移动 std：：ostringstream 时出现奇怪的 clang c++ ubsan 错误

问：

这可能不是发布此内容的正确论坛，因为它看起来像一个错误，我可能应该向 llvm 团队报告。如果您同意，请告诉我，我会这样做。

这是产生 ubsan 错误的代码，以防万一我错了：

OS = MacOS Ventura
Compiler = Clang 16.0.0 (Manually built LLVM with default options)

重现步骤：

clang++ -fsanitize=undefined main.cpp
./a.out

main.cpp

#include <sstream>

struct MyStruct
{
    static MyStruct create() noexcept
    {
        return MyStruct{};
    }

private:
    std::ostringstream oss_;
};

int main()
{
    MyStruct::create();
}

输出：

~/usr/bin/../include/c++/v1/sstream:730:43: runtime error: member access within address 0x7ff7b265a298 which does not point to an object of type 'std::ostringstream'
0x7ff7b265a298: note: object is of type 'std::__1::basic_ostringstream<char, std::__1::char_traits<char>, std::__1::allocator<char>>'
 f7 7f 00 00  40 11 8b 0d 01 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00
              ^~~~~~~~~~~~~~~~~~~~~~~
              vptr for 'std::__1::basic_ostringstream<char, std::__1::char_traits<char>, std::__1::allocator<char>>'
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior ~/usr/bin/../include/c++/v1/sstream:730:43 in
~/usr/bin/../include/c++/v1/ostream:198:7: runtime error: cast to virtual base of address 0x7ff7b265a298 which does not point to an object of type 'std::ostream'
0x7ff7b265a298: note: object is of type 'std::__1::basic_ostream<char, std::__1::char_traits<char>>'
 f7 7f 00 00  c8 11 8b 0d 01 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00
              ^~~~~~~~~~~~~~~~~~~~~~~
              vptr for 'std::__1::basic_ostream<char, std::__1::char_traits<char>>'
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior ~/usr/bin/../include/c++/v1/ostream:198:7 in
~/usr/bin/../include/c++/v1/ostream:198:13: runtime error: member call on address 0x7ff7b265a308 which does not point to an object of type 'std::ios'
0x7ff7b265a298: note: object is base class subobject at offset 112 within object of type 'std::__1::basic_ostream<char, std::__1::char_traits<char>>'
 f7 7f 00 00  c8 11 8b 0d 01 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00
              ^
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior ~/usr/bin/../include/c++/v1/ostream:198:13 in
~/usr/bin/../include/c++/v1/ios:711:15: runtime error: member call on address 0x7ff7b265a308 which does not point to an object of type 'std::ios_base'
0x7ff7b265a298: note: object is base class subobject at offset 112 within object of type 'std::__1::basic_ostream<char, std::__1::char_traits<char>>'
 f7 7f 00 00  c8 11 8b 0d 01 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00
              ^
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior ~/usr/bin/../include/c++/v1/ios:711:15 in
~/usr/bin/../include/c++/v1/ios:712:5: runtime error: member access within address 0x7ff7b265a308 which does not point to an object of type 'std::ios'
0x7ff7b265a298: note: object is base class subobject at offset 112 within object of type 'std::__1::basic_ostream<char, std::__1::char_traits<char>>'
 f7 7f 00 00  c8 11 8b 0d 01 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00
              ^
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior ~/usr/bin/../include/c++/v1/ios:712:5 in
~/usr/bin/../include/c++/v1/ios:713:5: runtime error: member access within address 0x7ff7b265a308 which does not point to an object of type 'std::ios'
0x7ff7b265a298: note: object is base class subobject at offset 112 within object of type 'std::__1::basic_ostream<char, std::__1::char_traits<char>>'
 f7 7f 00 00  c8 11 8b 0d 01 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00
              ^
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior ~/usr/bin/../include/c++/v1/ios:713:5 in