我有以下程序:
#include <vector>
struct Comp1
{
float x;
std::vector<int> vec;
};
int main()
{
std::vector<char> data;
data.resize(sizeof(Comp1));
Comp1* ptr1 = new (&data[0]) Comp1({.3f,{3,4,2,1}});
data.resize(sizeof(Comp1)*2);
Comp1* ptr2 = new (&data[sizeof(Comp1)]) Comp1({.2f,{2,3,4}});
ptr1->~Comp1();
std::vector<char>::iterator itrStart = data.begin();
std::vector<char>::iterator itrEnd = itrStart + sizeof(Comp1);
data.erase(itrStart,itrEnd);
ptr2 = reinterpret_cast<Comp1*>(&data[0]);
ptr2->~Comp1();
return 0;
}
编译没有问题。在我的机器上执行没有问题。通过GDB运行它，没有任何报告。我的理解是，我在上面所做的一切都是正确的(除了当我将
std::launder从reinterpret_cast转换为char*吗？也许我错过了Comp1*的使用)。但是，使用以下方法在此程序上调用DrMemory:
drmemory.exe test.exe -callstack_max_frames 40 -malloc_max_frames 40 -free_max_frames 40
给我以下错误输出:
Dr. Memory version 2.2.0 build 1 built on Jul 1 2019 00:42:20
Windows version: WinVer=105;Rel=1909;Build=18363;Edition=Enterprise
Dr. Memory results for pid 20424: "test.exe"
Application cmdline: "bin/test.exe -callstack_max_frames 40 -malloc_max_frames 40 -free_max_frames 40"
Recorded 117 suppression(s) from default C:\Program Files (x86)\Dr. Memory\bin\suppress-default.txt
Error #1: UNADDRESSABLE ACCESS of freed memory: reading 0x01975230-0x01975234 4 byte(s)
# 0 std::vector<>::~vector [C:/MSYS2-32/mingw32/include/c++/10.1.0/bits/stl_vector.h:680]
# 1 Comp1::~Comp1 [C:/Tests/test.cpp:3]
# 2 main [C:/Tests/test.cpp:21]
Note: @0:00:01.329 in thread 2068
Note: next higher malloc: 0x01975258-0x01975268
Note: 0x01975230-0x01975234 overlaps memory 0x01975228-0x01975238 that was freed here:
Note: # 0 replace_operator_delete [d:\drmemory_package\common\alloc_replace.c:2975]
Note: # 1 __gnu_cxx::new_allocator<>::deallocate [C:/MSYS2-32/mingw32/include/c++/10.1.0/ext/new_allocator.h:133]
Note: # 2 std::allocator_traits<>::deallocate [C:/MSYS2-32/mingw32/include/c++/10.1.0/bits/allocator.h:187]
Note: # 3 std::_Vector_base<>::_M_deallocate [C:/MSYS2-32/mingw32/include/c++/10.1.0/bits/stl_vector.h:354]
Note: # 4 std::vector<>::_M_default_append [C:/MSYS2-32/mingw32/include/c++/10.1.0/bits/vector.tcc:675]
Note: # 5 std::vector<>::resize [C:/MSYS2-32/mingw32/include/c++/10.1.0/bits/stl_vector.h:940]
Note: instruction: mov 0x04(%edx) -> %ecx
Error #2: UNADDRESSABLE ACCESS of freed memory: reading 0x0197522c-0x01975230 4 byte(s)
# 0 std::vector<>::~vector [C:/MSYS2-32/mingw32/include/c++/10.1.0/bits/stl_vector.h:680]
# 1 Comp1::~Comp1 [C:/Tests/test.cpp:3]
# 2 main [C:/Tests/test.cpp:21]
Note: @0:00:01.447 in thread 2068
Note: next higher malloc: 0x01975258-0x01975268
Note: 0x0197522c-0x01975230 overlaps memory 0x01975228-0x01975238 that was freed here:
Note: # 0 replace_operator_delete [d:\drmemory_package\common\alloc_replace.c:2975]
Note: # 1 __gnu_cxx::new_allocator<>::deallocate [C:/MSYS2-32/mingw32/include/c++/10.1.0/ext/new_allocator.h:133]
Note: # 2 std::allocator_traits<>::deallocate [C:/MSYS2-32/mingw32/include/c++/10.1.0/bits/allocator.h:187]
Note: # 3 std::_Vector_base<>::_M_deallocate [C:/MSYS2-32/mingw32/include/c++/10.1.0/bits/stl_vector.h:354]
Note: # 4 std::vector<>::_M_default_append [C:/MSYS2-32/mingw32/include/c++/10.1.0/bits/vector.tcc:675]
Note: # 5 std::vector<>::resize [C:/MSYS2-32/mingw32/include/c++/10.1.0/bits/stl_vector.h:940]
Note: instruction: mov (%edx) -> %edx
Error #3: UNADDRESSABLE ACCESS of freed memory: reading 0x01975234-0x01975238 4 byte(s)
# 0 std::_Vector_base<>::~_Vector_base [C:/MSYS2-32/mingw32/include/c++/10.1.0/bits/stl_vector.h:336]
# 1 std::vector<>::~vector [C:/MSYS2-32/mingw32/include/c++/10.1.0/bits/stl_vector.h:683]
# 2 Comp1::~Comp1 [C:/Tests/test.cpp:3]
# 3 main [C:/Tests/test.cpp:21]
Note: @0:00:01.471 in thread 2068
Note: next higher malloc: 0x01975258-0x01975268
Note: 0x01975234-0x01975238 overlaps memory 0x01975228-0x01975238 that was freed here:
Note: # 0 replace_operator_delete [d:\drmemory_package\common\alloc_replace.c:2975]
Note: # 1 __gnu_cxx::new_allocator<>::deallocate [C:/MSYS2-32/mingw32/include/c++/10.1.0/ext/new_allocator.h:133]
Note: # 2 std::allocator_traits<>::deallocate [C:/MSYS2-32/mingw32/include/c++/10.1.0/bits/allocator.h:187]
Note: # 3 std::_Vector_base<>::_M_deallocate [C:/MSYS2-32/mingw32/include/c++/10.1.0/bits/stl_vector.h:354]
Note: # 4 std::vector<>::_M_default_append [C:/MSYS2-32/mingw32/include/c++/10.1.0/bits/vector.tcc:675]
Note: # 5 std::vector<>::resize [C:/MSYS2-32/mingw32/include/c++/10.1.0/bits/stl_vector.h:940]
Note: instruction: mov 0x08(%eax) -> %edx
Error #4: UNADDRESSABLE ACCESS of freed memory: reading 0x0197522c-0x01975230 4 byte(s)
# 0 std::_Vector_base<>::~_Vector_base [C:/MSYS2-32/mingw32/include/c++/10.1.0/bits/stl_vector.h:336]
# 1 std::vector<>::~vector [C:/MSYS2-32/mingw32/include/c++/10.1.0/bits/stl_vector.h:683]
# 2 Comp1::~Comp1 [C:/Tests/test.cpp:3]
# 3 main [C:/Tests/test.cpp:21]
Note: @0:00:01.489 in thread 2068
Note: next higher malloc: 0x01975258-0x01975268
Note: 0x0197522c-0x01975230 overlaps memory 0x01975228-0x01975238 that was freed here:
Note: # 0 replace_operator_delete [d:\drmemory_package\common\alloc_replace.c:2975]
Note: # 1 __gnu_cxx::new_allocator<>::deallocate [C:/MSYS2-32/mingw32/include/c++/10.1.0/ext/new_allocator.h:133]
Note: # 2 std::allocator_traits<>::deallocate [C:/MSYS2-32/mingw32/include/c++/10.1.0/bits/allocator.h:187]
Note: # 3 std::_Vector_base<>::_M_deallocate [C:/MSYS2-32/mingw32/include/c++/10.1.0/bits/stl_vector.h:354]
Note: # 4 std::vector<>::_M_default_append [C:/MSYS2-32/mingw32/include/c++/10.1.0/bits/vector.tcc:675]
Note: # 5 std::vector<>::resize [C:/MSYS2-32/mingw32/include/c++/10.1.0/bits/stl_vector.h:940]
Note: instruction: mov (%eax) -> %ecx
Error #5: UNADDRESSABLE ACCESS of freed memory: reading 0x0197522c-0x01975230 4 byte(s)
# 0 std::_Vector_base<>::~_Vector_base [C:/MSYS2-32/mingw32/include/c++/10.1.0/bits/stl_vector.h:335]
# 1 std::vector<>::~vector [C:/MSYS2-32/mingw32/include/c++/10.1.0/bits/stl_vector.h:683]
# 2 Comp1::~Comp1 [C:/Tests/test.cpp:3]
# 3 main [C:/Tests/test.cpp:21]
Note: @0:00:01.504 in thread 2068
Note: next higher malloc: 0x01975258-0x01975268
Note: 0x0197522c-0x01975230 overlaps memory 0x01975228-0x01975238 that was freed here:
Note: # 0 replace_operator_delete [d:\drmemory_package\common\alloc_replace.c:2975]
Note: # 1 __gnu_cxx::new_allocator<>::deallocate [C:/MSYS2-32/mingw32/include/c++/10.1.0/ext/new_allocator.h:133]
Note: # 2 std::allocator_traits<>::deallocate [C:/MSYS2-32/mingw32/include/c++/10.1.0/bits/allocator.h:187]
Note: # 3 std::_Vector_base<>::_M_deallocate [C:/MSYS2-32/mingw32/include/c++/10.1.0/bits/stl_vector.h:354]
Note: # 4 std::vector<>::_M_default_append [C:/MSYS2-32/mingw32/include/c++/10.1.0/bits/vector.tcc:675]
Note: # 5 std::vector<>::resize [C:/MSYS2-32/mingw32/include/c++/10.1.0/bits/stl_vector.h:940]
Note: instruction: mov (%eax) -> %edx
===========================================================================
FINAL SUMMARY:
DUPLICATE ERROR COUNTS:
SUPPRESSIONS USED:
ERRORS FOUND:
5 unique, 5 total unaddressable access(es)
0 unique, 0 total uninitialized access(es)
0 unique, 0 total invalid heap argument(s)
0 unique, 0 total GDI usage error(s)
0 unique, 0 total handle leak(s)
0 unique, 0 total warning(s)
0 unique, 0 total, 0 byte(s) of leak(s)
0 unique, 0 total, 0 byte(s) of possible leak(s)
ERRORS IGNORED:
2 potential error(s) (suspected false positives)
(details: C:\Users\david\AppData\Roaming\Dr. Memory\DrMemory-test.exe.20424.000\potential_errors.txt)
8 unique, 14 total, 19443 byte(s) of still-reachable allocation(s)
(re-run with "-show_reachable" for details)
Details: C:\Users\david\AppData\Roaming\Dr. Memory\DrMemory-test.exe.20424.000\results.txt
我是否错过了我的程序的某些内容，还是在这种情况下DrMemory无法真正确定我在做什么？
最佳答案
用你的代码
data.resize(sizeof(Comp1)*2);
这是 vector 使用的存储空间的修改事件。发生这种情况时， vector 中的所有指针，迭代器和引用都会失效。那意味着
ptr1->~Comp1();
正在访问无效对象，并且您有未定义的行为。这不是内存泄漏，而是非法访问问题，这是Memory Dr诊断的原因。