gcc/testsuite/gnat.dg/unchecked_convert1.adb

   1 -- { dg-do run }
   2 -- { dg-options "-gnatws" }
   3
   4 with Ada.Unchecked_Conversion;
   5
   6 procedure Unchecked_Convert1 is
   7
   8   type Byte is mod 2**8;
   9
  10   type Stream is array (Natural range <>) of Byte;
  11
  12   type Rec is record
  13     I1, I2 : Integer;
  14   end record;
  15
  16   function Do_Sum (R : Rec) return Integer is
  17   begin
  18     return R.I1 + R.I2;
  19   end;
  20
  21   function Sum (S : Stream) return Integer is
  22     subtype Chunk is Stream (1 .. Rec'Size / 8);
  23     function To_Chunk is new Ada.Unchecked_Conversion (Chunk, Rec);
  24   begin
  25     return Do_Sum (To_Chunk (S(S'First ..  S'First + Rec'Size / 8 - 1)));
  26   end;
  27
  28   A : Stream (1..9) := (others => 0);
  29   I : Integer;
  30
  31 begin
  32   A (9) := 1;
  33   I := Sum (A(1..8));
  34 end;