分段故障試圖在gdb

Question

打印一個Objective-C場在GDB我得到一個分段錯誤，如果我試圖做到以下幾點：

print bg->top 

代碼看起來有點像這樣：

@interface Sprite : Object 
{ 
@public 
    int top; 
    /* Other fields */ 
} 
@end 

bg = [Sprite load: "test.png"]; 
/* GDB is at a breakpoint after the above line */ 

我得到的消息是：

(gdb) print bg->top 

Program received signal SIGSEGV, Segmentation fault. 
0x6a7e3048 in libobjc-2!__objc_class_links_resolved() from C:\MinGW\bin\libobjc-2.dll 
The program being debugged was signaled while in a function called from GDB. 
GDB remains in the frame where the signal was received. 
To change this behavior use "set unwindonsignal on". 
Evaluation of the expression containing the function 
(objc_lookup_class) will be abandoned. 
When the function is done executing, GDB will silently stop. 

這是爲什麼？

我正在使用GNU Objective-C運行時，而我沒有使用GNUStep。

Answer 1

'bg'是如何申報的？通過使用GNU GDB雪碧* BG

(gdb) p bg->top 
$1 = 0 

ID BG或雪碧*使用 '身份證BG' 必須轉換BG正確類BG

，

(gdb) p bg->top 
There is no member named top. 

(gdb) p ((struct Sprite *)bg)->top 
$1 = 0 

（GDB）在linux下7.3.50.20110421-cvs ，你用的是哪個版本的gdb？

是在主應用程序中分別在DLL /庫或 中實現的Sprite類？

其可能也可能是 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39465