[Bug target/120326] problems with attribute __ms_struct__

[uecker at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120326

--- Comment #3 from uecker at gcc dot gnu.org ---
Those should not get the same TYPE_CANONICAL. tagged_types_tu_compatible_p
should be changed to detect this case which is due to different packing of bit
fields. It works correctly for this:

struct {
  unsigned char a;
  unsigned char b;
  unsigned long c;
} a;
struct {
  unsigned char a;
  unsigned char b;
  unsigned long c;
} __attribute__((packed)) b;