是否可以从集合中提取包含 unique/shared 指针字段的结构

Question

所以基本上我有一组结构 A 的实例。我想提取一个实例，修改字段。其中一个字段是唯一的 ptr。我不太擅长阅读 C++ 错误，看起来该字段在提取时被删除了。 IE。唯一指针的析构函数被调用。

示例：此处当我尝试访问字段时 'weight'

我得到的是：

SUMMARY: AddressSanitizer: heap-use-after-free /usr/lib/llvm-11/include/c++/v1/memory:2490:19 in std::__1::unique_ptr<int, std::__1::default_delete<int> >::get() const
[ctest] Shadow bytes around the buggy address:
[ctest]   0x0c0e7fff84a0: fd fd fd fd fd fa fa fa fa fa fd fd fd fd fd fd
[ctest]   0x0c0e7fff84b0: fd fd fd fa fa fa fa fa fd fd fd fd fd fd fd fd
[ctest]   0x0c0e7fff84c0: fd fa fa fa fa fa fd fd fd fd fd fd fd fd fd fa
[ctest]   0x0c0e7fff84d0: fa fa fa fa 00 00 00 00 00 00 00 00 00 fa fa fa
[ctest]   0x0c0e7fff84e0: fa fa 00 00 00 00 00 00 00 00 00 fa fa fa fa fa
[ctest] =>0x0c0e7fff84f0: fd fd fd fd fd fd fd fd[fd]fa fa fa fa fa 00 00
[ctest]   0x0c0e7fff8500: 00 00 00 00 00 00 00 fa fa fa fa fa fa fa fa fa
[ctest]   0x0c0e7fff8510: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
[ctest]   0x0c0e7fff8520: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
[ctest]   0x0c0e7fff8530: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
[ctest]   0x0c0e7fff8540: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
[ctest] Shadow byte legend (one shadow byte represents 8 application bytes):
[ctest]   Addressable:           00
[ctest]   Partially addressable: 01 02 03 04 05 06 07 
[ctest]   Heap left redzone:       fa
[ctest]   Freed heap region:       fd
[ctest]   Stack left redzone:      f1
[ctest]   Stack mid redzone:       f2
[ctest]   Stack right redzone:     f3
[ctest]   Stack after return:      f5
[ctest]   Stack use after scope:   f8
[ctest]   Global redzone:          f9
[ctest]   Global init order:       f6
[ctest]   Poisoned by user:        f7
[ctest]   Container overflow:      fc
[ctest]   Array cookie:            ac
[ctest]   Intra object redzone:    bb
[ctest]   ASan internal:           fe
[ctest]   Left alloca redzone:     ca
[ctest]   Right alloca redzone:    cb
[ctest]   Shadow gap:              cc

Struct A {
    std::unique_ptr<int> weight;
}

auto& element = set_.extract(set_iterator).value();
std::cout << *(element.weight);

Answer 1

节点在提取时未删除，但不久之后，在您使用之前。

具体来说，您不保存节点句柄.extract() returns，而是直接获取其管理的部分节点的引用。
在完整语句的末尾，该引用变为悬空，因为没有人保留拥有它的节点句柄。

因此，AddressSanitizer 检测到heap-use-after-free。

存储节点句柄，或保存您想要的节点部分，但要避免悬挂引用。

是否可以从集合中提取包含 unique/shared 指针字段的结构

Is it possible to extract a struct containing fields that are unique/shared pointers from a set

c++

c++20

address-sanitizer

stdset

dangling-pointer