-- { dg-do run } -- { dg-options "-gnatws" } with Ada.Unchecked_Conversion; procedure Unchecked_Convert1 is type Byte is mod 2**8; type Stream is array (Natural range <>) of Byte; type Rec is record I1, I2 : Integer; end record; function Do_Sum (R : Rec) return Integer is begin return R.I1 + R.I2; end; function Sum (S : Stream) return Integer is subtype Chunk is Stream (1 .. Rec'Size / 8); function To_Chunk is new Ada.Unchecked_Conversion (Chunk, Rec); begin return Do_Sum (To_Chunk (S(S'First .. S'First + Rec'Size / 8 - 1))); end; A : Stream (1..9); I : Integer; begin I := Sum (A(1..8)); end;