Re: [fpc-devel] Incompatible assignments but no compile error (char array and shortstring)

[Sven Barth via fpc-devel]

Am 16.04.2022 um 22:35 schrieb Wayne Sherman via fpc-devel:
Tested with fpc 3.3.1 trunk (as of 2022-Mar-12) and 3.2.2 stable.
Ubuntu 20.04 64-bit
Good compile time error checking is one of the wonderful things about
Pascal.  But some char array and shortstring assignments which are not
size compatible do not produce a compile error as expected.  Please
see below.

{$mode objfpc}{$H+}
type
   TCharArray8    = packed array[0..7] of Char;
   TCharArray9    = packed array[0..8] of Char;
   TShortString8  = string[8];

const
   StringConst8 = '12345678';
   StringConst9 = '123456789';

   CharArrayConst8a: TCharArray8 = '12345678';
   CharArrayConst8b: TCharArray8 = StringConst8;
   CharArrayConst8c: TCharArray8 = ('1','2','3','4','5','6','7','8');

   //CharArrayConst8d: TCharArray8 = '123456789';   //compile error as expected
   //CharArrayConst8e: TCharArray8 = StringConst9;  //compile error as expected
   //CharArrayConst8f: TCharArray8 =
('1','2','3','4','5','6','7','8','9'); //compile error as expected

   ShortStringConst8a: TShortString8 = '12345678';
   ShortStringConst8b: TShortString8 = StringConst8;
   ShortStringConst8c: TShortString8 = '123456789';   //did not get
expected compile error (bug?)
   ShortStringConst8d: TShortString8 = StringConst9;  //did not get
expected compile error (bug?)

var
   CharArrayVar8:   TCharArray8;
   CharArrayVar9:   TCharArray9;
   ShortStringVar8: TShortString8;

begin
   CharArrayVar8 := '12345678';
   CharArrayVar8 := StringConst8;
   CharArrayVar8 := ['1','2','3','4','5','6','7','8'];  //requires fpc 3.3.1
   CharArrayVar8 := CharArrayConst8c;

   //CharArrayVar8 := ['1','2','3','4','5','6','7','8','9']; //compile
error as expected
   CharArrayVar8 := '123456789';   //did not get expected compile error (bug?)
   CharArrayVar8 := StringConst9;  //did not get expected compile error (bug?)

   CharArrayVar8 := ShortStringVar8;
   ShortStringVar8 := CharArrayVar8;

   ShortStringVar8 := '12345678';
   ShortStringVar8 := CharArrayConst8a;
   ShortStringVar8 := TCharArray8(['1','2','3','4','5','6','7','8']);
//requires fpc 3.3.1

   ShortStringVar8 := '123456789';   //did not get expected compile error (bug?)
   ShortStringVar8 := CharArrayVar9; //did not get expected compile error (bug?)
   ShortStringVar8 :=
TCharArray9(['1','2','3','4','5','6','7','8','9']); //did not get
expected compile error (bug?) (requires fpc 3.3.1)

end;

Should I open a couple of bug reports?

For ShortString types it is by design that they're truncated implicitely 
(the most that current Delphi versions do is issue a warning). However 
the assignments to the static char array should be checked.

Regards,
Sven
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