Re: [fpc-pascal] Class var in record breaks pointer cast

2026-02-06 Thread Sven Barth via fpc-pascal 
Martin Frb via fpc-pascal  schrieb am Do.,
5. Feb. 2026, 15:54:

> On 05/02/2026 15:45, Martin Frb via fpc-pascal wrote:
> "class var" seems to start a section, like "public type"
>

It not only seems so, it *is* so.

While it's not explicitly me mentioned for records it is somewhat mentioned
for classes:
https://www.freepascal.org/docs-html/current/ref/refsu24.html#x74-980006.3.2

Regards,
Sven

>
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Re: [fpc-pascal] Class var in record breaks pointer cast

2026-02-05 Thread Hairy Pixels via fpc-pascal 
 On Feb 5, 2026 at 9:54:04 PM, Martin Frb via fpc-pascal <
[email protected]> wrote:

> type
>   TMyRec = record
> class var
>z: UInt32;
> var  // new section, normal fields // tested 3.3.1
>   x, y: UInt32;
>   end;
>

oh it was a parsing issue, good find, thanks. For some reason I thought
"class" could only contain one list of names.
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Re: [fpc-pascal] Class var in record breaks pointer cast

2026-02-05 Thread Martin Frb via fpc-pascal 

On 05/02/2026 15:45, Martin Frb via fpc-pascal wrote:






type
  TMyRec = record
    class var z: UInt32;
    x, y: UInt32;
  end;





Ok found something...

I tried debugging, and noted that with the class var, the record had no 
debug info for any field.

And expecting memory did not reveal any data, if wrote to other fields.

"class var" seems to start a section, like "public type"

So all 3 fields in your example are class vars.

Try the below:

type
  TMyRec = record
    class var
       z: UInt32;
    var  // new section, normal fields // tested 3.3.1
      x, y: UInt32;
  end;

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Re: [fpc-pascal] Class var in record breaks pointer cast

2026-02-05 Thread Martin Frb via fpc-pascal 

On 05/02/2026 14:42, Martin Frb via fpc-pascal wrote:

On 05/02/2026 14:34, Hairy Pixels via fpc-pascal wrote:
Is this a bug? Adding the class var field changes prints 0 and 
without it prints 100 as expected. The class var is just a static 
field that isn't actually part of the record so how could it affect 
the memory layout?


A class var is (as the name suggest "not instance") not part of the 
instance. (instead a scoped global var).


So a pointer to the instance can not be to the memory that holds the 
class var data.


Sorry, strike above / messed up the field names while reading. You 
aren't accessing "z".



My bad.





type
  TMyRec = record
    class var z: UInt32;
    x, y: UInt32;
  end;

var
  r: TMyRec;
  p: pointer;
begin
  r.x := 100;
  p := @r;

  writeln(PUInt32(p)^);
end.


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Re: [fpc-pascal] Class var in record breaks pointer cast

2026-02-05 Thread Martin Frb via fpc-pascal 

On 05/02/2026 14:34, Hairy Pixels via fpc-pascal wrote:
Is this a bug? Adding the class var field changes prints 0 and without 
it prints 100 as expected. The class var is just a static field that 
isn't actually part of the record so how could it affect the memory 
layout?


A class var is (as the name suggest "not instance") not part of the 
instance. (instead a scoped global var).


So a pointer to the instance can not be to the memory that holds the 
class var data.




type
  TMyRec = record
    class var z: UInt32;
    x, y: UInt32;
  end;

var
  r: TMyRec;
  p: pointer;
begin
  r.x := 100;
  p := @r;

  writeln(PUInt32(p)^);
end.


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