M2compiler-V3/compiler/tests/t_variant.mod

MODULE TVariant;
(* Variant records: plain fields pack before the CASE tag; every
   branch's fields overlay in one region after the tag.  Exit 31. *)
VAR ExitCode : INTEGER;
TYPE
  Kind = (circle, square, rect);
  Shape = RECORD
    id : INTEGER;
    CASE k : Kind OF
      circle : radius : INTEGER;
    | square : side : INTEGER;
    | rect : w, h : INTEGER;
    END;
  END;
VAR s : Shape;
BEGIN
  ExitCode := 0;
  s.id := 7;
  s.k := rect;
  s.w := 3;
  s.h := 4;
  IF s.id = 7 THEN ExitCode := ExitCode + 1 ELSE ExitCode := 100 END;
  IF s.k = rect THEN ExitCode := ExitCode + 2 ELSE ExitCode := 101 END;
  IF s.h = 4 THEN ExitCode := ExitCode + 4 ELSE ExitCode := 102 END;

  (* w and h share storage: the last store wins *)
  s.w := 9;
  IF s.h = 9 THEN ExitCode := ExitCode + 8 ELSE ExitCode := 103 END;

  (* switching branch reuses the same slot *)
  s.k := square;
  s.side := 5;
  IF s.side = 5 THEN ExitCode := ExitCode + 16 ELSE ExitCode := 104 END
END TVariant.