gcc/testsuite/gnat.dg/specs/size_clause2.ads

-- { dg-do compile }
-- { dg-options "-gnatws" }

package Size_Clause2 is

  -- The alignment of the record is capped to the greatest power of 2
  -- factor of the size, so that the real size is 40 too and the size
  -- of a component of type R1 in a packed record can be 40.
  type R1 is record
    I : Integer;
    B : aliased Boolean;
  end record;
  for R1'Size use 40;

  type S1 is record
    rr : R1; -- size must be 40
  end record;
  pragma Pack(S1);

  -- The record is explicitly given alignment 1 so its real type is 40 too.
  -- The size of a component of type R2 in a packed record is naturally 40.
  type R2 is record
    I : Integer;
    B : aliased Boolean;
  end record;
  for R2'Size use 40;
  for R2'Alignment use 1;

  type S2 is record
    rr : R2; -- size must be 40
  end record;
  pragma Pack(S2);

  -- The record is explicitly given alignment 4 so its real type is 64.
  -- That's not OK, because the size of a component of type R3 in a packed
  -- record cannot be 40 so the size clause is violated.
  type R3 is record
    I : Integer;
    B : aliased Boolean;
  end record;
  for R3'Size use 40;  -- { dg-error "size for .R3. too small" }
  for R3'Alignment use 4;

  type S3 is record
    rr : R3; -- size must be 40
  end record;
  pragma Pack(S3);

end Size_Clause2;