Generic function specialization compilation error

[Laurent92]

Hello,
I got this compilation error while experimenting with generic classes and functions and I have no idea what could have caused it.

Code: Text  [Select][+][-]

1. Free Pascal Compiler version 3.2.2 [2021/05/16] for aarch64
2. Copyright (c) 1993-2021 by Florian Klaempfl and others
3. Target OS: Darwin for AArch64
4. Compiling main.pas
5. fgl.pp(1668,8) Note: Call to subroutine "function TFPGMap<System.ShortString,System.Pointer>.IndexOf(const AKey:ShortString):LongInt;" marked as inline is not inlined
6. main.pas(44,1) Fatal: Internal error 2002071001
7. Fatal: Compilation aborted
8. Error: /usr/local/bin/ppca64 returned an error exitcode

Is this a bug of the compiler (should I open an issue on GitLab?) or is it simply not possible to do that with Objet Pascal?

Code: Pascal  [Select][+][-]

1. program main;
2.  
3. uses
4.   TypInfo, FGL;
5.  
6. type
7.   TIndex = 0..99;
8.   TGenericObjects = specialize TFPGMap<ShortString, Pointer>;
9.  
10.   generic TGenericObject<T> = class(TObject)
11.   private
12.     FList: array[TIndex] of T;
13.   public
14.     procedure Add(AIndex: TIndex; AElement: T);
15.   end;
16.  
17.   TGenericObjectFactory = class(TObject)
18.   public
19.     generic function GetGenericObject<T>: specialize TGenericObject<T>;
20.     generic procedure Add<T>(AIndex: TIndex; AElement: T);
21.   private
22.     FGenericObjects: TGenericObjects;
23.   end;
24.  
25. generic function TGenericObjectFactory.GetGenericObject<T>: specialize TGenericObject<T>;
26. var
27.   GenericObjectType: PTypeInfo;
28. begin
29.   GenericObjectType := TypeInfo(T);
30.   Result := specialize TGenericObject<T>(FGenericObjects[GenericObjectType^.Name]^);
31. end;
32.  
33. generic procedure TGenericObjectFactory.Add<T>(AIndex: TIndex; AElement: T);
34. var
35.   GenericObject: specialize TGenericObject<T>;
36. begin
37.   GenericObject := specialize GetGenericObject<T>; // <-- this line causes the bug
38.   GenericObject.Add(AIndex, AElement);
39. end;
40.  
41. procedure TGenericObject.Add(AIndex: TIndex; AElement: T);
42. begin
43.   FList[Aindex] := AElement;
44. end;
45.  
46. begin
47. end.

[Bart]

No internal error using fpc main, so probably fixed.
Now someone should test fpc 3.2 fixes branch.

Bart

[TRon]

Now someone should test fpc 3.2 fixes branch.

No issues with fixes 3.2 but tested on x86_64 only.

[Laurent92]

When I add a class type restriction to the generic methods, it compiles without error.

Maybe this helps the compiler because T can be anything without any restrictions.

Code: Pascal  [Select][+][-]

1. {$MODE OBJFPC}
2. {$H+}
3. program main;
4.  
5. uses
6.   TypInfo, FGL;
7.  
8. type
9.   TIndex = 0..99;
10.   TGenericObjects = specialize TFPGMap<ShortString, Pointer>;
11.  
12.   generic TGenericObject<T> = class(TObject)
13.   private
14.     FList: array[TIndex] of T;
15.   public
16.     procedure Add(AIndex: TIndex; AElement: T);
17.   end;
18.  
19.  
20.   TGenericObjectFactory = class(TObject)
21.   public
22.     generic function GetGenericObject<T: class>: specialize TGenericObject<T>; // <-- HERE
23.     generic procedure Add<T: class>(AIndex: TIndex; AElement: T); // <-- HERE
24.   private
25.     FGenericObjects: TGenericObjects;
26.   end;
27.  
28. generic function TGenericObjectFactory.GetGenericObject<T>: specialize TGenericObject<T>;
29. var
30.   GenericObjectType: PTypeInfo;
31. begin
32.   GenericObjectType := TypeInfo(T);
33.   Result := specialize TGenericObject<T>(FGenericObjects[GenericObjectType^.Name]^);
34. end;
35.  
36. generic procedure TGenericObjectFactory.Add<T>(AIndex: TIndex; AElement: T);
37. var
38.   GenericObject: specialize TGenericObject<T>;
39. begin
40.   GenericObject := specialize GetGenericObject<T>;
41.   GenericObject.Add(AIndex, AElement);
42. end;
43.  
44. procedure TGenericObject.Add(AIndex: TIndex; AElement: T);
45. begin
46.   FList[Aindex] := AElement;
47. end;
48.  
49. begin
50. end.

Code: Text  [Select][+][-]

1. Free Pascal Compiler version 3.2.2 [2021/05/16] for aarch64
2. Copyright (c) 1993-2021 by Florian Klaempfl and others
3. Target OS: Darwin for AArch64
4. Compiling main.pas
5. fgl.pp(1668,8) Note: Call to subroutine "function TFPGMap<System.ShortString,System.Pointer>.IndexOf(const AKey:ShortString):LongInt;" marked as inline is not inlined
6. Assembling main
7. Linking main
8. ld: warning: -multiply_defined is obsolete
9. -macosx_version_min has been renamed to -macos_version_min
10. 50 lines compiled, 0.6 sec
11. 1 note(s) issued
12.  

[PascalDragon]

Now someone should test fpc 3.2 fixes branch.

No issues with fixes 3.2 but tested on x86_64 only.

The internal error only exists in some of the code generators (including aarch64, but excluding x86_64), so this is likely a platform specific issue...

[Laurent92]

@PascalDragon
Ok, thanks the info!