查看原始答案以分析问题代码中对象生命周期。这个回答仅隔离错误。
我制作了一个最小化的复制版本。虽然有更多代码,但涉及的库代码要少得多。并且更容易跟踪。
template<size_t N>
struct X
{
int i = N;
typedef X<N> self;
virtual int GetValue() { return 0; }
X() { std::cerr << "X<" << N << ">() default ctor" << std::endl; }
X(const self& right) : i(right.i) { std::cerr << "X<" << N << ">(const X<" << N << "> &) copy-ctor" << std::endl; }
X(self&& right) : i(right.i) { std::cerr << "X<" << N << ">(X<" << N << ">&& ) moving copy-ctor" << std::endl; }
template<size_t M>
X(const X<M>& right) : i(right.i) { std::cerr << "X<" << N << ">(const X<" << M << "> &) conversion-ctor" << std::endl; }
template<size_t M>
X(X<M>&& right) : i(right.i) { std::cerr << "X<" << N << ">(X<" << M << ">&& ) moving conversion-ctor" << std::endl; }
~X() { std::cerr << "~X<" << N << ">(), i = " << i << std::endl; }
};
template<size_t N>
X<N> make_X() { return X<N>{}; }
int main()
{
std::initializer_list< X<0> > foo
{
make_X<1>(),
make_X<2>(),
make_X<3>(),
make_X<4>(),
};
std::cerr << "Reached end of main" << std::endl;
return 0;
}
输出在x64上都不好:
C:\Code\SO22924358>cl /EHsc minimal.cpp
Microsoft (R) C/C++ Optimizing Compiler Version 18.00.21005.1 for x64
Copyright (C) Microsoft Corporation. All rights reserved.
minimal.cpp
Microsoft (R) Incremental Linker Version 12.00.21005.1
Copyright (C) Microsoft Corporation. All rights reserved.
/out:minimal.exe
minimal.obj
C:\Code\SO22924358>minimal
X<1>() default ctor
X<0>(X<1>&& ) moving conversion-ctor
X<2>() default ctor
X<0>(X<2>&& ) moving conversion-ctor
X<3>() default ctor
X<0>(X<3>&& ) moving conversion-ctor
X<4>() default ctor
X<0>(X<4>&& ) moving conversion-ctor
~X<0>(), i = 2
~X<2>(), i = 2
~X<0>(), i = 1
~X<1>(), i = 1
Reached end of main
~X<0>(), i = 4
~X<0>(), i = 3
~X<0>(), i = 2
~X<0>(), i = 1
以及x86:
C:\Code\SO22924358>cl /EHsc minimal.cpp
Microsoft (R) C/C++ Optimizing Compiler Version 18.00.21005.1 for x86
Copyright (C) Microsoft Corporation. All rights reserved.
minimal.cpp
Microsoft (R) Incremental Linker Version 12.00.21005.1
Copyright (C) Microsoft Corporation. All rights reserved.
/out:minimal.exe
minimal.obj
C:\Code\SO22924358>minimal
X<1>() default ctor
X<0>(X<1>&& ) moving conversion-ctor
X<2>() default ctor
X<0>(X<2>&& ) moving conversion-ctor
X<3>() default ctor
X<0>(X<3>&& ) moving conversion-ctor
X<4>() default ctor
X<0>(X<4>&& ) moving conversion-ctor
~X<0>(), i = 2
~X<2>(), i = 2
~X<0>(), i = 1
~X<1>(), i = 1
Reached end of main
~X<0>(), i = 4
~X<0>(), i = 3
~X<0>(), i = 2
~X<0>(), i = 1
这绝对是编译器的一个漏洞,且是一个相当严重的漏洞。如果你在Connect上提交了报告,我和其他人会乐意支持。
shared_ptr
。std::shared_ptr<Base>
对象是通过转换临时的std::shared_ptr<Derived1>
(和2)对象来初始化的。 但这不应该导致Derived1
(和2)对象本身的死亡,因为在shared_ptr
转换期间,每个对象的引用计数应该达到2。或者也许移动构造函数用于转换,并且引用计数被窃取了。 - Ben Voigtshared_ptr
对象被释放,一个是空的shared_ptr<Derived1>
(正确!),但另一个是一个shared_ptr<Base>
,它持有其中一个对象,然后将其释放。我已经确认通过移动构造函数来窃取引用,所以它实际上从未到达 2。 - Ben Voigt