[Lazarus] Lazarus Bug: No exception raised when attempting to access an array outside of range.

[Michael Van Canneyt]

On Mon, 1 May 2017, Graham Ward via Lazarus wrote:

> Hi,
>
> Apologies if this email has been sent to the wrong location (I'm a brand 
> new user to the Lazarus emailing list).
>
> Note I even tried the following line, which is obviously wrong (as the 
> array has a maximum index of 71)
>
>    ColIndex[175] := 500;
>
> In other languages (that I am more familiar with) an exception (Error : 
> Array index outside of range) would have been raised. Why does the 
> Lazarus compiler not raise a similar error?

The Free Pascal compiler does not do range checking by default, you need to
enable it  with -Cr (there is an option in the project option dialog).

araminta: ~ >fpc ta.pp -Cr
araminta: ~ >./ta
Runtime error 201 at $00010D50
   $00010D50
araminta: ~ >cat ta.pp

Var
   I : Integer;
   A : Array of byte;
   B :  Array of byte;

begin
   SetLength(A,12);
   SetLength(B,12);
   for I:=0 to length(A)+1 do
     A[i]:=1;
end.

Michael.