我在C++程序中遇到了一个奇怪的段错误。我可以用小代码重现它,但不明白为什么会发生。下面是代码:段错误的好奇案例
a.hpp:
#pragma once
#include <boost/shared_ptr.hpp>
#include "b.hpp"
class A
{
public:
explicit A();
private:
std::string str1_;
B b_;
std::string str2_;
};
typedef boost::shared_ptr<A> A_ptr;
a.cpp
#include "a.hpp"
A::A() {}
b.hpp
#pragma once
#include <string>
class B
{
public:
B();
private:
std::string str1_;
};
b.cpp
#include "b.hpp"
B::B() {}
main.cpp中做的
#include "a.hpp"
int main()
{
A_ptr a(new A());
}
输出:
% make
g++ -Wall -Wextra -g -fno-inline -O0 -c -o main.o main.cpp
g++ -Wall -Wextra -g -fno-inline -O0 -c -o a.o a.cpp
g++ -Wall -Wextra -g -fno-inline -O0 -c -o b.o b.cpp
g++ -o main main.o a.o b.o
dsymutil main
现在这个运行良好。我从a.hpp
删除B b_
(的b_
声明),保存a.cpp
(触发生成),然后再次运行make
:与
% make
g++ -Wall -Wextra -g -fno-inline -O0 -c -o a.o a.cpp
g++ -o main main.o a.o b.o
dsymutil main
现在程序段错误:
(gdb) bt
#0 0x00007fff97f106e5 in std::string::_Rep::_M_dispose()
#1 0x00007fff97f10740 in std::basic_string<char, std::char_traits<char>, std::allocator<char> >::~basic_string()
#2 0x0000000100001091 in A::~A (this=0x1001008b0) at a.hpp:8
#3 0x00000001000011da in boost::checked_delete<A> (x=0x1001008b0) at checked_delete.hpp:34
#4 0x0000000100001026 in boost::detail::sp_counted_impl_p<A>::dispose (this=0x1001008d0) at sp_counted_impl.hpp:78
#5 0x0000000100000d9a in boost::detail::sp_counted_base::release (this=0x1001008d0) at sp_counted_base_gcc_x86.hpp:145
#6 0x0000000100000dd4 in boost::detail::shared_count::~shared_count (this=0x7fff5fbff568) at shared_count.hpp:305
#7 0x0000000100000f2b in boost::shared_ptr<A>::~shared_ptr (this=0x7fff5fbff560) at shared_ptr.hpp:159
#8 0x0000000100000aac in main() at main.cpp:5
如果我make clean
和make
,然后程序运行时没有段错误。请帮我理解为什么程序段错误,如果一个类的成员被删除和项目建成没有干净。