[Pkg-pascal-devel] Castle Game Engine build failure on armel.

[Abou Al Montacir]

Hi Michalis,

On Sun, 2021-11-07 at 01:41 +0100, Michalis Kamburelis wrote:
> I see it fails at
> 
>   TTestGame Time:00.136 N:1 E:1 F:0 I:0
>     00.028  TestGameData  Error: EAssertionFailed
>       Exception:   Assertion failed (castledebugtransform.pas, line 504)
>       at   $00CB1A14  TDEBUGTRANSFORMBOX__DESTROY,  line 454 of
> /<<PKGBUILDDIR>>/src/game/castledebugtransform.pas
> 
> The referenced assertion is at
> https://github.com/castle-engine/castle-engine/blob/631ecfe85ccb4f6b05e8a5da8a93bdb06ed36fea/src/game/castledebugtransform.pas#L504
> .
> 
> Unfortunately I have no idea what is the culprit. This same assertion,
I did some debug on a porter box to try to find the root cause.
> and the whole testcase, works on the systems where I test (including
> Linux/x86_64, Linux/i386, Linux/Arm -- the latter on Raspberry Pi). It
Sometimes, some bugs appear only on some targets. On others they may be hidden
or show in a very weird manner.
> is tempting to suspect that this is FPC bug, although that's weak when
> I didn't do any investigation.
You may be right according to the below debugging trial. 
(gdb) r --suite=TTestCastleResources
Starting program: /home/mazen/castle-game-engine-7.0~alpha.1+dfsg/tests/test_castle_game_engine --suite=TTestCastleResources

[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/arm-linux-gnueabi/libthread_db.so.1".

Breakpoint 1, TCREATURE__CREATE (AOWNER=0xb5912dc0, AMAXLIFE=100, vmt=<incomplete type>, this=0xb4aa0740)
    at /home/mazen/castle-game-engine-7.0~alpha.1+dfsg/src/game/castlecreatures.pas:1463
1463	  FDebugTransform := TDebugTransform.Create(Self);
(gdb) c
Continuing.

Breakpoint 2, TDEBUGTRANSFORMBOX__CREATE (AOWNER=0xb4aa0740, vmt=<incomplete type>, this=0x127869c)
    at /home/mazen/castle-game-engine-7.0~alpha.1+dfsg/src/game/castledebugtransform.pas:446
446	begin
(gdb) n
447	  inherited Create(AOwner);
(gdb) p AOwner
$2 = (^TCOMPONENT) 0xb4aa0740
(gdb) n
448	  FBoxColor := Gray;
(gdb) p Self.FParent
warning: can't find linker symbol for virtual table for `TDEBUGTRANSFORMBOX' value
$3 = (^TCASTLETRANSFORM) 0x0
(gdb) 

If my knowledge is good, Tcompopnent.Create should set parent to AOwner, which
is not the case here.
> 
> The latest CGE master has this assertion (and this testcase) too, so
> it likely still fails. The old CGE 6.4 had a very different
> castledebugtransform.pas unit, so it likely avoided the problem by
> accident.
> 
> My simplest suggestion would be to remove armel from supported
> architectures.
I would have a trial to fix the issue before, maybe this can be fixed easily.
Or if it shows FPC compiler issue, the definitely this is important, even if CGE
is never used by anyone.
>  I do not have access to Linux/armel machine, so I do
> not regularly test CGE on it. I could get access to it (I recall
> Debian gave me temporary access to such machine in the past, for the
> purpose of testing CGE).
This we can arrange ;-)
>  But
> 
> - Due to lack of regular testing, in a few months I could break something
> again.
> 
> - I do not want this to block CGE from migrating to Debian testing on
> more popular architectures.
Valid point.
> 
> I do not think that CGE, combined with armel, is popular enough to
> make it matter. (Though I'm eager to hear from some CGE user on armel
> to say that I'm wrong :) ).
I don't think anyone is going to use CGE on armel, but it is a good way to test
the compiler itself as I stated above.
So this maybe worth I spend some time on it.
-- 
Cheers,
Abou Al Montacir
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