gdb/testsuite/gdb.ada/unchecked_union/unchecked_union.adb

   1 --  Copyright 2019-2020 Free Software Foundation, Inc.
   2 --
   3 --  This program is free software; you can redistribute it and/or modify
   4 --  it under the terms of the GNU General Public License as published by
   5 --  the Free Software Foundation; either version 3 of the License, or
   6 --  (at your option) any later version.
   7 --
   8 --  This program is distributed in the hope that it will be useful,
   9 --  but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 --  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11 --  GNU General Public License for more details.
  12 --
  13 --  You should have received a copy of the GNU General Public License
  14 --  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  15
  16 with System;
  17 with Pck; use Pck;
  18
  19 procedure Foo is
  20    type Key is (Alpha, Omega);
  21
  22    type Inner(Disc : Key := Omega) is record
  23       case Disc is
  24          when Alpha =>
  25             Small : Integer range 0..255;
  26          when others =>
  27             Large : Integer range 255..510;
  28       end case;
  29    end record;
  30    pragma Unchecked_Union (Inner);
  31
  32    type Outer(Disc : Key := Alpha) is record
  33       case Disc is
  34          when Alpha =>
  35             Field_One : Integer range 0..255;
  36          when others =>
  37             Field_Two : Integer range 255..510;
  38       end case;
  39    end record;
  40    pragma Unchecked_Union (Outer);
  41
  42    type Pair is record
  43       Pone : Inner;
  44       Ptwo : Outer;
  45    end record;
  46
  47    Value : Pair;
  48
  49 begin
  50    Do_Nothing (Value'Address);          -- BREAK
  51 end Foo;