This simple package causes a GNAT bug box

package Short is
   bug : Short_Integer;
end Short;

+===========================GNAT BUG DETECTED==============================+
| 4.1.0 20060116 (prerelease) AVR-Ada snapshot (avr-unknown-none) GCC error:|
| in gnat_to_gnu, at ada/trans.c:2588                                      |
| No source file position information available                            |


A somewhat related case is the derivation of Integer types:

package AVR_B2 is
   type Toto is new Integer;
end AVR_B2;