C++ 为什么g++；不介意初始值设定项列表分配给（const std:：string&；）一个（std:：string）？还有其他的怪事

我在做作业时遇到了这个问题。当您拥有继承类a的类B，并且B通过调用B的构造函数中a的构造函数来初始化a中的变量时，应该在a的构造函数中初始化的变量保持未初始化状态。如果我们创建类A的对象，这似乎不会发生，即使看起来唯一的区别是继承和构造函数链

下面是一个简单的例子：

#include <iostream>
#include <string>

class A {
public:
    A(std::string s)
    : s_(s) {}

    ~A(){}

    void Print() const {
        std::cout << s_ + "123";
    }
private:
    const std::string& s_;
};

class B : public A {
public:
    B(std::string s)
    : A(s) {}
};

int main()
{
  //A a = A("123");
  //a.Print();
  B b = B("123");
  b.Print();
}

#包括
#包括
甲级{
公众：
A（标准：：字符串s）
：s_uz（s）{}
~A（）{}
void Print（）常量{
标准：：cout
为什么编译器不会因为A的构造函数而给出错误
可能是因为A的构造函数格式良好，因此编译器必须接受它才能符合标准

允许您将引用绑定到局部变量。构造函数返回后，引用将无效，但如果程序在从构造函数返回后从未间接通过引用，则从技术上讲，这没有问题。编译器证明程序将这样做并非易事（此问题通常类似于停止问题）

编译器会通过以下方式发出警告：

警告：将引用成员“”绑定到堆栈分配的参数“”[-Wdangling字段]


如何使用该值设置引用

您已将引用绑定到局部变量。不清楚您试图做什么，但可能不应该使用引用成员来实现这一点


为什么
为什么
因为程序的行为是未定义的。任何更改都可能以任何方式影响程序的行为。在不更改程序的情况下，该行为甚至可以更改。或者它可能不会更改。程序的行为没有任何保证。
您确定要在此处使用引用类成员：
const std:：string&s？显示的代码在有或没有额外文字的情况下被破坏，这与继承无关。引用类成员使用引用临时对象初始化，然后立即被销毁，所有后续使用都会导致未定义的行为，这只是valgrind的报告方式。这是一个错误我没有注意到这一点（我对C++不是很有经验），vscode也没有注意到。谢谢。有一个简单的“std:：string”实际上就是我想做的。显然我使用的是g++而不是gcc。我需要应用什么标志来启用此警告？目前我有-Wall-Wextra-pedantic。@Lupilum您需要使用clang++编译器来获取引用的警告。message告诉您哪个标志控制警告。但是默认情况下它是启用的，所以您不需要任何标志。
g++ -c -g -std=c++17 -Wall -Wextra -pedantic main.cpp -o main.o
g++ main.o   -o main
valgrind ./main
==22551== Memcheck, a memory error detector
==22551== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==22551== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info
==22551== Command: ./main
==22551==
==22551== error calling PR_SET_PTRACER, vgdb might block
==22551== Conditional jump or move depends on uninitialised value(s)
==22551==    at 0x4F4FA9A: std::basic_ostream<char, std::char_traits<char> >& std::__ostream_insert<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*, long) (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.25)
==22551==    by 0x109BAF: A::Print() const (main.cpp:15)
==22551==    by 0x1099EB: main (main.cpp:32)
==22551==
==22551== Conditional jump or move depends on uninitialised value(s)
==22551==    at 0x545C928: fwrite (iofwrite.c:35)
==22551==    by 0x4F4FB83: std::basic_ostream<char, std::char_traits<char> >& std::__ostream_insert<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*, long) (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.25)
==22551==    by 0x109BAF: A::Print() const (main.cpp:15)
==22551==    by 0x1099EB: main (main.cpp:32)
==22551==
==22551== Conditional jump or move depends on uninitialised value(s)
==22551==    at 0x54689B4: _IO_file_xsputn@@GLIBC_2.2.5 (fileops.c:1226)
==22551==    by 0x545C9E6: fwrite (iofwrite.c:39)
==22551==    by 0x4F4FB83: std::basic_ostream<char, std::char_traits<char> >& std::__ostream_insert<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*, long) (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.25)
==22551==    by 0x109BAF: A::Print() const (main.cpp:15)
==22551==    by 0x1099EB: main (main.cpp:32)
==22551==
==22551== Conditional jump or move depends on uninitialised value(s)
==22551==    at 0x5468A85: _IO_file_xsputn@@GLIBC_2.2.5 (fileops.c:1275)
==22551==    by 0x545C9E6: fwrite (iofwrite.c:39)
==22551==    by 0x4F4FB83: std::basic_ostream<char, std::char_traits<char> >& std::__ostream_insert<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*, long) (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.25)
==22551==    by 0x109BAF: A::Print() const (main.cpp:15)
==22551==    by 0x1099EB: main (main.cpp:32)
==22551==
==22551== Conditional jump or move depends on uninitialised value(s)
==22551==    at 0x5468210: _IO_file_write@@GLIBC_2.2.5 (fileops.c:1198)
==22551==    by 0x5468B9E: new_do_write (fileops.c:457)
==22551==    by 0x5468B9E: _IO_file_xsputn@@GLIBC_2.2.5 (fileops.c:1277)
==22551==    by 0x545C9E6: fwrite (iofwrite.c:39)
==22551==    by 0x4F4FB83: std::basic_ostream<char, std::char_traits<char> >& std::__ostream_insert<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*, long) (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.25)
==22551==    by 0x109BAF: A::Print() const (main.cpp:15)
==22551==    by 0x1099EB: main (main.cpp:32)
==22551==
==22551== Syscall param write(buf) contains uninitialised byte(s)
==22551==    at 0x54ED264: write (write.c:27)
==22551==    by 0x546822C: _IO_file_write@@GLIBC_2.2.5 (fileops.c:1203)
==22551==    by 0x5468B9E: new_do_write (fileops.c:457)
==22551==    by 0x5468B9E: _IO_file_xsputn@@GLIBC_2.2.5 (fileops.c:1277)
==22551==    by 0x545C9E6: fwrite (iofwrite.c:39)
==22551==    by 0x4F4FB83: std::basic_ostream<char, std::char_traits<char> >& std::__ostream_insert<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*, long) (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.25)
==22551==    by 0x109BAF: A::Print() const (main.cpp:15)
==22551==    by 0x1099EB: main (main.cpp:32)
==22551==
==22551== Syscall param write(count) contains uninitialised byte(s)
==22551==    at 0x54ED264: write (write.c:27)
==22551==    by 0x546822C: _IO_file_write@@GLIBC_2.2.5 (fileops.c:1203)
==22551==    by 0x5468B9E: new_do_write (fileops.c:457)
==22551==    by 0x5468B9E: _IO_file_xsputn@@GLIBC_2.2.5 (fileops.c:1277)
==22551==    by 0x545C9E6: fwrite (iofwrite.c:39)
==22551==    by 0x4F4FB83: std::basic_ostream<char, std::char_traits<char> >& std::__ostream_insert<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*, long) (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.25)
==22551==    by 0x109BAF: A::Print() const (main.cpp:15)
==22551==    by 0x1099EB: main (main.cpp:32)
==22551==
==22551== Syscall param write(buf) points to uninitialised byte(s)
==22551==    at 0x54ED264: write (write.c:27)
==22551==    by 0x546822C: _IO_file_write@@GLIBC_2.2.5 (fileops.c:1203)
==22551==    by 0x5468B9E: new_do_write (fileops.c:457)
==22551==    by 0x5468B9E: _IO_file_xsputn@@GLIBC_2.2.5 (fileops.c:1277)
==22551==    by 0x545C9E6: fwrite (iofwrite.c:39)
==22551==    by 0x4F4FB83: std::basic_ostream<char, std::char_traits<char> >& std::__ostream_insert<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*, long) (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.25)
==22551==    by 0x109BAF: A::Print() const (main.cpp:15)
==22551==    by 0x1099EB: main (main.cpp:32)
==22551==  Address 0x1ffefff910 is on thread 1's stack
==22551==  in frame #5, created by A::Print() const (main.cpp:14)
==22551==
==22551== Conditional jump or move depends on uninitialised value(s)
==22551==    at 0x5468BB0: new_do_write (fileops.c:458)
==22551==    by 0x5468BB0: _IO_file_xsputn@@GLIBC_2.2.5 (fileops.c:1277)
==22551==    by 0x545C9E6: fwrite (iofwrite.c:39)
==22551==    by 0x4F4FB83: std::basic_ostream<char, std::char_traits<char> >& std::__ostream_insert<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*, long) (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.25)
==22551==    by 0x109BAF: A::Print() const (main.cpp:15)
==22551==    by 0x1099EB: main (main.cpp:32)
==22551==
==22551== Conditional jump or move depends on uninitialised value(s)
==22551==    at 0x5468BEB: _IO_file_xsputn@@GLIBC_2.2.5 (fileops.c:1279)
==22551==    by 0x545C9E6: fwrite (iofwrite.c:39)
==22551==    by 0x4F4FB83: std::basic_ostream<char, std::char_traits<char> >& std::__ostream_insert<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*, long) (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.25)
==22551==    by 0x109BAF: A::Print() const (main.cpp:15)
==22551==    by 0x1099EB: main (main.cpp:32)
==22551==
==22551== Conditional jump or move depends on uninitialised value(s)
==22551==    at 0x545CA65: fwrite (iofwrite.c:45)
==22551==    by 0x4F4FB83: std::basic_ostream<char, std::char_traits<char> >& std::__ostream_insert<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*, long) (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.25)
==22551==    by 0x109BAF: A::Print() const (main.cpp:15)
==22551==    by 0x1099EB: main (main.cpp:32)
==22551==
==22551== Conditional jump or move depends on uninitialised value(s)
==22551==    at 0x545CA6A: fwrite (iofwrite.c:45)
==22551==    by 0x4F4FB83: std::basic_ostream<char, std::char_traits<char> >& std::__ostream_insert<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*, long) (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.25)
==22551==    by 0x109BAF: A::Print() const (main.cpp:15)
==22551==    by 0x1099EB: main (main.cpp:32)
==22551==
==22551== Conditional jump or move depends on uninitialised value(s)
==22551==    at 0x4F4FB91: std::basic_ostream<char, std::char_traits<char> >& std::__ostream_insert<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*, long) (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.25)
==22551==    by 0x109BAF: A::Print() const (main.cpp:15)
==22551==    by 0x1099EB: main (main.cpp:32)
==22551==
==22551==
==22551== HEAP SUMMARY:
==22551==     in use at exit: 0 bytes in 0 blocks
==22551==   total heap usage: 2 allocs, 2 frees, 73,216 bytes allocated
==22551==
==22551== All heap blocks were freed -- no leaks are possible
==22551==
==22551== For counts of detected and suppressed errors, rerun with: -v
==22551== Use --track-origins=yes to see where uninitialised values come from
==22551== ERROR SUMMARY: 13 errors from 13 contexts (suppressed: 0 from 0)

g++ -c -g -std=c++17 -Wall -Wextra -pedantic main.cpp -o main.o
g++ main.o   -o main
valgrind ./main
==22561== Memcheck, a memory error detector
==22561== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==22561== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info
==22561== Command: ./main
==22561==
==22561== error calling PR_SET_PTRACER, vgdb might block
==22561== Conditional jump or move depends on uninitialised value(s)
==22561==    at 0x10AC50: void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct<char*>(char*, char*, std::forward_iterator_tag) (basic_string.tcc:217)
==22561==    by 0x10A7DD: void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct_aux<char*>(char*, char*, std::__false_type) (basic_string.h:236)
==22561==    by 0x10A472: void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct<char*>(char*, char*) (basic_string.h:255)
==22561==    by 0x10A15B: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) (basic_string.h:440)
==22561==    by 0x10A05E: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > std::operator+<char, std::char_traits<char>, std::allocator<char> >(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, char const*) (basic_string.h:5928)
==22561==    by 0x109E66: A::Print() const (main.cpp:15)
==22561==    by 0x109C8B: main (main.cpp:32)
==22561==
==22561== Conditional jump or move depends on uninitialised value(s)
==22561==    at 0x10AD84: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_create(unsigned long&, unsigned long) (basic_string.tcc:137)
==22561==    by 0x10AC69: void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct<char*>(char*, char*, std::forward_iterator_tag) (basic_string.tcc:219)
==22561==    by 0x10A7DD: void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct_aux<char*>(char*, char*, std::__false_type) (basic_string.h:236)
==22561==    by 0x10A472: void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct<char*>(char*, char*) (basic_string.h:255)
==22561==    by 0x10A15B: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) (basic_string.h:440)
==22561==    by 0x10A05E: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > std::operator+<char, std::char_traits<char>, std::allocator<char> >(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, char const*) (basic_string.h:5928)
==22561==    by 0x109E66: A::Print() const (main.cpp:15)
==22561==    by 0x109C8B: main (main.cpp:32)
==22561==
...
had to cut here to fit into character limit
...
==22561==
==22561== Conditional jump or move depends on uninitialised value(s)
==22561==    at 0x10A9F0: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_S_copy(char*, char const*, unsigned long) (basic_string.h:337)
==22561==    by 0x10AED7: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_S_copy_chars(char*, char*, char*) (basic_string.h:382)
==22561==    by 0x10ACB0: void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct<char*>(char*, char*, std::forward_iterator_tag) (basic_string.tcc:225)
==22561==    by 0x10A7DD: void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct_aux<char*>(char*, char*, std::__false_type) (basic_string.h:236)
==22561==    by 0x10A472: void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct<char*>(char*, char*) (basic_string.h:255)
==22561==    by 0x10A15B: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) (basic_string.h:440)
==22561==    by 0x10A05E: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > std::operator+<char, std::char_traits<char>, std::allocator<char> >(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, char const*) (basic_string.h:5928)
==22561==    by 0x109E66: A::Print() const (main.cpp:15)
==22561==    by 0x109C8B: main (main.cpp:32)
==22561==
==22561== Conditional jump or move depends on uninitialised value(s)
==22561==    at 0x109DE1: std::char_traits<char>::copy(char*, char const*, unsigned long) (char_traits.h:348)
==22561==    by 0x10AA1D: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_S_copy(char*, char const*, unsigned long) (basic_string.h:340)
==22561==    by 0x10AED7: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_S_copy_chars(char*, char*, char*) (basic_string.h:382)
==22561==    by 0x10ACB0: void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct<char*>(char*, char*, std::forward_iterator_tag) (basic_string.tcc:225)
==22561==    by 0x10A7DD: void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct_aux<char*>(char*, char*, std::__false_type) (basic_string.h:236)
==22561==    by 0x10A472: void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct<char*>(char*, char*) (basic_string.h:255)
==22561==    by 0x10A15B: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) (basic_string.h:440)
==22561==    by 0x10A05E: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > std::operator+<char, std::char_traits<char>, std::allocator<char> >(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, char const*) (basic_string.h:5928)
==22561==    by 0x109E66: A::Print() const (main.cpp:15)
==22561==    by 0x109C8B: main (main.cpp:32)
==22561==
==22561== Conditional jump or move depends on uninitialised value(s)
==22561==    at 0x4C366E6: memmove (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==22561==    by 0x109E05: std::char_traits<char>::copy(char*, char const*, unsigned long) (char_traits.h:350)
==22561==    by 0x10AA1D: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_S_copy(char*, char const*, unsigned long) (basic_string.h:340)
==22561==    by 0x10AED7: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_S_copy_chars(char*, char*, char*) (basic_string.h:382)
==22561==    by 0x10ACB0: void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct<char*>(char*, char*, std::forward_iterator_tag) (basic_string.tcc:225)
==22561==    by 0x10A7DD: void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct_aux<char*>(char*, char*, std::__false_type) (basic_string.h:236)
==22561==    by 0x10A472: void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct<char*>(char*, char*) (basic_string.h:255)
==22561==    by 0x10A15B: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) (basic_string.h:440)
==22561==    by 0x10A05E: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > std::operator+<char, std::char_traits<char>, std::allocator<char> >(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, char const*) (basic_string.h:5928)
==22561==    by 0x109E66: A::Print() const (main.cpp:15)
==22561==    by 0x109C8B: main (main.cpp:32)
==22561==
==22561== Conditional jump or move depends on uninitialised value(s)
==22561==    at 0x4C36711: memmove (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==22561==    by 0x109E05: std::char_traits<char>::copy(char*, char const*, unsigned long) (char_traits.h:350)
==22561==    by 0x10AA1D: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_S_copy(char*, char const*, unsigned long) (basic_string.h:340)
==22561==    by 0x10AED7: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_S_copy_chars(char*, char*, char*) (basic_string.h:382)
==22561==    by 0x10ACB0: void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct<char*>(char*, char*, std::forward_iterator_tag) (basic_string.tcc:225)
==22561==    by 0x10A7DD: void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct_aux<char*>(char*, char*, std::__false_type) (basic_string.h:236)
==22561==    by 0x10A472: void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct<char*>(char*, char*) (basic_string.h:255)
==22561==    by 0x10A15B: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) (basic_string.h:440)
==22561==    by 0x10A05E: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > std::operator+<char, std::char_traits<char>, std::allocator<char> >(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, char const*) (basic_string.h:5928)
==22561==    by 0x109E66: A::Print() const (main.cpp:15)
==22561==    by 0x109C8B: main (main.cpp:32)
==22561==
==22561== Conditional jump or move depends on uninitialised value(s)
==22561==    at 0x4C367EE: memmove (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==22561==    by 0x109E05: std::char_traits<char>::copy(char*, char const*, unsigned long) (char_traits.h:350)
==22561==    by 0x10AA1D: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_S_copy(char*, char const*, unsigned long) (basic_string.h:340)
==22561==    by 0x10AED7: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_S_copy_chars(char*, char*, char*) (basic_string.h:382)
==22561==    by 0x10ACB0: void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct<char*>(char*, char*, std::forward_iterator_tag) (basic_string.tcc:225)
==22561==    by 0x10A7DD: void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct_aux<char*>(char*, char*, std::__false_type) (basic_string.h:236)
==22561==    by 0x10A472: void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct<char*>(char*, char*) (basic_string.h:255)
==22561==    by 0x10A15B: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) (basic_string.h:440)
==22561==    by 0x10A05E: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > std::operator+<char, std::char_traits<char>, std::allocator<char> >(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, char const*) (basic_string.h:5928)
==22561==    by 0x109E66: A::Print() const (main.cpp:15)
==22561==    by 0x109C8B: main (main.cpp:32)
==22561==
==22561== Invalid read of size 8
==22561==    at 0x4C367EE: memmove (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==22561==    by 0x109E05: std::char_traits<char>::copy(char*, char const*, unsigned long) (char_traits.h:350)
==22561==    by 0x10AA1D: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_S_copy(char*, char const*, unsigned long) (basic_string.h:340)
==22561==    by 0x10AED7: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_S_copy_chars(char*, char*, char*) (basic_string.h:382)
==22561==    by 0x10ACB0: void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct<char*>(char*, char*, std::forward_iterator_tag) (basic_string.tcc:225)
==22561==    by 0x10A7DD: void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct_aux<char*>(char*, char*, std::__false_type) (basic_string.h:236)
==22561==    by 0x10A472: void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct<char*>(char*, char*) (basic_string.h:255)
==22561==    by 0x10A15B: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) (basic_string.h:440)
==22561==    by 0x10A05E: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > std::operator+<char, std::char_traits<char>, std::allocator<char> >(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, char const*) (basic_string.h:5928)
==22561==    by 0x109E66: A::Print() const (main.cpp:15)
==22561==    by 0x109C8B: main (main.cpp:32)
==22561==  Address 0x1fff001000 is not stack'd, malloc'd or (recently) free'd
==22561==
==22561==
==22561== Process terminating with default action of signal 11 (SIGSEGV)
==22561==  Access not within mapped region at address 0x1FFF001000
==22561==    at 0x4C367EE: memmove (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==22561==    by 0x109E05: std::char_traits<char>::copy(char*, char const*, unsigned long) (char_traits.h:350)
==22561==    by 0x10AA1D: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_S_copy(char*, char const*, unsigned long) (basic_string.h:340)
==22561==    by 0x10AED7: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_S_copy_chars(char*, char*, char*) (basic_string.h:382)
==22561==    by 0x10ACB0: void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct<char*>(char*, char*, std::forward_iterator_tag) (basic_string.tcc:225)
==22561==    by 0x10A7DD: void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct_aux<char*>(char*, char*, std::__false_type) (basic_string.h:236)
==22561==    by 0x10A472: void std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct<char*>(char*, char*) (basic_string.h:255)
==22561==    by 0x10A15B: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) (basic_string.h:440)
==22561==    by 0x10A05E: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > std::operator+<char, std::char_traits<char>, std::allocator<char> >(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, char const*) (basic_string.h:5928)
==22561==    by 0x109E66: A::Print() const (main.cpp:15)
==22561==    by 0x109C8B: main (main.cpp:32)
==22561==  If you believe this happened as a result of a stack
==22561==  overflow in your program's main thread (unlikely but
==22561==  possible), you can try to increase the size of the
==22561==  main thread stack using the --main-stacksize= flag.
==22561==  The main thread stack size used in this run was 8388608.
==22561==
==22561== HEAP SUMMARY:
==22561==     in use at exit: 1,089,515 bytes in 1 blocks
==22561==   total heap usage: 2 allocs, 1 frees, 1,162,219 bytes allocated
==22561==
==22561== LEAK SUMMARY:
==22561==    definitely lost: 0 bytes in 0 blocks
==22561==    indirectly lost: 0 bytes in 0 blocks
==22561==      possibly lost: 0 bytes in 0 blocks
==22561==    still reachable: 1,089,515 bytes in 1 blocks
==22561==         suppressed: 0 bytes in 0 blocks
==22561== Rerun with --leak-check=full to see details of leaked memory
==22561==
==22561== For counts of detected and suppressed errors, rerun with: -v
==22561== Use --track-origins=yes to see where uninitialised values come from
==22561== ERROR SUMMARY: 197 errors from 12 contexts (suppressed: 0 from 0)
src.make:32: recipe for target 'valgrind-run' failed
make: *** [valgrind-run] Segmentation fault (core dumped)