Did I find a bug here?

[reinert <reinkor@gmail.com>]

Assume this simple program:

procedure test0 is
  type ABC_Type is (A,B,C);
  subtype AB_Type is ABC_Type with Static_Predicate => AB_Type in A | B;
  X : ABC_type    := A;
begin
-- alternative 1:  
case AB_Type(X) is
    when A => null;
    when B => null;
    when others => null; -- ??? should the compiler complain here?
  end case;
--alternative 2:
  case AB_Type(X) is
    when A => null;
    when B => null;
  end case;
end test0;

Should the compiler complain about "when others => null" here?
My compiler does not (running debian 10, updated, gnat-8).
I find it strange that both alternatives goes through.

reinert