1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
| #include <cstdio>
struct A {
~A() {
puts("~A()");
throw 0;
}
};
int main() {
try {
A();
puts("after ~A()");
} catch (...) {
puts("catch");
}
}
|
分别用C++98和11标准进行编译及运行
1
2
3
4
5
6
7
8
9
10
11
12
13
14
| $ g++ examples/destructor-throw.cpp -std=c++98 && ./a.out
~A()
catch
$ g++ examples/destructor-throw.cpp -std=c++11 && ./a.out
examples/destructor-throw.cpp:6:9: warning: '~A' has a non-throwing exception specification but can still throw [-Wexceptions]
throw 0;
^
examples/destructor-throw.cpp:4:5: note: destructor has a implicit non-throwing exception specification
~A() {
^
1 warning generated.
~A()
libc++abi: terminating with uncaught exception of type int
Abort trap: 6
|
开启C++11标准后，编译器已经给出了警告。实际上，C++11起，析构函数默认是noexcept的，抛出异常将会terminate。
做一点修改，再次编译
1
2
3
4
5
6
7
8
| #include <cstdio>
struct A {
- ~A() {
+ ~A() throw(int) {
puts("~A()");
throw 0;
}
|
1
2
3
4
5
6
7
8
9
10
11
12
| $ g++ examples/destructor-throw.cpp -std=c++11 && ./a.out
~A()
catch
$ g++ examples/destructor-throw.cpp -std=c++17 && ./a.out
examples/destructor-throw.cpp:4:10: fatal error: ISO C++17 does not allow dynamic exception specifications [-Wdynamic-exception-spec]
~A() throw(int) {
^~~~~~~~~~
examples/destructor-throw.cpp:4:10: note: use 'noexcept(false)' instead
~A() throw(int) {
^~~~~~~~~~
noexcept(false)
1 error generated.
|
给析构函数添加动态异常说明后，程序不会崩溃。要注意的是，动态异常说明在C++11中标记为弃用，C++17起已经移除了。
总结：不要把异常抛出析构函数。