[fpc-devel]Another FPC versus Delphi issue

[Peter Vreman]

> While using FreePascal in our Programming Education and Contest Hosting
> system (PEACH), we encountered another issue.  Consider this program
> (students try strange things):
> 
> program LongArray;
> 
> var
>   a: array [ Integer ] of Integer;
>   i: Integer;
> 
> begin
> 
>   for i := 0 to 1000 do begin
>     a [ i ] := i
>   end { for i }
> 
> ; writeln ( a [ 1000 ] )
> end.
> 
> Under Delphi (v5) this gives an compile-time error (Data type too
> large:  exceeds 2GB).  Under fpc 1.0.4 it works without options
> (Integer is 16 bit), and crashes with option -Sd (Delphi mode, Integer
> is 32 bit): Segmentation fault.  Also fpc 1.1 made it crash.  By the
> way, WITHOUT option -gl (to get more extensive runtime error info), the
> crash is "silent", and you can only see it when you examine the exit
> status, which is 103 (file not open!?) or 139 when using option -Cr
> (range checking).
> 
> It seems to me that fpc should give a compile-time error, rather
> than crash.

It allocates only 4 bytes for the array. That will result in memory overwritting and the
strange behaviour you write.