Hi,

Could it be correct that there's a bug in Delphi7 where the compiler directive {$Q-} and {$Q+} works completely the 
opposite?

When trying to build an existing Delhi 7 project in Delphi 2010 i found this weird behaviour.
In D7 {$Q-} set overflow cheking on and in Delphi 2010 off ?????

Regards,
Arno Brinkman
ABVisie

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Arno Brinkman wrote:

> Could it be correct that there's a bug in Delphi7 where the compiler
> directive {$Q-} and {$Q+} works completely the opposite?

Assuming D7 build 8.1, not very likely.
 
> When trying to build an existing Delhi 7 project in Delphi 2010 i
> found this weird behaviour.  In D7 {$Q-} set overflow cheking on and
> in Delphi 2010 off ?????

Could it be that you use include files where overflow checking is
turned on/off based on VERxxx defines and that you did not include the
VER210 yet?

-- 
Pieter

'That seems to point up a significant difference between Europeans
 and Americans. A European says: "I can't understand this, 
 what's wrong with me?" An American says: "I can't understand 
 this, what's wrong with him?"' -- Terry Pratchett

Hello Pieter,

>> Could it be correct that there's a bug in Delphi7 where the compiler
>> directive {$Q-} and {$Q+} works completely the opposite?
>
> Assuming D7 build 8.1, not very likely.

Yes, that build.

>> When trying to build an existing Delhi 7 project in Delphi 2010 i
>> found this weird behaviour.  In D7 {$Q-} set overflow cheking on and
>> in Delphi 2010 off ?????
>
> Could it be that you use include files where overflow checking is
> turned on/off based on VERxxx defines and that you did not include the
> VER210 yet?

I can very easy reproduce this.
Simple make a new application in Delphi 7.
Drop a button on the form, double click and enter this code there:

procedure TForm1.Button1Click(Sender: TObject);
var
  lTotal, lIndex: Integer;
begin
{$OVERFLOWCHECKS OFF}
  lTotal := 0;
  for lIndex := 1 to 20 do
  begin
    lTotal := (131 * lTotal) + 97;
  end;
  lTotal := Abs(lTotal);
{$OVERFLOWCHECKS ON}
end;


Save the project and run the application in Delphi 7, i get an overflow error.

Reopen the application in Delphi 2010 and no overflow error.


Regards,
Arno Brinkman
ABVisie

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Firebird open source database with many powerful SQL features:
  http://www.firebirdsql.org
  http://www.firebirdsql.info

General database developer support:
  http://www.databasedevelopmentforum.com

Support list for Interbase and Firebird users:
  firebird-support@yahoogroups.com

Nederlandse firebird nieuwsgroep:
  news://newsgroups.firebirdsql.info

"Arno Brinkman" wrote:
> I can very easy reproduce this.
> Simple make a new application in Delphi 7.
> Drop a button on the form, double click and enter this code there:
>
> procedure TForm1.Button1Click(Sender: TObject);
> var
>  lTotal, lIndex: Integer;
> begin
> {$OVERFLOWCHECKS OFF}
>  lTotal := 0;
>  for lIndex := 1 to 20 do
>  begin
>    lTotal := (131 * lTotal) + 97;
>  end;
>  lTotal := Abs(lTotal);
> {$OVERFLOWCHECKS ON}
> end;
>
>
> Save the project and run the application in Delphi 7, i get an 
> overflow error.
>
> Reopen the application in Delphi 2010 and no overflow error.

Arno,

I can confirm that Q+ and Q- are inverted in operation also in D2005.
Looking at the disassembly, there are JNO:s in the Q- state and not in 
the Q+ state.

Regards
Tom

Arno Brinkman wrote:

> > Assuming D7 build 8.1, not very likely.
> 
> Yes, that build.
> 
> > > When trying to build an existing Delhi 7 project in Delphi 2010 i
> > > found this weird behaviour.  In D7 {$Q-} set overflow cheking on
> > > and in Delphi 2010 off ?????
> > 
> > Could it be that you use include files where overflow checking is
> > turned on/off based on VERxxx defines and that you did not include
> > the VER210 yet?
> 
> I can very easy reproduce this.
> Simple make a new application in Delphi 7.
> Drop a button on the form, double click and enter this code there:
> 
> procedure TForm1.Button1Click(Sender: TObject);
> var
>  lTotal, lIndex: Integer;
> begin
> {$OVERFLOWCHECKS OFF}
>  lTotal := 0;
>  for lIndex := 1 to 20 do
>  begin
>    lTotal := (131 * lTotal) + 97;
>  end;
>  lTotal := Abs(lTotal);
> {$OVERFLOWCHECKS ON}
> end;
> 
> 
> Save the project and run the application in Delphi 7, i get an
> overflow error.

Indeed strange when you use them inside a method the effect seems to be
reversed. Moving them outside the method should work OK.

> Reopen the application in Delphi 2010 and no overflow error.

So whatever the cause was, it looks like this is fixed in the later
versions.

-- 
Pieter

"Let's not bring age into this discussion. I will not let 
 my opponent's youth and inexperience become an issue."
 -- Ronald Reagan on Walter Mondale
...

Hi,

>> Save the project and run the application in Delphi 7, i get an
>> overflow error.
>
> Indeed strange when you use them inside a method the effect seems to be
> reversed. Moving them outside the method should work OK.
>
>> Reopen the application in Delphi 2010 and no overflow error.
>
> So whatever the cause was, it looks like this is fixed in the later
> versions.

Yes, but because we share code between projects we need to solve it by IFDEFs VERxxx.

Something for in the "notes or gotchas when converting to D2010" list :-)

Result can be worser then you think, cause when you expect error when an overflow happens, it doesn't happen...

Regards,
Arno Brinkman
ABVisie

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Firebird open source database with many powerful SQL features:
  http://www.firebirdsql.org
  http://www.firebirdsql.info

General database developer support:
  http://www.databasedevelopmentforum.com

Support list for Interbase and Firebird users:
  firebird-support@yahoogroups.com

Nederlandse firebird nieuwsgroep:
  news://newsgroups.firebirdsql.info