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digitalmars.D.learn - GtkD crash

reply mark <mark qtrac.eu> writes:
I'm porting a simple game to GtkD to learn the library and more 
about D.

Unfortunately, I've hit a show-stopping crash.

I have a subclass of ApplicationWindow which has this method:

     private void onChangeState(int score, Board.State state) {
         import std.format: format;

         string message;
         if (state == Board.State.GAME_OVER)
             message = format("%,d Game Over", score);
         else if (state == Board.State.USER_WON) {
             if (score > highScore) {
                 message = format("%,d New High Score!", score);
                 highScore = score; // TODO save highScore
             } else
                 message = format("%,d You Won!", score);
         } else // still playing
             message = format("%,d/%,d", score, highScore);
         statusLabel.setText(message); // BUG
     }

This method gets passed to another widget which calls it whenever 
the game's state or score changes.

If the BUG line is commented out, the program runs fine (well, 
except that the Label always shows "0/0").

But if the BUG line is uncommented (as above), it crashes:

$ dub
Performing "debug" build using 
/home/mark/opt/ldc2-1.20.0-linux-x86_64/bin/ldc2 for x86_64.
gtk-d:gtkd 3.9.0: target for configuration "library" is up to 
date.
gravitate ~master: target for configuration "application" is up 
to date.
To force a rebuild of up-to-date targets, run again with --force.
Running ./gravitate
onChangeState 0 PLAYING
Program exited with code -11

Here's what it looks like in gdb (slightly edited):

$ gdb gravitate
GNU gdb (Ubuntu 8.1-0ubuntu3.2) 8.1.0.20180409-git
[snip]
This GDB was configured as "x86_64-linux-gnu".
[snip]
Reading symbols from gravitate...done.
(gdb) run
Starting program: /home/mark/app/gravitate/d/gravitate
[Thread debugging using libthread_db enabled]
Using host libthread_db library 
"/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7ffff6e02700 (LWP 7017)]
[New Thread 0x7ffff6601700 (LWP 7018)]
[New Thread 0x7ffff5e00700 (LWP 7019)]
[New Thread 0x7ffff55ff700 (LWP 7020)]
[New Thread 0x7ffff4dfe700 (LWP 7021)]
[New Thread 0x7fffdffff700 (LWP 7022)]
[New Thread 0x7fffdf7fe700 (LWP 7023)]
[New Thread 0x7fffce3a5700 (LWP 7024)]
[New Thread 0x7fffcdba4700 (LWP 7025)]
onChangeState 0 PLAYING

Thread 1 "gravitate" received signal SIGSEGV, Segmentation fault.
0x0000555555704cc1 in gamewindow.GameWindow.onChangeState(int, 
board.Board.State) (this=0x7ffff7ecf700, score=0,
     state=board.Board.PLAYING) at gamewindow.d:182
182	        statusLabel.setText(message);
(gdb) bt
warning: (Internal error: pc 0x555555703fbf in read in psymtab, 
but not in symtab.)
warning: (Internal error: pc 0x555555703fbf in read in psymtab, 
but not in symtab.)
[ + several more like these ]


gamewindow.GameWindow.onChangeState(int, board.Board.State) 
(this=0x7ffff7ecf700, score=0, state=board.Board.PLAYING) at 
gamewindow.d:182
warning: (Internal error: pc 0x555555703fbf in read in psymtab, 
but not in symtab.)

(this=0x7fffcc92d000) at board.d:60
warning: (Internal error: pc 0x555555703fbf in read in psymtab, 
but not in symtab.)
warning: (Internal error: pc 0x555555703a2b in read in psymtab, 
but not in symtab.)

_D5board5Board6__ctorMFDFiEQzQv5StateZvZCQBnQBk (warning: 
(Internal error: pc 0x555555703fbf in read in psymtab, but not in 
symtab.)
this=0x7fffcc92d000, warning: (Internal error: pc 0x555555703fbf 
in read in psymtab, but not in symtab.)
onChangeState=...)
     at board.d:42
warning: (Internal error: pc 0x555555703fbf in read in psymtab, 
but not in symtab.)
warning: (Internal error: pc 0x555555703a2b in read in psymtab, 
but not in symtab.)

0x555555703fbf in read in psymtab, but not in symtab.)
gamewindow.GameWindow.makeWidgets()warning: (Internal error: pc 
0x555555703fbf in read in psymtab, but not in symtab.)
warning: (Internal error: pc 0x555555703fbf in read in psymtab, 
but not in symtab.)
  (warning: (Internal error: pc 0x555555703fbf in read in psymtab, 
but not in symtab.)
warning: (Internal error: pc 0x555555703a2b in read in psymtab, 
but not in symtab.)
this=0x7ffff7ecf700)warning: (Internal error: pc 0x555555703fbf 
in read in psymtab, but not in symtab.)
  at gamewindow.dwarning: (Internal error: pc 0x555555703fbf in 
read in psymtab, but not in symtab.)
warning: (Internal error: pc 0x555555703fbf in read in psymtab, 
but not in symtab.)
:58
warning: (Internal error: pc 0x555555703a2b in read in psymtab, 
but not in symtab.)

0x555555703a2b in read in psymtab, but not in symtab.)
_D10gamewindow10GameWindow6__ctorMFC3gtk11ApplicationQnZCQCdQBuwarning:
(Internal error: pc 0x555555703a2b in read in psymtab, but not in symtab.)
warning: (Internal error: pc 0x555555703a2b in read in psymtab, 
but not in symtab.)
  (warning: (Internal error: pc 0x555555703a2b in read in psymtab, 
but not in symtab.)
this=0x7ffff7ecf700, warning: (Internal error: pc 0x555555703a2b 
in read in psymtab, but not in symtab.)
application=0x7ffff7ed3360)warning: (Internal error: pc 
0x555555703a2b in read in psymtab, but not in symtab.)
  at gamewindow.dwarning: (Internal error: pc 0x555555703a2b in 
read in psymtab, but not in symtab.)
warning: (Internal error: pc 0x555555703a2b in read in psymtab, 
but not in symtab.)
:31

_D3app4mainFAAyaZ__T12__dgliteral2TC3gio11ApplicationQnZQBkMFQBaZv
(GioApplication=0x7ffff7ed3360)
     at app.d:13

_D7gobject8DClosureQj__T17d_closure_marshalTDFC3gio11ApplicationQnZvZQBtUPSQCv1c5types8GClosurePSQDr
wQw6GValuekQrPvQcZv (closure=0x555555bfd8e0, return_value=0x0,
n_param_values=1, param_values=0x7ffff7ef49c0, invocation_hint=0x7fffffffd6f0
"\b", marshal_data=0x0) at DClosure.d:122

/usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0

/usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0

/usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0

/usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0

/usr/lib/x86_64-linux-gnu/libgio-2.0.so.0

/usr/lib/x86_64-linux-gnu/libgio-2.0.so.0

(this=0x7ffff7ed3360, argv=...) at Application.d:931

(gdb)
Feb 21 2020
parent reply Ron Tarrant <rontarrant gmail.com> writes:
On Friday, 21 February 2020 at 08:55:43 UTC, mark wrote:


         statusLabel.setText(message); // BUG


Where is statusLabel instantiated?

Other than that, I see nothing wrong here.
Feb 21 2020
parent reply mark <mark qtrac.eu> writes:
Thanks for your question, it led me to focus on the Label and now 
I've solved the problem.

I thought that onChangeState was never called before the Label 
was constructed, but it turns out it is called before. So now I 
use:

	if (statusLabel !is null)
	    statusLabel.setText(message);

Now it works.

Thanks!
Feb 21 2020
parent Ron Tarrant <rontarrant gmail.com> writes:
On Friday, 21 February 2020 at 13:36:58 UTC, mark wrote:


 I thought that onChangeState was never called before the Label 
 was constructed


That's one of the 'features' (wink wink) of GtkD. It's possible 
to call the function as a class function (uninstantiated, in 
other words) or as an object function (instantiated). There are 
times when it's handy to have either at your disposal.


 Now it works.

 Thanks!
Feb 22 2020