我尝试重新激活此线程，但没有提供更多详细信息。
我也有同样的问题。这很容易重现：
#include <string>
int main()
{
std::string name;
return 0;
}
然后编译：
clang++ -D_LIBCPP_DEBUG=1 main.cpp
我们得到：
Undefined symbols for architecture x86_64:
"std::__1::__libcpp_db::__insert_c(void*)", referenced from:
void std::__1::__libcpp_db::__insert_c<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >*) in main-7ff3c5.o
"std::__1::__libcpp_db::__erase_c(void*)", referenced from:
std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >::~basic_string() in main-7ff3c5.o
"std::__1::__c_node::~__c_node()", referenced from:
std::__1::_C_node<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >::~_C_node() in main-7ff3c5.o
"std::__1::__get_db()", referenced from:
std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >::basic_string() in main-7ff3c5.o
std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >::~basic_string() in main-7ff3c5.o
"typeinfo for std::__1::__c_node", referenced from:
typeinfo for std::__1::_C_node<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > in main-7ff3c5.o
"vtable for std::__1::__c_node", referenced from:
std::__1::__c_node::__c_node(void*, std::__1::__c_node*) in main-7ff3c5.o
NOTE: a missing vtable usually means the first non-inline virtual member function has no definition.
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
如果我使用 brew 提供的 g++-9（一个真正的 g++ 而不是伪装的 Apple Clang 编译器），它可以完美地编译和运行。
忘记使用libc++的debug模式，只能这样解决吗？
注意：我在https://forums.developer.apple.com/thread/99194 看到了同样的问题
仍然没有答案。