Hello,

I'm just porting some C code to pascal. This code contains constant structure definitions which use other constants of simple types.

However FPC reports "Error: Illegal expression" when using a constant within an constant record definition.

program Project1;
type
  TMyRecord = record
    x: Integer;
  end;
const                  
  MYRECORDCONST2: TMyRecord = (x: 5); //< compiles fine
  MYINTEGERCONST: Integer = 5;        //< defining integer const
  MYRECORDCONST1: TMyRecord = (x: MYINTEGERCONST); //< using constant is
no possible
begin
end.

Is this intended or should I fill in a bug report? If it's intendet, I'm wondering why?

Regards
Simon Ameis

For historical reasons, "MYINTEGERCONST: Integer = 5" does not declare a constant, but an initialised variable. To declare a constant, use

const
   MYINTEGERCONST = 5;

If you want to explicitly specify its type, you can use

const
   MYINTEGERCONST = Integer(5);

Jonas

Op 2019-06-12 om 22:25 schreef Simon Ameis:

myintegerconst is a typed initialized variable depending on the $J state.

Use

   MYINTEGERCONST = Integer ( 5);

to define a true integer const. True consts don't occupy memory.

Hello
Typed constants work just like initialized variables. Maybethis is the problem?

Try:
MYINTEGERCONST = 5;
or
MYINTEGERCONST = Integer(5);

Regards,
Michał.

W dniu 2019-06-12 o 22:25, Simon Ameis pisze:

PM Simon Ameis wrote

MYINTEGERCONST: Integer = 5; //< defining integer const

It's a writeable constant, so not a constant consta if you get my drift. Declaring it just as

  MyIntegerConst = 5;

might work just fine. I'm too lazy to chek that for you.

It's not a bug. There's no support in FPC/Pascal for using constants with a defined type in other declarations.
Define your MYINTEGERCONST without a type, and it should work.

const
  MYINTEGERCONST = 5;

Dejan Boras wrote

It's not a bug. There's no support in FPC/Pascal for using constants with a defined type in other declarations. Define your MYINTEGERCONST without a type, and it should work.

Thanks all. It was a bit late and while working with existent code, I didn't came up with this idea.

The compiler switch {$WriteableConst OFF} doesn't change anything in regards to typed constants. The only way is to use real constants which may have an explicit typecast.