generic
   type Item (<>) is private;
   with function "=" (L, R : Item) return Boolean is <>;
package pak1 is
end pak1;


with pak1;
package pak2 is
   type T is tagged null record;
   package new_pak1a is new pak1 (Item => T'Class);    --OK by AI05-71
   package new_pak1b is new pak1 (Item => T'Class, "=" => "=");       --ERROR:
   package new_pak1c is new pak1 (Item => T'Class, "=" => pak2."=");  --ERROR:
end pak2;

The compiler accepts this program; it should reject new_pak1b and new_pak1c because function "=" (L, R : T'Class) does not exist.  The equality operator is defined only for "specific type T that is not limited, and not an anonymous access type" (ARM 4.5.2(6)); class-wide types are not "specific" per ARM 3.9(3).

The reason why new_pak1a is legal is because of the special rule in AI05-71 which only applies when _not_ specifying an actual for the generic formal "=".