E2599 Field definition not allowed in helper type (Delphi)

This occurs whenever you try to define a field inside a helper type.

type
  aRecord = record
  end;
  aHelperRecord = record helper for aRecord
    A: Integer; // issues error: E2599
  end;

This can be fixed by only declaring methods in the helper type.

type
  aRecord = record
  end;
  aHelperRecord = record helper for aRecord
    function A: Integer; 
  end;

See Also