1.

Did the design change, or is this a bug?

Jason