gdb不知为何显示2次析构_breakpoint 1 at 0x41320000: stext. (2 locations)-优快云博客

本文探讨了使用GDB调试器时遇到的一个现象：虚析构函数被显示调用了两次。通过提供的代码示例和详细的GDB调试过程，分析了问题的原因，并指出这通常发生在使用delete操作符删除虚基类派生的对象时。

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gdb不知为何显示2次析构

(金庆的专栏 2016.11)

gdb 显示2次 A::~A():

(gdb) bt
#0  A::~A (this=0x602010, __in_chrg=<optimized out>) at main.cpp:10
#1  0x0000000000400a96 in A::~A (this=0x602010, __in_chrg=<optimized out>)
    at main.cpp:12
#2  0x00000000004009c0 in main () at main.cpp:18

代码如下：

class A
{
public:
    A() {}
    virtual ~A() 
    {
        cout << "~A()" << endl;
    }
};

int main()
{
    A* p = new A;
    delete p;
    return 0;
}

打断点显示：2 locations:

(gdb) b A::~A
Breakpoint 1 at 0x400a40: A::~A. (2 locations)

完整的 gdb 输出:

g++ -g main.cpp
[jinq@localhost test]$ gdb a.out
GNU gdb (GDB) Red Hat Enterprise Linux 7.6.1-80.el7
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-redhat-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /home/jinq/test/a.out...done.
(gdb) b A::~A
Breakpoint 1 at 0x400a40: A::~A. (2 locations)
(gdb) run
Starting program: /home/jinq/test/a.out

Breakpoint 1, A::~A (this=0x602010, __in_chrg=<optimized out>) at main.cpp:12
12          }
Missing separate debuginfos, use: debuginfo-install glibc-2.17-106.el7_2.8.x86_64 libgcc-4.8.5-4.el7.x86_64 libstdc++-4.8.5-4.el7.x86_64
(gdb) bt
#0  A::~A (this=0x602010, __in_chrg=<optimized out>) at main.cpp:12
#1  0x00000000004009c0 in main () at main.cpp:18
(gdb) s

Breakpoint 1, A::~A (this=0x602010, __in_chrg=<optimized out>) at main.cpp:10
10          {
(gdb) bt
#0  A::~A (this=0x602010, __in_chrg=<optimized out>) at main.cpp:10
#1  0x0000000000400a96 in A::~A (this=0x602010, __in_chrg=<optimized out>)
    at main.cpp:12
#2  0x00000000004009c0 in main () at main.cpp:18
(gdb) ^CQuit
(gdb)

虚析构函数并且是delete才这样。