Question

在GDB中，如果我尝试执行以下操作，则会出现分段错误：

print bg->top

代码看起来有点像这样：

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

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

我得到的信息是：

(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.

为什么会这样？

我正在使用GNU Objective-C运行时，我没有使用GNUStep。

Answer 1

如何宣布'bg'？ id bg或Sprite * bg

使用'id bg' 你必须把bg强制转换为正确的类，

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

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

使用Sprite * bg

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

使用GNU gdb（GDB）7.3.50.20110421-cvs 在linux下，你使用的是哪个版本的gdb？

是在DLL /库中单独实现的Sprite类在主要的应用程序？

可能它可能是一些表现形式 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39465

试图在gdb中打印Objective-C字段的分段错误

1 个答案: