Lazarus setLength type mismatch - arrays

Question

i am building a Compiler and i get this Error Code, when i compile the programm:
compiler_main.pas(55,4) Error: Type mismatch
the code is the following:
unit Compiler_main;
{$mode objfpc}{$H+}
interface
uses
Classes, SysUtils, FileUtil, SynEdit, Forms, Controls, Graphics, Dialogs,
StdCtrls, ExtCtrls;
type
{ TForm1 }
TForm1 = class(TForm)
GroupBox1: TGroupBox;
GroupBox2: TGroupBox;
Image1: TImage;
Image2: TImage;
Splitter1: TSplitter;
Splitter2: TSplitter;
SynEdit1: TSynEdit;
SynEdit2: TSynEdit;
SynEdit3: TSynEdit;
procedure Image1Click(Sender: TObject);
procedure Image2Click(Sender: TObject);
procedure setForCompiling(var dataSect: array of String; var textSect: array of String; var bssSect: array of String);
procedure setDataSect (var dataSect: array of String);
//////////FUNCTIONS////////////////////
function compile () : boolean;
private
{ private declarations }
public
{ public declarations }
end;
var
Form1: TForm1;
var INTarray: array of integer;
implementation
{$R *.lfm}
{ TForm1 }
{
procedure Tform1.setTextSect (var textSect: array of String);
begin
end; }
procedure Tform1.setDataSect(var dataSect: array of String);
begin
setLength (dataSect, 1);
dataSect[0]:= 'section .data';
end;
procedure Tform1.setForCompiling(var dataSect: array of String; var textSect: array of String; var bssSect: array of String);
begin
Synedit2.Lines.Clear;
Synedit3.Lines.Clear;
setDataSect (dataSect);
end;
function getMistake (mistake: boolean) : boolean;
begin
if mistake = false then
begin
getMistake:= true;
end else
begin
getMistake:= false;
end;
end;
function Tform1.compile() : boolean;
var momLine : integer = 0;
var totalLines : integer;
var posBracketOpen : Byte;
var posBracketClose : Byte;
var posTextBracketOpen : Byte;
var posTextBracketClose: Byte;
var mistake : boolean = false;
var dataASM : array of string;
var textASM : array of string;
var bssASM : array of String;
begin
setForCompiling(dataASM, textASM, bssASM);
totalLines:= synEdit1.lines.count;
while momline < totalLines do
begin
inc (momline);
end;
compile:= getMistake (mistake);
end;
procedure TForm1.Image1Click(Sender: TObject);
begin
Showmessage ('Ein deutscher Compiler, programmiert von NONAME. NUR UNTER LINUX BENUTZBAR!');
end;
procedure TForm1.Image2Click(Sender: TObject);
begin
if Compile = true then
begin
Synedit3.Lines.add ('Fehlerfrei Compiliert!');
end else
begin
Synedit3.Lines.add ('Es wurde mindestens ein Fehler festgestellt! Bitte korrigiere diesen.');
end;
end;
end.
my Programm is programmed in Lazarus and bases on NASM and gets Compiled in the newest Laz-version in Linux.
I hope, you can help me.
Ok, it works now.

Answer 1

This is the setLength that generates error:
procedure Tform1.setDataSect(var dataSect: array of String);
begin
setLength (dataSect, 1);
dataSect[0]:= 'section .data';
end;
This code is incorrect because dataSect is not a dynamic array as you would expect but an open array parameter that you can't change.
You will need to change your function declaration to not use open array:
first use builtin type TStringDynArray (I am not sure if it available in Lazarus), or declare it like
type TStringDynArray = array of string;
Then use this type everywhere instead array of string.
procedure Tform1.setDataSect(dataSect: TStringDynArray);
begin
setLength (dataSect, 1);
dataSect[0]:= 'section .data';
end;
Also you don't need to use var parameter var dataSect: TStringDynArray - dynamic arrays are always passed by reference and all changes will be applied to original array, if you want to prevent this - you will need to explicitly create new copy of array like NewDataSect := Copy(dataSect);