Hi,

While trying to solve https://bugs.freepascal.org/view.php?id=38306 I got this error I have never seen before.

_gdeque.pp(249,4) Error: Global Generic template references static symtable _gdeque.pp(302) Fatal: There were 1 errors compiling module, stopping Fatal: Compilation aborted

Line 249 is the "end;" of a method (IncreaseCapacity) of a generic class.

If I remove this line the error goes away:

Elems := Min(EmptyElems, FStart);
Elems and EmptyElems are local vars to that method. FStart is a private variable of the class.

function Min(const A,B: SizeUInt): SizeUInt;  //no need to drag in the
entire Math unit ;-)
begin
  if (A<B) then
    Result := A
  else
    Result := B;
end;

This function is not part of the class definition. I defined it in the implementation section of the unit.

Once I moved that function to be a nested function of the method IncreaseCapacity (it's only used there), the error goes away.

It seems I cannot use a stand-alone function that is declared in the implementation of the unit?
Why is that?

Bart

Bart via fpc-devel schrieb am Fr., 8. Jan.
2021, 20:07:

It seems I cannot use a stand-alone function that is declared in the implementation of the unit?

Correct.

Why is that?

Generics are a stream of tokens that is reparsed when specialized. Functions declared in the implementation section are simply not available then thus its forbidden right away. This is Delphi compatible.

Regards,
Sven

PM Sven Barth wrote

> It seems I cannot use a stand-alone function that is declared in the > implementation of the unit? Generics are a stream of tokens that is reparsed when specialized. Functions declared in the implementation section are simply not available then thus its forbidden right away. This is Delphi compatible.

Thanks for explaining this.
The errormessage is probably technically correct, but for me it might be a little more informative (so that I can tell what I did wrong).

Bart via fpc-devel schrieb am Sa., 9. Jan.
2021, 05:17:

Right click the error message in Lazarus, then click "Help". For me a dialog with the following text appeared:

"A generic declared in the interface section of a unit must not reference symbols that belong solely to the implementation section of that unit."

The *why* is not important for users. Those that are interested can ask, just like you did.

Regards,
Sven

PM Sven Barth wrote

Right click the error message in Lazarus, then click "Help". For me a dialog with the following text appeared:

Hah!
Learned something new today!

The *why* is not important for users. Those that are interested can ask, just like you did.

Then let me rephrase it.
Error messages of the compiler normally point you in the right direction like:

  qtest.lpr(367,3) Fatal: Syntax error, ";" expected but "identifier

TESTINCCAP" found
It's sort of obvious there is a missing semicolon.

OTOH: "Global Generic template references static symtable" only means something to me (as an fpc user) if I know what a static symtable is (I assume this is an internal datastructure in the compiler). Since I have no clue, I have absolutely no idea how to fix that error. In my case I commented out all lines in the given procedure and uncommented them one by one to finally get at the offending line in question.
I then made an educated guess that (sine accessing functions like Format() is OK), it must have something to do with the declaration of the "Min()" function.

It would have helped if the error message was a little less cryptic, and/or if it pointed to the line that caused the error in the first place.

Of course I have no idea wether or not this error message only applies to the situation I encountered...

Bart

I have clarified the message a bit.

Displaying the message at the correct location would be more involved... you might want to open a bug report for that so that it's remembered somewhere, but it's definitely going to be a low priority one.

Regards,
Sven

AM Sven Barth wrote

Displaying the message at the correct location would be more involved... you might want to open a bug report for that so that it's remembered somewhere, but it's definitely going to be a low priority one.

https://bugs.freepascal.org/view.php?id=38342

Bart via fpc-devel schrieb am Mo., 11.
Jan. 2021, 03:42:

Thanks.

Regards,
Sven