Hello everybody,

I'm happy to announce that release 2.1.4 aka 2.2.0 beta is out. We ask our users to test the changes made in the last few years. This beta will be available for about two months, whereafter 2.2.0 will be released. Helping us to test version 2.1.4 now, can avoid problems when you finally update your fpc-version to 2.2.0.

Greetings

Joost
(on behalf of the whole FPC team)

I stopped testing of 2.2, it can not be used with MSEide+MSEgui because of win32 widestring problems, sorry :-(

Martin

Hi,

I tried to compile my current project with the new compiler (2.1.4). This resulted in the following error:

-----8<-----
/home/bartek/Dev/units/vmath.pp(435,29) Error: Can't take the address of constant expressions
-----8<-----

-----8<-----
destructor TLazyVariableManager.Destroy;
var
	i: integer;
begin
	for i:=0 to LazyVariableList.count -1 do
		TLazyVector4(LazyVariableList.items[i]).Free;
	freeandnil(LazyVariableList); // <-- 435 is here
end;
-----8<-----
The definition is:
-----8<-----
	TLazyVariableManager = class
	private
		fLazyVariableList: TFPList;
	public
		constructor Create;
		destructor Destroy; override;
		procedure run;
                // properties
		property LazyVariableList: TFPList read fLazyVariableList write
fLazyVariableList;
	end;
-----8<-----
Seems like the handling of properties has changed. Replacing with
FLazyVariableList helps of course, but then again I get the same error here:
-----8<-----
/home/bartek/Dev/units/glgui/glgui.pp(376,26) Error: Can't take the address of
constant expressions
-----8<-----
constructor TGLGUI3DMouseMapper.Create(aOwnerDesktop: TGLGUIDesktop);
begin
	OwnerDesktop:=aOwnerDesktop;
	OwnerDesktop.MouseMapper:=self; // 376 is here
end;
-----8<-----
Definition snippet:
-----8<-----
                // properties
                property OwnerDesktop: TGLGUIDesktop read fOwnerDesktop write
fOwnerDesktop;
-----8<-----

What are the changes in handling properties? And how do I have to change my code to work again. Or what would be "the right thing" to do in my situation?

Thanks in advance
bartek

The error is IMO somewhat cryptic, but you cannot pass a property as var parameter anymore. This to be inline with properties implemented by a Setter.

Marc

Marc Weustink wrote

The error is IMO somewhat cryptic, but you cannot pass a property as var parameter anymore. This to be inline with properties implemented by a Setter.

Strange, this change has not yet been merged to the fixes branch (so it's definitely not yet in 2.1.4)

Jonas

This made me curious, and I checked my links. Seems like I accidentally compiled with fpc 2.3.1. I am very sorry, my bad :( . But OTOH, I still want to know what I need to do to get my code to work with 2.3.1 .

bartek

As Marc said: do not pass properties as var-parameters (regardless of the implementation of the properties).

Jonas

OK. And what about this:
-----8<-----
/home/bartek/Dev/units/glgui/glgui.pp(376,33) Error: Can't take the address of
constant expressions
-----8<-----
constructor TGLGUI3DMouseMapper.Create(aOwnerDesktop: TGLGUIDesktop);
begin
        OwnerDesktop:=aOwnerDesktop;
        OwnerDesktop.MouseMapper:=self; // 376 is here
end;
-----8<-----

Definition snippet:
-----8<-----
                // properties
                property OwnerDesktop: TGLGUIDesktop read fOwnerDesktop write fOwnerDesktop;
-----8<-----

bartek

You cannot write to fields of properties. The reason is that any property accessor should be transparently replaceable by a function call, and if you do that in the above expression then your assignment would change something inside the (temporary) function result rather than in the field.

Jonas

The problem is that the old behaviour was even buggy while the current is only unexpected.

Thank you very much, now everything works like a charm.

bartek