Old project cannot be compiled in Delphi 4 due to pointers issue

I'm not experienced in Delphi at all and I have a very old project that can be compiled in Delphi of 2nd,3rd versions but isn't working in Delphi 4. The problem is about pointers that are working differently in the newer version.

These pieces of code cause error "Variable required":

pEnabled := @pClrWire_s^.enabled;

pEnabled        := @Enabled;

pNEnabled    := @pName_s^.Enabled;

where pEnabled is:

const
pEnabled : ^boolean   = nil;

and pClrWire_s and pName_s are pointers as well:

pClrWire_s : TpImage;      {pointer to an image of colored wire}
pName_s    : TpNamed;      {pointer to the identifier}

Description of TpImage and TpNamed are found in other files of the project:

type
  TpImage   = ^TImage;

TpNamed = ^TNamed;
TNamed = class(TLabel)

Can this problem be solved without serious rewriting of the whole code? and what causes such problem with Delphi 4?

Solution

Here is a complete solution tested with latest Delphi (D10.3 which really is Delphi version 26 if you compare with early Delphi version number, but that is an other story):

unit Unit1;

interface

uses
  Winapi.Windows, Winapi.Messages,
  System.SysUtils, System.Variants, System.Classes,
  Vcl.Graphics, Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.ExtCtrls;

type
  TpImage = ^TImage;

{$J+}   // enable writable constant
const
  pEnabled : ^boolean   = nil;

var
  pClrWire_s : TpImage;

type
  TForm1 = class(TForm)
  private

  public

  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

end.

As Dalija Prasnikar and Gerry Coll said in their respective comment, the key is to enable assignable typed constant. You can do it either using {$J+} in the source code or using the project options located at Project options / Building / Delphi compiler / Compiling / Syntax options / Asignable typed constant.

Let me know if it works for you.